Samuel Dos Santos

Oduvaldo Vendrametto
email: oduvaldov@uol.com.br

Miguel León González
email: miguel.leon@uol.com.br

Creusa Fernandes Correia

Samuel Dereste
email: samuel_dereste@yahoo.com.br

Santos

Potential of Building Information Modeling -BIM -Tools Inside Brazilian Civil Construction Scenery

Keywords: CAD, BIM, Software productivity, Basic Projects, Final Projects

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

The civil construction industry in Brazil has been suffering, since 2006, a great amount of investments that resulted in a great development in this area, since housing construction until infrastructure works. Besides, problems with project development and construction process are very common in this area. When compared with other industries of the country, it is still considered delayed because of work organization, work division, labor, etc. [START_REF] Peralta | Um modelo do processo de projeto de edificações, baseado na engenharia simultânea, em empresas construtoras incorporadoras de pequeno porte[END_REF].

Analyzing the project tools used in this area worldwide, the CAD -Computer Aided Design -software are very common. This family of tool was responsible for the replacement, from clipboard to computer, of the project process in the engineering area. Used in the aeronautics, mechanics and construction, it has made the project process more effective, allowing the utilization of digital files that could be transmitted and edited in a faster way, changing the scenario of project development.

In the civil construction area, the CAD tools have presented bottlenecks of integration that difficult the evolution in a vector platform. To allow the integration with another software, it is necessary the joint of information that are not possible in this platform. Considered a CAD evolution, emerges the BIM -Building Information Modeling -tools.

The main difference between CAD and BIM tools is the object construction. While CAD are vector information, the BIM models are parametric, which allows the insertion of a different kind of information, like material type, cost, time do produce, codes, etc. Other important characteristic is the possibility of project development in different integrated platforms, what allows different professionals (Architects, Engineers, and Designers) working in a same model real-time, what wasn't possible in CAD platforms.

The BIM technology has been used worldwide, and according to [START_REF] Migilinskas | The Benefits, Obstacles and Problems of Practical Bim Implementation in 11th International Conference on Modern Building Materials, Structures and Techniques, MBMST[END_REF][START_REF] Meireles | Estratégia para uma integração avançada do BIM no processo construtivo in 3º Seminário BIM -Sinduscon[END_REF], in order to get a successful BIM implementation is necessary the adjustment of projects development variables that need to be carefully studied for a better project performance. In Brazil, the BIM technology have been implemented in some privates and public enterprises like Brazilian Army and Foundation for the Education Development of Sao Paulo State -FDE, in search of better project development routines.

The goal of this paper is to analyses the BIM tools potential in Brazilian scenery, stablishing a comparison between the performance between CAD and BIM tools. The strategy to develop this paper was based on a technical review focused on periodical papers as well as a survey applied of experts of project development in Brazil. This paper is organized into sections as follows: introduction, technical review, case study, discussion, and finally, conclusions and references.

-Technical review

Project development in Brazil

Project process has been suffering, in Brazil, a big conceptual evolution, that amplify their function in the process. Nowadays projects are very important because they are a font for building process improvement. The importance of project elaboration is growing because it is the major source of improvement of building performance, reducing production costs and occurrence of faults in both product and process, generating an optimization in the implementation activities.

In this stage, the decision-making affects the costs, speed of execution and quality of project. If the right decisions are not taken at this stage, many problems can arise and be solved by different professionals, who are not necessarily qualified, contributing to higher costs and losses [START_REF] Peralta | Um modelo do processo de projeto de edificações, baseado na engenharia simultânea, em empresas construtoras incorporadoras de pequeno porte[END_REF][START_REF] Franco | Aplicação de diretrizes de racionalização construtiva para evolução tecnológica dos processos construtivos em alvenaria estrutural não armada[END_REF].

Advances in project development were motivated by various market environmental factors in challenge of greater excellence in costs that could make companies more attractive to customers, who are becoming more rigorous. It can be seen, at Fig. 1, the importance of early stages (viability, conception and project development) for project development. Despite the low initial investment of resources, there is great potential for improving process, reducing the failures and enabling cost reduction. Adapted from [START_REF] Franco | Aplicação de diretrizes de racionalização construtiva para evolução tecnológica dos processos construtivos em alvenaria estrutural não armada[END_REF] According [START_REF] Peralta | Um modelo do processo de projeto de edificações, baseado na engenharia simultânea, em empresas construtoras incorporadoras de pequeno porte[END_REF], some entrepreneurs in Brazil understand projects like a cost in productive scenery. Great part of the enterprises starts raising money before construction (residential buildings). At this logic, the projects development has been seen like an expense, and the production team solves the problems of construction, that should be resolved before execution, in other words, at construction. A major investment at project development (fig. 2) allows costs reduction and redistribute de the payments during construction. It is possible because of the mayor variables control and project compatibility.

CAD Tools

The first applications of computers to assist the engineering steps began in the 1950s, when the Massachusetts Institute of Technology (MIT) started the discussion of CAD technology. CAD systems of this generation were limited to the description of twodimensional geometric entities, creating and manipulating drawings in monochrome graphics terminals. According [START_REF] Souza | Tecnologia CAD/CAM -Definições e estado da arte visando auxiliar sua implantação em um ambiente fabril in XXIII Encontro Nacional de Engenharia de Produção -ENEGEP[END_REF], these systems has already propitiated advantages such as possibility of sending and receiving drawings by electronic means; management of drawings and information; precision in the design; faster recovery and modification or updating drawings.

During the years 1960-1980, the use of CAD systems has limited the application in large companies such as aerospace and automotive, because of the high costs involved, since software / hardware until qualification of the workforce, which required users with a greater degree of statement. However, at the end of the 90s, with the development of the Windows Operating System, a very robust for applications in PCs, there was a migration of companies that developed their UNIX systems for Windows. This fact has reduced the cost of hardware and the need for highly specialized users. In these first CAD tools, construction elements were the simple junction of geometric entities such as lines, arcs and curves. It was the direct transfer of drawing executed manually on the drawing board to the computer [START_REF] Souza | Tecnologia CAD/CAM -Definições e estado da arte visando auxiliar sua implantação em um ambiente fabril in XXIII Encontro Nacional de Engenharia de Produção -ENEGEP[END_REF].

Besides all undeniable qualities of CAD implementation on project processes, for AEC -Architecture, Engineering and Construction -area, the CAD tools presented bottlenecks of integration quite difficult to be overcame. The vectorial software architecture became difficult CAD platform integration with other software, and this lack made the emergence of new software.

BIM Tools

BIM tools can be defined like CAD platforms improvements aiming AEC area. The BIM implementation is the utilization of information systems (IS) in the construction industry. It has been an issue of great importance in order to enhance the effectiveness of construction projects throughout their life cycle and across different construction business function, since construction until utilization [START_REF] Jung | Building information modelling (BIM) framework for practical implementation in Automation in Construction[END_REF]. Fig. 3. -BIM Instances [START_REF] Migilinskas | The Benefits, Obstacles and Problems of Practical Bim Implementation in 11th International Conference on Modern Building Materials, Structures and Techniques, MBMST[END_REF] The main difference between BIM and CAD tools is the architecture of the software. The CAD software structure is vectorial while BIM tools are parametric. This characteristic permits the development of collaborative and tridimensional objects, where different professionals can work integrated. The BIM utilization on AEC area can integrate all the whole project process, since conception until construction and operation (fig. 3) [START_REF] Migilinskas | The Benefits, Obstacles and Problems of Practical Bim Implementation in 11th International Conference on Modern Building Materials, Structures and Techniques, MBMST[END_REF].

These tools are used for visualizing and coordinating in the AEC (architecture, engineering and construction) area. By definition, permits avoiding errors and omissions, improves productivity, support scheduling, safety, cost and quality management. It incorporates all the building components, including geometry, spatial relationships, properties and quantities [START_REF] Chen | A BIM-based construction quality management model and its application in Automation in Construction[END_REF][START_REF] Volk | Building Information Modeling (BIM) for existing buildings -Literature review and future needs in Automation in Construction[END_REF].

