Dimitris Mourtzis
email: mourtzis@lms.mech.upatras.gr

Sophia Fotia

Michael Doukas

Performance Indicators for the Evaluation of Product-Service Systems Design: A Review

Keywords:

Recently, industries have shifted their focus on the combined ecosystem of products-services. The innovative business strategy of PSS provides an integrated solution that gives the potential for sustainability gains for both company and customer. Similarly to other business aspects, the PSS efficiency design is evaluated through performance indicators, during the phase of concept evaluation, which is the last phase before launching a product-service. This phase plays a critical role for the success of a PSS. A successful evaluation prevents design modifications or redesign, significantly reduces the cost and lead time of PSS development. There is however, limited work on integrated evaluation approaches for PSS design models, and also a lack of a collective accounting of the most important key performance indicators (KPIs) devoted on PSS. The present work attempts to contribute in these directions, and proposes a conceptual framework for the effective evaluation of PSS design using important KPIs.

Introduction

The intensive global competition and technological advances force the actors of a supply chain to optimize their activities in order to deliver high-value productsservices with low costs and diminished time-to-market. This optimization relies on waste elimination, improved process control, efficient manpower utilization, and employment of smart and flexible systems [START_REF] Chryssolouris | Manufacturing Systems: Theory and Practice[END_REF]. PSS is a value proposition strategy that offers products-services and is designed to be: competitive, satisfy customer needs, and have a lower environmental impact than traditional business models [START_REF] Mont | Clarifying the concept of product-service system[END_REF]. The importance of the shift towards selling functionality instead of products is illustrative by the fact that software and electronics add nearly 40% to the cost of a new car nowadays, while this figure is bound to increase [START_REF] Robert | This Car Runs on Code[END_REF]. Moreover, measuring the performance of a PSS offering is crucial for a firm, since it influences its competitiveness in the market, its cost-effectiveness, and finally, its overall business performance [START_REF] Mont | Clarifying the concept of product-service system[END_REF], [START_REF] Goedkoop | Product Services Systems, Ecological and Economic Basics[END_REF][START_REF] Baines | State-of-the-art in product-service systems, Proceedings of the Institution of Mechanical Engineers[END_REF]. Following the principle of "what cannot be measured cannot be improved" and the plan-do-check-act methodology [START_REF] Gries | KPI measurement in engineering design-A case study[END_REF], continuous monitoring of the implemented processes is required during the entire lifecycle of the system. Thus, the use of KPIs is necessary. KPIs can provide insights about the performance of a company and can facilitate decision making. Moreover, KPIs can be employed to reduce non-adding value activities, which comprise approximately the 60% of a company's activities [START_REF] Dombrowski | Ballanced Key Performance Indicators in Product Development[END_REF].

Due to the significant differences between products and services, the concept evaluation of PSS differs from ordinary evaluation problems. Product characteristics and service activities influence one another, creating difficulties in defining the weight factors of each evaluation criterion. However, there are few works concerning PSS performance indicators [START_REF] De Castro Rodrigues | A proposal to support the value proposition in Product Oriented Service, business model of Product Service Systems[END_REF].

Except for limited research on integrated evaluation approaches for PSS models [START_REF] Vasantha | A review of product-service systems design methodologies[END_REF], there is a lack of studies that collect the main KPIs for measuring the efficiency of a PSS. The proposed work contributes with a collection and discussion of major PSS design models and existing KPIs that are appropriate for the PSS design activity.

PSS design models

The design models are simplified descriptions of the design process to assist the designer accomplishing the task. Although a great amount of literature work has been focused on PSS design models , there are surprisingly limited studies on integrated evaluation models for PSS [START_REF] Vasantha | A review of product-service systems design methodologies[END_REF], as well as collective accounting KPIs that could be used on PSS. In order for such a collection to be accomplished, the literature devoted to PSS design models and KPIs, is taken into account under a comparative review.

The review methodology that is followed to identify and collect KPIs for specific PSS designs is shown in Fig. 1. After examining the PSS design models, requirements for performance measurement are extracted, and finally, the KPIs that satisfy these requirements are classified. As Fig. 1 illustrates, the light gray area includes the major PSS design models, applicable and representative in the category that they belong to. The dark gray area consists of the requirements derived from these models. It is noted that some models belong to more than one category. The color coding is used to group KPIs under four general representative classes, namely KPIs for Business, Customers, Leanness, and Sustainability.

PSS is strongly related to sustainability and customer, thus, increasing sustainability and satisfying the customers should be the target of every PSS design model [START_REF] Mont | Clarifying the concept of product-service system[END_REF], [START_REF] Goedkoop | Product Services Systems, Ecological and Economic Basics[END_REF][START_REF] Baines | State-of-the-art in product-service systems, Proceedings of the Institution of Mechanical Engineers[END_REF]. Several models [START_REF] Lelah | Collaborative network with SMEs providing a backbone for urban PSS: a model and initial sustainability analysis[END_REF][START_REF] Xing | A service innovation model for synergistic community transformation: integrated application of systems theory and product-service systems[END_REF][START_REF] Joore | A Multilevel Design Model: the mutual relationship between product-service system development and societal change processes[END_REF][START_REF] Müller | PSS layer methodapplication to microenergy systems, introduction to product/service-system design[END_REF] have been developed with dominant aims these two aspects, thus, evaluation approaches measuring them through PSS are of great importance. Sustainability has three pillars: (i) Environment, (ii) Economy, and (ii) Society [START_REF] Maxwell | Developing sustainable products and services[END_REF], while customer perspective mainly contains requirements associated to satisfaction and acceptability [START_REF] Lee | Evaluating new concepts of PSS based on the customer value: Application of ANP and niche theory[END_REF]. Indeed, Fig. 1 depicts that the most frequent requirements of PSS models are Customer and Sustainability.

One of the first approaches to model PSS design [START_REF] Aurich | Life cycle oriented design of technical Product-Service Systems[END_REF], aims to synchronize the development processes of the products and the services, incorporating the input from the customer in the process. Under the same concept, the Propensity Framework [START_REF] Dewit | Towards a propensity framework for Product-service transitions[END_REF] attempts to enable a synergy between products and services, via the Front-End of Innovation (FEI) process, and using evaluation criteria based on customer's expectations and user experience.

According to many researchers [START_REF] Shimomura | A Unified representation scheme for effective PSS development[END_REF][START_REF] Maussang | Product-service system design methodology: from the PSS architecture design to the products specifications[END_REF][START_REF] Welp | Modelling approach for the integrated development of industrial product-service systems[END_REF], in order to achieve a competitive PSS, the integration of physical product and services should be considered in the early phase of design. At these models, the customer value is also identified in the first phase of design. Similarly, in the Shell model [START_REF] Weber | Modelling of product-service systems (PSS) based on the PDD approach[END_REF], which is proposed for PSS Engineering development, the customer is considered in the beginning of the design giving explicit feedback to the design procedure of the model.

Inspired by the similarity between service design and hardware design process, the fast-track design process is proposed in [START_REF] Alonso-Rasgado | The design of functional (total care) products[END_REF]. Importantly, the authors stress that the use of this methodology ensures that the customer becomes fully aware of the value of the total care product business solution. Moreover, they present many PSS oriented requirements for performance measurement, namely service reliability, maintenance, stability, uncertainty, average waiting times, and reliability (short-and long-time). Finally, they outline the importance of quantitative performance measurements in the functional product provision.

Similar requirements are extracted by IPS 2 models [START_REF] Welp | Modelling approach for the integrated development of industrial product-service systems[END_REF], [START_REF] Müller | A Generic PSS Development Process Model Based On Theory And An Empirical Study[END_REF][START_REF] Sadek | Ein modellorientierter Ansatz zur Konzeptentwicklung industrieller Produkt-Service Systeme[END_REF], Service models [START_REF] Rapaccini | Service development in product-service systems: a maturity model[END_REF][START_REF] Komoto | Integration of a service CAD and a life cycle simulator[END_REF], ServiceCAD/CAD PSS [START_REF] Komoto | Integration of a service CAD and a life cycle simulator[END_REF][START_REF] Sakao | Modeling design objects in CAD system for Service/Product Engineering[END_REF][START_REF] Mckay | A representation scheme for digital product service system definitions[END_REF], Life Cycle Simulation (LCS) [START_REF] Komoto | Integration of a service CAD and a life cycle simulator[END_REF], [START_REF] Garetti | Life Cycle Simulation for the design of Product-Service Systems[END_REF] design models, Knowledge-sharing network for PSS design [START_REF] Chirumalla | Knowledge-Sharing Network for Product-Service System Development: Is it atypical? The Philosopher's Stone for Sustainability[END_REF], and web PSS [START_REF] Zhu | A Web-based Product Service System for aerospace maintenance, repair and overhaul services[END_REF] design models. In addition to the aforementioned requirements, the necessity of measuring the server's availability, risk, and knowledge-sharing aspects, has been also considered.

