• 한국철도학회논문집
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• 제8권4호
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• pp.348-353
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• 2005

In designing the structures of railway rolling stocks, deterministic methods associated with the concept of a safety factor have been traditionally used. The deterministic approaches based on the mean values of applied loads and material properties have been used as safety verification for the design of rolling-stock car body structures. The uncertainties in the applied loading for the high speed train and the strength of new materials in the rolling stocks require the application of probabilistic approaches to ensure fatigue safety in the desired system. Pressure loadings acting on the car body when the train passes through tunnels show reflected pressure waves for high-speed trains and they may cause a fatigue failure in vehicle bodies. Use of new material technology as body structures also introduces uncertainties in the material strength. A probabilistic approach is more adaptable in designing reliable structures when the pressure waves from the tunnels pounds and new material technology is adopted. In this paper, it is proposed that a fatigue design and assessment method based on a reliability which deals with the loading variations on a railway vehicle due to the pressure reflected in tunnels and the strength variations of material. Equation for the fatigue reliability index has been formulated to calculate the reliability assessment of a vehicle body under fluctuating pressure loadings in a tunnel. Considered in this formulation are the pressure distribution characteristics, the fatigue strength distribution characteristics, and the concept of stress-transfer functions due to the pressure loading.

• 한국철도학회논문집
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• 제14권4호
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• pp.333-340
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• 2011

본 논문은 유럽 TSI와 국내철도차량안전기준에 정의된 건널목 충돌사고시나리오에서 요구하는 성능의 대형 변형체 장애물의 유한요소 모델에 대하여 2가지 종류의 모델을 개발하여 한국형 분산형 고속철도 차량에 적용하고 평가하였다. 규정에서 요구하는 대형 장애물은 기존 강체모델에서 현재의 변형체모델로 변경되었으며 규정에 정의된 방법으로 변형체 강성 값이 검증되어야 한다. 여러 번의 시뮬레이션을 통해 기준을 만족하는 균일한 밀도와 강성의 솔리드 형 장애물 모델과 균일하지 않은 셸 형 장애물 모델 등 2가지를 개발하였다. 본 연구에서 개발된 대형장애물을 사용하여 분산형 고속열차를 대상으로 규정의 대형장애물 충돌시뮬레이션을 수행하였고 그 결과를 평가하였다. 셸 형과 솔리드 형 장애물은 열차와 충돌 후 거동에 상당한 차이가 있었고, 셸 모델이 더 가혹한 결과를 나타내었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1624-1626
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• 2004

On the 105th year of the Korean Railroad, Korea railroad is at the advent of the high speed operation with an commercial operation of KTX(Korea Train eXpress), the fifth high speed line in the world, between Pusan and Seoul at the speed of 300km/hr. In order to enhance nation competitiveness in $21^{st}$ century, Korea Railroad is faced with a task of improving the railroad network in the areas of new line constructions, betterment of existing rail lines, increasing the operation speed and transportation capacity and modernization of rolling stock fleet.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.249-256
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• 1998

Design target values of transmission loss in a high-speed train wall are suggested by calculating the difference between interior and exterior noise levels of it. Exterior noise level distribution on the boundary of train wall is calculated by Sysnoise, with sound source input prepared by experiments. Two kinds of exterior sound sources are considered, the rolling noise of train wheels on the rail and the aerodynamic noise from the pantograph. Interior noise level is provided by high-speed design target. Transmission loss characteristics according to the frequency band are examined.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.437-445
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• 2002

The development of railway vehicle and bogie involves the proper selection of design parameters not only to achieve high speed of the train but also to reduce the vibration. In this study, an analytical model of a high speed freight car is developed to find the critical speed. The high speed freight car can generate the snake motion of the lateral, rolling and yawing motion of the car body and the bogie. The numerical analysis for the equation motions with 17 degrees of freedom showed the running stability and the critical speed due to the snake motion. Also the vibration modes of the high speed freight car was calculated using ADAMS RAIL software, which showed that the critical speed have the yawing modes of the car body and the bogie.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.1-14
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• 2013