In general steps, the use of the tool improves an increase of efficiency and precision in project process, reduces the errors with a better information coordination, allows the simulation of some project components, generating of documentation to production, reduces the maintenance costs [START_REF] Volk | Building Information Modeling (BIM) for existing buildings -Literature review and future needs in Automation in Construction[END_REF].

The enterprises are implementing BIM tools in their processes but this process are not equal worldwide. In the USA, for example, there is a great government effort for BIM implementation while in Brazil this implementation is happening in some companies alone. Therefore, to understand the BIM tools potential in front of CAD tools, there was made a case study to discuss about this subject.

3

Case Study

To understand the potential of BIM besides CAD tools in AEC enterprises of Sao Paulo region, in Brazil, there was made an online survey to experts, searching information about, last year:

-Type of projects developed; -Total area projected; -Number of professionals involved on project development; -Total time spent on project development; -Total time spent by each professional on project development; -Team experience in software utilization. This information could permit the establishment of metrics that could define the potential of the tools on project development in Brazilian scenery.

-Sampling

Ten companies of Sao Paulo Region were interviewed, formed by small, medium and large companies. There was 60% composed by small companies, 30 % by medium and 10 % large ones (fig. 4). The types of projects developed by the company are important to show how they are using of technology. To this survey, of respondents, 37,5% were big buildings projects focusing only architecture, 25% were little and medium building projects focusing only architecture, and 37% were infrastructure projects and execution (fig. 5).

-Software utilization and users profile

From respondents, 44% of the companies uses BIM solutions while 67% of the respondents uses CAD solutions (fig. 6). The average experience of the companies using the tools are 10 years to BIM users and 12 years to CAD users (fig. 7).

-BIM x CAD productivity analysis

Having a productivity parameter of the tools, there was made an analysis, in the last 12 months, about the quantity of projects developed by each company, analyzing: number of projects developed, square meters projected, professionals involved in the process and time expended by each designer. This information permitted the analysis of the time spent for square meter projected.

Besides these particularities, the tool utilization can change with particularities of project characteristics in construction area. There was made a comparison between the different project development steps in an enterprise. To initial steps, the designer spent less time and generates gross floor area compared with final projects (for execution) where the level of detailing is more effective. To compare these differences, there was compared the productivity between enterprises.

The results have shown that, to Basic Projects, the BIM users spent 0,44 h for square meter developed while CAD users spent 1,55 h for square meter. To Final Projects, BIM users spent 0,74 h for square meter while CAD users spent 1,08 h for square meter (figs 7,8).

Discussion

The BIM experts [START_REF] Migilinskas | The Benefits, Obstacles and Problems of Practical Bim Implementation in 11th International Conference on Modern Building Materials, Structures and Techniques, MBMST[END_REF][START_REF] Souza | Tecnologia CAD/CAM -Definições e estado da arte visando auxiliar sua implantação em um ambiente fabril in XXIII Encontro Nacional de Engenharia de Produção -ENEGEP[END_REF][START_REF] Jung | Building information modelling (BIM) framework for practical implementation in Automation in Construction[END_REF][START_REF] Migilinskas | The Benefits, Obstacles and Problems of Practical Bim Implementation in 11th International Conference on Modern Building Materials, Structures and Techniques, MBMST[END_REF][START_REF] Chen | A BIM-based construction quality management model and its application in Automation in Construction[END_REF][START_REF] Volk | Building Information Modeling (BIM) for existing buildings -Literature review and future needs in Automation in Construction[END_REF] lists the qualities and effectiveness in tool utilization, besides they don't establish a difference of project development and its steps. The BIM tools, compared with CAD solutions, are more efficient, but, considering the project step, the differences are significant. The utilization of BIM tools to initial projects spent 0,44 hour for each square meter developed against 1,55 hour for each square meter in CAD tools. This fact denotes the efficiency of the tool in initial projects, where the time spent for each square meter is lower than other project steps.

To final projects, in both technologies, designers needed to spend more time in activities development, and the time grown up to 0,74 hour for each square meter developed by BIM users, and 1,08 hour for each square meter developed by CAD users. This consequence of different project instances definitions is not necessary at the initial projects. Even thought, BIM users spent less time than CAD users.

Another aspect to be considered, discussed by the authors cited, is the growing demand of informatics tools integration. BIM tools allows an integration of different project instances, what can permit, in the future, an optimization of the project time production in the final projects.

Conclusions

The informatics tools used in the civil construction scenario modified the project process development since their implementation. CAD tools became the project process more effective, but with difficult integration bottlenecks that was broken by BIM tools implementation.

The comparison of productivity between BIM and CAD shows that the first are more efficient than the conventional tools, considering different companies scenarios. Basic projects development using BIM tools spent 30% of the time used by CAD tools. It can be explained by the modeling facility interface. Otherwise, to final projects, BIM tools spents 68% of the time spent by CAD tools, what ratify the efficiency of them.

In the Brazilian scenery, the viability of BIM implementation can be guaranteed by the results obtained, demonstrating that even small offices can get good productivity returns with the implementation of the technology.

Fig. 1 .Fig 2 .

 12 Fig. 1. Investment in Projects Fig 2. Costs and Monthly Payments Adapted from [4]Adapted from[START_REF] Franco | Aplicação de diretrizes de racionalização construtiva para evolução tecnológica dos processos construtivos em alvenaria estrutural não armada[END_REF]

Fig. 4 .

 4 Fig. 4. Companies Profile Fig 5. Business Line

Fig. 6 .

 6 Fig. 6. Users type percent Fig 7. Time Experience

Fig. 7 .

 7 Fig. 7. BIM Users Fig 8. CAD Users

Acknowledgment

The authors would like to thank CAPES (Coordenação de aperfeiçoamento de pessoal de nível superior) and Paulista University (UNIP) for the financial support to develop this work.


Børge Sjøbakk
email: borge.sjobakk@sintef.no

Lars Skjelstad
email: lars.skjelstad@sintef.no

Proposing a Standard Template for Construction Site Layout: A Case Study of a Norwegian Contractor

Keywords:

Having an efficient construction site layout can significantly impact the productivity, cost and safety of a construction project. Construction site layout planning is therefore recognized as a critical step in construction planning by researchers. In literature this is often described as an optimization process where some objectives (e.g. safety, cost savings) are pursued within the constraints of the site and facilities requirements. Such models are usually complex and difficult for practitioners to apply, and usually result in each project having its unique site layout plan. The authors challenge this by proposing a standard layout template that can easily be utilized in planning of multiple construction sites. It is argued that each site should be treated as a factory and that similarity between sites should be pursued due to the nature of the construction industry. The template has been developed in collaboration with a Norwegian contractor, utilizing the action research approach.

Introduction

It is generally agreed that having an efficient site layout can significantly impact the productivity, cost and safety on construction sites [START_REF] El-Rayes | Trade-off between safety and cost in planning construction site layouts[END_REF]. Planning of a site layout involves identification of temporary facilities (TFs) needed to support construction activities, such as barracks, workstations and cranes, and appropriate positioning of the TFs within the boundaries of the construction site [START_REF] Tommelein | Site-layout modeling: How can artificial intelligence help?[END_REF]. The site layout tries to meet multiple objectives, such as minimizing hazards, travel distance and material handling time and avoiding obstruction of flows of material, equipment and personnel [START_REF] Tommelein | Site-layout modeling: How can artificial intelligence help?[END_REF][START_REF] Elbeltagi | Dynamic layout of construction temporary facilities considering safety[END_REF]. Usually, all these objectives cannot be met at the same time, and since the early 1970s construction site planning has received much attention from researchers within mathematical optimization [START_REF] Elbeltagi | Schedule-dependent evolution of site layout planning[END_REF][START_REF] Isaac | Sadeghpour A A comparative study of layout planning problems[END_REF]. Since then a range of models have been developed to automatically generate optimal layouts for construction sites [START_REF] Andayesh | Dynamic site layout planning through minimization of total potential energy[END_REF].