Moreover, lean product-service design approaches are another requirement for competitiveness. The lean approach focuses on eliminating non-value activities from processes by applying a robust set of performance change tools, and emphasizes on excellence in operations to deliver superior customer service. To grasp the lean approach in a service-company, senior managers must recognize that all organizationsmanufacturing and non-manufacturing-ultimately deliver value to a customer in the form of a product and/or service [START_REF] Resta | Towards a framework for lean operations in product-oriented product service systems[END_REF]. Indicators of how lean is the system [START_REF] Bhasin | Lean and performance measurement[END_REF] are significant to establish such a design. [START_REF] Rapaccini | Service development in product-service systems: a maturity model[END_REF][START_REF] Komoto | Integration of a service CAD and a life cycle simulator[END_REF] Lean PSS [START_REF] Resta | Towards a framework for lean operations in product-oriented product service systems[END_REF] Financial Productivity Customer 3

KPIs for assessment of PSS design

This section discusses the most appropriate KPIs for PSS assessment. The definition of KPIs depends on each problem's specific objectives, goals, and criteria [START_REF] Chryssolouris | Manufacturing Systems: Theory and Practice[END_REF]. Academic research has proposed a number of methodologies for developing and selecting KPIs according to the objectives of each company. The development of KPIs can follow the SMART principle i.e. being specific, measurable, attainable, realistic, and timely [START_REF] Abramovici | An Indicator Framework for Monitoring IPS2 in the Use Phase[END_REF]. It is also crucial to notice that performance measurement systems should focus on what is important to measure and not simply what is easily measureable [START_REF] Cedergren | Evaluation of performance in a product development context[END_REF][START_REF] Driva | Measuring product development performance in manufacturing organosations[END_REF]. According to these principles, an attempt to collect the appropriate KPIs for PSS design evaluation is carried out. KPIs are classified with respect to the direction of fulfillment requirements. These classes are the following: Customers (C), Business (B), Sustainability (S), and Leanness (L). Summarizing, Table 1 lists the KPIs that are associated to PSS design. It is commonly accepted that the realization of value in a PSS can only be achieved when customers are on focus and if services' evaluation is strongly connected to them [START_REF] Kimita | Evaluation of customer satisfaction for PSS design[END_REF]. Customer satisfaction and customer acceptance are among the most useful measures for several business strategies, and many researchers have developed measurement approaches and indicators for these purposes [START_REF] Parasuraman | SERVQUAL: A Multiple-Item Scale for Measuring Consumer Perceptions of Service Quality[END_REF][START_REF] Griffin | PDMA Success Measurement Project: Recommended Measures for Product Development Success and Failure[END_REF][START_REF] Mohammadi | Lean Product Development-Performance Measurement System[END_REF][START_REF] Taisch | Towards a Performance Measurement System for Lean-Oriented Global Product Development[END_REF][START_REF] Morlock | Concept for a Performance Measurement Method for the Organization of the IPSS Delivery. Product Services Systems and Value Creation[END_REF][START_REF] Meier | Key Performance Indicators for assessing the planning and delivery of industrial services: in 2nd International Through-life Engineering Services Conference[END_REF][START_REF] Geng | A new importance-performance analysis approach for customer satisfaction[END_REF][START_REF] Lee | Dynamic and multidimensional measurement of product-service system (PSS) sustainability: a triple bottom line (TBL)-based system dynamics approach[END_REF]. In this direction, the SERVQUAL scale [START_REF] Parasuraman | SERVQUAL: A Multiple-Item Scale for Measuring Consumer Perceptions of Service Quality[END_REF] is introduced for assessing customer perception of service quality in service and retail companies. Additionally, another evaluation approach is proposed using importance-performance analysis, since the attributes of performance and importance are not independent variables, and the performance has a non-linear relationship with the overall satisfaction [START_REF] Geng | A new importance-performance analysis approach for customer satisfaction[END_REF].

In the context of sustainability assessment of a PSS, most studies stress the 'environmental' aspect, probably since this aspect is measured relatively easily. There are limited methods that focus on measuring simultaneously all three sustainability components [START_REF] Lee | Dynamic and multidimensional measurement of product-service system (PSS) sustainability: a triple bottom line (TBL)-based system dynamics approach[END_REF]. Environmental performance is usually connected with energy efficiency [START_REF] Olsthoorn | Environmental indicators for business: a review of the literature and standardisation methods[END_REF][START_REF] May | Improving Energy Efficiency in Manufacturing via KPI Intelligence Based on Plant Integration[END_REF][START_REF] Payman | An analysis of metrics used to measure performance in green and sustainable supply chains[END_REF][START_REF] Saadany | Environmental performance measures for supply chains[END_REF] and the level of material use in lease / reuse the PSS systems for waste prevention [START_REF] Tasaki | A quantitative method to evaluate the level of material use in lease/reuse systems of electrical and electronic equipment[END_REF]. However, the consideration of social and economic dimensions are also important measures of sustainability [START_REF] Lee | Dynamic and multidimensional measurement of product-service system (PSS) sustainability: a triple bottom line (TBL)-based system dynamics approach[END_REF]. In this direction, the Analytical Hierarchy Process is used in [START_REF] Chou | An approach to assessing sustainable productservice systems[END_REF] to weight the importance of the indicators for each company under sustainability terms. The authors propose the use of sustainable product-service efficiency indicator, as to ratio of the product service value to its sustainability impact.

As shown in Fig. 1, the class of KPIs for Business is the most literature-stressed approach for the evaluation of PSS. The five phases of the PSS lifecycle, i.e. the planning, development, implementation, delivery and use, and closure are defined in [START_REF] Rese | An Ontology of Business Models for Industrial Product-Service Systems[END_REF]. Usually, the performance measure of these five phases falls under the customer-based measures. Particularly, the planning of the PSS is closely related to the customer as it includes the requirements, specifications, and the offer of a customised PSS. An indicator framework is the foundation of the measurement and monitoring of Industrial PSS (IPS 2 ) in the use-oriented business model [START_REF] Abramovici | An Indicator Framework for Monitoring IPS2 in the Use Phase[END_REF]. While developing the indicator framework, the PSS performance, PSS lifecycle cost, and influencing factors have to be identified as major aspects for the provider. In order to evaluate better the IPS 2 delivery, a classification of performance indicators under the areas of delivery planning and delivery performance has been carried out [START_REF] Morlock | Concept for a Performance Measurement Method for the Organization of the IPSS Delivery. Product Services Systems and Value Creation[END_REF]. The performance dimensions identified are: resource planning, management of the network partners, and IT system efficiency. The concept has been enhanced by introducing feedback loops in an IPS 2 control model. Moreover, knowledge has a high importance for PSS providers and its availability is a challenge. The provider needs an adequate knowledge about the end-user's process as well as a concrete knowledge about the product. To satisfy these requirements, an approach for evaluating the knowledge within a company and to specify the re-quired knowledge for providing a specific PSS is proposed in [START_REF] Schenkl | Knowledge Evaluation for PSS Providers[END_REF]. Furthermore, a conceptual model for assessing the readiness of collaborative networked organizations for PSS delivery is proposed in [START_REF] Durugbo | Readiness assessment of collaborative networked organisations for integrated product and service delivery[END_REF]. Finally, the terms risk and uncertainty have often been used interchangeably in industry [START_REF] Meier | Industrial Product-Service Systems-IPS2[END_REF]. A conceptual representation of risk and uncertainty is provided in [START_REF] Erkoyuncu | Uncertainty Challenges in Service Cost Estimation for Product-Service Systems in the Aerospace and Defence Industries[END_REF]. The study proposes risk representation in relation to knowledge indeterminate and probabilistic or deterministic outcome.

Conclusions

This research work presents a collection of PSS design models and identifies the role and importance of KPIs in the PSS design. Secondly, it provides a collection of existing KPIs that are appropriate for PSS design, classifying them into customer-, business-, sustainability-, and leanness-based measures. This work could be a guideline for supporting the selection of appropriate KPIs for the evaluation of PSS. Further to that, taking into account the reviewed PSS design models , and their systematic reviews [START_REF] Baines | State-of-the-art in product-service systems, Proceedings of the Institution of Mechanical Engineers[END_REF][START_REF] Vasantha | A review of product-service systems design methodologies[END_REF], a conceptual framework for effective PSS design using KPIs is proposed (Fig. 2). According to this framework, the design procedure contains two main stages: (i) PSS design process, and (ii) PSS design expectations. Several models from literature (see Fig. 1)

Representation scheme

Identify the stakeholders

The first stage contains the specifications of the PSS type (product-, use-, and result-oriented [START_REF] Baines | State-of-the-art in product-service systems, Proceedings of the Institution of Mechanical Engineers[END_REF]) according the product/service to be developed, also contains the Business type (Business to Business, Business to Customer, Business to Government), as well as the identification of stakeholders involved in the PSS. Furthermore, for an effective design procedure, a comprehensive PSS representation schema should be included [START_REF] Vasantha | A review of product-service systems design methodologies[END_REF].

The second stage focuses on what requirements the stakeholders have, and which of these have to be considered and fulfilled. This stage sets the basis of the evaluation strategy that has to be followed. For an effective PSS model, the fulfilling of the requirements of: Customers, Business model (e.g. Leanness, Sustainably, financial aspects), and Environment (e.g. energy consumption, CO2 emissions), has to be the main care. For this reason, the implementation of a comprehensive evaluation of the developed PSS model is needed, throughout their life-cycle, using appropriate KPIs. This KPIs give feedback to the designer for improving the PSS design.

Future work involves a systematic classification of evaluation approaches for PSS design and the formulation of KPIs in mathematical expressions together with mechanisms for their measurement.

Fig. 1 .

 1 Fig. 1. PSS design models, evaluation requirements, and mapping of KPIs

Fig. 2 .

 2 Fig. 2. The conceptual framework proposed for effective PSS design

Table 1 .

