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김거영(Kim Geo-young),조현직(Cho Hyun-Jik),구정서(Koo Jeong-Seo) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
Through this study, standard design guidelines for the high speed EMU have been derived to meet the crashworthiness requirements of the Korean rollingstock safety regulation. The crashworthiness regulation requires some performance requirements for two heavy collision accident scenarios; a train-to-train collision at the relative speed of 36 kph, and a collision against a standard deformable obstacle of 15 ton at 110 kph. The complete train set will be composed of 2TC-6M with 13 ton axle load, different from KTX with the power car of 17 ton axle load. Using theoretical and numerical analyses, some crashworthy design guidelines were derived in terms of mean crush forces and energy absorptions for main crushable structures and devices. The derived design guidelines were evaluated and improved using one dimensional spring-mass dynamic simulations. It is shown from the simulation results that the suggested design guidelines can easily satisfy the domestic crashworthiness requirements.
Filament winding 공법 GFRP 원형튜브의 에너지 흡수특성에 관한 연구
김거영(Kim Geo-Young),구정서(Koo Jeong-Seo) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
In this paper, quasi-static crushing tests of composite circular tubes under axial compression load are conducted to investigate the energy absorption characteristics. Circular tubes used for this experiment are glass/epoxy (GFRP) composite tubes, which is fabricated by the filament winding method. One edge of the composite tube is chamfered to reduce the initial peak load and to prevent catastrophic failure during crushing process. Two suggested trigger mechanisms for the composite tubes are investigated. Crushing modes are mainly affected by thickness/diameter ratio, and average crushing loads are mainly affected by their cross-sections. Energy absorption characteristics vary significantly as a function of the tube geometry, trigger mechanism, t/D ratio and the cross-sectional shape.
주기적 변동 측풍을 고려한 철도차량의 이론적 탈선 안전성 평가
김거영(Geo Young Kim),구정서(Jeong Seo Koo),노주현(Joo Hyun Rho) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.2
본 논문에서는 주기적으로 변동하는 측풍이 작용할 때 철도차량의 탈선 안전성을 평가하기 위한 이론식을 도출하고, 도출된 이론식은 동역학 프로그램으로 이용하여 검증하였다. 탈선 안전성은 국제철도기술기준(TSI)에서 요구하는 윤중 감소비를 기준으로 평가하였는데, 측풍뿐만 아니라 곡선구간 주행시 횡방향으로 작용하는 원심력도 동시에 고려하였다. 큰 차체의 관성과 상대적으로 강성이 낮은 2차 현가장치로 인하여 차체의 횡방향 고유진동수가 1Hz 이하 저주파 구간에 존재하게 되며, 이 주파수와 동일한 주기의 측풍이 일정시간 지속되고 댐핑계수가 작을 때 차량의 윤중 감소 값이 비정상적으로 증가하여 측풍 원인 탈선 위험이 높아지는 것으로 확인되었다. 이때 차체의 공진주파수 이론 값은 수치 시뮬레이션 값과 비교하여 5% 이하로 잘 일치하였다. In this paper, a theoretical formula is proposed to evaluate the derailment safety of rollingstock under cyclical crosswind conditions and verified by using the multibody dynamics software. The derailment safety is evaluated by the wheel unloading criteria of the TSI in EU, considering the simultaneous effects of the crosswind and the centrifugal force on a curved track. In the case of rollingstock, because of the high inertia of the carbody and the relatively low stiffness values of the second suspensions, there are low lateral natural frequencies less than 1 Hz. It is proven using the suggested theoretical formula that the wheel unloading increases abnormally according to the elapsed time, and the risk of derailment increases when the frequency of a crosswind is same as the lateral natural frequency of the carbody and the damping coefficient is small. The theoretical estimations for the resonance frequency of the carbody are in good agreements with the simulation results within 5% deviation.
김거영 ( Geo Young Kim ),김현태 ( Hyun Tae Kim ),구정서 ( Jeong Seo Koo ) 한국안전학회(구 한국산업안전학회) 2016 한국안전학회지 Vol.31 No.3
Since defects in the wheels of railway vehicles, which occur due to wears with the rail, cause serious damage to the running device, the diagnostic monitoring system for condition-based maintenance is required to secure the driving safety. In this paper, we studied to apply a useful Cepstrum analysis to detect periodic structure in spectrum among the vibration signal processing techniques for the fault diagnosis of a rotating body such as wheel. In order to analyze in variations of train velocity, the Cepstrum analysis was performed after a domain change of the vibration signal from time domain to rotation angle domain. When domains change, it is important to use a interpolation for a uniform interval of the rotation angle. Finally, the Cepstrum analysis for wheel flat detection was verified by using the vibration signal including the disturbance resulting from the rail irregularities and the vibration of bogie components.
차체의 압괴특성에 의한 충돌 후 타고오름 거동에 관한 연구
김거영(Kim Geo-young),구정서(Koo Jung-Seo),박민영(Park Min-Young) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7
This paper proposed a new 2D multibody dynamic modeling technique to analyze overriding behavior taking place during train collision. This dynamic model is composed of nonlinear spring, damper and mass by considering the deformable characteristics of carbodies as well as energy absorbing structures and components. By solving this dynamic model of rollingstock, collision energy absorption capacity, acceleration of passenger sections, impact forces applied to interconnecting devices, and overriding displacements can be well estimated. For a case study, we choose KHST (Korean High Speed Train), obtained crush characteristic data of each carbody section from 3D finite element analysis, and established a 2D multibody dynamic model. This 2D dynamic model was suggested to describe the collision behavior of 3D Virtual Testing Model.