In spite of its importance, site layout planning has often been either overlooked or considered to be of less importance by practitioners [START_REF] Tommelein | Interactive dynamic layout planning[END_REF]. Often, site layout objects are located on a first-come first-served basis at the sites [START_REF] Andayesh | Dynamic site layout planning through minimization of total potential energy[END_REF]. When planned the layout is often determined in an ad hoc manner based on various factors, such as rules of thumb, expertise, code of practice and previous experience [START_REF] Chau | A knowledge-based system for construction site level facilities layout[END_REF]. Such methods have traditionally been preferred over advanced optimization models by practitioners due to their simplicity [START_REF] Tommelein | Site-layout modeling: How can artificial intelligence help?[END_REF]. However, a consequence of such approaches is that the site layout is greatly impacted by the preferences of the person responsible for the design of the layout [START_REF] Tommelein | Site-layout modeling: How can artificial intelligence help?[END_REF].

The authors take the stance that a tool to support practitioners in construction site layout planning should be easy to use, require a minimum of data and promote similarity between different construction sites. The construction site should be viewed as a production plant in that TFs are located in a predefined manner relative to each other, the building and the site. The layout should sufficiently incorporate concerns for travel distances, safety, etc. without requiring vast effort put into the pursuit of an optimal solution. Further, it should be recognizable for employees, vendors and other actors visiting the site to minimize the time used searching for equipment, goods and other facilities. This paper proposes such a tool in the form of a standard template for construction site layout. The template can be used by a contractor (or an architect) to rapidly establish the construction site layout in a consistent and recognizable way, and communicate the layout to relevant actors. It has been developed in close collaboration with a Norwegian contractor.

The remainder of the paper is structured as follows: First, the research method and case company are described. Thereafter, some theoretical background on the construction site layout problem is described. This is followed by a description of the proposed template, including how it was developed together with the case company. Finally, the paper is concluded.

Case Description

The research is carried out utilizing the actions research method. In action research, the researchers and the problem holder (in this case a Norwegian Contractor) collaborate in solving real life problems while they keep a research interest in mind [START_REF] Greenwood | Introduction to action research : social research for social change[END_REF]. This creates a mutual dependence on the researchers' and the problem holder's skills and competences, which in turn generates new knowledge for both parties [START_REF] Greenwood | Introduction to action research : social research for social change[END_REF]. The researchers and the problem holder are both partners in a three-year research project related to high performance work systems and efficient industrialized operations in project-based industries in Norway.

The problem holder is a contractor located in the middle of Norway. It mainly carries out construction within commercial building, public works (e.g. schools, culture centers, sports installations) and large-scale housing projects. The company has traditionally focused on carpentry; however, a few years ago it acquired a concrete work company from the same region. In large-scale projects with turnkey contracts the company collaborates with, and coordinates, a number of subcontractors within multiple disciplines, such as HVAC and electrical installation.

The company has developed some standard operating procedures based on lean construction. This is mainly concerned with the Last Planner methodology [START_REF] Ballard | The last planner system of production control[END_REF], where trade foremen set up realistic weekly work plans and explore inter-disciplinary dependencies through weekly work planning meetings while keeping the master schedule in mind. Further, the different trades work through the building in a predefined manner; each trade completes its work in a room or section, proceeds to the next one and is succeeded by another trade. This is carried out from the top to the bottom of the building to reduce spillage in completed areas. In this way, the different trades can work in parallel without getting in each other's' way.

When starting new projects, the company has traditionally operated with simplistic and static site layouts, if any, often suggested by the architect of the project. Often, the site layout has evolved in a more ad hoc manner, with the first trades at the site (usually concrete work) defining the site layout.

The contractor is often involved in several parallel projects, causing the company to man different sites simultaneously. The company organizes its workforce in several multidiscipline teams, with the size of the teams reflecting experiences with previous projects. For example, the company claims that teams of 6-12 people are optimal for completing the carpentering in an apartment. Yet, lack of material, vacations, injuries etc., necessitates that people move from one site to another from time to time, in order to keep all teams within the preferred size and all projects to meet their due date.

No matter how well planned a single project is, time is spent searching for materials, seeking information, accessing nearest waste-containers etc. Moving personnel between sites and having guest workers on site increases time spent on non-valueadding activities. The need for a standardized site layout was therefore raised by both workers and management.

3

The Construction Site Layout Challenge

Designing a good construction site layout is a challenging task. Available site space is often a limited resource [START_REF] Tommelein | Interactive dynamic layout planning[END_REF], and the site topography and location of fixed facilities within the site often restrict the choice of layout [START_REF] Chau | A knowledge-based system for construction site level facilities layout[END_REF]. Within these boundaries required temporary facilities (TFs) should be dimensioned and appropriately positioned in order to achieve smooth and low-cost flow of materials, people and equipment within the site while maintaining safety concerns [START_REF] Tommelein | Site-layout modeling: How can artificial intelligence help?[END_REF][START_REF] Elbeltagi | Dynamic layout of construction temporary facilities considering safety[END_REF].

In establishing a construction site layout/utilization plan, numerous aspects should be addressed [START_REF] Elbeltagi | Dynamic layout of construction temporary facilities considering safety[END_REF]11,[START_REF] Zouein | Genetic algorithm for solving site layout problem with unequal-size and constrained facilities[END_REF]: the site boundary must be identified; required TFs need to be determined based on planned project activities; size needs and other constraints associated with each TF must be established; the relative position of each TF must be decided; and, the timing of the establishment and removal of the TFs during the project must be defined. In practice, however, the construction site layout is often determined on a first-come first serve basis [START_REF] Andayesh | Dynamic site layout planning through minimization of total potential energy[END_REF], with the detailed site layout being left to the day-to-day scheduling of trade foremen and managers [START_REF] Chau | A knowledge-based system for construction site level facilities layout[END_REF]. This can lead to decreased safety and productivity [START_REF] Andayesh | Dynamic site layout planning through minimization of total potential energy[END_REF], with inappropriate locations often leading to relocation of TFs or extra material handling that could have been avoided [START_REF] Chau | A knowledge-based system for construction site level facilities layout[END_REF]. This is especially the case when space is not a limited factor in projects and TFs are located randomly within the site boundaries [11]. According to [START_REF] Tommelein | Site-layout modeling: How can artificial intelligence help?[END_REF], empirical evidence suggest that the layout is affected by: (1) the role of the person doing it; (2) a person's level of involvement with the project; (3) the personal relationships between individuals making layout decisions and their authority within the organization; (5) a single person choosing among alternative strategies depending on the project's nature.

As construction site layout is an exercise where multiple, often conflicting objectives are pursued within the restrictions of the construction site and project details, it has captured the interest of researchers within mathematical optimization for several decades [START_REF] Elbeltagi | Schedule-dependent evolution of site layout planning[END_REF][START_REF] Isaac | Sadeghpour A A comparative study of layout planning problems[END_REF]. Numerous models have been have been developed to automatically generate optimal layouts for construction sites [START_REF] Andayesh | Dynamic site layout planning through minimization of total potential energy[END_REF]. The earliest construction site layout planning (CSLP) models generated static layouts spanning the entire project duration [START_REF] Elbeltagi | Schedule-dependent evolution of site layout planning[END_REF], whereas more recent models typically incorporate concerns for changes over the duration of the construction projects. These are often denoted dynamic site layout planning (DSLP) models to distinguish them from static CSLP models [START_REF] Elbeltagi | Dynamic layout of construction temporary facilities considering safety[END_REF][START_REF] Andayesh | Dynamic site layout planning through minimization of total potential energy[END_REF].

