• International Journal of Automotive Technology
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• v.7 no.1
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• pp.25-34
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• 2006

For decades, simulation technique has been well validated in areas such as computer and communication systems. Recently, the technique has been much used in the area of transportation and traffic forecasting. Several methods have been proposed for investigating complex traffic flows. However, the dynamics of vehicles and diversities of driver characteristics have never been considered sufficiently in these methods, although they are considered important factors in traffic flow analysis. In this paper, we propose a traffic simulation tool called Multi-Agent for Traffic Simulation with Vehicle Dynamics Model (MATDYMO). Road transport consultants, traffic engineers and urban traffic control center managers are expected to use MATDYMO to efficiently simulate traffic flow. MATDYMO has four sub systems: the road management system, the vehicle motion control system, the driver management system, and the integration control system. The road management system simulates traffic flow for various traffic environments (e.g., multi-lane roads, nodes, virtual lanes, and signals); the vehicle motion control system constructs the vehicle agent by using various vehicle dynamic models; the driver management system constructs the driver agent capable of having different driving styles; and lastly, the integrated control system regulates the MATDYMO as a whole and observes the agents running in the system. The vehicle motion control system and driver management system are described in the companion paper. An interrupted and uninterrupted flow model were simulated, and the simulation results were verified by comparing them with the results from a commercial software, TRANSYT-7F. The simulation result of the uninterrupted flow model showed that the driver agent displayed human-like behavior ranging from slow and careful driving to fast and aggressive driving. The simulation of the interrupted flow model was implemented as two cases. The first case analyzed traffic flow as the traffic signals changed at different intervals and as the turning traffic volume changed. Second case analyzed the traffic flow as the traffic signals changed at different intervals and as the road length changed. The simulation results of the interrupted flow model showed that the close relationship between traffic state change and traffic signal interval.

• Korean System Dynamics Review
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• v.9 no.1
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• pp.57-71
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• 2008

This research paper describes a complex and vague settings in which organization makes a decision and explains a role of decision maker's learning process. The original paper, written by Cohen, March, Olsen in 1972, said that all members of organization depended on the technology taken through trials and errors, which is the 'learning' process literally. But they intended to exclude the learning process in their simulation model because their PORTRAN model couldn't replicate the learning concept. As a result, they couldn't explain how all agents of garbage can simulation model resolve the problem dynamically. To overcome this original paper's limitations, we try to rebuild a learning process simulation model using by system dynamics approach that can capture the linkage between organization leanings and agents-based decision-makings. Our learning simulation results reveal two points. First, decision maker's leanings process improves the efficiency of decision making in complex situation. Second, group learning shows a superior efficiency to an individual learning because group members share organizational memory and energy.

• Korean System Dynamics Review
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• v.7 no.2
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• pp.149-170
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• 2006

In this paper, an energy-economy-environment dynamic simulation model was developed to using system dynamics methodology. It describes current energy-economy-environment systems and forecasts changes caused by levying of carbon tax. The model is composed of three modules: an energy module, an economic module and an environmental module. Variables are interrelated in each module, and three modules are linked by several linkage variables. Setting up the linkage variables is an important factor for the composition of the model. The simulation result shows a change of the national GDP, usage of energy, and $CO_2$ emissions under levying and reinvestment of carbon tax considering various scenarios for the charging cost.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1382-1390
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• 2010

We can see interactions between rigid body and fluid every day, anywhere. This kind of rigid body-fluid simulation is one of the most difficult problems in physically-based modeling, mainly due to heavy computations. In this paper, we present a real-time dynamics model for simulating stone skipping, which is a popular rigid body-fluid interaction in the real world. In comparison to the previous works, our improved dynamics model supports the rotation of the stones and also computes frictional forces with respect to the air. We can simulate a realistic result for various user input by using proposed model. Additionally, we present a water surface model to show more realistic ripples interactively. Our methods can be easily adapted to other interactive dynamics systems including 3D game engines.

