• 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.

• 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.

• Korean System Dynamics Review
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• v.10 no.1
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• pp.5-32
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• 2009

This paper revisited the key advances on System Dynamics modeling about traditional macro-economic models and economic growth structures, and then tries to elaborate a new model based on the endogenous growth theory that incorporates new growth factors, relevant to knowledge/technology as well as the Environment, into traditional growth models. Accordingly, the new model augments the acceleration and multiplier loops and the balancing ones representing market clearing mechanism with a simple numerical example. The authors thus provides macroeconomic System Dynamics analysts with a milestone to model macro-economic structures reflecting on traditional and cutting-edge theories on sustainable economic growth and general equilibrium modeling.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.162-163
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• 2011

This paper presents the system dynamics methodology for modeling and control the production/inventory system. Under system dynamics point of view, we can apply some production/inventory policies as if we use the control laws for dynamics systems, then the behavior of system is analyzed and evaluated to improve the performance of production/inventory system. We also utilize the hybrid modeling method for the dynamic of production system with the combination of Matlab/Simulink and Matlab/Sateflow. Finally, the numerical simulation results are carried out in Matlab/Simulink environment and compare with the results from other works. It is shown that our approach can obtain some good performances (such as operational cost, stability of inventory, customer service level).

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.2
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• pp.346-363
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• 2015

We have performed integrated dynamics modeling for a supercavitating vehicle. A 6-DOF equation of motion was constructed by defining the forces and moments acting on the supercavitating body surface that contacted water. The wetted area was obtained by calculating the cavity size and axis. Cavity dynamics were determined to obtain the cavity profile for calculating the wetted area. Subsequently, the forces and moments acting on each wetted part-the cavitator, fins, and vehicle body-were obtained by physical modeling. The planing force-the interaction force between the vehicle transom and cavity wall-was calculated using the apparent mass of the immersed vehicle transom. We integrated each model and constructed an equation of motion for the supercavitating system. We performed numerical simulations using the integrated dynamics model to analyze the characteristics of the supercavitating system and validate the modeling completeness. Our research enables the design of high-quality controllers and optimal supercavitating systems.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.6
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• pp.61-70
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• 2003

A multibody system dynamics analysis program is presented using one of the most useful programming methodologies, the object-oriented modeling, The object-oriented modeling defines a problem from the physical world as an abstract object. The object becomes encapsulated with the data and method, Analysis is performed using the object's interface, It is then possible for the user and the developer to modify and upgrade the program without having particular knowledge of the analysis program, The method presented in this paper has several advantages, Since the mechanical components of the multi-body system are converted into the class, the modification, exchange, distribution and reuse of classes are increased. It becomes easier to employ a new analysis method and interface with other S/W and H/W systems, Information can be communicated to each object through messaging. This makes the modeling of new classes easier using the inheritance, When developing a S/W for the computer simulation of a physical system, it is reasonable to use object-oriented modeling.

• Korean Journal of Computational Design and Engineering
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• v.14 no.4
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• pp.261-270
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• 2009

We can save a lot of efforts and time to perform various kinds of multibody system dynamics simulations if the equations of motion of the multibody system can be formulated automatically. In general, the equations of motion are formulated based on Newton's $2^{nd}$law. And they can be transformed into the equations composed of independent variables by using velocity transformation matrix. In this paper the velocity transformation matrix is derived based on a topological modeling approach which considers the topology and the joint property of the multibody system. This approach is, then, used to formulate the equations of motion automatically and to implement a multibody system dynamics simulation program. To verify the the efficiency and convenience of the program, it is applied to the lifting simulation of a floating crane.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.14-20
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• 2014

This study, the reliability of weapon systems acquisition and research and development in order to increase the effect of the modeling and simulation method has been studied using computational fluid dynamics. Weapon system acquisition, Test & Evaluation for use in the modeling and simulation can reduce the reliability of the time and cost savings and possible predictions and verification, and can provide useful data. However, the current weapon system acquisition and active use of modeling and simulation and verification do not even use the software are restricted. In this study, using computational fluid dynamics (CFD) modeling and simulation using the GAMBIT and FLUENT modeling and simulation was performed. The result is better than previous research results were confirmed in future weapon systems acquisition and research and development are expected to be actively used.

• Korean System Dynamics Review
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• v.8 no.1
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• pp.97-115
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• 2007

In System Dynamics, causal maps are used as a tool for analyzing dynamic problems and discussing the outcome of analyzed problems. However there are some limitations to use causal maps. In the drawing phase of causal maps, the high abstraction of variables that constitutes problems makes it difficult to find out correct information. And principles or rules to check errors on causal maps are not sufficient yet. Moreover, simulation modeling tasks are required to be concerned separately from drawing causal maps because causal maps cannot provide enough information to simulation modeling. In order to overcome these limitations, this study shows ways that ensure validity, increase power of expression of causal maps and improve the connection between causal maps and simulation modeling.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.45-53
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• 2014

This study presents a system dynamics modeling approach to simulate daily streamflow in a watershed including wastewater treatment plant which contributes to irrigation water supply. The conceptual system dynamics model considering the complex and dynamic hydrological processes in the watershed was developed. The model was calibrated and validated each for two years based on observed flow data. Model performances in terms of $E_{NS}$, RSR, PBIAS, and $R^2$ were 0.64, 0.60, -3.6 %, and 0.64 for calibration period, and 0.66, 0.58, -2.6 %, and 0.66 for validation period, respectively, showing an applicability on generating the daily streamflow. System dynamics modeling approach could help better understand the hydrological behavior of the watershed being reused wastewater for agriculture, by providing graphical dynamics of the hydrological processes as well as conventional rainfall-runoff model results.