From a research point of view, there are several challenges associated with existing construction site layout models [START_REF] Ning | A decision-making system for construction site layout planning[END_REF]: there is an overweight of static CSLP models; FTs are treated as rectangular blocks (denoted equal-area CSLP models); most of the CSLP research concentrates on improving various optimization algorithms instead of establishing how to select the best out of proposed layouts; and, many models are single-objective optimization (SOO) models that fail to incorporate concerns for multiple layout objectives. From practitioners' view, there are several practical shortcomings of these models that make them prefer simple and well-understood models [START_REF] Tommelein | Site-layout modeling: How can artificial intelligence help?[END_REF]: expertise is required for selecting an appropriate model and formulating each layout problem; the models require a substantial amount of data as input; the models are uneasy to use and alter; and, when substantial simplification is introduced in order to use a model, the results from it may be difficult to interpret.

From the authors' point of view, a large shortcoming of existing models is that they result in each construction project having its own unique site layout [START_REF] Zolfagharian | Current Trends in Construction Site Layout Planning[END_REF]. Arguably, the actors on site will be able to move most easily, quickly and safely within the site when the site layout in some way is standardized and recognizable. This especially applies for contractors with several parallel and sequential projects, which are able to reap learning effects from each project and apply in the others. As is evident, tools to support efficient construction site layout design must also be easy and fast to use, in order for practitioners to adapt them. In the next section, such a tool is proposed.

Proposing a Template for Construction Site Layout

A lot of research is done within the field of site optimization and lean construction.

Still we find that many site optimization methods are too comprehensive to be carried out in construction firms, and also they often rely on a lot of input that is not available with sufficient precision at the time needed. Lean construction has provided valuable input on planning, whilst site layout, 5S, Poka-Yoke and waste in general still needs to be implemented to a larger degree. The proposed model opens for such activities.

Considering aspects that need to be addressed when designing the site layout as a starting point, the following steps were followed in order to develop a standardized site layout to be used as a template for future site layout planning: (1) Identification of temporary facilities (TFs) that should be included in the site layout; (2) establishment of reciprocity between facilities through a closeness rating analysis (CRA); (3) use of the CRA to establish site areas; (4) establishment of relationships between building and site ambit, as well as reciprocal distances between the different areas on site; (5) mapping of the different areas in a generic construction site template. With respect to the latter, the main side of the site, normally the one with road access, was defined and denoted side A. Further, sides B and C, which are secondary in terms of access, were also defined. On large building sites, these sides are often available. Finally, it was decided what must be located on side A, and what might be located on sides B and C (and even D) due to lack of space, improved access to building, or due to different project phases on different sides of a large building.

The TFs include all equipment and locations needed during the construction period. In collaboration with the case company, the following TFs were identified: walkway; barracks; tower crane; power supply; equipment containers; waste containers; entry/exit; material receipt; area for return of goods; inventory; workstation for masonry; parking/area for emergency vehicles; traffic artery; workstation for plumbing; workstations for others; and, the main entrance of the building. In addition the site might have areas that are not available due to preparation for gardens, parking lots etc., that also is expected to be completed alongside the building itself. These areas are simply considered not available for TFs.

A closeness rating analysis (CRA) was carried out to identify TFs' reciprocal dependencies (Fig 1). This is a way of rating layout objects against each other with respect to closeness importance, based on considerations such as frequency of interaction and safety concerns. The rating itself is a matter of team-work. Managers, skilled workers and researchers discussed each intersection in the matrix to get a balanced and compromised first solution. Of course, if experiences over time show disadvantages with the chosen solution, this first designed solution is subject to adjustments. Still, it represents a well-funded first setup. The input to the analysis was derived during a 3 hour meeting including sharing of experiences and theory, and discussion before decision.

When going through the results of the analysis, some groups of TFs materialized due to their similar score/pattern in the CRA: (1) material handling (material receipt, inventory and area for return of goods); (2) barracks (barracks and parking/emergency vehicles); (3) work stations (workstations masonry, plumbing and others); ( 4) lift (tower crane); ( 5) transportation (entry/exit and traffic artery); ( 6) waste (waste containers); and ( 7) equipment (equipment containers). By grouping the TFs in such a manner made the analysis more manageable in that it simplified the task and created a sense of overview. As power supply and walkways are needed on multiple locations, it was decided to leave them out of the analysis and rather draw these up where and when needed.

Fig. 1. Closeness Rating Analysis for Construction Site Facilities

The next step was to determine how these groups could be distributed over the available site. In doing so, the researchers established a priority chart showing the relationships between the groups of TFs and the distance from the building to the site ambit (Fig. 2). The next step was to transfer this into a schematic illustration of a construction site, resulting in the proposed template. This was done by analyzing the CRA and the priority chart, and coming up with additional requirements to the layout. For example, the building must be accessible from all sides in terms of a walkway. Further, it is not desirable to spread over multiple sides of the building if there is sufficient space on one side. The traffic artery should force one-directional traffic flow. Power supply need to be a grid on big sites, preferably with access from all sides of the building. Waste-bin access is as important as position of input material. Safety in terms of access to a defined spot with vehicles must not be compromised. Cranes also play an important role in emergency situations if available in the situation. The learnings could then be used to draw a number of possible layouts, from which the project team jointly had to identify the preferred alternative.

Our case-company landed on the layout shown in Fig. 3. If possible, it is considered an advantage with all facilities on one side. This presupposes that cranes can cover both building and the "factory side area". If not, multiple sides should be considered for the site layout. The work therefore also identified what facilities and areas to be moved out to sides B and C in terms of a priority list.

Conclusion

The constructor has implemented the new site layout and introduced it in the company as its way to arrange facilities. The project presented a doable solution for site arrangement which was developed together with the company. This increases the possibility for it to be used on a regular basis. At all construction sites a lot of time is spent on searching for materials and tools, and we suggest that this waste is reduced with the suggested model. After experience is gained, adjustments to the first developed layout can be made. A learning curve is expected as the solution is repeated a number of times. Also, between projects similarities allow for easier transfer of people according to needed progress without sacrificing too much time on getting acquainted with the new site. Management should repeat the exercise for different project phases, to build a library of standardized solutions to cover necessary dynamics into the practical solution. The method itself should be part of the company's project execution model. Its simplicity increases its applicability.

A lot of research is done within the field of site optimization and lean construction. Still we find that many site optimization methods are too comprehensive to be carried out in construction firms. Often, they rely on a lot of input that is not available with sufficient precision at the time needed. Lean construction has provided valuable input on planning, whilst site layout, 5S, Poka-Yoke and waste in general still needs to be implemented to a larger degree. The proposed model opens for such activities.

Fig. 2 .

 2 Fig. 2. Priority Chart

Fig. 3 .

 3 Fig. 3. Template for Construction Site Layout at Norwegian Contractor

Acknowledgements. This work has been conducted within the project HPWS.no funded by the Research Council of Norway. The authors would like to thank the participants of the projects for providing valuable empirical data.


Cristina De Oliveira

Nélio Danilo De Castro
email: danilomdecastro@gmail.com

João Dos Reis

Minoro Abe

Cristina Corrêa De Oliveira

Danilo Medeiros De Castro

Nélio Fernando Dos Reis

João Gilberto Mendes Dos Reis

Jair Minoro

Priority Modes of Transport for Soybeans from the Center-West Region in Brazil

Keywords: Grains, Paraconsistency, Decision-making, soybean

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Brazil was ranked as the world's eighth largest economy, with a Gross Domestic Product (GDP) of U$ 2.4 trillion dollars in 2013 [3]. Agribusiness productivity has been increasing due to the high technology employed, and accounts for 22% of the Brazilian GDP [START_REF] Brasil | Ministério da Agricultura, Pecuária e Abastecimento: Projeções do Agronegócio: Brasil 2013/2014[END_REF].