 1 KPIs for PSS design assessment (Customer:C, Buisiness:B, Sustainability:S, Lean:L)

	KPIs	Reference	Class	KPIs	Reference	Class
	Satisfaction	[37-44]	C	Overall Equipment	[34]	B
				Effectiveness
	Acceptability	[15],[39]	C	Technical availability	[34]	B
	Acceptance rate	[42, 43]	C	Flexibility	[34]	B
	Availability for pro-	[34]	C	Stability	[34]	B
	duction plan
	Number of identified	[41]	C, L	Machine Reliability	[34]	B
	customer needs
	Consideration of	[41]	C, L	Service Reliability	[34]	B
	customer needs
	On-time delivery	[40],[42]	C	Service Assurance	[34]	B
	Rescheduling quota	[42, 43]	C	Team Qualification	[34]	B, C
	Efficiency of need	[41]	C, L	Feeling quality	[34]	B, C
	identification
	Customer Needs rate	[41]	C, L	Knowledge	[54-57]	B
				Management
	Requirement Incon-	[41]	C, L	PS Maintenance Effi-	[42],[52 ]	B
	sistency			ciency
	Efficiency of collabo-	[41]	C, L	Development cost	[34]	B
	ration
	Privacy	[41]	C, L	Service delivery costs	[43]	B
	Product flexibility	[34]	C, B	Environmental quality	[49]	S, B
				cost function
	Expansion flexibility	[34]	C, B	No. of bottlenecks	[40]	L
	Energy Efficiency	[46-51]	S	Scheduling Inefficien-	[40]	L
				cy
	Sustainable product-	[51]	S	Defects detected in	[40]	L
	service efficiency			development stages
	Lease/ Reuse	[50]	S	Requirement Incon-	[40]	L
				sistency

Acknowledgements. This work has been partially supported by the H2020 EC funded project "Cloud Manufacturing and Social Software-based Context Sensitive Product-Service Engineering Environment for Globally Distributed Enterprise -DIVERSITY" (GA No: 636692).

Availability

Knowledge-sharing Network


Claudio L Meirelles

Marcia De

Terra Silva

Jose B Sacomano
email: jbsacomano@gmail.com

Marcia Terra Da Silva

Quality of Service in Small and Medium Enterprises

Keywords: Small and Medium Enterprises,, Service, Quality, SERVQUAL

de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Small and medium enterprises (SMEs) represent about 99% of the active companies in the world and are the main source of employment. Also, it is appropriate to highlight the European Union with 66.7% of the formal employment, and Brazil with 51.6% of jobs generated in the private sector. Among the Brazilian SMEs, the service sector is the second with the major number of companies, representing 33% of the market, second only to commerce. On the other hand, the tourism sector stands out representing in total contribution, considering direct and indirect activities, 9.3% of Brazil's GDP [START_REF] Sebrae/Dieese | Anuário do trabalho na micro e pequena empresa[END_REF][START_REF] Hoof | Cleaner production in small firms taking part in Mexico`s sustainable supplier program[END_REF][START_REF] Sadaba | Project risk management methodology for small firms[END_REF][START_REF] Sebrae | Boletim estudos e pesquisas[END_REF]5]. The tourism sector includes a variety of companies, such as lodging and food services, transportation companies and travel agencies, among others. This article deals with the quality of service of small travel agencies.

Service is an activity in which the end result is not a physical product; it is directed to meet consumer needs. Some features of services stand out, such as: intangibility, simultaneity, heterogeneity and perishability [START_REF] Almeida | Uma revisão da literatura sobre "servitização": bases para a proposição de um modelo conceitual de decisão[END_REF]. Given these characteristics, a different quality measurement tool used for the assessment of product quality is required.

The quality of service is directly related to the customer's expectation. It is a combination of what the client expected, what he found during the provision of the service and how much he was satisfied after the execution of the activity. If the initial expectation was exceeded, the service is considered of a good quality [START_REF] Heckert | Qualidade de serviços nas organizações do terceiro setor[END_REF].

However, understanding how the customer assesses the quality of service demands specific techniques. Several tools can be presented, such as Grönroos Model, SERVQUAL Model, Perception-Expectancy Model, Evaluation of Service and Value Model, SERVPERF Model, Ideal Performance Model, among others [START_REF] Miguel | Uma revisão dos modelos para medição da qualidade em serviços[END_REF].

Among the hitherto models presented, SERVQUAL arises as a widespread questionnaire in the academic work, because of its ease application and diagnosis ability [START_REF] Berry | Um modelo conceitual de qualidade de serviços e suas implicações para a pesquisa no future[END_REF]. This questionnaire aims to measure the customer's expectations and perceptions, and should be adapted according to the main business attributes and activities.

Given the importance that the SMEs have on the economy in general, and in the tourism sector in Brazil, this article is justified by the need to developing tools to evaluate the service quality of small companies. Due to the difficulty of empirical research in small service companies in Brazil, it draws attention the low number of articles on the subject, opening, therefore, a gap for studies.

The main objective of this work is to verify whether the dimensions of the SERVQUAL tool are adequate or enough to evaluate the quality of service of a small size enterprise, that belongs to the tourism segment, whose main customers are other small and medium enterprises (SMEs).

2

Literature Review

Service Quality

To understand the quality formation of service is crucial for an enterprise to achieve competitive advantage. Thus, a service provided with quality makes the customers more satisfied, resulting in loyalty to the company, positive divulgation for other costumers, new orders and consolidation in the market [START_REF] Carvalho | Avaliando indicadores de desempenho não-financeiro no setor de serviço sob a perspectiva do cliente: o caso de uma agencia bancaria[END_REF][START_REF] Souza | Uma ferramenta para avaliação da qualidade em serviços -a janela do cliente[END_REF][START_REF] Kirchner | Avaliação da qualidade de serviços de uma empresa agrícola[END_REF].

The improving of the service quality is linked to the enterprise's ability to evaluate intangible results, i.e., the customers' subjective judgment about the service. In this case, subjective means that the evaluation is influenced by prior experiences and personal needs. Specifically in the tourism sector, quality refers to the attributes of the service provided by a travel agent [START_REF] Lee | Developing and validating a multidimensional quality scale for mega-events[END_REF].

Indicators, such as quality level, are essential for the planning and control of internal processes of the enterprises. A clear reading of the indicators allows organizations to develop strategies and identify issues that will directly impact on their results [START_REF] Hora | Confiabilidade em questionários para qualidade: Um estudo com o coeficiente alfa de Cronbach[END_REF]. For that reason, many scholars focus their efforts on developing tools that would allow measuring the quality of services provided. It is noteworthy that the SERVQUAL model, despite some criticism about its efficiency, is used as a basis for the development of other models [START_REF] Miguel | Uma revisão dos modelos para medição da qualidade em serviços[END_REF].

The SERVQUAL questionnaire measures customers' expectation and perception of the service in 5 quality dimensions, Reliability, Promptness, Safety, Empathy and Tangible Aspects [START_REF] Kirchner | Avaliação da qualidade de serviços de uma empresa agrícola[END_REF], [START_REF] Emmendoerfer | Terceirização e Parceirização de Serviços em Saneamento em Minas Gerais: Um Estudo Teórico -Empírico[END_REF], [START_REF] Parasuraman | A multiple-item scale for measuring consumer perceptions of service quality[END_REF]. The same questionnaire captures the managers' vision of the quality dimensions, acknowledging the gap between managers' and clients' vision.

There are some critics of SERVQUAL model and Cronin and Taylor developed an alternative model, SERVPERF. This model considers the costumer's satisfaction a better metric to forecast the desire for a new purchase, improving then the SERVQUAL questionnaire to measure the costumer's satisfaction [START_REF] Cronin | Measuring service quality: A reexamination and extension[END_REF].

For this setting, the authors used the SERVQUAL questionnaire and three additional questions designed to evaluate the feelings toward the services provider: customer's satisfaction, total quality of services and the repurchase intention.

The SERVQUAL has become one of the most used models to measure service quality, and it has been adapted to the various application sectors, such as: retail companies, airlines, restaurants, hotels, online education, hospitals, internet services, banks, supply chain, public service, among others [START_REF] Kirchner | Avaliação da qualidade de serviços de uma empresa agrícola[END_REF], [START_REF] Liu | Applying the fuzzy SERVQUAL method to measure the service quality in certification & inspection industry[END_REF].

Despite being widely used, including the tourism sector, in the literature for this study no articles with the application of the SERVQUAL in travel agencies were found, which opens a gap that this study aims to investigate.

Methodology

This study aims to identify the existence of correlations among variables within a population, analyzing a given phenomenon and trying to relate it to another. Fernandes and Gomes define that the descriptive research mode aims to "describe, analyze or verify relationships between facts and phenomena. That is, be aware of what, with whom, how and what is the intensity of the phenomenon under study" [START_REF] Fernandes | Relatórios de pesquisa nas ciências sociais: características e modalidades de investigação[END_REF].

Data collection was performed at a specific moment, so the search is considered a cross-section in time and uses structured questionnaires with closed questions, in order to identify the quality of service purchased by a particular group of SMEs.

Population and sample

The survey was conducted with SMEs who participated in International Missions carried out by a small travel agency, located in São Paulo and specialized in International Business Tourism for SMEs. We interviewed 29 entrepreneurs, being: 10 small and medium printing industries, from the Federal District, capital of Brazil, who participated in an International Mission to SHANGHAI / DUBAI, and 19 small and medium enterprises from different economic sectors and from different regions of Brazil who participated in an International Mission to USA / Panama.

Data collection

We adapted the SERVQUAL questionnaire and tested it with one of the travel agency owners. Some questions were revised to reflect the reality of the tourism sector and, in order to enlarge the possibilities of analysis, three additional questions of the SERVPERF were included.

