• Journal of the Korean Society of Clothing and Textiles
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• v.11 no.2 s.24
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• pp.91-100
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• 1987

To develop the comfortable pesticid-proof clothes, wearing trials for 7 types of existing pesticide-proof clothes were done measuring skin temperature, pulse rate, humidity and temperature of inside clothing and subjective feeling such as thermal, humid and comfort sensations at $28{\pm}1^{\circ}C$, $75{\pm}5\%$ RH, 2.3 m/sec wind speed. (Experiment 1). On the base of above results, wearing trials of 6 types of new pesticide-proof clothes and 3 types of pesticide-proof clothes as control group were done with the same method as experiment 1. (Experiment 2). The results obtained were as follows 1. Heat stress was lower in newly designed pesticide-proof clothes with mesh running shirts. 2. For the body temperature regulation, it was confirmed that 6 types of new pesticide-proof clothes made of microporous fabric were better than the others.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.907-908
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• 2006

The energy storage systems are being widely researched for the electric power. The operations running in a vacuum chamber mainly consists of a composite flywheel rotor, superconductor bearings, a motor/generator and its controller. Among composed the apparatus, the floating magnet bearing consists of the ring-type permanent magnets with epoxy resin impregnation for reinforcement and surface protection. In order to storage as much energy as possible, the flywheel is supposed to be rotated with very high speed. The magnetic field is analyzed by using the Maxwell 2D/3D for the simulations.

• The KSFM Journal of Fluid Machinery
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• v.5 no.2 s.15
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• pp.43-49
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• 2002

In this paper, the steady-state performances analysis of a tilting pad gas bearing(TPGB) we analyzed by using finite element method for compressible Reynolds' equation. TPGB is used in a high-expansion-ratio expander running at a speed of 230,000 rpm. In order to solve the nonlinear finite element equations, the Newton-Raphson method is applied. The variations of the loading capacity, friction force and tilting angle of a single pad v.s. eccentricity direction of eccentricity and bearing number are investigated. The condition for the equilibrium of a pad, which is important for safe working of the bearing, is stated. The performances of the three pad bearing such as loading capacity, friction moment are predicted.

• Journal of the Korean Society for Railway
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• v.10 no.4
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• pp.431-437
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• 2007

This paper describes the dynamic modeling of a railway vehicle when it is under braking force. It is important for the enhancement of braking performance to establish a proper dynamic model of a railway vehicle because the braking performance is affected by some dynamic forces generated by a railway vehicle when it undergoes braking. In this paper, a dynamic model for one vehicle is suggested to compute the dynamic behavior of a railway vehicle in the HILS(Hardware In-the-loop Simulation) system for the railway vehicle braking devices. To simplify the dynamic model, friction between a wheel and a rail is assumed that there exist only the static and the dynamic friction forces. Static friction coefficient is also assumed to be a function of the running speed. Some simulations are carried out with various braking forces, and the braking characteristics according to the change of the braking force are discussed. This study can provide some fundamental results to construct the HILS system for braking devices of a railway vehicle.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.185-191
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• 1999

This paper deals with a method to predict the noise level inside metro electric cars running a single-line tunnel at the speed of 80km per hour using ray tracing method, a kind of ray acoustics generally used for a high-frequency and air-born noise analysis. The interior of the car including a under-frame, seats, side doors, end doors, door-pockets, side panels, end panel, a roof panel and so on is modeled. And in order to describe the noise power coming inside, artificial noise sources are designated using sound transmission loss data of each section measured from simple tests and external noise level. The noise level inside the car is calculated and its properties are investigated. The results satisfy the criteria on noise level inside the car.

• International Journal of Railway
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• v.5 no.2
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• pp.71-76
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• 2012

Recently, axle load, operating speed and traffic density on railroads have had a tendency to increase and thereby cause additional pressure applied on used track. These operating conditions frequently result in service failure due to wear caused by wheel-rail contact and fatigue damage under cyclic loading. Among rail defects, the transverse crack, which has been the most dangerous type of fatigue damages, is developed from the subsurface crack near the rail running face and grows perpendicular to the rail surface. Therefore, it is necessary to investigate systematically the growth behavior of transverse crack for rail steel under mixed mode. In this study, the fatigue crack growth behavior of the transverse crack in rail steel was experimentally investigated under mixed-mode variable amplitude loadings.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1922-1929
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• 2008

In order to install ATP system for KTX safety running, a study has been done to examine measures to ensure the interface between KTX and ATP system. Although onboard signaling system is efficient and has been verified both at home and abroad, alternatives for optimum installation shall be adopted so as to show designated performance taking into account the given peripheral device. A solution to interface between beacon and onboard system shall be presented especially for the KTX, which runs on both high speed and conventional line (ATP-ATS). Furthermore, the method for controlling the braking process and recorder shall be studied.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.255-261
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• 2008

The importance of maintenance of rail surface defects is increasing according to the KTX operation. That is because during high speed operation of rolling stocks, rail surface defects shorten fatigue life of rail, accelerate track degradation and deteriorate ride comfort. Rail grinding has been applied for effective rail maintenance in Kyeong-Bu HS line. This paper evaluates the effectiveness of rail grinding in term of rail fatigue life. To this end, the stresses of the ground rail are measured under KTX running and the equivalent stress range is calculated by RMC after the frequency analysis done with Rainflow counting method. Also, Pamglen-Miner rule is applied to predict the fatigue life of ground rail. The result of the analysis shows that the fatigue life of ground rail is increased by 15%.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.477-480
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• 2011

장경간 케이블 교량은 과도한 변위 발생 등의 이유로 엄격한 안전성 및 사용성이 요구되는 철도교량에서는 제한적으로 적용되고 있다. 즉, 철도교량으로서 요구되는 주행안전성과 승차감을 만족하기 위해서는 면밀한 분석이 필요하다. 본 연구에서는 교량/열차 상호작용 해석을 수행하여 열차에서의 응답을 통해 교량 상을 주행하는 열차의 주행안전성 및 승차감을 직접적으로 평가하고자 하였다. 즉, 중앙경간 300m의 현수교를 주행하는 KTX 열차에 대하여 열차 내부의 가속도와 윤중감소율을 구해 평가하는 방법을 취하였다. 또한, 이동 열차하중과 지진하중이 동시에 작용할 경우를 고려한 교량/열차/지진 상호작용해석을 수행하여 지진 시의 응답을 평가하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.485-488
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• 2011

본 연구에서는 경부고속철도의 콘크리트궤도에서 열차주행안전측면에서 관리해야할 레일패드강성의 상한값을 차량 및 궤도의 동특성과 운영환경을 고려하여 결정하는 방법을 제시하였다. 차량과궤도의 상호작용의 해석의 중요 입력파라메타인 궤도틀림과 관련하여 프랑스 및 독일에서 제시한 궤도틀림 PSD(Power Spectral Density)와 경부 1단계구간 콘크리트궤도에서 계측한 궤도틀림 자료를 통하여 얻은 PSD를 기초로 하여 넓은 범위의 주파수영역에서 적용할 수 있는 콘크리트궤도의 궤도틀림 PSD를 제시하였다. 제시된 PSD 기준모델을 사용하여 시간영역에서의 궤도틀림 입력을 Random Generation을 통하여 구한 후 개발된 차량-궤도 상호작용해석 기법을 사용하여 레일패드에 따른 윤중감소율을 산정하였다. 산정된 윤중감소율에 대하여 국내 철도차량 안전기준에 관한 규칙의 탈선계수 규정을 적용하여 주행안전측면에서 허용할 수 있는 레일패드강성의 상한값을 제시하였다.