The Center-West Region is the major producing area of soybean complex, with 41,785 thousand tons [START_REF] Brasil | Ministério da Agricultura, Pecuária e Abastecimento: Projeções do Agronegócio: Brasil 2013/2014[END_REF], and accounts for 48% of the domestic production. Soybeans are the most important commodity for the Brazilian trade balance. Despite their expressive share in exports, soybeans are a low aggregate-value product and require a well-performed logistics process that can reduce costs from raw material through exports. In order to meet the demand, the organizations must evaluate new transportation ways, whether combining or not modes of transport [START_REF] Ballou | Gerenciamento da Cadeia de Suprimentos[END_REF].

The overall purpose of this work is to employ the Paraconsistent Decision Method (PDM) that allows choosing the mode of transport for soybean distribution from the Center-West Region, considering some factors such as capacity, availability, reliability, periodicity and speed. The specific objectives of this study are deciding upon a tool that might help the decision-making process involving experts from several logistics areas and considering the stakeholders' opinions, and presenting a tool that allows a quantitative evaluation of all items, which results in numerical outputs generated by the model and can be easily understood and compared.

The PDM was developed on the basis of the Evidential Paraconsistent Annotated Logic Eτ (Logic Eτ), and its main advantage lies in the fact that input parameters are set according to the experts' thinking structure, thus consolidating a collective logic translated into mathematical expressions.

Background

Paraconsistent, Paracomplete and Non-alethic Logics

In what follows, we sketch the non-classical logics discussed in the paper, establishing some conventions and definitions. Let T be a theory whose underlying logic is L. T is called inconsistent when it contains theorems of the form A and ¬A (the negation of A). If T is not inconsistent, it is called consistent. T is said to be trivial if all formulas of the language of T are also theorems of T. Otherwise, T is called non-trivial.

When L is classical logic (or one of several others, such as intuitionistic logic), T is inconsistent if T is trivial. So, in trivial theories the extensions of the concepts of formula and theorem coincide. A paraconsistent logic is a logic that can be used as the basis for inconsistent but non-trivial theories. A theory is called paraconsistent if its underlying logic is a paraconsistent logic.

Many logicians have appreciated issues such as those described above. In 1910, the Russian logician Nikolaj A. Vasil'év (1880-1940) and the Polish logician Jan Lukasiewicz (1878-1956) independently glimpsed the possibility of developing such logics. Nevertheless, Stanislaw Jaskowski was in 1948 effectively the first logician to develop a paraconsistent system, at the propositional level. His system is known as 'discussive' (or discursive) propositional calculus. Independently, some years later, the Brazilian logician Newton C.A. da Costa (1929-) constructed for the first time hierarchies of paraconsistent propositional calculi C i , 1 ≤i≤ω of paraconsis-tent first-order predicate calculi (with and without equality), of paraconsistent description calculi, and paraconsistent higher-order logics (systems NF i ,1 ≤i≤ω). Another important class of non-classical logics are the paracomplete logics. A logical system is called paracomplete if it can function as the underlying logic of theories in which there are formulas such that these formulas and their negations are simultaneously false. Intuitionistic logic and several systems of many-valued logics are paracomplete in this sense (and the dual of intuitionistic logic, Brouwerian logic, is therefore paraconsistent).

Consequently, paraconsistent theories do not satisfy the principle of noncontradiction, which can be stated as follows: of two contradictory propositions, i.e. one of which is the negation of the other, one must be false. In addition, paracomplete theories do not satisfy the principle of the excluded middle, formulated in the following form: of two contradictory propositions, one must be true [START_REF] Abe | Paraconsistent Artificial Neural Networks: an Intr Computer Science[END_REF], [START_REF] Silva Filho | Torres Logic -Introducing Paraconsistent Artificial Neural 3[END_REF]. Finally, logics that are simultaneously paraconsistent and paracomplete are called non-alethic logics.

Soybean Production

Soybeans, corn and dry beans are the main agricultural products in Brazil. Soybean complex accounts for 49% of the grain cultivation areas [START_REF] Brasil | Ministério da Agricultura Pecuária e Abastecimento, Secretaria de Política Agrícola[END_REF]. Soybeans are greatly important because of their use in animal feed and human food industries; and they are the main product exported by the Country [3] [START_REF] Brasil | Ministério Desenvolvimento, Indústria e Comércio Exterior, Secretaria de Comércio Exterior: Aliceweb[END_REF].

The grain production in Brazil is estimated at 194 million tons spread over 56.9 million hectares, i.e. three million tons per hectare. Grain crops achieved the highest productivity rate in recent years, and production is expected to reach 199 million tons in 2015, and 252 million tons in the 2023/2024 season, with a productive area increasing to 67 million hectares [START_REF] Brasil | Ministério da Agricultura, Pecuária e Abastecimento: Projeções do Agronegócio: Brasil 2013/2014[END_REF].The Center-West region has favorable topography and climate conditions, attractive prices, and large areas available for cultivation; and in 2014, it accounted for 48.5% of the Brazilian production, despite its infrastructure deficiencies.

The transportation of grains can be made through several modes of transport, which are chosen according to the features, extension and benefits of the transport network, including costs of each mode of transport. Brazil's huge geographic area of 8.5 million km 2 must be taken into account, with its 1.5 million kilometers of roads, 28 thousand kilometers of railroads, and 50,000 kilometers of navigable waterways, and four sea ports in the South and Southeast Regions that are used to export soybean grains, which totaled 36.3 million tons in 2014 [START_REF] Brasil | Ministério dos Transportes: Projeto de Reavaliação de Estimativas e Metas do PNLT[END_REF].

Soybeans are the most important commodity in Brazil and account for 14% of the Brazilian trade balance [START_REF] Brasil | Ministério do Desenvolvimento, Indústria e Comércio Exterior[END_REF]. The commodity, however, has a low aggregate-value and the choice for modes of transport may affect exports, considering that Center-West producers are between 1,000 and 2,500 kilometers away from the main Brazilian ports -the Port of Santos, located in the State of São Paulo, and the Port of Paranaguá located in the State of Paraná.

Modes of Transport in Brazil

The modes of grain transportation used in Brazil are waterways, railroads and roads [START_REF] Brasil | Ministério dos Transportes: Projeto de Reavaliação de Estimativas e Metas do PNLT[END_REF]12], and are distributed according to their ascending order of importance, respectively. Every mode of transport has operating characteristics, particularities, advantages and disadvantages.

The main characteristics of rail transport are the capacity to convey bulk freights with high-energy efficiency, low cost per ton in medium to long-distance conveyances, higher safety and lower risks of accident, robbery or theft when compared to other modes of transport [12]. Low speed and lack of flexibility concerning delivery changes are the main disadvantages of rail transport.

Water transport is advantageous for bulk cargo transportation over the open sea or through the coastline or rivers, and although freight volumes are advantageous, the good performance of this mode of transport depends on climate conditions [START_REF] Ballou | Gerenciamento da Cadeia de Suprimentos[END_REF].

Finally, the road transport is flexible for short-distance travels, but costs are highly dependent on fuel prices [START_REF]The World Bank: How to decrease freight logistics costs in Brazil[END_REF].

In Brazil, logistics costs account for 22% of the costs of export products. Those costs directly affect the GDP, with their 20% share, and transportation alone accounts for 56% of food costs [START_REF]The World Bank: How to decrease freight logistics costs in Brazil[END_REF]. The study of the modes of transport and the use of tools to elect them demonstrate the high importance of efficient transportation systems for the Brazilian economic development [11] [13].

Materials and Methods

This article aims to carry out an applied science research for exploratory purposes, which, according to Zikmund [START_REF] Zikmund | Business Research Methods[END_REF], should be carried out to solve doubtful situations or find out business opportunities, and is the first step to any subsequent research. It has a quantitative approach and uses questionnaires about the features and modes of transport. The attributes were defined as literature review. Thus, the characteristics associated to any item of transportation that one should take into account when deciding upon the modes of transport and their financial-economic aspects [START_REF] Junior | Modal choice for transportation of hazardous materials: the case of land modes of transport of bio-ethanol in Brazil[END_REF] are listed in Table 1: The development of tools that may help choosing the modes of transport is essential to the organizational strategy, and the evaluation of the performance of transportation services may be used for such purpose [START_REF] Ballou | Gerenciamento da Cadeia de Suprimentos[END_REF].