Results

The average notes of the expectation and the average notes of the performance by each evaluated dimension were calculated. The differences between expectation and performance generated the column of GAPS presented in three tables, one for each traveling group, and one consolidating the results of both groups. The event's profile of the enterprises that participated was used to analyze the results.

The first result shown in Table 1 refers to the first group of entrepreneurs. This group, composed of small and medium enterprises, attended the world's largest retail trade fair, the National Retail Federation -NRF, which features lectures discussing trends in retail market, and went to technical visits to the local market. In Panama the participants visited the Colon Zone, place directed to make imports in small quantities and a great mix. The group's goal was to meet the trends of the retail market. The enterprise has to fulfill the activities and schedules promised in the travel program.

6.53

The enterprise fulfilled the activities and schedules promised in the travel program.

6.95 0.42

The enterprise must inform to the customers the details of the activities that will be performed in the travel program.

6.74

The enterprise informed to the customers the details of the activities that were performed in the travel program.

6.89 0.15

The staff must always be available to help customers.

6.63

The staff was always available to help customers. 6.74 0.11

The costumer has to feel safe to travel with the staff.

6.68

The costumer felt safe to travel with the staff. 6.95 0.27

The staff has to be polite.

6.68

The staff was polite. 6.84 0.16 The enterprise will give individual attention to the customers.

6.15

The enterprise gave individual attention to the customers. 6.73 0.58

The staff will give personal attention to the customers 6.16

The staff gave personal attention to the customers. 6.68 0.52

It was expected that the staff knew what the customer's needs were.

6.0

The staff knew what the customer's needs were. 5.95 -0.05

In the coming years my use of the enterprise will be: 6.21 The service of the enterprise is:

6.58 My feelings about the enterprise's services can best be described as: 6.58 Analyzing the results of this group, the highlights are: (a) the highest average expectation column (6.89) was in the topic "The enterprise has to be reliable"; (b) the lowest average expectation column (6.0) was in the topic "It was expected that the staff knew what the customer's needs were; (c) "the largest GAP (0.58) was between the topics" The enterprise will give individual attention to the customers" and "The enterprise gave individual attention to the customers "; (d) the lowest GAP (-0.05 ) was between the topics "It was expected that the enterprise's staff knew what the customer's needs were" and "The staff knew what the customer's needs were". The last three questions in the questionnaire evaluating the enterprise overall showed a very positive evaluation (6.21, 6.58 and 6.58), even having a dimension with a negative GAP.

The second result, shown in Table 2, refers to entrepreneurs who participated in the International Mission Shanghai / Dubai. This group was composed of small and medium enterprises of the printing sector, which participated in a specific fair of the graphic sector in Shanghai, and went to technical visits to specialized factories in printing equipment. In Dubai technical visits to the local market and to the embassy were made to understand the opportunities for the sector in this country.

EXPECTANCY BEFORE THE TRIP

Avg. PERFORMANCE AFTER THE TRIP

Avg. GAP

The staff must be well-dressed.

4.8

The staff was well-dressed. 6.3 1.5 The enterprise has to be reliable.

6.2

The enterprise was reliable. 6.5 0.3 The enterprise has to generate business opportunities.

5.2

The enterprise generated business opportunities.

0.3

The enterprise has to fulfill the activities and schedules promised in the travel program.

5.9

The enterprise fulfilled the activities and schedules promised in the travel program.

0.6

The enterprise must inform to the customers the details of the activities that will be performed in the travel program.

6.1

The enterprise informed to the customers the details of the activities that were performed in the travel program.

0.4

The staff must always be available to help the customers.

5.6

The staff was always available to help the customers.

6.1 0.5

The costumer has to feel safe to travel with the staff.

6.1

The costumer felt safe to travel with the staff.

0.3

The staff has to be polite.

6.5

The staff was polite. 6.7 0.2 The enterprise will give individual attention to the customers.

5.1

The enterprise gave individual attention to the customers. 6.0 0.9

The staff will give personal attention to the customers.

5.4

The staff gave personal attention to the customers.

0.8

It was expected that the staff knew what the customer's needs were.

3.9

The staff knew what the customer's needs were.

4.8 0.9

In the coming years my use of the enterprise will be: 6.1 The service of the enterprise is: 6.4 My feelings about the enterprise's services can best be described as: 6.3 The main results of this group were: (a) the highest average expectation column (6.5) was in the topic "The staff has to be polite"; (b) the lowest average expectation column (3.9) was in the topic "It was expected that the staff knew what the customer's needs were"; (c) the largest GAP with an average of 1.5 was in the topic "The staff must be well dressed" and "The staff was well dressed "; (d) the lowest GAP with an average of 0.02 was in the topics "The staff has to be polite" and "The staff was polite". The last three questions in the questionnaire evaluating the enterprise overall showed a very positive evaluation (6.1, 6.4 and 6.3).

The two groups were consolidated in Table 3, for general analysis.

Table 3. Results of the two research group consolidated (Source: Author).

EXPECTANCY BEFORE THE TRIP

Avg. PERFORMANCE AFTER THE TRIP

Avg. GAP

The staff must be well-dressed.

5.79

The staff was well-dressed. 6.52 0.73 The enterprise has to be reliable.

6.65

The enterprise was reliable. 6.83 0.18 The enterprise has to generate business opportunities.

6.03

The enterprise generated business opportunities.

6.24 0.21

The enterprise has to fulfill the activities and schedules promised in the travel program.

6.31

The enterprise fulfilled the activities and schedules promised in the travel program.

0.48

The enterprise must inform to the customers details of the activities that will be performed in the travel program.

6.52

The enterprise informed to the customers the details of the activities that were performed in the travel program.

6.76 0.24

The staff must always be available to help customers.

6.27

The staff was always available to help customers.

0.25

The customer has to feel safe to travel with the staff.

6.52

The customer felt safe to travel with the staff.

0.24

The staff has to be polite.

6.62

The staff was polite. 6.79 0.17 The enterprise will give individual attention to the customers.

5.79

The enterprise gave individual attention to the customers.

0.69

The staff will give personal attention to the customers.

5.9

The staff gave personal attention to the customers.

0.62

It was expected that the staff knew what the customer's needs were.

5.27

The staff knew what the customer's needs were.

0.28

In the coming years my use of the enterprise will be: 6.17 The service of the enterprise is:

6.52 My feelings about the enterprise's services can best be described as: 6.48 The main results of the consolidated groups in Table 3 were: (a) the highest average expectation was in the column (6.65) in the topic "The enterprise has to be reliable"; (b) the lowest average expectation was in the column (5.27) in the topic "It was expected that the staff knew what the customer's needs were"; (c) the biggest GAP at an average of 0.73 was in the topics "The staff must be well-dressed" and "The staff was well-dressed "; (d) the lowest GAP at an average of 0, 17 was in the topic "The staff has to be polite" and "The staff was polite". The last three questions in the questionnaire evaluating the company overall showed a very positive evaluation (6.17, 6.52 and 6.48).

The topic with the greatest positive GAP was about the enterprise's staff way of dressing. It demonstrates the impact of the formalization in attendance, as in the agency all the staff works with suit and tie, which is not common in SMEs in Brazil.

The highest average expectation was placed on "confidence". It can be explained by the characteristic of SMEs in Brazil, in which the owners often centralize decisions and have difficulty to deliver a new project in other company's hands. These two issues arise a question about the understanding of what SMEs value in the service, since the organization emphasizes tangibles and customers seem to want confidence.

Open interviews with the partners of the company and with the business customers were made. The partners said that the most important topics were about (1) "the staff knowing what the customer's needs were" and (2) "the enterprise generating business opportunities". From the two topics, the first stands out as the topic with lower avera-ge expectation among the SMEs, which is an antagonistic result than expected; and the second topic did not have an average or relevant GAP. The clients acknowledged they had low expectations about the ability of a supplier to understand their problems.

The individual analysis per group has some specific features that are hidden in the consolidated analysis. This observation is made clear in the topic about "the staff knowing what the customer's needs were", in which the two groups evaluated the service in different ways.

Another topic that drew attention was the positive evaluation in the general context of the services quality provided, 6.52 in 7.0 points. Despite some quality flaws, the entrepreneurs were satisfied with the services provided.

Conclusion

According to the data analysis, some results will be used as the main connecting thread this research in order to draw the conclusions of this study.  The individual analysis of the results brings specific characteristics of the groups, which is lost when doing a consolidated analysis of all customers entrepreneurs; * Some characteristics of the SMEs in Brazil, such as trust, can be observed in the results  Considering that the travel agency specialized in developing missions to internationalize SME's; the specific topics on business should have a relevant positive evaluation, which did not happen, but the result of the three last questions that assess the general quality of the service offered had a very positive result.

Thus, conclude that the SERVQUAL questionnaire was of value to determine characteristics of SMEs and the punctual quality of the service provided. The inclusion of the three questions of the SERVPERF questionnaire identified in general, whether the punctual quality of the service was converted or not in customers' satisfaction.

Analyzing the results, one can identify the necessity of a variable in the tool that shows the main reason that allowed the service of being considered of good quality, and the variable that best suits this purpose is related to "learning". This variable explains why business man were satisfied, even without closing deals, the essential objective of the trip, and would like to travel with the agency again. This conclusion was taken based on three topics: 1. The main purpose of the trips was to develop the internationalization of the enterprise; 2. The SMEs did not mark as relevant the expectation in topics related to business; 3. The participating enterprises of the missions had no experience with the process of internationalization.