• Korean System Dynamics Review
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• v.9 no.1
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• pp.155-170
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• 2008

The purpose of this study was to develop a system dynamics model for management of glucose metabolism disorders that demonstrated dynamic relationships between insulin and plasma glucose levels over the time. The model was developed to 1) represent the physiology of glucose metabolism for an normal adult subject, 2) to draw causal loop diagram that demonstrate feedback systems of glucose regulation in normal condition and pathologic condition of the type 2 diabetes, 3) to develop an interactive computer simulation model for management of glucose metabolism disorders. The simulation results showed the plasma glucose level for normal persons varied from 75 to 140 which was consistent with clinical findings. As an example for patients we selected a case which varied from 110 to 310. Two types of interventions were chosen to review the model; meal control and insulin administration. The simulation results for those cases also matched well with clinical findings. The developed model can be used as an effective educational tool for patients to develop healthy lifestyle choices. The results also provide a blueprint for health providers to maintain normal blood glucose levels in diabetes patients.

• Korean System Dynamics Review
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• v.2 no.1
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• pp.93-112
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• 2001

Inter-Organizational Cooperation is the most common and important strategy in modern public and privet sectors managerial activities. In this paper the concepts of inter-organizational cooperation means not selfish cooperation as in the game circumstance and theory, but general collaborative action between organizations, they have share same goal. The achievement level of jointed-goal of inter-organization is depended upon the performance of cooperation, which resulted from the conditions and circumstances of cooperation. This paper analyses the effect of inter-organizational cooperation on achievement level of the jointed goal between two organizations with computer simulation model of the system dynamics approach. In the computer simulation model, three factors, goal perception, communication, and control, are considered as a key conditions of cooperation, which impact on the performance of cooperation. Simulation model was constructed with focus on the dynamic interactions between these three factors and the achievement level of jointed-goal. Consequently, the results found in this paper may provide further grounds for reducing the time delay that included in the conditions of cooperation.

• Environmental Engineering Research
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• v.19 no.2
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• pp.165-174
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• 2014

A model combining multi-dimensional discretized population balance equations with a computational fluid dynamics simulation (CFD-DPBE model) was developed and applied to simulate turbulent flocculation and sedimentation processes in sediment retention basins. Computation fluid dynamics and the discretized population balance equations were solved to generate steady state flow field data and simulate flocculation and sedimentation processes in a sequential manner. Up-to-date numerical algorithms, such as operator splitting and LeVeque flux-corrected upwind schemes, were applied to cope with the computational demands caused by complexity and nonlinearity of the population balance equations and the instability caused by advection-dominated transport. In a modeling and simulation study with a two-dimensional simplified pond system, applicability of the CFD-DPBE model was demonstrated by tracking mass balances and floc size evolutions and by examining particle/floc size and solid concentration distributions. Thus, the CFD-DPBE model may be used as a valuable simulation tool for natural and engineered flocculation and sedimentation systems as well as for flocculant-aided sediment retention ponds.

• Korean System Dynamics Review
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• v.7 no.1
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• pp.67-90
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• 2006

A series of system dynamics model was developed for forecasting demand and supply of human resource in the electricity industry. To forecast demand of human resource in the electric power industry, BLS (Bureau of Labor Statistics) methodology was used. To forecast supply of human resource in the electric power industry, forecasting on the population of our country and the number of students in the department of electrical engineering were performed. After performing computer simulation with developed system dynamics model, it is discovered that the shortage of human resource in the electric power industry will be 3,000 persons per year from 2006 to 2015, and more than a double of current budget is required to overcome this shortage of human resource.

• Proceedings of the Korean System Dynamics Society
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• 2006.04a
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• pp.19-40
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• 2006

A system dynamics model is developed to investigate the applicability of the agent based modeling concept in the system dynamics model. The assumed problem is to forecast the size and structure of the organization with the developing market environment. The agent based modeling concept is applied to the organization part, and the other parts of the model such as market, facilities, etc. are developed with the traditional system dynamics technique. The simulation results show the agent based modeling part can be combined with the traditional system dynamics modeling with more precisions. However, the complexity increases and the simulation times are longer than those of the traditional method.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.2
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• pp.53-63
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• 1993

A numerical modeling technique is proposed for computer simulations of high speed valve train dynamic terms in the valve spring reaction forces are calculated using linear vibration theory for given kinematic valve motions. Because the spring dynamics are analyzed before the time stepping integration, spring surge phenomena can be included without using additional computer time. In addition to that, steady state response of the valve dynamics can be obtained by just one cycle simulation. Consequently, valve train dynamics can be simulated very quickly without noticeable errors in accuracy. The experimental result prove the computer model developed here is accurate and also computationally efficient. The model is especially useful for cam profile optimizations.