• Korean System Dynamics Review
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• v.15 no.1
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• pp.29-50
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• 2014

This study aims to comprehensively understand the dynamics of the dementia as a social problem and to find out its causes and solutions, using the systems thinking approach. The contents of the study are as follows. Firstly, it examines the existing studies on the dementia, draws their limitations and further presents the major variables to understand the dementia as a social problem. Second, it analyzes the structure of the causation in order to find out the dynamics of the problem. Lastly, it concludes with the suggestions to solve the problem based on its feedback structure presented in the causal loop diagrams. This study is expected to make a useful and basic material to grope for the solutions, as the first research to dynamically understand the dementia as a social problem.

• Korean System Dynamics Review
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• v.9 no.2
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• pp.129-154
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• 2008

As a practical means to upgrade urban sustainability, this paper focuses on resource cyclical systems concerned with the waste of electric and electronic equipment (WEEE) in Korea. Borrowing System Dynamics concepts and approaches, it examines behavioral changes of WEEE dynamics to observe whether the existing management methods can be readjusted. The measurement is based upon both reuse and material and thermal recycle simulation works in the individual stage of WEEE discharge, collection, and treatment, going beyond the traditional recycle-only customs. This research estimates that the newly introduced Extended Producer Responsibility (EPR) system would definitely exert a significant impact on the final stage of WEEE treatment, decreasing the final treatment volume in the first half of the research period. The trend, nonetheless, would be reversed in the second half, mainly owing to the additional waste volume originated from the local government and recycling center. Sensitivity analysis poses, among others, that the local government-supported reuse center should take charge of a pivotal role in the long run. The research also shows that sufficientand necessary conditions for the WEEE management and treatment should be given to the combined efforts, both from the private sectors and the public domains. Based on these research findings, the paper recommends that key stakeholders including the producer and the public organizations should devise how to jointly carry out specific agenda centered around partnership or network buildings.

• Korean Journal of Computational Design and Engineering
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• v.14 no.2
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• pp.69-76
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• 2009

The development of a simulation system requires many sub modules such as a dynamic module, a visualization module, etc. If a different freeware is used for each sub modules, it is hard to develop the simulation system by incorporating them because they use their own data structures. To solve this problem, a high-level data structure, called Dynamics Scene Graph Data structure (DSGD) is proposed, by wrapping data structures of two freeware; an Open Dynamics Engine (ODE) for the dynamic module and an Open Scene Graph (OSG) for the visualization module. Finally, to evaluate the applicability of the proposed data structure, it is applied to the block erection simulation in shipbuilding. The result shows that it can be used for developing the simulation system.

• Journal of Hydrogen and New Energy
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• v.32 no.1
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• pp.1-10
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• 2021

Water electrolysis technology, which generates hydrogen using renewable energy resources, has recently attracted great attention. Especially, the polymer electrolyte membrane water electrolysis system has several advantages over other water electrolysis technologies, such as high efficiency, low operating temperature, and optimal operating point. Since research that analyzes performance characteristics using test bench have high cost and long test time, however, model based approach is very important. Therefore, in this study, a system model for water electrolysis dynamics of a polymer electrolyte membrane was developed based on MATLAB/Simulink®. The water electrolysis system developed in this study can take into account the heat and mass transfer characteristics in the cell with the load variation. In particular, the performance of the system according to the stack temperature control can be analyzed and evaluated. As a result, the developed water electrolysis system can analyze water pump dynamics and hydrogen generation according to temperature dynamics by reflecting the dynamics of temperature.

• Korean System Dynamics Review
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• v.8 no.2
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• pp.253-273
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• 2007

To measure the effect of school zone on housing cost, Linear Regression Model is widely used, and school zone is known as a key determinant of housing cost in Korea. However, when the Hierarchical Linear Model (HLM) is applied with the same data, school effect on housing cost becomes statistically non-significant. It is because HLM effectively separates the effect of individual housing's attributes from the group effect. In sum, the housing cost of Kangnam, where good public schools are located, is apparently is higher than that of Kangbuk. However, the school effect on housing cost (Level 2) becomes non-significant when individual housing's attributes (Level 1) are controlled with HLM.

• Korean System Dynamics Review
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• v.9 no.1
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• pp.143-154
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• 2008

This study has tried to suggest a new model that can effectively redistribute the tickets in the online ticket resale market, while suggesting a new allocation mechanism based on an agent negotiation. To this end, this study has analyzed and simulated the secondary ticket market through System dynamics. As a result of these simulations, it has been proved that the price stability of ticket resale market leads to an increase in revenue. An agent negotiation helps to stabilize the ticket prices that are usually inclined to rise at auction, benefiting all the participants in the negotiations, consequently showing a Pareto solution.

• Korean System Dynamics Review
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• v.2 no.1
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• pp.51-68
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• 2001

Politicians are competing to persuade their policies and to oppose other's. Policy persuasion is based on two independent reasons; moral causes vs. economic outcomes. There have been few studies on investigating and comparing their structural differences. This paper studies how policy makers use moral causes and economic outcomes in persuading their policies. Causal and cognitive structures of persuasions for and against sunshine policy are compared by cognitive map analysis. Finally, this study discusses how to use causal map analysis to understand moral causes and economic outcomes as tools for policy persuasion.

• Korean System Dynamics Review
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• v.15 no.1
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• pp.5-27
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• 2014

The purpose of this study is to analyze the school autonomy policy based on the system thinking perspective using causal loop diagrams. School autonomy was the main educational policy concerning school domain during the last government and was the instrument for school-based management, but it was not implemented effectively in site. The school autonomy policy practically disappeared as an explicit policy agenda in the current government. This study displays causal loop diagrams about the policy's logic and contents of school autonomy, in terms of curriculum, human resource management, and a supportive system. The causal loop diagrams depicting the implementation of the school autonomy policy are suggested concerning excessive enforcement and the confirmative mechanism for policy implementation. The conclusion provides some research implications and future directions.

• Journal of the Korea Society for Simulation
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• v.8 no.4
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• pp.89-107
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• 1999

There are many issues in computer simulation such as verifying model code, validating models, understanding the dynamics of systems and training the personnel. The developers of simulation tool have been interested in the animation since it can help solve the problems related to the above listed issues. In practice, animation is one of the popular method for displaying the simulation output for solving these problems. Trying to display all the graphic objects representing the dynamics of the models being simulated, however, causes the distraction of focus, which results in solving the above listed problems difficult. The redundant graphic objects also Increase the computer computation overhead. This paper presents a hierarchical animation environment in which the users can have better focus on the dynamics of system components. In hierarchical animation environment the users can observe the dynamics of system by selectively choosing the hierarchical level and components with in a level of the hierarchically structured model. Especially when the model is large and complex the selection of observation level is needed. The design approach of the hierarchical animator is based on the DEVS(Discrete Event system Specification) formalism which is theoretically well grounded means of expressing modular and hierarchical models.

• Korean Journal of Materials Research
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• v.10 no.8
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• pp.581-588
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• 2000

Phase transition of the Lennard-Jonesian binary system with a free surface was studied by employing molecular dynamics simulation. The main focus of this study was to investigate the effect of size misfit and solute concentration on phase transition during heating and quenching. For a binary system with a free surface, the melting point and the critical quenching rate decrease as size misfit and solute concentration increase.