• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.1-7
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• 2003

In order to predict vibrations occurred during end-milling processes, the cutting dynamics was modelled by using neural network and combined with structural dynamics by considering dynamic cutting state. Specific cutting force constants of the cutting dynamics model were obtained by averaging cutting forces. Tool diameter, cutting speed, fled, axial and radial depth of cut were considered as machining factors in neural network model of cutting dynamics. Cutting farces by test and by neural network simulation were compared and the vibration displacement during end-milling was simulated.

• Korean System Dynamics Review
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• v.6 no.2
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• pp.37-52
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• 2005

Conflict resolution in decision-making groups is studied using a System Dynamics model. The model is developed using a grounded-theory approach. Some preliminary results are shown. The results seem to be in line with much empirical research done in the management literature about conflict and conflict resolution at the group level of analysis. Ideas for further research are discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.90-97
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• 2014

This paper presents a simplified dynamics model, dynamics simulations, and computed torque control experiments of the Delta high-speed parallel robot. Using the typical Newton-Euler method, a simplified but accurate dynamics model with practical assumptions is derived. Accuracy and fast calculations of the dynamics are essential in the computed torque control for high-speed applications. It was found that the simplified dynamics equation is in very god agreement with the ADAMS model, and the calculation time of the inverse kinematics and inverse dynamics is about 0.04 msec. From the dynamics simulations, the cycle trajectory along the y-axis requires less peak motor torque and a lower angular velocity and less power than that along the x-axis. The computed torque control scheme can reduce the position error by half as compared to a PD control scheme. Finally, the developed Delta parallel robot prototype, half the size of the ABB Flexpicker robot, can achieve a cycle time of 0.43 sec with a 1.0kg payload.

• Korean System Dynamics Review
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• v.17 no.2
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• pp.33-56
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• 2016

In this paper, a system dynamics model for explaining the application, grant and maintenance of patents is provided. Existing literatures regarding the patent application system are mostly econometric approaches that consider only economic variables such as GDP and R&D. The model in this paper includes patent variables such as disputes as well as economic variables. Moreover, we show that the model can be used in not only a quantitative prediction but also policy experiment. The results of the policy experiment shows that strengthening protection of patents tend to increase the propensity to patent more than R&D investment.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.109-118
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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 field test results and simulation results of the ADAMS/Car demonstrates the validity of the proposed functional suspension modeling method. This model is suitable for real-time vehicle dynamics analysis.

• 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.

• Korean System Dynamics Review
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• v.9 no.1
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• pp.73-92
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• 2008

Internet portal sites have served customers for more than a decade in Korea. There have been several such sites have survived, succeeded and led the internet industry. What is the source of their competitiveness? We assumed that the network effect, which can vary dynamically, is an important factor; so we tried to build and analyze a system dynamics model on portal sites that represent their advertising business model. This model includes not only the network effect, but also customer's' expectations of the quality of portal sites, which also varies dynamically. As a result of our research, we can state that the network effect is important to stabilize and increase portal sites' quality, market share, income and cash flow. And we know that investment at a level above that which is merely required is necessary to preserve and stabilize their business.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.11
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• pp.1476-1478
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• 1999

A musculotendon model is proposed to predict muscle force during muscle fatigue due to the continuous functional electrical stimulation(FES). Muscle fatigue dynamics can be modeled as the electrical admittance of muscle fibers and included in activation dynamics based on the{{{{ { Ca}^{2+ } }}}} kinetics. The admittance depends on the fatigue variable that monotonically increase or decrease if electrical pulse exists or not, and on the stimulation parameters and the number of applied pulses. In the response of the change in activation the normalized Hill-type contraction dynamics connected with activation dynamics decline the muscle shortening velocity and thus its force under muscle fatigue. The computer simulation shows that the proposed model can express the muscle fatigue and its recovery without changing any stimulation parameters.

• Journal of Korea Trade
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• v.26 no.2
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• pp.21-44
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• 2022

Purpose - This study quantifies sources of trade balance dynamics over the business cycle in Korea. Specifically, we quantify the relative importance of domestic and foreign factors on trade balance dynamics using a small open economy real business cycle (SOE-RBC) model and provide policy implications for stabilization policies. Aggregate productivity and interest rate spreads are considered domestic factors affecting the trade balance. A world interest rate (the U.S. interest rate) is considered a foreign factor. Design/methodology - Following Neumeyer and Perri (2005), we build the SOE-RBC model with three types of shocks: aggregate productivity, interest rate spread, and world interest shocks. The model is estimated by the generalized method of moments (GMM) using relevant business cycle statistics. The estimated model is used for quantifying the relative importance of domestic and foreign factors on trade balance dynamics in Korea. Findings - Our main findings can be summarized as follows: 85.64% of the trade balance fluctuations in Korea are explained by domestic factors, the remaining 14.35% by foreign factors. Particularly, trade balance dynamics are mostly accounted for by the change in aggregate productivity shocks (85.58%). World interest rate shocks considerably explain trade balance (14.35%), whereas the role of interest rate spread shocks that represent domestic risks is limited (0.08%). Although aggregate productivity is key in explaining trade balance dynamics in Korea, interest rates still have an essential role. This is because aggregate productivity changes induce interest rate spread variations and, thus, the trade balance significantly. The results suggest that government policies mitigating fluctuations in aggregate productivity would be effective for stabilization policies in Korea by reducing the trade balance volatility. Originality/value - Existing studies on the emerging market business cycle examine mostly Latin American countries, and the main object of the studies is the volatility of consumption rather than trade balance dynamics. Conversely, our study examines Korea rather than Latin American countries. Additionally, we examine sources of trade balance dynamics, which are relatively more important in Korea, rather than those of the volatility of consumption. Hence, we estimate the model to explicitly match moments related to trade balance in the data.

• 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.