• Journal of Power System Engineering
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• v.7 no.3
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• pp.61-68
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• 2003

Steering characteristics is an important factor in the evaluation of vehicle quality. To estimate steering characteristics in the vehicle conceptual design stage, vehicle dynamics simulation methods are very efficient. However, it is often difficult to simulate vehicle dynamics for the specific driving scenarios in open-loop driving environment. An efficient driver-in-the-loop vehicle model will be efficient for this job. A good tire model is also very important for the accurate vehicle dynamics simulation. In this research, a driver model is used to simulate vehicle steering dynamics for a 8-dof vehicle model with STI(Systems Technology, Inc.) tire model. For the demonstration of this model, a SUV(sports utility vehicle) and a sedan were simulated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.834-840
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• 2001

A real time multibody vehicle dynamics model has been developed and implemented using a subsystem synthesis method based on recursive formulation. To verify real time simulation capability the developed model has been applied to HMMWV(High Mobility Multipurpose Wheeled Vehicle) with steering system. For the kinematically driven steering system, the coupled front suspension-steering subsystem can be decoupled into two SLA suspension subsystems, which improves the efficiency of simulation. To investigate theoretical efficiency, operational counting method has been also employed to compare the proposed model with the conventional recursive dynamics model. Various simulations such as unsymmetric bump run, step steering(J-turn) and sine steering input test have been carried out to verify the real time feasibility of the proposed model.

• 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.

• Journal of Drive and Control
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• v.19 no.3
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• pp.39-46
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• 2022

In South Korea, to evaluate the rollover safety of domestic vehicles, the maximum slope angle of the vehicle is specified, which is verified by the rollover safety test of driving vehicles. However, the domestic rollover safety test is not suitable for buses, because the small amount of static stability factor (SSF) will invalidate the rollover experimental equation due to the high center of mass position of buses. To solve the above problems, a dynamic model of the bus is prepared with assumptions of mass and suspension spring properties. Subsequently, the maximum slope angle of the model was computed by using the simulation of multi-body dynamics, and the result was compared with actual test results to validate the dynamics model. Also, the rollover Fishhook (roll stability) test was conducted in the simulation for driving model. During the simulation, roll angle and roll rate were calculated to check if a rollover occurred. Through the rollover simulation of buses, the domestically regulated formula for rollover safety and the procedure of rollover test for driving vehicles are evaluated. The conclusion is that the present regulation of rollover test should be reconsidered for buses to ensure to get the valid results for rollover safety.

• Korean System Dynamics Review
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• v.14 no.3
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• pp.75-103
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• 2013

The purpose of this study is to use system dynamics to establish the relation among each variable through the construction process of Community Planning Model, and examine what changes policy scenarios per alternative cause in Community Planning through policy simulation of the constructed model. Therefore, this study extracted chief variables of Community Planning Projects through precedent researches related to Community Planning, and extracted variables were prepared as causal map to examine in what causal cycle feedback structure within Community Planning they can be explained. Next, Community Planning Model was constructed based on the prepared causal map. The model was verified by specialists' interviews and simulation of example areas. This study, which aimed to construct Community Planning Model using system dynamics, has a significance in that it prepared the foundation to provide useful methodology in monitoring the progress of project or establishing the plan of future Community Planning Projects.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.28-38
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• 2012

The characteristics of vibration and noise of a compressor used for electric appliances have significant influence on the quality of the products. For improvement on the quality of electric appliances, investigations for understanding the dynamic behaviour of the compressor are essential. Since Virtual Lab for the dynamics model and MAXWELL for the electromagnetics model are separate software programs with no interface, the joint simulation of the models could not be performed. This study suggests a way to develop the compressor model capable of the joint simulation with MATLAB/SIMULINK linking a flexible multi-body dynamics model, a torque model, and an electricity control model. The compressor model is found to be able to perform I/O data transfer among the sub-models and joint simulation. The simulation results of the flexible body and rigid body dynamics models were compared to check availability of the joint simulation system. In addition, the simulated vibration and driving torque of the compressor mechanisms were compared with measurements. Through the simulations, the influence of springs and LDT on the dynamic behaviour of the compressor was examined. This study examines the influence of the dynamic behaviour of the compressor mechanisms through joint simulation of the flexible multi-body dynamics model and electromagnetic circuit allows analysis.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.644-646
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• 2014

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.599-604
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• 2005

A functional suspension model is proposed as a kinematic describing function of the suspension, that represents the relative wheel displacement in polynomial form in terms of the vertical displacement of the wheel center and steering rack displacement. The relative velocity and acceleration of the wheel is represented in terms of first and second derivatives of the kinematic describing function. The system equations of motion for the full vehicle dynamic model are systematically derived by using velocity transformation method of multi-body dynamics. The comparison of test and simulation results demonstrates the validity of the proposed functional suspension modeling method. The model is computationally very efficient to achieve real-time simulation on TMS 320C6711 150 MHz DSP board of HILS (hardware-in-the-loop simulation) system for ECU (electronic control unit) evaluation of semi-active suspension.

• Korean System Dynamics Review
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• v.7 no.1
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• pp.27-49
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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.

• Korean System Dynamics Review
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• v.15 no.2
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• pp.27-50
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• 2014

Korea government established the energy technology development plan (2011-2020) and declared to be a leader of the green energy technologies. The plan aims for 10% market share in the green energy industry, 12% energy efficiency improvement, and 15% greenhouse gas reduction. In order to achieve these goals, the government has tried to calculate the whole scale of national energy R&D investment, annual budget and specific expenditures for new technologies by computer simulation. The simulation modules include the R&D investment model, GDP model, energy consumption and $CO_2$ emission model by System Dynamics. Based on these simulation modules, I tested various scenarios for effectiveness of energy R&D investments until 2020. The results show that Korea should increase national energy R&D investment to 2.3 billion U.S. dollars, and switch the investment from electricity and nuclear power to the renewable energy.