This conclusion makes it clear that small and medium enterprises that would like to internationalize need more than the final result, import\export, they also have the necessity of filling out deficiencies of new knowledge, which opens a gap in the study focused on SME.

Table 1 .

 1 Results of the search of the group USA / Panama (Source: Author).

	EXPECTANCY BEFORE THE TRIP	Avg.	PERFORMANCE AFTER THE TRIP	Avg.	GAP
	The staff must be well-dressed.	6.31	The staff was well-dressed.	6.63	0.32
	The enterprise has to be reliable.	6.89	The enterprise was reliable.	7	0.11
	The enterprise has to generate business opportunities.	6.47	The enterprise generated busi-ness opportunities.	6.63	0.16

Table 2 .

 2 Results of the research of the group Shangai/Dubai (Source: Autor).


Alice Rondini
email: alice.rondini@unibg.it

Fabiana Tornese
email: fabiana.tornese@unisalento.it

Maria Grazia Gnoni
email: mariagrazia.gnoni@unisalento.it

Giuditta Pezzotta
email: giuditta.pezzotta@unibg.it

Roberto Pinto
email: roberto.pinto@unibg.it

Business process simulation for the design of sustainable Product Service Systems (PSS)

Keywords: PSS, Customer, Sustainability, Simulation, Hybrid modelling

Nowadays, a lot of manufacturing companies are shifting their value proposition from a product-centric perspective to sustainable Product-Service-Systems (PSS). This transition allows companies to improve the customization of their offer and to contribute to the reduction of material flow and consumption; nonetheless, it poses some new challenges in terms of mindset and organization. In particular, the analysis of the literature about PSS shows that there is still a gap concerning the evaluation and the monitoring of new or reengineered PSS provision processes using business process simulation. Few examples of simulation in PSS field can be found, and multidimensional models considering customer perspective and environmental sustainability beyond the economic driver are not yet available. Thus, the purpose of this paper is to compare different simulation paradigms and to define the most suitable to support the engineering phase of a sustainable, customer-oriented PSS. Two possible alternatives were identified and discussed through a test-case.

1

Introduction

Facing the difficult economic juncture, an increasing number of companies has been enlarging its value proposition starting to provide services in addition to their products, moving from a product-centric perspective towards the provision of sustainable Product-Service Systems (PSSs). This is contributing, from one side, to increase their revenues and customer satisfaction and, from the other side, to a dematerialization of their offering [START_REF]Product-Service Systems and sustainability, opportunities for sustainable solutions[END_REF]. In particular, different are the advantages and the benefits achieved with the introduction of a PSS: (i) differentiation from competitors, (ii) customers lockin and (iii) competitors lock-out thank to the provision and selling of a unique solution [START_REF] Neely | Exploring the financial consequences of the servitization of manufacturing[END_REF]. Nevertheless, the shift to the PSS paradigm also poses some critical challenges to companies, as they are required to review the entire organization [START_REF] Neely | Exploring the financial consequences of the servitization of manufacturing[END_REF]. Furthermore, failing to manage this mindset shift can lead to limited payoffs and unsuitable revenues, thus originating the so-called "service paradox" [START_REF] Gebauer | Overcoming the service paradox in manufacturing companies[END_REF]. This is the reason why Service Engineering (SE) [START_REF] Bullinger | Service engineering-methodical development of new service products[END_REF], a relatively new research field, has been developed to adapt existing engineering know-how to services. It is not a completely mature discipline, and a common standard to deal with PSS and services is still missing [START_REF] Cavalieri | Product-Service Systems engineering: state of the art and research challenges[END_REF]. Within this context, many authors [START_REF] Welp | Modelling approach for the integrated development of industrial Product-Service Systems[END_REF][START_REF] Aurich | Life cycle oriented design of technical Product-Service Systems[END_REF][START_REF] Shimomura | A unified representation scheme for effective PSS development[END_REF] defined possible design methodologies for PSS but none of the existing provide suggestions to i) manage the dynamics involved in a PSS (e.g. customer interaction or participation in the provision process; moving human resources and high variability in customer behaviour), ii) monitor and implement a PSS, and iii) manage the customer and company co-creation process. Therefore, considering these issues, the main goal of the paper is to answer to the following research questions (RQ):

1. What are the main KPIs of a PSS delivery process that should be evaluated to guarantee high customer value and to make it sustainable in the long term? 2. How do simulation paradigms (DES -Discrete Event Simulation, SD System Dynamics, ABM -Agent-Based Modelling, and Hybrid Modelling) allow gathering and managing the dynamics involved in a PSS? 3. How is it possible to integrate the environmental sustainability and customer satisfaction performances into a PSS simulated process? On this basis, this study is based on the following four steps:

1. Identification of the main KPIs that should be monitored in a PSS delivery process; 2. Literature analysis of the state of the art in simulation modelling for sustainable PSS; 3. Identification of the existing simulation paradigms allowing sustainable PSS delivery process measurement; 4. Adoption and comparison of the simulation paradigms identified in a test-case. The remaining part of the paper is structured as follows: section 2 describes the main KPIs to be considered in a PSS. Section 3 presents a brief literature review about simulation and environmental sustainability in PSS, whereas section 4 provides an overview of the test case together with considerations about the two different approaches. Section 5 presents the conclusions and possible further development directions.

2

Identification of the main KPIs to be monitored in a PSS

Literature analysis provides a useful overview to define the main performance that should be evaluated in a PSS delivery process. In particular, the co-creation process between the customer and the company is a leading concept to understand how the value is created in a PSS. Adopting the Service-Dominant logic, the roles of producers and consumers are not distinct, meaning that value is always co-created, jointly and reciprocally, in interactions among providers and beneficiaries through the integration of resources and application of competences [START_REF] Vargo | Service-dominant logic: continuing the evolution[END_REF]. From this point of view, both the customer (in terms of satisfaction) and the company (in terms of profitability and efficiency) perspectives might be taken into account. Moreover, one of the main elements emerged from the literature review is that, among the main advantages of a PSS, sustainability is becoming more and more relevant [START_REF] Mont | Clarifying the Concept of Product-Service System[END_REF]. For this reason, it has been taken into account as well in our study.

To summarize and answer the RQ1, we consequently defined three main dimensions for the evaluation of a PSS delivery process: (i) process efficiency, (ii) customers' satisfaction, and (iii) environmental sustainability.

To measure and monitor these dimensions, we tried to adapt and translate existing product-based knowledge into the service field. Among the existing tools largely used in traditional manufacturing industry to tackle the dynamics and to monitor the process , simulation is the most well-known, but its application to the PSS field is still largely unexplored [START_REF] Meier | Design for Engineering of Dynamic Business Models for Industrial Product-Service Systems[END_REF]. In particular since "the interaction of people with processes and technology results in an infinite number of possible scenarios and outcomes that are not possible to predict and evaluate using widely popular static process modelling methods" [START_REF] Hlupic | Business Process Modelling and Analysis Using Discrete-Event Simulation[END_REF], simulation has been selected. In this paper we will define simulation as "the process of designing a model of a real system and conducting experiments with this model for the purpose of understanding the behavior of the system and/or evaluating various strategies for the operation of the system" [START_REF] Shannon | Introduction to the Art and Science of Simulation[END_REF].

3

State of the art about simulation modelling for sustainable PSS delivery process

Concerning the adoption of simulation in the SE context, we have been looking for examples of simulation frameworks including both customers' involvement in the PSS delivery process and the environmental advantages carried out by the introduction of a PSS offering. No framework seems to provide a broad perspective considering these two dimensions as part of everyday business, but some studies actually deal with one or the other.

There are three main simulation paradigms widely used to model manufacturing systems: Discrete Event Simulation (DES), System Dynamics (SD) and Agent-Based Modelling (ABM). SD can easily represent flows and cause-effect relations in a system at a strategic level, starting from the consideration that the behavior of a system is strongly dependent on its structure. DES is process-centric and focuses more on the tactical/operational dimension level; it is, based on entity flows, resource sharing and sequences of activities. On the other hand, ABM is more effective in the modelling of individuals' behavior, through a bottom-up approach in which agents have their own rules and become active elements of the model [START_REF] Maisenbacher | Applicability of Agent-Based Modeling for supporting Product-Service System development[END_REF]. All of them cannot be immediately adopted into the PSS field and literature highlights that the underpinning reasons must be sought in some key features of a PSS that are difficult to simulate, such as the presence of human beings whose behavior cannot be easily translated into an equation [START_REF] Duckwitz | Simulation of human behavior in knowledge-intensive services[END_REF], the difficulty to define specific set of resources to allocate to service activities [START_REF] Chesbrough | A research manifesto for service science[END_REF] and the still undefined concept of PSS productivity [START_REF] Gronroos | Service productivity: towards a conceptualization of the transformation of inputs into economic results in services[END_REF]. Nevertheless, there are few examples of the adoption of simulation modelling paradigms for both the assessment of (i) PSS sustainability and (ii) PSS customer and company's performance.

Regarding the evaluation of sustainability, there are two noteworthy examples. Lee et al. [START_REF] Lee | Dynamic and multidimensional measurement of product-service system (PSS) sustainability: a triple bottom line (TBL)-based system dynamics approach[END_REF] show the application of SD to a PSS whereas [START_REF] Lovrić | Sustainable revenue management: A smart card enabled agent-based modelling approach[END_REF] try to put together economic, social and environmental sustainability through a decision support system based on ABM.