For field research were asked only road modes, rail and waterway, which are systems available for the state of Mato Grosso do Sul, to eight logistics experts engaged in the academic area, in graduate and post-graduate programs, with 4 to 27 years of experience, one of them with fifteen years of experience in productive processes and logistics operations in trade business. The opinions, interests and skills of each of them were taken into account.

We used the Saaty scale [START_REF] Saaty | How to make a decision: The Analytic Hierarchy Process[END_REF] ranging from 1 to 9, where one means low importance of a feature and nine means extreme importance of a feature for the mode of transport, with intermediate levels of importance between 1 and 9. Data were normalized by using the same proportion and converting values in the 0 to 1 interval of the PDM, called favorable evidence. The complement rule was employed for contrary evidence.

Data Analysis

This research consisted of a group decision-making, where two groups were formed according to the time of experience of their members; the first group was formed by experts with up to ten years of experience and the second group was formed by experts with more than ten years of experience in logistics systems. Each expert opinion issued by type of modal, with the degree of favorable evidence for each attribute in Table 1; the degree of contrary evidence was calculated by the complement of favorable evidence, according to Table 2, which shows an excerpt from the original study.

Rail

Size of Vehicles 0,88 0,12 0,20 0,80 0,76 0,24 1,00 0,00 Cargo Volume 0,20 0,80 1,00 0,00 0,88 0,12 0,64 0,36 Demand 0,76 0,24 0,75 0,25 0,25 0,75 0,90 0,10 Services Available 0,52 0,48 0,75 0,25 0,20 0,80 0,88 0,12 Delivery Changes 0,52 0,48 0,64 0,36 0,25 0,75 1,00 0,00 Order Fulfillment 0,52 0,48 0,54 0,46 0,40 0,60 0,75 0,25 Period of Time 0,65 0,35 0,75 0,25 0,80 0,20 0,75 0,25 Number of Travels 0,64 0,36 0,75 0,25 0,75 0,25 0,75 0,25 Handling Time 0,75 0,25 0,75 0,25 1,00 0,00 0,75 0,25 Distance 0,64 0,36 0,88 0,12 0,75 0,25 0,77 0,23 Variable Cost 0,75 0,25 0,64 0,36 0,20 0,80 0,76 0,24 Fixed Cost 0,20 0,80 0,20 0,80 0,88 0,12 0,75 0,25

The PDM was developed by using the Para-Analyzer based on Logic Eτ, with MIN and MAX operators, where MAX maximizes favorable evidences and minimizes contrary evidences in the group, and the MIN operator minimizes favorable evidences and maximizes contrary evidences between the groups. The use of both operators allows one to determine database inconsistencies [START_REF] Silva Filho | Torres Logic -Introducing Paraconsistent Artificial Neural 3[END_REF]. The level of demand depends on the security and confidence in decision-making and the responsibility it entails [START_REF] Silva Filho | Torres Logic -Introducing Paraconsistent Artificial Neural 3[END_REF]. The level of demand was set at 0.5 and the global analysis, whose result is equal to the factors' influence, is determined by the weighted average of the factors or features. The global analysis was calculated in duplicate considering only the aspects involved in the mode of transport, without taking into account the costs, indicated by the pink marker, and the global analysis with the costs, indicated in the x form by the green marker. By splitting the global analysis, we aimed to ascertain the influence of costs in the evaluation of the mode of transport.

Outcomes of Logic Eτ τ τ τ

The results indicate that the global analysis for water transport is in the central area of the Unit Square in the Cartesian Plane (USCP), which indicates a consensus in the analysis of some features, i.e. demand, delivery changes, order fulfillment, period of time and handling time, because of their low favorable evidence levels for grain transportation, as shown in Figure 1.

The global analysis for rail transport is in the truth area, which evidences that it is t most appropriate type for same area, as shown in Figure

The global analysis for road transport divergent points in the assessment, which is the volume and size. for rail transport is in the truth area, which evidences that it is t most appropriate type for transportation of grains, with all evidences falling in s shown in Figure 2. for road transport, see Figure 3, is in the truth area, with only two assessment, which is the capacity aspect with its features cargo

Conclusion

The research achieved its purpose of making, thereby quantifying detailing the items of each assessment. One may ascertain that costs did not change significantly in the evaluation and helped decision makers choose the mode of tran port.

This analysis also supports its waterway network spreads over network, and its efficient tension, with 28 thousand kilometers, the railroad network shows the best favorable evidences for grain transportation million kilometer network, Country, and any evaluation should take and size, into account, especially commodities. The research achieved its purpose of presenting a tool that allows a group decision quantifying the experts' opinions, which may be contradictory, and detailing the items of each assessment. One may ascertain that costs did not change significantly in the evaluation and helped decision makers choose the mode of tran supports the modes of grain transportation used in Brazil, given that spreads over 50,000 km, which corresponds to 3.3% of the road , and its efficient use depends on climate conditions. Despite its reduced e tension, with 28 thousand kilometers, the railroad network shows the best favorable evidences for grain transportation when all features are taken into account. With a network, road is the most popular method of transportation in the any evaluation should take some of its features, especially cargo volume , especially because of the high costs for low aggregate-value Costs group decisioncontradictory, and detailing the items of each assessment. One may ascertain that costs did not change significantly in the evaluation and helped decision makers choose the mode of trans-, given that the road Despite its reduced extension, with 28 thousand kilometers, the railroad network shows the best favorable 1.5 road is the most popular method of transportation in olume value

Fig 1 .

 1 Fig 1. Water Transportation

Fig. 2 .

 2 Fig. 2. Rail Transportation

Fig. 3 .

 3 Fig. 3. Road Transportation

Table 1 .

 1 Features of the Modes of Transport

	Aspects	Features
	Capacity	Size of Vehicles Cargo Volume
	Availability	Demand Services Available
	Reliability	Delivery Changes Order Fulfillment
	Periodicity	Period of Time Number of Travels
	Speed	Handling Time Distance
	Costs	Variable Cost Fixed Cost

Table 2 .

 2 Database of specialist's evidences

				Group > 10			Group <= 10
			spec 1	spec 2	spec 7	spec 8
	Aspects	Features	µ µ µ µ1 1 1 1	λ λ λ λ1 1 1 1	µ µ µ µ2 2 2 2	λ λ λ λ2 2 2 2	µ µ µ µ7 7 7 7	λ λ λ λ7 7 7 7	µ µ µ µ8 8 8 8	λ λ λ λ8 8 8 8

  Abe, J.M., Paraconsistent Artificial Neural Networks: an Introduction, Lecture Notes In nce 3214, Springer, 942-948 (2004) Da Silva Filho, J.I., Torres, G.L., Abe, J.M.: Uncertainty Treatment Using Paraconsistent

						Boundary
						Lines
						Borders
						Global
						Analysis
						Features
		0,4	0,6	0,8	1,0
		Introducing Paraconsistent Artificial Neural (2010)
	Central	Intelligence	Agency:	The	world	fact	book,
	https://www.cia.gov/library/publications/the-world-factbook/geos/br.html


Jin-Baek Kim
email: jinbaek@cau.ac.kr

Social Network Analysis of a Supply Network Structural Investigation of the South Korean Automotive Industry

Keywords: supply chain, supply network, social network analysis, the South Korean automotive industry

établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Many studies on supply chains investigated linear relationships between supplying and buying companies, by adopting the perspective of hierarchical value chains. However, the companies constituting a supply chain usually belong to supply chains of other companies and commonly have relationships with other companies. Hence, by adopting a network perspective on supply chains or considering supply networks rather than supply chains, one can better understand the supply chain structure of a company or an industry [START_REF] Choi | Supply networks and complex adaptive systems: control versus emergence[END_REF][START_REF] Harland | A taxonomy of supply networks[END_REF][START_REF] Kim | Effects of a trust mechanism on complex adaptive supply networks: an agent-based social simulation study[END_REF][START_REF] Lamming | An initial classification of supply networks[END_REF][START_REF] Park | Social Network Analysis for Smart Business[END_REF][START_REF] Surana | Supply chain network: a complex adaptive systems perspective[END_REF].

