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유한요소법을 이용한 전차선로-팬터그래프 동적상호작용 해석 프로그램의 개발 및 검증
조용현(Cho Yong Hyeon),강윤석(Kang Youn-suk),이기원(Lee Kiwon) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-
We have developed a catenary-pantograph dynamic simulation program by using the finite element method and verified the accuracy according to the EN 50319. During the validation process, we have reviewed which the time integration methods is proper for this application. among the Newmark method, Wilson theta method and alpha method. We conclude that the alpha method is the best in terms of computation time and accuracy.
탄성파시험에 의한 프리캐스트 슬래브궤도의 강성구조와 충전성능 평가
이일화(Lee Il-Wha),조성호(Joh Sung-Ho),장승엽(Jang Seung-Yup),강윤석(Kang Youn-Suk),한성우(Han Sung-Woo) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-
Recently, precast concrete tracks are replacing ballast track for efficient and economic maintenance of track. Precast concrete railroad tracks are manufactured in factory, and transported to railroad construction site for installation. Therefore, quality of precast concrete track itself should be sufficiently good. On the contrary to the convenient manufacturing of precast concrete track, the installation of a precast concrete track requires careful steps. Typically, a precast concrete track is placed on an approximately 15-cm thick lean concrete layer. A mortar is filled between lean concrete layer and precast concrete track to adjust the sloping angle of a precast concrete track for a safe train operation at a curvy section. Then, the use of filled mortarproduces a void underneath a precast concrete track, which is harmful to structural safety of a precast concrete track undercyclic loading. Therefore, it is essential to make sure that there is no void left beneath a precast concrete track after mortar filling. In the continuous resonance method, the amplitude of frequency response measured using an instrumented hammer and an accelerometer is plotted against a pseudo-depth, which is half of the wave velocity divided by frequency. The frequency response functions are measured at consecutive measurement locations, 6-cm interval between measurement points, and then combined together to generate a 2-D plot of frequency response. The sections with strong reflections or large amplitude of frequency response are suspicious areas with internal voids and unfilled areas. The 2-D frequency response plot was efficient in locating problematic sections just by examining the color shade of a visualized plot in 2-D format. Some of the problematic sections were drilled to make a visual inspection of mortar filling. The visual image of interface between mortar and precast concrete track was verified using the validity of the continuous resonance technique adopted in this research.