Considering the company and the customer performance perspectives, there are only few studies. One of them is focused on the possible application of life cycle simulation to PSS [START_REF] Garetti | Life Cycle simulation for the design of Product -Service Systems[END_REF] and another is an application of SD to the analysis of the impact of PSS in a manufacturing company [START_REF] Bianchi | Influencing factors of successful transitions towards Product-Service Systems: a simulation approach[END_REF]. Moreover, we found a single application of DES in services, specifically focused on efficiency in social services [START_REF] Harpring | Improving efficiency in social services with discrete events simulation[END_REF]. Only one approach has been specifically developed to analyze the performance of a PSS [START_REF] Tateyama | Service Flow Simulation using scene transition nets (STN) including satisfaction-attribute value functions[END_REF]. In addition, some interesting applications of ABM to PSS development focusing on customer's satisfaction have been found [START_REF] Maisenbacher | Applicability of Agent-Based Modeling for supporting Product-Service System development[END_REF], [START_REF] Kim | A systematic approach for new service concept generation: application of agent-based simulation[END_REF].

Next to the three "pure" simulation paradigms presented, hybrid modelling grew out of the need to combine the advantages of two or more of these approaches, integrating in one model specific features from the different techniques. This allows attaining a higher flexibility and working at different levels of abstraction, exploiting at the same time the strengths of each method [START_REF] Wang | Hybrid modeling and simulation for complementing Lifecycle Assessment[END_REF]. For these reasons, the opportunity to use a hybrid model has been considered as a possible way to better deal with the complexity and the dynamics of a PSS.

As a first conclusion, we can state that some attempts to evaluate sustainability or customer satisfaction in a PSS through a simulation approach already exist, meaning that simulation can help to gather the dynamics of a PSS. This provides an answer to RQ2, but still leaves a gap in the performance analysis because none of them considers all the three KPIs identified from a multidimensional perspective. On this base, to answer RQ3 we choose to analyze the system through two modelling solutions: a DES model, focusing more on the delivery process and activities of which the PSS is made up and a hybrid model, taking advantage of the specific features of both DES-ABM, in which customers are modelled through the ABM approach. This gives more centrality to their interaction with the PSS provider.

4

Test case

In order to better evaluate the potentiality of the identified approaches, we applied DES and ABM to a real case from the automotive sector where the service market can be four or five times larger than the market for products, and where nowadays there is a strong commitment to environmental sustainability. We decided to use a truck standard maintenance process as a test case, due to the extensive experience of some of the authors in that area. The process works as follows: first, the customer arrives at the workshop with his truck and is received by a receptionist. Then, the workshop foreman performs an initial diagnosis, provides a general quotation for the estimated services, and schedules the intervention. At its turn, the truck is exposed to three different maintenance activities and, if no additional problems arise, it is checked out and brought back to customer. If, instead, unplanned problems arise, or the final check does not show a proper condition, another maintenance activity is carried out. As in reality, there are two types of customers: (i) customer with a single truck and (ii) customers with a truck fleet. Of course, at the scheduling, the customer with a fleet available would bear better a long waiting time than the customer with only one truck that may eventually decide to leave the system before being serviced. For the sake of simplicity, at this point of the analysis the truck utilization of both the two customers would not be considered. As hinted before, the automotive sector is characterized by high pressure from the environmental point of view. In relation to a maintenance process, there are different elements that can be taken into account; however, for the case presented in this study, only the use of refurbished spare parts has been considered: that is, the customer has the possibility to choose between new or refurbished spare parts both for the scheduled maintenance and for the unplanned problems solving phase.

All the data related to the number of maintenance requests, the activities duration, the customer willingness to wait, the number of utilized spare parts and the resources employed have been taken from the company database and direct observations. Data related to sustainability have been inferred from literature (e.g., the percentage related to the adoption of refurbished spare parts [START_REF] Mckenna | Energy savings through direct secondary reuse: an exemplary analysis of the German automotive sector[END_REF]).

For what concerns the measurement of the main KPIs, we decided to use resources utilization coefficients (workers and work spaces) to give a proxy for the economic efficiency, while the total waiting time, the total service time and the percentage of customers leaving the system before being served (they do not want to wait too much time in queue) help to understand what is the service level perceived by the customer. Finally, the environmental gain due to the customer's choice of buying refurbished spare parts is modelled through the indicator of CO2 avoided emissions. In this case, a general reference value has been gathered from a study about remanufactured diesel engines [START_REF] Smith | The value of remanufactured engines. Life-cycle environmental and economic perspectives[END_REF], not considering the variety of spare parts that can be substituted in a truck maintenance process. This approximation can be justified observing that the focus of the analysis is not the real case, but the application of the simulation to evaluate KPIs in a PSS.

Two models have been built: a DES model built using Arena Rockwell simulation and a hybrid DES-ABM model built using Anylogic. Input data, not reported in this paper, were the same in both the two models. In Table 1, the results (mean values) of the simulation considering the three main dimensions identified are reported considering both DES and hybrid models. The total simulation time is equal to six months; the service company is open five days a week, eight hours per day. The results obtained are aligned with the as-is real data.

The test case performed represents just an initial step in defining an integrated PSS simulation approach. In this sense, the work performed helped to shed light on the possible use of business process simulation in assessing PSS performance, confirming that this tool can reveal useful to manage PSS dynamism. In this sense, both the two approaches suggested (DES and Hybrid model) provide an answer to RQ2 having an acceptable fit with reality. Moreover, both are capable to measure the three main areas of performance indicated. This last point, that answers RQ3, is demonstrated by the data shown in Table 1 with the results related to company, customers and sustainability dimensions. Results from the two approaches are almost similar, but there is a discrepancy in the percentage of customer leaving the system. This is caused by one of the main problems emerged in DES with Arena software that has some limitations in defining the schedule arrival of trucks. The initial distribution reveals less random than expected; for this reason, the number of truck waiting is higher and consequently a higher percentage of customer leaves the system. This reason also explains the difference in the service time (from 1,8 to 1,4 days). The less random distribution indeed causes higher queues in the initial part of the process where the customer cannot decide to leave the queue. Finally, the negligible difference in the number of entities entering the system can be influenced as well by this problem. Apart from this clear difference in the two approaches, the work performed for this study also highlights some advantages of hybrid technique with respect to DES. In particular, the use of ABM to model customers' behavior and preferences creates a considerable advantage in terms of model definition and use. This method allows for the definition of copious rules that agents have to follow and in this way facilitates the creation of the DES part that describes the process. The pure DES approach indeed can describe the customer rule for the simple test case, but it required additional technical expedients and work. Due to space constraint, data and other simulations results have been omitted. However, they are available -with the exception of those subject to non-disclosure agreement -upon request to the corresponding author.

Further analysis can encompass the adoption of the two approaches to describe a more complex PSS process. Through this, the advantages of the hybrid simulation paradigm would become clearer. The use of the approaches in more complex scenarios can be also a good starting point for the analysis of additional drivers to measure the three main KPIs identified (e.g. costs as a driver for efficiency, a qualitative evaluation of customer service, material consumption, energy utilization and waste reduction to evaluate environmental sustainability).

5

Conclusions and further developments

The study presented in this paper illustrates a possible integrated simulation approach to evaluate a PSS from multiple perspectives. First, a literature analysis has been performed to define a set of integrated and effective metrics for PSSs. In this still open research area, we decide to consider three main performance dimensions: i) customer satisfaction, ii) economic efficiency and iii) environmental sustainability (RQ1).

In the second stage, a literature analysis on simulation paradigms has been carried out showing that DES, ABM and SD have been rarely applied to design services and PSSs. The hybrid simulation paradigm is also still unexplored in PSS environment.

Two possible simulation approaches have been defined to test the different simulation approaches: the first one is based on DES paradigm, and the latter uses a hybrid model, which integrates advantages of DES and ABM paradigms. The two have been applied in a test case and evaluated through their ability to describe the customer and companies' complexity. The results show that both the models allowed the measurement of the performance of the three metrics defined (RQ2), but the hybrid model revealed more useful in defining PSS and customer interaction monitoring the three strategic perspectives (RQ3).

Further developments can regard the analysis of more complex test cases with the introduction of other variables and constraints, in order to investigate the potentialities of hybrid modelling for PSS more in depth.

Table 1 .

 1 Results of simulations

	Criteria	Parameter	DES	Hybrid
				model
		N° customers entering the system	597	611
		N° customers served	513	568
		Mechanics utilization	44%	44%


Toshiya Kaihara
email: kaihara@kobe-u.ac.jp

Daisuke Kokuryo

Swee Kuik

A Proposal of Value Co-Creative Production with IoT-based Thinking Factory Concept for Tailor-made Rubber Products

Keywords: Value co-creation, Smart factory, IoT, CPS, Multiagent system

Production companies are required to notice the importance of the paradigm shift from "use value" into "value in use" about their products and services. Value co-creative activity between the producers and consumers is essential to realise the paradigm shift in practical business case. The IoT(Internet of Things) is a powerful infrastructure to digitalise and increase the integration of vertical and horizontal value chains in the business process. We propose a value co-creative production system model under IoT environment with an innovative "Thinking factory" concept. Our current target is the rubber industry which is required to provide tailor-made products as human-machine delicate interface.

Introduction

Nowadays production companies are required to pay attention into the importance of the paradigm shift from "use value" into "value in use" about their products and services. Value co-creative activity between the producers and consumers is essential to realise the paradigm shift in practical business case. The IoT(Internet of Things) is a powerful infrastructure to digitalise and increase the integration of vertical and horizontal value chains in the business process. Therefore smart production concept is now paid great attention in accordance with the development of ICT. Industry 4.0 in Germany [1] and Industrial Internet Consortium (IIC) initiative in USA [2] are the most famous projects focusing on the smart factory. IoT (Internet of Things) and CPS (Cyber Physical System) are their key technologies to support the realization of Smart factory.