Social network analysis (SNA) methods have been used to study the structure of societies and to identify important entities in a society. If supply chains are modeled as a network, then SNA methods can be useful tools for analysis. Borgatti and Li [START_REF] Borgatti | On social network analysis in a supply chain context[END_REF] argued that SNA concepts are particularly useful to identify the patterns of inter-firm relationships in a supply network that lead to competitive advantages through the diffusion of information and management of material flows. Choi and Kim [START_REF] Choi | Structural embededness and supplier management: a network perspective[END_REF] pointed out that SNA methods can complement the traditional perspective on supply chain by capturing the complexity needed to understand a company's strategy or behavior.

Although the potential has been recognized [START_REF] Autry | Supply chain capital: the impact of structural and relational linkages on firm execution and innovation[END_REF][START_REF] Borgatti | On social network analysis in a supply chain context[END_REF][START_REF] Carter | The use of social network analysis in logistics research[END_REF], there are still relatively few empirical studies on real-world supply networks using SNA methods [START_REF] Kim | Modular Production and Hyundai Production System : The Case of Hyundai MOBIS[END_REF]. One reason for that is the difficulty in obtaining comprehensive information on supply chain relationships among companies, which is necessary to construct a complete social network. Another reason is because SNA methods are oriented to analyzing societies not companies working in the supply chain. Social network analysis theory and the way of interpreting results in sociology cannot be directly applied to the supply chain context. In this study, we used data from Korean Auto Industries Cooperative Association (KAICA) to construct a social network representing the supply network structure of the South Korean automotive industry. The KAICA is a non-profit organization, founded in 1962, to develop the South Korean automotive industry. Most major companies in auto parts and components manufacturing industries operating in Korea are KAICA members. The KAICA collects data every year from its members on their major customers. The data used in this paper is customer information from 275 member companies of KAICA for 2013.

The constructed supply network was analyzed based on centrality metrics. Kim et al. [START_REF] Kim | Modular Production and Hyundai Production System : The Case of Hyundai MOBIS[END_REF] proposed a theoretical framework that links widely used social network metrics to supply network constructs based on the insight earned from case-based interpretations [START_REF] Choi | Unveiling the structure of supply networks: case studies in Honda, Acura, and DaimlerChrysler[END_REF]. One conclusion from that study is that the framework can both supplement and complement case-based analysis of supply networks. However, the conclusion was based on an application to small scale supply networks (less than 50 companies) of a part of an automotive supply chain(final assembly). In this study, a relatively large scale supply network (close to 400 companies) was constructed and analyzed, based on social network analysis metrics. A more comprehensive supply network model provides an opportunity to further validate the theoretical framework but also creates challenges in applying the theory. In this study, we focused on validating and extending the theory, although we referred to Kim et al. [START_REF] Kim | Modular Production and Hyundai Production System : The Case of Hyundai MOBIS[END_REF]'s framework to interpret SNA metrics in the supply networks.

About the South Korean Automotive Industry

As of 2013, there are five major auto makers producing cars in South Korea. They are Hyundai Motor, Kia Motor, Korea GM, SsangYong Motor, and Renault-Samsung Motors. In 2013, the Hyundai-Kia Motor Group produced 3.451 million cars, which corresponds to 76% of total cars produced in South Korea [10]. GM Korea, SsangYong, and Renault-Samsung accounted for 15.1%, 6.4%, and 6%, respectively, of domestic automobile production. The number of cars produced and sold in South Korea by these five companies is shown in Fig. 1. As can be seen, all five auto makers produce more than they sell in South Korea and thus export cars overseas.

Hyundai and Kia Motor have supply chains that are vertically integrated by companies belonging to the group. Key suppliers of Hyundai and Kia Motor are Hyundai Mobis, which provides key module and system components, Hyundai Dymos supplying power train components; Hyundai Powertech supplying transmission components; Hyundai Wia supplying engine and transmission components; and Hyundai Steel providing steel material. These Hyundai-Kia Motor Group companies are under the command of a group chairman. 3

Analysis of the South Korean Automotive Supply Network Using Social Network Analysis Metrics

When building a social network model, relationships between entities may be modeled as directed or undirected links. Kim et al. [START_REF] Kim | Modular Production and Hyundai Production System : The Case of Hyundai MOBIS[END_REF] suggested that directed links are useful to describe material flows, whereas undirected links are helpful when examining contractual relationships or information flow. In this study, the supply network was modeled as both directed and undirected networks, and was investigated to understand the material flows and information flows in the supply network.

The constructed supply network was analyzed using Gephi 0.8.2, an open source software for social network analysis. The visual representation of the supply network can be seen in Fig. 2.. That graph is composed of 395 companies, including 285 KAICA member companies and their customers who may or may not be KAICA members.

Fig. 2. Visual representation of the South Korean automotive industry supply network

As stated in the previous section, the auto makers play central roles in the South Korean automotive industry. Among the first tier suppliers of the auto-makers, technology and capital intensive parts, such as engine and power train components are provided by the large-sized companies of a group, and parts requiring precision engineering, such as casted/forged parts, are supplied by medium-sized independent companies having close ties with auto-makers. The second-tier suppliers providing commodity like parts, such as iron rods, bolts, nuts, etc., are usually independent small-and medium-sized companies. Such a hierarchical structure can be ascertained from Fig. 2.

An interesting observation is that Hyundai Mobis, a module component supplier, is as distinctive as the auto-makers. Hyundai Mobis plays a key role in the Hyundai-Kia Motor Group and is recognized as the key driver of productivity and innovation. The graph seems to reflect this reality. Mando and Delphi, key module and system component manufacturers for Hyundai-Kia and GM, respectively, also have high visibility in the graph. This is also a reflection of the reality that auto makers have moved toward module-based production.

One of the most commonly used social network analysis metrics is degree centrality, which measures the number of direct ties to a node. Degree centrality can be interpreted as operational load and influential scope [START_REF] Borgatti | On social network analysis in a supply chain context[END_REF][START_REF] Kim | Modular Production and Hyundai Production System : The Case of Hyundai MOBIS[END_REF]. The degree centrality results of both directed and undirected networks were similar, as summarized in Table 1. Companies that showed a high degree centrality were mostly auto-makers or part manufacturers belonging to the Hyundai-Kia Motor Group. Kim et al. [START_REF] Kim | Modular Production and Hyundai Production System : The Case of Hyundai MOBIS[END_REF] argued that companies having high degree centrality in undirected network are the ones having strong influence on others. Considering the influence of Hyundai-Kia Motor Group on the South Korean automotive industry, this argument seems to be validated and the result shows the degree of power concentration in the South Korean automotive industry. In addition, the degree centrality of GM and Delphi was higher than its operational scale in South Korea. This result indicates that the importance of the GM group in the South Korean automotive industry may be under-estimated; and also shows the possibility of using SNA to discover new perspectives in the supply chains. Hyundai Dymos 12

Another one of the most commonly used social network analysis metrics is betweenness centrality, which measures the frequency of a node that appears on the shortest path between a pair of other nodes [START_REF] Everett | The centrality of groups and classes[END_REF][START_REF] Freeman | Centrality in social networks: conceptual clarification[END_REF]. In the social network context, the betweenness is interpreted as the degree of gate-keeping that a node does for the other nodes.