In this paper, a finite element analysis technique of rolling stock models for collision-induced derailments was suggested using rolling contacts for wheel-rail interaction. The collision-induced derailments of rolling stock can be categorized into two patterns of wheel-climb and wheel-lift according to the friction direction between wheel flange and rail. The wheel-climb derailment types are classified as Climb-up, Climb/roll-over and Roll-over-C types, and the wheel-lift derailment types as Slip-up, Slip/roll-over and Roll-over-L types. To verify the rolling contact simulations for wheel-rail interaction, dynamic simulations of a single wheelset using Recurdyn of Functionbay and Ls-Dyna of LSTC were performed and compared for the 6-typical derailments. The collision-induced derailment simulation of the finite element model of KHST (Korean High Speed Train) was conducted and verified using the theoretical predictions of a simplified wheel-set model proposed for each derailment type.

• 한국소음진동공학회논문집
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• 제20권5호
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• pp.477-485
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• 2010

In this study, we suggested several approaches to evaluate the collision acceleration of a carbody under the article 16 of the Korean rolling stock safety regulations. There are various methods to evaluate the rigid body accelerations such as the displacement comparison method by double integration of filtered acceleration data, the velocity comparison method by direct integration of filtered acceleration data, and the analysis method of a velocity-time curve. We compared these methods one another using the 1D dynamic simulation model of Korean high-speed EMU composed of nonlinear springs or bars, dampers, and masses. From the simulation results, the velocity-time curve analysis method and the displacement comparison method are recommended to filter high frequency oscillations and evaluate the maximum and average accelerations of a carbody after a train collision.

• 대한기계학회논문집
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• 제12권6호
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• pp.1217-1226
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• 1988

본 연구에서는 고속연속주조의 기초적 연구로서 벌징만을 선택하여 주조속도 의 변화에 의한 주편의 거동을 해석하기 위해 응력을 변형률, 변형률속도, 온도의 함 수로서 잡고 크리프 변형과 탄소성 변형을 동시에 고려한 모델을 도입하여 주편내에서 의 벌징량, 변형률 등의 상태를 밝히며, 고속주조에 있어서 고려해야 할 사항에 대하 여 고찰한다.

• Advances in Computational Design
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• 제4권1호
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• pp.33-41
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• 2019

In this study, 2-mm Al/Cu bimetallic laminates were produced using asymmetric roll bonding (RB) process. The asymmetric RB process was carried out with thickness reduction ratios of 10%, 20% and 30% and mismatch rolling speeds 1:1, 1:1.1 and 1:1.2, separately. For various experimental conditions, finite element simulation was used to model the deformation of bimetallic Al/Cu laminates. Specific attention was focused on the bonding strength and bonding quality of the interface between Al and Cu layers in the simulation and experiment. The optimization of mismatch rolling speed ratios was obtained for the improvement of the bond strength of bimetallic laminates during the asymmetric RB process. During the finite element simulation, the plastic strain of samples was found to reach the maximum value with a high quality bond for the samples produced with mismatch rolling speed 1:1.2. Moreover, the peeling surfaces of samples around the interface of laminates after the peeling test were studied to investigate the bonding quality by scanning electron microscopy.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.581-585
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• 2005

For the Korean high speed railway rolling stock, which is developed through the G7 research project, various tests such as components test, prototype train test, on-line test have been carried out for years. In order to obtain the system stability, mutual interface between each part (rolling stock, track, bridge, electricity and signal) should be verified. For this reason, track performance according to the speed increase of HSR has been monitored in field. Especially, through the analyses of accumulated data, structural and running stability of HSR has been evaluated. With this viewpoint, this paper presents the track performance test method and the test results corresponding to 350km/h speed increase of HSR.