On the other hand, Kobe area is the birthplace of the rubber industry in Japan and the country's largest base of chemical shoes. It is utmost important for Kobe area to realize an innovative outcome of the rubber industry under the global competition. This innovation is expected to enhance the competence of Japanese manufacturing technology. We focus on the shoe industry with rubber materials as consumer products, because it is one of very important production businesses in Kobe area as mentioned before.

Currently because of current modern life and life longevity, it has become common to put on shoes daily for long time. Shoes have become very important to support the total body weight of its own. Consumers pay much concern to foot comfort or shoes fit feeling in various life scenes, such as health promotion , rehabilitation, running or other sports, business use, and so on. Thus the shoes industry is one of the most suitable target to try to implement the value in use concept with the idea of tailor-made rubber products.

In this paper we introduce our research activity as a part of the Innovative Design and Production Technology Project under the cross-ministerial SIP (Strategic Innovation Promotion) program [3] supported by Cabinet Office, Government of Japan [4]. We propose design/manufacturing systems targeting value-co-creation for our life innovation focusing shoes as pioneer model in the rubber industry as well as realising tailor-made rubber products with reactive 3D printer in our R&D activity.

Thinking factory concept under IoT

As we mentioned before, smart production concept is now paid great attention as IoT environment is spreding. Industry 4.0 and IIC are the most famous projects focusing on the smart factory. The technological map between Industry 4.0 and IIC is illustrated in figure 1. Industry 4.0 was first introduced by the German Government in order to increase visibility of the operational activities in the factory by use of advanced manufacturing technologies and promote decentralisation management [START_REF] Dworschak | Competences for Cyber-physical Systems in Manufacturing -First Findings and Scenarios[END_REF]. The key focus is on the development of cyber physical system (CPS) [START_REF] Lee | A: A Cyber-Physical Systems architecture for Industry 4.0-based manufacturing systems[END_REF]. CPS is defined as the advanced manufacturing technologies for controlling and handling inter-operative systems, where physical assets is associated with computational capabilities and elements. In this context, Lee et al. provides the 5C architecture guideline for Industry 4.0 in which the data sources are based on sensor, controller and networked systems. This proposed architecture includes the smart connection level, data-to-information conversion level, cyber level, cognition level and configuration level [START_REF] Zuehlke | SmartFactory̶Towards a factory-of-things[END_REF].

The Industrial Internet Consortium (IIC) was established in March 2014 by an alliance of technology development companies [2]. These partnership companies include AT&T, Cisco, GE and Intel. They are currently working on the focused areas of improvement in software and hardware platforms towards excellent networking by identifying and implement best practices using IoT. Currently, these partnership companies attempt to incorporate new strategy by rectifying the current system weaknesses to ease of implementation by IoT. In addition, the development on networking connectivity via cloud computing is one of the key focuses for the IIC for improving and standardising the core activities for implementation guideline using IoT shown in figure1.

Our thinking factory concept for realizing the value co-creative production is shown in figure 2. Several kinds of users are interactively connected with thinking factory under IoT environment. Our concept also contains CPS, cloud computing and big data analysis, and it focus more on uses value creation as well as producers value.

For sustainable value creation, our thinking factory mutually circulates both traditional producer innovation providing values and user innovation providing values created by users participation. Involvement of users in design and development evolves wide spectrum of technologies realizing potential needs. Proposal by researchers of new product or service will inspire idea creation of future product or service.

Value co-creatiive production between value producer and value consumer could be established by our thinking factory concept under IoT environment as illustrated in figure 3. Value market is constructed in the "Value in use" production, and the development about both product and customer is carried out under the mechanism.

CPS is a decentralization concept through the intelligent system to arrive at smart production. Several developed technologies for managing computational element between its physical assets and computational capabilities enables CPS with cloud platform. We have already proposed "Real-Virtual fusion manufacturing system" concept [START_REF] Qian | Production Scheduling with Social Contract Based Approach for Real-Virtual Fusion Manufacturing System[END_REF] Several research activities are executing now in our project, and we will explain consumer-baed supply chain for tailor-made rubber products as an example. The consumer-based supply chain model is proposed to manage and handle the inter-relationship of supplier-manufacturer and manufacturer-distributor parties. In recent literature, the research works on production inventory policy only focus on either supplier-manufacturer inventory or manufacturer-distributor inventory policies in multiple product conditions [START_REF] Hoque | An optimal solution technique to the single-vendor multi-buyer integrated inventory supply chain by incorporating some realistic factors[END_REF], [START_REF] Rad | Optimizing an integrated vendor-managed inventory system for a single-vendor two-buyer supply chain with determining weighting factor for vendor s ordering cost[END_REF]. However, the interaction of all supply chain members for planning inventory policy may have direct impact on cost savings. As illustrated in figure 5, both parties (i.e. suppliermanufacturer and manufacturer-distributor) require to work closely in order to achieve cost minimisation for the entire supply chain network. In this modelling, the multiple distributors are responsible for different product customisations and delivery according to the requirements of the consumer segments. In fact, the inventory policy in product customisations for supplier-manufacturer and manufacturer-distributor parties can vary in terms of quantities, ordering size and differential consumer segments. These variations may then increase the operational costs along a supply chain. In our activity the integrated production inventory policy in a supply chain is relatively complex to be planned for 3D printing product customisations. The policy usually needs to incorporate with the demand fluctuation, ordering size, differential consumer segments, and 3D printing machine capabilities. Figure 6 illustrates a schematic diagram of the integrated inventory policy for both parties in 3D printing product customisations. The raw materials and components used can actually move across multiple entities along a supply chain, such as supplying, producing and distributing to consumers.

The appropriate supply chain planning in inventory policy from initial acquisition, make-to-order and production-distribution is required to minimise the associated cost along its value chain. This is also known as three echelon supply chain perspective. For optimising the gained profit and added value for implementation, there is a need to develop an integrated system modelling to simulate the complexities of differential consumer requirements in 3D printing rubber product customisations. tory" structure targeted to the rubber industry in Kobe area. Deep involvment of users into the IoT based production system were investigated, and that is an important difference from Industry 4.0 or IIC in the abroad. The framework of users' participation to value co-creation was constituted by Kobe University, prefectural research institute located in Kobe area, and many leading business companies as provider or user. Our activity tries to realise the innovative paradigm shift from "use value" production into "value in use" production in the near future.

Fig. 1 .

 1 Fig. 1. Industry 4.0 and IIC

Fig. 2 .Fig. 3 .

 23 Fig. 2. Thinking factory concept with customers involvement

3Fig. 4 .

 4 Fig. 4. Value co-creative tailor made production system

Fig. 5 .

 5 Fig. 5. Supply chain network for product customisation

Fig. 6 .

 6 Fig. 6. Integrated inventory policy in 3D printing product customisation and consumer segments

  which includes CPS characteristics in dynamic pro-

	Internet of Things (IoT)
	Consumers' Wants • Performance Data Consumers' Wants • Performance Data	Professional User Professional User	Semi-Professional User and/or Casual User Non-Professional User Semi-Professional User and/or Casual User Non-Professional User
	• Status and • Status and
	Timeline to Timeline to
	receive products receive products		Consumers and/or Users ClassificaƟon Consumers and/or Users ClassificaƟon	• SoŌware Interface Plaƞorm to collect data from differenƟal consumer' perspecƟves • SoŌware Interface Plaƞorm to collect data from differenƟal consumer' perspecƟves
				• Data Security Systems from • Data Security Systems from
				Cloud CompuƟng Providers Cloud CompuƟng Providers
	• OpƟmisaƟon SelecƟon and SpecificaƟons • Trade-off Decision CustomisaƟon and • OpƟmisaƟon SelecƟon and SpecificaƟons • Trade-off Decision CustomisaƟon and d	Data Processing Data Processing	Data Management System via Cloud CompuƟng Data Management System via Cloud CompuƟng	• Network ConnecƟvity Plaƞorm SelecƟon • Stability of the Networking Plaƞorm • Network ConnecƟvity Plaƞorm SelecƟon • Stability of the Networking Plaƞorm
	Order fulfilment Order fulfilment
				• SoŌware Interface Plaƞorm to • SoŌware Interface Plaƞorm to
			Data Management Data Management	collect data from M2M collect data from M2M
			System via CPS System via CPS	• Data Security Systems from • Data Security Systems from
				M2M M2M
			Data InterpretaƟon Data InterpretaƟon
		Suppliers Suppliers	OEM OEM	Distributors Distributors Di t ib

Conclusion

We introduced our proposed concept on "value co-creative production system model" under IoT environment, which facilitates an innovative "Thinking fac-

Ackowledgement

Our activity is fully supported by the Innovative Design and Production Technology Project under the cross-ministerial SIP (Strategic Innovation Promotion) program organized by NEDO (New Energy and Industrial Technology Development Organization) and Cabinet Office, Government of Japan.


Taehun Kim
email: taehun_kim@postech.ac.kr

Seunghwan Bang
email: seunghwanb@postech.ac.kr

Kiwook Jung
email: kiwook@postech.ac.kr

Hyunbo Cho
email: hcho@postech.ac.kr

Decomposing packaged services towards configurable smart manufacturing systems

Keywords: manufacturing service, smart manufacturing, production planning

Smart Manufacturing Systems have the ability to adapt to rapidly changing requirements. Software components of the manufacturing systemservices under Service Oriented Architecture-must be configured dynamically to meet such requirements. Currently, software vendors provide packaged services, so they are not easily reconfigurable. Thus, engineers or production managers face difficulty in composing services with the appropriate functionality and quality. The objective of this paper is to discuss high-level requirements for such a unit service concept and provide an initial use case to illustrate how the unit service concept may apply new technologies to improve service. We propose a decomposition of target service according to standard model, and we claim the limitations of decomposed unit services, and new technologies and opportunities for each decomposed services.