The results of betweenness centrality were different in directed and undirected network, as can be seen in Table 2. In the directed network model of supply network, two major first-tier suppliers of the Hyundai-Kia Motor Group, Hyunidai Mobis and Mando, showed the highest betweenness centrality. Companies with high betweenness centrality in the directed network model were key manufacturers of various parts, such as S&T Dynamics (powertrain components), Daewon Indusrty (car seat), Namyang Industry (steering and braking system), Central (steel rods), Yuratech (spark plugs), Halla-Visteon (climate control system), and Magna Powertrain Korea (pumps). Some of these companies (e.g. Halla-Visteon, Magna Powertrain Korea) were large-sized companies whereas others are medium sized companies.

In an undirected network model, the list of companies with high between-ness centrality was similar to the companies having high degree centrality. Kim et al. [START_REF] Kim | Modular Production and Hyundai Production System : The Case of Hyundai MOBIS[END_REF] argued that betweenness centrality in directed network indicates operational criticality, whereas betweenness centrality in undirected network is related to the role of mediating relations. When applying that argument to a result, the operational criticality argument for directed network seems to be validated, whereas the relational mediation argument appears to need further verification and refinement. In addition, the result suggests that in automotive supply network, key parts and suppliers are widely distributed to various parts beside key module components.

In terms of the number of units produced in South Korea, GM's proportion(15.1%) of the South Korean automotive industry is greater than SsangYong (6.4%) and Renault-Samsung (6%) but is significantly smaller than Hyundai-Kia(76%). However, in terms of degree centrality and betweenness centrality, GM's significance in the South Korean automotive supply network seems to be more than what is suggested by the number of produced units [10]. SssangYong and Renault-Samsung are similar in terms of the number of produced units. However, SsangYong showed higher between-ness centrality than Renault-Samsung in the directed network model, whereas Renault-Samsung's between-ness in the undirected network was higher than SsangYong's.

Based on the theoretical framework of Kim et al. [START_REF] Kim | Structural investigation of supply networks: a social network approach[END_REF], that fact can be interpreted to mean SsangYong is more operationally critical than Renault-Samsung, whereas Renault-Samsung has a greater potential to connect separated groups of suppliers. This new insight seems to make sense, yet it needs further investigation. Closeness centrality, calculated by the average of the minimal length to the other nodes, is also one of the most commonly used social network analysis metrics [START_REF] Everett | The centrality of groups and classes[END_REF][START_REF] Freeman | Centrality in social networks: conceptual clarification[END_REF]. Nine companies displayed high closeness centrality in the supply network are shown in Table 3. These companies can be classified into the following three types: 1) auto manufacturers(Hyundai, Kia, GM), 2) key module suppliers(Hyundai Mobis, Mando), and 3) companies providing commodity like products (Continental Automotive Electronics, Taeyang Metal, Youngsin Metal, Youngshin Precision) to many companies. Kim et al. [START_REF] Kim | Modular Production and Hyundai Production System : The Case of Hyundai MOBIS[END_REF] argued that companies with higher closeness centrality are those who can act autonomously and navigate freely across the network to access resources in a timely manner. This result confirms that those kinds of companies seem to be independent.

But it seems what allows the companies to access information and resources is not just closeness but the nature of the relationships with key companies.

Conclusion

It is difficult to obtain knowledge on an industry structure and dynamics through an analysis focusing on individual companies. Using the SNA approach to analyze the supply network, it was possible to better understand the structure of the South Korean automotive industry. This study confirms the potential of the SNA approach as applied to supply network studies. However, it should be noted that prior domain knowledge, as well as SNA-based analysis, on the industry helped in reaching an understanding. In this sense, the SNA methods seem to be useful in confirmatory as well as exploratory studies.

One limitation of this paper is the data. As stated earlier, most major South Korean companies in the automotive industry were included in the data. However, many South Korean companies are suppliers for overseas companies and the complete supply network of those overseas companies was not included in the data that were analyzed. Considering the trend of rapid globalization, the structure and operation of the companies belonging to overseas supply networks may affect the structure and operations of the South Korean companies. Also, because some companies that are primarily in other industries, such as electronics, are not members of Korean Auto Industries Cooperative Association (KAICA), they are not included in the supply network, which was analyzed in this research. Considering the trend of the ITautomobile convergence, the analysis may have missed some important IT companies that are critical to automotive industry.

Another limitation of this research stems from the characteristics of SNA methodologies. Important aspects of business relationships, such as intensity of relationships and scale of transactions, are hard to model as social networks. This research regarded those relationships as all being equal. Of course, by modeling the relationship this way, it is possible to obtain a new perspective from the analysis. However, especially from the practitioner's perspective, this may be considered as a significant barrier to applying the SNA to real industry examples. As Park [START_REF] Park | Social Network Analysis for Smart Business[END_REF] pointed out, SNA methods are not robust against sampling. Unlike typical statistical analysis where samples are generally independent, entities in the social network are all linked with each other and affect the result of analysis. Hence, to obtain unbiased results, the complete network needs to be modeled and analyzed.

The biggest contribution of this research to the literature is that this is the first trial on applying SNA methods to large-scale supply networks and the entire automotive supply chains of a country. Despite the limitations stated above, by building a relative large social network model containing most major South Korean automotive companies and by using a previously validated framework for the interpretation of SNA metrics in the supply network context, we believe that the results of this study have credibility.

In this study, the focus was on analyzing the overall South Korean automotive industry.

As for future research, comparative research on the supply networks of Hyundai Motor and Kia Motor and other companies will be performed. A comparison of the South Korean automotive companies and Japanese automotive companies may also be an interesting future research topic.

Fig. 1 .

 1 Fig. 1. Domestic production and sales by auto makers in South Korea as of 2013(thousand units) [10]

Table 1 .

 1 List of companies having high degree centrality

	In-degree centraility (supply load)		Degree centrality (influential scope)
	Rank	Company	Value	Rank	Company	Value
	1	Hyundai Motor	196	1	Hyundai Motor	196
	2	Kia Motor	173	2	Kia Motor	173
	3	GM	125	3	GM	125
	4	Hyundai Mobis	67	4	Hyundai Mobis	72
	5	Ssangyong Motor	43	5	Ssangyong Motor	43
	6	Renault-Samsung	28	6	Renault-Samsung	28
		Motors			Motors
	7	Mando	14	7	Mando	20
	8	Delphi	12	8	Hyundai Wia	14
	8	Hyundai Wia	12	9	Delphi	12
	8	Hyundai Powertech	12	9	Hyundai Powertech	12
				9

Table 2 .

 2 List of companies having high betweenness centrality

	Between-ness centrality in directed network	Between-ness centrality in undirected network
	(operational criticality)			(relational mediation)
	Rank	Company	Value	Rank	Company	Value
	1	Hyundai Mobis	228.0	1	Hyundai Motor	30088.4
	2	Mando		52.5	2	Kia Motor	19725.3
	3	Hyundai Dymos	40.3	3	GM	19075.0
	4	S&T Dynamics	21.2	4	Hyundai Mobis	7488.1
	5	Halla	Visteon	18.2	5	Renault-Samsung	5583.5
		Climate Control			Motors
	6	Daewon		11.5	6	Mando	3720.6
	7	Magna Powertrain	10.8	7	Hanjoo Metal	3477.0
		Korea
	8	Namyang Industries	9.0	8	Ssangyong Motor	3128.4
	9	Central		8.5	9	Hyundai Dymos	2422.6
	10	Yura Tech		6.0	10	Delphi	2393.9

Table 3 .

 3 List of companies having high closeness centrality (undirected network)

	Rank	Company	Value
	1	Hyundai Motor	1.9
	2	Kia Motor	2.0
	3	GM	2.2
	4	Hyundai Mobis	2.3
	5	Mando	2.4
	5	Continental Automotive Electronics	2.4
	7	Taeyang Metal	2.5
	7	Youngsin Metal	2.5
	7	Youngshin Precision	2.5

adfa, p. 1, 2011. © Springer-Verlag Berlin Heidelberg 2011