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나성훈(Na Sung-Hoon),서사범(Suh Sa-Bum),손기준(Son Ki-Jun),김정환(Kim Jung-Hwan) 한국철도학회 2001 한국철도학회 학술발표대회논문집 Vol.- No.-
In order to evaluate the effect of impact load at support stiffness transition area, the field estimations are performed at the transition zone between earthwork and bridge on test operation of KTX. Due to differential settlement caused by the variations of track support stiffness, large impact forces are investigated. However, the measured values such as wheel load, rail stress, displacement and acceleration in the transition area shows that the stiffness changes in the transition area are not abrupt, and the stiffness in the infra track structure varies continuously. In this experimental study. the parameters influencing safety of transition area are not governed by partial or local stiffness because cumulative passing loads are not sufficient on test operation of KTX.
구봉근(Koo Bong-Kuen),서사범(Suh Sa-Bum) 한국철도학회 2000 철도저널 Vol.3 No.1
The rail temperature is important to preserve the joint gap for standard length of rail and to determine the installation temperature which has direct influence on the rail buckling and failure in welded part for continuous welded rail(CWR). Therefore, we have measured and investigated various characteristics of rail temperature for each kind of rail. As the results of this, the correlation between the atmosphere temperature and the rail temperature which is commonly used by Korean Railway should be reconsidered. Also, the daily highest & lowest rail temperature was occurred when each temperature is higher and when it's lower. For the light rail, the rail temperature by the sun-light increases quickly and decreases late. But the time where the highest temperature is attained is same. There are some differences between the shade and sunny place about 3.0~4.0℃. The temperature of rail web is almost close to the conversion rail temperature for rail expansion. The wind of 1 m/s has an influence on the rail temperature around 5℃.
고속철도 궤도패드의 최소 수직 스프링계수 결정에 관한 연구
김정일(Kim Jeong-il),양신추(Yang Sin-Chu),김연태(Kim Yun-Tae),서사범(Suh Sa-Bum) 한국철도학회 2005 한국철도학회 학술발표대회논문집 Vol.- No.-
Railway noise and vibration has been recognized as major problems with the speed-up of rolling stock. As a kind of solution to these problems, the decrease of stiffness of track pad have been tried. However, in this case, overturning of rail due to lateral force should be considered because it can have effect on the safety of running train. Therefore, above two things - decrease of stiffness of track pad and overturning of rail due to lateral force - should be considered simultaneously for the appropriate determination of spring coefficient of track pad. With this viewpoint, minimum spring coefficient of track pad is estimated through the comparison between the theoretical relationship about the overturning of rail and 3-dimensional FE analysis result. Two kinds of Lateral force and wheel load are used as input loads. Extracted values from the conventional estimation formula and the Shinkansen design loads are used. It is found that the overturning of rail changes corresponding to the change of the stiffness of track pad and the ratio of lateral force to wheel load. Moreover, it is found that the analysis model can have influence on the results. Through these procedure, minimum spring coefficient of track pad is estimated.
이지하(Lee Jee-Ha),황성호(Hwang Sung-Ho),나성훈(Na Sung-Hoon),김정환(Kim Jung-Hwan),서사범(Suh Sa-Bum) 한국철도학회 2004 한국철도학회 학술발표대회논문집 Vol.- No.-
When the track designer analyze the track structure uses many known & unknown parameters. Unknown parameters, equivalent rail support spring factor, unit rail support spring factor, track damping coefficient, should be assumed. Known parameters are section properties (area, section factor, etc.), material properties(modulus of elasticity, mass, etc) and track conditions(wheel load, loading conditions, gauge, etc.). In the assumption of track design parameters, some parameters can be overestimated or under estimated. The purpose of this study is to verify design parameters used in track design, in the way of experimental measurements. Data of displacements, banding stresses, loads, accelerations are measurable at track site. From these data, unknown parameters are derived. Compare these assumed and derived parameters, estimate the entire track stability.
구봉근,서사범 충북대학교 건설기술연구소 2000 建設技術論文集 Vol.19 No.1
Deterioration of track geometry is grooved due to ballast sinking by repeated train load. In order to improve riding quality for track, this kind of deterioration of track geometry should be repaired. Recently this is being done by MTT(Multiple Tie Tamper). As repair works of track deterioration destabilize track ballast at stable condition, it's necessary to have slow speed operation of train until ballast is stabled after track repair works. Therefore, this study measure effectively track stability condition before/after realignment of track for track repair technology. As a result of this study, we realize that track stability condition pretty bad(for example, ballast resistance force is reduced half and rail stress is increased around 30% after track repair works).