• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.120-126
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• 2004

This study proposed the analysis of mass position detection due to the change of the mass and strifeless of structure by using the original and modified dynamic characteristics. The method is applied to examples of the cantilevers beam and the 3 degrees of freedom system by modifying the mass. The predicted detection of the mass positions and magnitudes are in good agrement with the present study from the structural reanalysis using the modified mass.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.120-127
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• 1998

In this study the dynamic characteristics of automatic transmission system due to the change of the planetary gear ratio is studied. To study the power flow and shift quality for power transmission the simulation program is developed using the modeling and analysis technique. The results from this study will be used in designing the basic structure of automatic transmission using planetary gear system.

• PNF and Movement
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• v.9 no.1
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• pp.1-9
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• 2011

Purpose : The purpose of this study is to analyze the effect of closed-chain exercise on weight supporting rate change within hemiplegic side and static dynamic balance ability in stroke patients. Methods : The subjects of the study were 13 hemiplegic patients who carried out closed-kinematic chain exercise program over 6 weeks. The exercises of the program are stand to sit with stall bar, stair-up & down by a hemiplegic leg and bridging exercise crossing the non-hemiplegic leg onto the hemiplegic leg. Each exercise was carried out over 3 sets of 10reps. Results : The results of this study were summarized as follows: 1. After intervention, there was a statistically significant change in the weight supporting rate within hemiplegic and non-hemiplegic side(P<0.05). 2. After intervention, there was a statistically significant change in the static balance(FICSIT-4) ability(P<0.05). 3. After intervention, there was a statistically significant change in the dynamic balance(FSST, TUG, FRT) ability(P<0.05). Conclusion : The results of the study suggests that closed-chain exercise program in stroke patients improves their weight supporting rate and enhance the static dynamic balance.

• Wind and Structures
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• v.20 no.2
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• pp.169-189
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• 2015

To investigate the effects of "sudden change" of wind fluctuations on vehicle running performance, which is caused by the artificial discrete simulation of wind field, a three-dimensional vehicle model is set up with multi-body dynamics theory and the vehicle dynamic responses in crosswind conditions are obtained in time domain. Based on Hilbert Huang Transform, the effects of simulation separations on time-frequency characteristics of wind field are discussed. In addition, the probability density distribution of "sudden change" of wind fluctuations is displayed, addressing the effects of simulation separation, mean wind speed and vehicle speed on the "sudden change" of wind fluctuations. The "sudden change" of vehicle dynamic responses, which is due to the discontinuity of wind fluctuations on moving vehicle, is also analyzed. With Principal Component Analysis, the comprehensive evaluation of vehicle running performance in crosswind conditions at different simulation separations of wind field is investigated. The results demonstrate that the artificial discrete simulation of wind field often causes "sudden change" in the wind fluctuations and the corresponding vehicle dynamic responses are noticeably affected. It provides a theoretical foundation for the choice of a suitable simulation separation of wind field in engineering application.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.1040-1047
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• 2006

Bridges are exposed to constantly changing weather conditions and temperature. The temperature change is induced by a change in atmospheric temperature and solar radiation. Atmospheric temperature change acts on the whole structure. Thus, it is relatively easy to consider in the design. Solar radiation, however, causes un-uniform temperature distribution in the structure, depending on the shape of the structure and its shadows. Un-uniform temperature distribution causes a torsional moment in bridge section and a deformation of bridge. A deformation can make differences of dynamic and static behavior of bridge. In this study, the method for analysis of static and dynamic behavior considering deformation and changes of material properties due to temperature variation was developed. By this method, it is found from dynamic analysis results that the change of frequency in analysis model is similar with test results of public used cable-stayed bridge. When a temperature goes down, a frequency goes up. And it is found that the change of frequency is affected by the change of material properties.

• Communications for Statistical Applications and Methods
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• v.12 no.1
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• pp.199-205
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• 2005

In general, simple correspondence analysis has handled mainly correspondence relations between the row and column categories but can not display the trends of their change over the time. For solving this problem, we will propose DSCA(Dynamic Simple Correspondence Analysis) of transition matrix data using supplementary categories in this study, Moreover, DSCA provides its trend of the change for the future by predicting and displaying trend toward the change from a standard point of time to the next.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1141-1146
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• 1993

The problem of tension control in metal-strip processing line is discussed. A new mathematical dynamic model which relates tension change, motor-speed change and roll-gap change is developed. Through the computer simulation of this model, parameter sensitivity, the tension transfer phenominon, and static and dynamic characteristics of strip tension were studied. Guidelines are developed to help one selecting locations of the master-speed drive in multi-drive speed control for tension adjustment and reducing the effect of interaction between tension and roll gap control.

• Journal of the Chungcheong Mathematical Society
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• v.29 no.2
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• pp.375-383
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• 2016

This paper investigates an optimal consumption, portfolio, and life insurance strategies of a family when there is a borrowing constraint and risk aversion change at the time of death of the breadwinner. A CRRA utility is employed and by using the dynamic programming method, we obtain analytic expressions for the optimal strategies.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.1
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• pp.113-119
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• 1991

The author is currently assistant professor of Management Science at Korea Advanced Institute of Science and Technology, following a few years as assistant professor of Industrial Engineering at Kyung Hee University, Korea. He received his doctorate from the department of Industrial Engineering and Operations Research, University of California, Berkeley. His research interests are time series and forecasting modelling, Bayesian forecasting and the related software development. He is now teaching time series analysis and econometrics at the graduate level.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1193-1199
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• 2010

Spot welding is the primary method of joining sheet metals in the automotive industry. As automobiles are subjected to fatigue loading, some spot welds may fracture before the whole system has failed. This local fracture of spot welds may lead to change in the dynamic response and consequently affect fatigue behavior of an automobile. Therefore, this change in dynamic response should be taken into consideration to assess the fatigue life of structures subjected to spectrum loading, such as automobiles. In this study, vibration fatigue analysis was performed by taking into consideration the change in the dynamic response due to accumulated damage at spot-welded parts. Fatigue tests were carried out on tensile-shear spot-welded specimens under constant amplitude loading condition. And the fatigue life of spot welds under spectrum loading was predicted using vibration fatigue analysis method based on finite element analysis.