• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.6
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• pp.311-322
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• 2017

In this study, the seismic performance of concrete-steel composite moment frame structures equipped with seismic retrofitting systems such as seismic reinforcement, base isolators, and bracing members, which are typical earthquake damage mitigation systems, is evaluated through nonlinear dynamic analyses. A total of five frame models were designed and each frame model was developed for numerical analyses. A total of 80 ground acceleration data were used to perform the nonlinear dynamic analysis to measure ground shear force and roof displacement, and to evaluate the behavioral performance of each frame model by measuring inter-story drift ratios. The analysis results indicate that the retrofitting device of the base isolator make a significant contribution to generating relatively larger absolute displacement than other devices due to flexibility provided to interface between ground and column base. However, the occurrence of the inter-story drift ratio, which is a relative displacement that can detect the damage of the structure, is relatively small compared with other models. On the other hand, the seismic reinforced frame model enhanced with the steel plate at the lower part of the column was found to be the least efficient.

• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.19-24
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• 2013

The aim of the study was a quantitative analysis of elite athlete's $540^{\circ}$ Dwihuryeochagi and effects of ground movements to the jumping height and kicking velocity. Eleven elite players(Taekwondo demonstration team) participated in this study. In order to get the kinetic and kinematic variables, ten Vicon cameras and a force plate were used. Foot segment velocity(FSV), vertical ground reaction force(GRF), impulse, ground time(GT) in phase 1, trunk angular velocity(TAV), vertical center of gravity(COG), flight time(FT) in phase 2 and kicking leg segment velocity(KSV) in phase 3 were measured and analyzed. Results indicated that there were similar patterns of variables among phases between subjects. Non-significant correlation(r=.145) between flight time(FT) and impulse was found. Also non-significant correlation(r=.119) between center of gravity(COG) and impulse was found. In conclusions, there were similar strategies in phase 1, phase 2, and phase 3 between subjects.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.3
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• pp.397-404
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• 2001

The behavior of unsteady wake vortices for the two-dimensional flat plate is simulated by a discrete vortex method. The flat plates and their wakes are represented by vortex sheets. The vortex sheets are replaced with discrete vortices. The freely deforming wake sheets are computed as a part of solution and the ground effect is included by a image method. In order to predict wake shapes accurately and to model closely coupled aerodynamic interference, a vortex core model and a vortex core addition scheme are used. The simulated wake shapes convecting behind the plates in unsteady motion are compared to a flow visualization result and other numerical results. The present results agree well with them. The present method is also applied to the aerodynamic analysis of flat plates in tandem configuration in ground effect.

• Earthquakes and Structures
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• v.4 no.6
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• pp.629-647
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• 2013

Loading protocols have been developed for quasi-static cyclic testing of structures and components. However, it is uncertain if protocols developed for conditions of intense ground shaking in regions of high seismicity would also be applicable to regions of low-moderate seismicity that are remote from the tectonic plate boundaries. This study presents a methodology for developing a quasi-static cyclic displacement loading protocol for experimental bracing evaluation of cold-formed steel stud shear walls. Simulations presented in the paper were based on conditions of moderate ground shaking (in Australia). The methodologies presented are generic in nature and can be applied to other regions of similar seismicity conditions (which include many parts of China, Korea, India and Malaysia). Numerous response time histories including both linear and nonlinear analyses have been generated for selected earthquake scenarios and site classes. Rain-flow cycle counting method has been used for determining the number of cycles at various ranges of normalized displacement amplitude. It is found that the number of displacement cycles of the loading protocol increases with increasing intensity of ground shaking (associated with a longer return period).

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.2 no.2
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• pp.69-78
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• 1991

전자파장해 측정에 사용되는 대표적인 측정시설에는 접지면(ground plane)을 갖춘 야외시험장 (open area test site), 전자파반무향실(semianechoic chamber), TEM(transverse Electromagnetic) cell, 평행판선로(parallel plate line), 헬름홀츠코일(Helmholtz coil), 전자파잔향실(reverberating chamber) 등이 있으며, 이러한 시설은 시험대상기기의 크기, 주파수대역, 적용규격의 규제치, 측정하고자 하는 전자기장의 형태 및 편파면, 그리고 시험신호의 전기적 특성(주파수영역 또는 시간영역) 등을 고려하여 선택되고 구성되 어야 한다. 실제로 시험장소를 건설하는데 막대한 비용이 소요되고, 큰 측정오차를 유발시킬 수 있기 때문에 매우 신중 하게 설계, 구성하여야 한다.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.277-279
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• 2003