Introduction

Smart Manufacturing Systems (SMSs) are defined by advent of new technologies that promote rapid and widespread information flow within the systems and surrounding its control [START_REF] Jung | Mapping Strategic Goals and Operational Performance Metrics for Smart Manufacturing Systems[END_REF]. New technologies, such as internet of things (IoT), big data analytics, and predictive analytics, enable collecting and processing of huge amounts of data, rapid and precise physical systems monitoring, and deeper and advanced analysis for those data. New technologies offer chances to develop new manufacturing services, or to improve previous services.

However, previous manufacturing supporting systems, such as enterprise resource planning, material requirements planning, and production planning, have limited availability to apply these technologies. Systems to support manufacturing for enterprises have variety scopes and level of details, but, the lack of a standard industry approach to production management results in customized software or use of a manual approach [START_REF]Workshop report on foundations for innovation in cyber-physical systems[END_REF]. The resulting systems have specified structure, low level of modularity and low level of interoperability. In the worst case, the existing system must be reconstructed before it applies new technologies for SM.

A configurable SMS is a manufacturing support system that dynamically composes unit level manufacturing services to satisfy manufacturing requirements. To be configurable, a whole packaged service should be decomposed into unit level services and be interoperable. Configurable SMS enables service oriented architecture based manufacturing support systems, and these systems can be operated with lower cost and easier management than existing systems, and can provide the most appropriate services to satisfy manufacturing requirements.

To prepare the era of SM, manufacturing services required should be collected and generalized. Thus, in this paper, we tried to start by analyzing one instance. We selected one production planning service as our target service to be analyzed, and discussed its decomposition and applicability of new technologies for SM. Section 2 describes target service details and its decomposition into unit services according to the standard model. Section 3 identifies the limitation of these services and opportunities to improve these services in the era of SM. Section 4 concludes the paper and discusses future work.

2

Target service description

Target service details

The target service is Production Planning and Management. This service is performed by three modules: (1) order-processing, (2) production-planning, and (3) productionmanagement. Each module interoperates through a specified interface. The orderprocessing module is involved in defining the relative importance of order, and selection of orders that will be serviced. The production plan will be based on the customer orders selected during order processing. The production-planning module generates a production plan considers manufacturing capability. The productionmanagement module tracks production and detects abnormal conditions. After detecting an abnormal condition, if the uncommitted production plan (future plan) is affected critically, then the production planning module modifies plan to consider the effect of abnormal condition.

This service covers production planning and revising of the plan when an abnormal situation happens. Specifically, the scope of this service is classified into level 3 and level 4 according to the functional hierarchy model [3]. Production-planning module performs level 4 activities, and the production-management module performs level 3 activities. This functional hierarchy model does not consider order processing (Fig. 1).

In the functional data flow model [3], the target service's scope covers orderprocessing, production scheduling, and production control functions. The order processing function is enabled by the order-processing module, and productionschedule function is enabled by production-planning module, and production control function is enabled by production-management module (Fig. 2).

Target service decomposition

We decomposed our target service into functions according to the functional data flow model, these functions order processing, production schedule, and production control. Each corresponds to a module of the target service. Each function is decomposed into sub-functions, which are acting as unit services in service-oriented architecture. Detailed description of sub-functions are as follows (Fig. 3).

• Order processing includes order prioritization, order selection, and order consolidation.

─ Order prioritization determines the relative importance of production orders, and uses it when partitioning an order if production cannot be performed. It generates the production order list with each order's priority. ─ Order selection determines which order to be produced in this scheduled period and generates the production order list for production schedule. Order selection should consider many attributes such as due date, production and transportation lead time, order priority, and minimum order quantity. ─ Order consolidation merges orders that have the same attributes such as product model group, due date, and special production requirements. This step reduces the number of variables used in the production schedule. ─ By these functions, the initial orders become production orders which are the input of the production schedule function.

• Production schedule includes product definition reference, capability reference, production request generation, schedule modification, and availability offer. ─ Product definition reference includes shared information between product production rule, bill of material, and bill of resources [3]. The information is related to how to produce this product. The information includes the parts and the numbers of them required to be assembled into this product, the operations required, and other customer-specific requirements. This information ensure production of exactly the required product. ─ Capability reference includes the production resources information including personal resources capability, equipment capability, and material capability. We use this information to prevent our schedule from exceeding the production capability. ─ Production request generation outputs requests for production. After the scheduling, the result of production schedule should be shared to ensure efficient production. The production request includes when and how many items should be produced or assembled, how many materials to be used, and where the items should be delivered. These production requests are generated according to production schedule. ─ Schedule modification adjusts the given schedule according to order and production environmental changes. We should modify our schedule if these changes happen frequently. ─ Availability offer provides availability information on whether components are available. After the scheduling, some orders are fulfilled whereas others are not.

Information about availability is conveyed to the customer and the order is mediated. ─ By these functions, requests production operation and availabilities for the production orders are generated. • Production control includes production response generation, identification of event and alarm information, and production capability management. ─ Production response generation outputs the production result data from the requests. Production response includes requested production quantity, actual production quantity, produced site, area and facility information, worker information, and start and end time of production operation. This process is required, to track the production requests and to compare the difference between the plan and real production. ─ Identification of event and alarm information identifies special problems that can affect to production; i.e., facility breakdown, drop of quality or yield, material shortage and other abnormal signs. ─ Production capability management manages personal, facility, material and energy capability during production. This component manages the records of committed capability usage and updates the history according to the production. This component also manages available capability information. ─ By these functions, the production responses are fed back to production schedule function to modify the schedule, and the capability is updated according to the real situation.

Limitations and opportunities

Limitation of target service

The services had limitation when the provided functions depended on the users' decision. Users may fail to make consistent and optimized decisions when they use the Fig. 3. Target service decomposition into unit level services production-planning service because of its high complexity [START_REF] Lanza | Ad-hoc Rescheduling and Innovative Business Models for Shock-robust Production Systems[END_REF]. In addition, because sensor and data gathering techniques are they should make decisions increases at some real-time decision-making points.

Order prioritization is critical to determine which order is produced or not. Improper priority can cause loss of critical customers' business because the priority of their order has been reduced and the schedule is prone to ignore lower-priority orders. However, order prioritization is done manually in many enterprises. Some simple rules were used: the highest priority is given to for the most frequent and most important customers, and the lowest priority is given to for small orders. Manual determination of order priorities causes operational problems, which result from inconsistent prioritization policy, and leads to inappropriate optimization.

For another example, schedule modification was dependent on the planners' decision. After the order or production environmental changes were reported, planners make decisions about the production, including cancellation of committed production request, re-allocation of facilities and materials, and determination of re-scheduling period. These decisions take time, but the planner cannot keep up with all change in order or production environment.

Opportunity discovery

New technologies and methods can be introduced to develop new services, or to improve services. Computational components and physical components of manufacturing enterprises are becoming increasingly seamlessly and closely integrated to perceive changes in the real system [START_REF]Workshop report on foundations for innovation in cyber-physical systems[END_REF]. Current efforts in the cyber-physical systemsbased approach will produce many new value-creation opportunities for future manufacturing [START_REF] Lee | Recent advances and trends in predictive manufacturing systems in big data environment[END_REF]. We will describe the opportunities application to our target service (Fig. 4).

At first, big data and predictive analytics can be used to innovate the services. For example, from the big data and predictive analytics, the past order prioritization and selection history are analyzed and patterns can be recognized. Pattern-recognitionbased order prioritization and selection can support consistent and optimized decisionmaking.

IoT and real-time information can be used to innovate manufacturing services. For example, real-time information gathering and processing enable real-time identification of event and alarm information from various sensors attached to the facilities. According to this real-time information, real-time production responses and dynamic schedule modification are possible [6, 7, and 8].

In addition, predictive analytics enables predictive maintenance, which in turn enables predictive maintenance-based production planning. Many approaches use fixed or periodic (deterministic) maintenance schedules; this time-based and hands-on equipment maintenance is still the norm in industrial processes, but this practice may be inefficient [START_REF] Hashemian | State-of-the-art predictive maintenance techniques[END_REF]. Production plan to exclude these unnecessary maintenance events increase their effectiveness.

Conclusion & future work

This paper described a target service, and decomposed function into unit services. Our target service consists order processing, production schedule, and production control functions, and each has several sub-functions (unit services). Several methods and new technologies, such as IoT, big data analysis, cyber physical system, and predictive analytics, can be used to innovate current unit services and whole function.

Towards SM, we plan to collect more instances, and we will generalize the set of manufacturing services from these instances. These services will be analyzed, and new and advanced services from their improving opportunities and relationships will be discovered. The services will be decomposed into unit level services to enable the dynamic composition of manufacturing services for specific requirements.

Acknowledgement

This work was partly supported by the ICT R&D program of MSIP/IITP [B0101-15-0650, Development of Smart Manufacturing Operation Platform for Hightech Industry].

Fig. 1 .

 1 Fig. 1. Scope of target service in the functional hierarchy model

Fig. 2 .

 2 Fig. 2. Scope of target service in the functional data flow model


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