• Strategy21
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• s.38
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• pp.83-111
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• 2015

In these days, 1949 revolt of admirals has a variety of evaluations. In 1949, many people thought that revolt of admirals is simply disobedience to Secretary of Defense. Revolt of admirals was considered that Navy was defeated to Air force. At that time, many people didn't put too much meaning this case. But at long last, the confidential documents about revolt of admirals opened to the public. This historic event's value was re-evaluated. Many researches were progressed in USA, On the other hand only some researches were progressed in Korea. So I try to study this topic and discover another meaning. Then, I will apply this lesson that obtained through study to our Korea Navy.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.78-80
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• 2005

Haptic interface apparatus is the device which can offer users virtual reality not only by visualization of virtual space but also by force or tactile feedback. In this paper, we designed and fabricated a 2D haptic interface device that can be used for various purposes, and implemented a virtual air-hockey system that users can easily find in game rooms. By suitable modeling and haptic rendering, users can feel the impact and the reaction force with his/her hand holding the handle through 2D haptic interface device when he/she hit an air-hockey puck with the handle. Through the trial demonstration. we observed the reasonable effect of direction and speed of a ball like doing in reality.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.2
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• pp.181-189
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• 1985

The effect of the Coriolis force on the 2-D turbulent boundary layer which is developed in the side wall of the rotating rectangular flow channel was investigated. In this study, we measured mean velocities, turbulent velocity components(axial as well as lateral ones) and Reynolds stresses of the turbulent boundary layer. For high Reynolds number flows, the turbulent boundary layer without pressure gradient is hardly affected by the rotation. For low Reynolds number flows, however, the shearing stress at suction side decreases. Consequently, the velocity near the wall become slower so that the thickness of the viscous sublayer expands. On the other hand, the velocity near the wall at pressure side turns out increased.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.326-331
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• 2000

In this study, residual stress was investigated experimentally to evaluate damaged layer in high-sped machining. In machining difficult-to-cut material, residual stress remaining in machined surface was mainly speared as compressive stress. The scale of this damaged layer depends upon cutting speed, feed per tooth and radial cutting depth. Damaged layer was measured by optical microscope. The micro-structure of damaged layer was a mixed maternsite and austenite. depth of damaged layer is increased with increasing of cutting temperature, cutting force and radial depth. On the other hand, that is slightly decreased with decreasing of cutting force. The increase of tool wear causes a shift of the maximum residual stress in machined surface layer.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.200-203
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• 2008

Water mist fire suppression system utilizes the fire suppression features such as cooling of fire source, dilution of ambient oxygen, and shielding of radiation heat with the evaporation of microscopic water droplets. The momentum of water mist is relatively low and the infiltration of water mist to the fire source is not effective. In addition to lower penetration force, the evaporated water vapor is liable to decline to limited portion of fire source due to its light weight and sparse density. On the other hand, the cycling water mist system is expected to improve the penetration force of water mist as well as the dilution coverage capability with the stratified spray characteristics. At this paper we present the analyzed fire suppression capability of intermittent water spray pattern by use of FDS which is computational fire dynamics fire model. We expect this analysis shall be supportive to the development of the prototype of water mist nozzle.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.375-382
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• 2001

This paper deals with the compensation method of AMD stroke by adopting variable gain feedback control strategy. The gains, generally known to be constant, are designed to have variable values according to the structural responses and the AMD stroke. This strategy has the advantage of compensating AMD stroke under any kind of loadings, on the other hand the conventional strategies work only under the specific loading. The strategy shows that the AMD stroke is compensated to prevent the stroke saturation and the control force is found not affected by the compensating operation while the control force is reduced and the control efficiency is decreased during the compensating operation in the conventional strategies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.157-162
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• 2003

This Paper presents a robust design of an Electrorheological(ER) damper using Taguchi method. Taguchi method is a robust design method that determines control parameters in the presence of noise effect. Electrode length, electrode gap, base oil viscosity and the weight ratio of ER particles are chosen for the control parameters and the temperature is considered to be a noise factor. The sensitivity of each factor with signal-to-noise(S/N) ratio and analysis of variance are investigated. The analysis results show that the electrode length and base oil viscosity of the ER fluid mostly affect the damping force in the absence of electric field. On the other hand, when the voltage is applied to the ER damper, the electrode length and the weight ratio of ER fluid exhibit significant effect. Based on the Taguchi method, an optimal configuration was designed and the robustness of the designed ER damper was validated by comparing the analysis and experimental results.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.4
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• pp.193-200
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• 2014

This paper examines the pounding problem between adjacent decks subjected to strong earthquakes. The elastomeric bearings in an isolated bridge reduce the stresses on the superstructure and cushion the impact by transferring smaller seismic forces to the substructure. On the other hand, these bearings also allow large horizontal displacement of the superstructure due to seismic forces. Bridges having various supporting soil conditions and different frequency ratios between adjacent decks are investigated by numerical analysis. In the analysis, decision making is conducted whether the collision took place or not and, the magnitude of pounding force and the duration time of collision are obtained and the results are discussed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.11a
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• pp.127-131
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• 2006

Depot have a lagged behind structure in the side of building up the view. With this reason, people have been recognized depot as hatred facility causes to have car noise, air pollution. In the other hand, depot become a underground and complex facility as a higher-value added building, and moreover, it need to understand the environment that depot structure have a specific field condition to apply green roof system. 1) Analysis proper waterproofing material and root barrier apply to depot need root penetrating test method 2) Suggest root barrier and waterproofing material relate to maintain and construction for green roof system 3) Construction condition for depot have crack movement of structure by vehicle vibration and root penetrating force by plant growth

• 한국전산유체공학회:학술대회논문집
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• 2002.05a
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• pp.29-34
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• 2002

TIn this study, the counter-jet flows which designed for improvement of aerodynamic performance of the blunt body vehicle have been analyzed. The variations of the drag force and jet penetration depth due to changes in the stagnation properties of counter jet new such as total pressure, mach number, and total temperature. The counter jet flow, which is injected toward incoming supersonic freestream at stagnation region of blunt cone-cylinder vehicle, have been studied by using upwind flux difference splitting navier-stokes method. The changes in the stagnation pressure and Mach number resulted in large effects on the wall pressure and drag force, on the other hand tile total temperature changes did not.