• Korean System Dynamics Review
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• v.13 no.2
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• pp.47-71
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• 2012

The purpose of this research is the examination of validity of data as well as simulation model, i.e. to simulate the real data in the SD model with the least error using the adjustments for the faithful reflection of real data to the simulation. In general, SD programs (e.g. VENSIM) utilize the Euler or Runge-Kutta method as an algorithm. It is possible to reflect the trend of real data via these two estimation methods however can cause the validity problem in case of the simulation requiring the accuracy as they have endogenous errors. In this article, the future population estimated by the Korea National Statistical Office (KNSO) to 2050 is simulated by the aging chain model, dividing the population into three cohorts, 0-14, 15-64, 65 and over cohorts by age and offering the adjustments to them. Adjustments are calculated by optimization with three different methods, optimization in EXCEL, manual optimization with iterative calculation, and optimization in VENSIM DSS, the results are compared, and at last the optimal adjustment set with the least error are found among them. The simulation results with the pre-determined optimal adjustment set are validated by methods proposed by Barlas (1996) and other alternative methods. It is concluded that the result of simulation model in this research has no significant difference from the real data and reflects the real trend faithfully.

• Proceedings of the Korean System Dynamics Society
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• 1999.08a
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• pp.59-86
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• 1999

조직행동론의 제 분야들 중에서 가장 다양한 이론들이 제시되고 있는 영역은 개인의 성취동기와 관련된 분야이다. 개인의 성취동기와 관련된 현상을 이해하고 설명하며 예측을 시도하려는 노력으로 다양한 이론들 내지는 개념적 모형들이 제시되어 왔다. 그러나 이론들을 일관성 있는 체계로서 통합하기란 상당히 어렵다. 이는 다양한 이론들을 통해 일관성 있게 정의된 구성개념이 없어 이론이나 모형들 간의 분명한 비교와 평가가 어렵기 때문이다. 또한 만족과 같은 주요 변수들에 대한 명확한 정의가 부족하기 때문이다 (Schwab ＆ Cummings, 1970)(중략)

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.221-228
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• 2011

This study is on the development of a System Dynamics Model for business feasibility analysis of an apartment house development project. In this study, we analyzed other apartment development projects and research projects, and identified the cash flow items, which consist of revenue and expenditure items. In addition, we made efforts to find the influence relationship among these using the system thinking method and developed a system dynamics model. In order to test the model, a case study was conducted in which it was applied to an apartment development project. Vensim, a System Dynamics Modeling and simulation software package was used to analyze and test the model. The model suggested in this study can help a developer to make decisions on project financing at the initial stage of an apartment house development project.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.220-220
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• 2015

Water, energy, and food security already became a risk that threatens people around the world. Increasing of resources demand, rapid urbanization, decreasing of natural resources and climate change are four major problems inducing resources' scarcity. Indeed, water, energy, and food are interconnected each other thus cannot be analyzed separately. That is, for simple example, energy needs water as source for hydropower plant, water needs energy for distribution, and food needs water and energy for production, which is defined as W-E-F nexus. Due to their complicated linkage, it needs a computer model to simulate and analyze the nexus. Development of a computer simulation model using system dynamics approach makes this linkage possible to be visualized and quantified. System dynamics can be defined as an approach to learn the feedback connections of all elements in a complex system, which mean, every element's interaction is simulated simultaneously. Present W-E-F nexus models do not calculate and simulate the element's interaction simultaneously. Existing models only calculate the amount of water and energy resources that needed to provide food, water, or energy without any interaction from the product to resources. The new proposed model tries to cope these lacks by adding the interactions, climate change effect, and government policy to optimize the best options to maintain the resources sustainability. On this first phase of development, the model is developed only to learn and analyze the interaction between elements based on scenario of fulfilling the increasing of resources demand, due to population growth. The model is developed using the Vensim, well-known system dynamics model software. The results are amount of total water, energy, and food demand and production for a certain time period and it is evaluated to determine the sustainability of resources.

• Journal of the Korea Society of Computer and Information
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• v.26 no.3
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• pp.77-88
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• 2021

The development history of China's big data is relatively short, and it has only been ten years so far. Although the application level of big data in real life is not high, some achievements have been made in the supply chain. Various kinds of data will be generated in the actual operation of the supply chain. If these data can be effectively classified and used, the "bullwhip effect" of the operation of the supply chain can be also effectively improved. Thus this paper proposes the development of a supply chain collaborative inventory management model and application framework using big data. In this study, we analyzed the supply chain of beer industry, which is the most prominent consumption industry with "bullwhip effect", and further established a big data collaborative inventory management model for the supply chain of beer industry based on system dynamics. We used the Vensim software for simulation and sensitivity test and after appling our model, we found that the inventory fluctuations of the participants in the beer industry supply chain became significantly smaller, which verified the effectiveness of the model. Our study can be also applied to the possible problems of the large data supply chain collaborative inventory management model, and gives certain countermeasures and suggestions.