Theory calculation way because verification is lacking, we compare and analyzed with calculation theory value and experiment value that is noted through a water tank model experiment based on connection theory way that is announced in existing.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.172.2-172.2
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• 2010

This study was carried out in order to reduce the installation expense of heating system for greenhouse comparing to geothermal heat pump and develope the coefficient of performance (COP) for a heat pump. For getting plenty of heat flux from geothermal energy. Surface water in river channel was used for getting a lots of geothermal heat by penetrating water through underground soil layer of the river bank that make heat transmission to passing water. The range of water temperature after the process of Ground filtration is 13~18 degrees celsius which is very similar to low heat source of geothermal heat pump system and the plenty amount of heat source from that make the number of geothermal heat exchanging hole and the expense for geothermal heat exchanger construction reduced. Drainage well is also used for returning filtration water to the aquifer that keep the water good recirculation from losing geothermal heat and water resource. For the COP improvement of Heat pump, thermal storage tank with separating insulation plate according to the temperature difference make the COP of Heat pump that is similar to thermal storage tank with diffuser. Developed thermal storage tank make construction expense cheaper than customarily used one's. and that sand filter and oxidation sand (FELOX) are going to be used for improving ground filtration water quality that make heat exchanger efficiency better. All above developed component skill are going to be set on the Ground filtration water source heat pump system and applied for medium, large scale for protected greenhouse in riverside area and on-site experiment is going to do for optimizing the heating system function and overcome the problem happening in the process of on-site application afterward.

• International Journal of Concrete Structures and Materials
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• v.9 no.3
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• pp.381-390
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• 2015

Investigating the microstructure of hardened cement mixtures with the aid of advanced technology will help the concrete industry to develop appropriate binders for durable building materials. In this paper, morphological, mineralogical and thermogravimetric analyses of autoclave-cured mixtures incorporating ground dune sand and ground granulated blast furnace slag as partial cementing materials were investigated. The microstructure analyses of hydrated products were conducted using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), differential thermal analysis (DTA), thermo-graphic analysis (TGA) and X-ray diffraction (XRD). The SEM and EDX results demonstrated the formation of thin plate-like calcium silicate hydrate plates and a compacted microstructure. The DTA and TGA analyses revealed that the calcium hydroxide generated from the hydration binder materials was consumed during the secondary pozzolanic reaction. Residual crystalline silica was observed from the XRD analysis of all of the blended mixtures, indicating the presence of excess silica. A good correlation was observed between the compressive strength of the blended mixtures and the CaO/$SiO_2$ ratio of the binder materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.4
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• pp.431-437
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• 2010

The purpose of this study is to compute the ground reaction forces during gait in the absence of force plates. The difficulties in using force plates for hemiparetic patients inspired us to initiate this study. Level-walking experiments were performed using a three-dimensional motion analysis system with synchronized force plates. Kinematic data were obtained from the three-dimensional trajectories of reflective markers. Gait events were also detected from the kinematic data. The human body was modeled as 13 rigid segments. The mass and the center of mass of each segment were determined from anthropometric data. Vertical ground-reaction forces obtained from the kinematic data were in good agreement with those obtained using the force plate. The computed and measured values of anterior and lateral ground reaction showed similar tendencies. The computation results can be used as the basic data for inverse dynamic analysis.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.119-128
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• 2006

This study was performed to see ground reaction force with different soccer studs with twelve players in Human Performance Laboratory(University of Calgary). Running speed was $4.0{\pm}0.2m/sec$ in straight running as well as vcut running. By using four different kinds of shoes; three different pairs of soccer shoes and one pair of jogging shoes, I reached a conclusion as following. In case of right and left ground reaction force, on the assumption that the positive magnitude of power is inversion and the negative is eversion, vcut running did not occur any inversion, which in the aspect of kinetic mechanics, thought to be decelerating movement. Because when eversion happens, it arises component force of power on heading direction about 8.6 times more than in the movement of straight running. In case of front and rear ground reaction, on the assumption that the positive magnitude of power is suspension power and the negative is propulsion, vcut movement is thought to be decelerating movement in the aspect of kinetic mechanics. Because on heading direction, this movement occurs component force of power about 1.8 times more suspension and 2.2 more propulsion than in the straight running movement. In case of vertical ground reaction, on the assumption that the first peak is the magnitude of power in impact and the second peak is the magnitude of power in active, we judged that the straight running movement performed more efficiently than the vcut movement in the aspect of kinetic mechanics. On the next study, I suppose that vcut running would make up an interesting subject in the aspect of improving kinetic performance ability.