• Journal of the military operations research society of Korea
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• v.29 no.2
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• pp.26-44
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• 2003

This study Is to forecast the damage of smallpox as a biological weapon and to measure the effect of potential responses (quarantine, vaccination and cure) to the spread of smallpox infection when a smallpox bioterrorism attack occurs. We designed the smallpox spreading simulation model through the literature study on a basis of some existing infectious disease models such as SIR, SEIR model by using Vensim program. In order to evaluate the performance of responses to smallpox, we measure the total infection population, infection sustaining duration, average infection rate and the infection spreading behavior of the smallpox. This study can help those who are related to the bioterrorism forecast the present and possible demage, and take more effective actions for minimizing the damage by smallpox bioterrorism.

• Proceedings of the Korean System Dynamics Society
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• 2004.08a
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• pp.109-128
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• 2004

The complexity of information and communication policy has been increasing due to its rapid changes and its expansions toward various fields. I used the2001, 2002 and 2003 White Papers on MIC(Ministry of Information and Communication Republic of Korea) as a reference and the Vensim PLE program to create a causal map. According to my analysis, no major feedback loop was found among the information and communication policies. Thus, it was impossible to conduct a causal map analysis on these policies. The causal map analysis is usually employed to understand a complex mechanism of entire policies by finding feedback loops among them. A lack of feedback loops makes it impossible to conduct the causal map analysis and means that the mechanism of such policies is even more complex to understand. The most important conclusion is that to consider feedback thought among the policies based on the systems thinking before making the policies.

• Korean System Dynamics Review
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• v.14 no.4
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• pp.5-35
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• 2013

The study examines the play theory based internet rumor process by using simulating tools, Vensim, which offer a new theoretical basis from which to explore complex adaptive social system. Internet rumor is not a simple linear diffusion process, but a complex interaction behavior between the actors of production and diffusion. Rumor actors consist of two type of diffusion, which is rumor mongers and playful mongers. These two type of mongers make the internet rumor as collective system. Playful mongers play strategically to maximize playfulness. Internet rumor as play is consequence of collective framing constituted by dynamic interaction and playfulness. The networking space spreading internet rumor function as a playground which mobilize play rule, ignoring fact based framing. Rumor as paly, even though it turns out to be a false and loses the public attentions rumor sustains the game play function which makes the rumor without natural extinction. The study proves that playful mongers is a main actors in rumor play ground.

• Journal of the Korea Society for Simulation
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• v.12 no.4
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• pp.61-71
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• 2003

Recently, a matter of the highest priority that the company must do for the satisfaction of customer service is that the company ensure the competitive power throughout the strategic cooperation in the market environment changing rapidly In this situation, one of allied strategies is the supply chain management and the outsourcing is one of the supply chain management strategies. In this paper, the inventory sharing system is introduced as the method to solve two inconsistency problem such as inventory and customer service. This paper also suggests how to increase customer service and to decrease inventory throughout construction of the inventory sharing system among outsourcing companies. For this, we experimented the effect of the inventory sharing system on the supply chain dynamics by using the simulation modeling and analyzed the validity about construction of the inventory sharing system presented in this study. The simulation is designed by Vensim(Process simulation package) and has some feedback loops.

• Journal of the military operations research society of Korea
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• v.28 no.2
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• pp.1-19
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• 2002

This study shows the effect of inventory policy change from supplier-based to customer-based. We focus on the service level, cost, and information distortion of the Military Supply Chain(MSC) with System Dynamics. We design MSC model according to field practician interviews by using Vensim. The simulation makes a comparison between supply-based inventory policy performances and order-based inventory policy performances. In order to evaluate the MSC performances, we measure the accumulation of backlog(service level), supply chain cost, and order percentage overshoot(information distortion). The results show that 1) changing inventory policy from supplier-based to end customer order-based gets a good customer service, reduces MSC cost, and prevents information distortion, 2) changing inventory policy from supplier-based to immediate customer order-based reduces a small amount of MSC cost and deteriorates customer service, and 3) supply level is main factor for MSC performances improvement. This study implicates the policy change makes a improvement of MSC performance without introducing information system.