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유영화(Young-Hwa You),엄주환(Ju-Hwan Um),엄기영(Ki-Young Eum) 한국철도학회 2003 철도저널 Vol.6 No.4
A quantitative analysis on the amounts of cant and lateral displacement of gravitational center due to the introduction of high-speed tilting car was carried out, based on the current alignment of the conventional line. In addition, the maximum allowable speed in curve and the level of improvement in maximum speed of tilting car were evaluated through the comparison with the maximum speed of locomotive. It was found that the tilting car produces an equivalent amount of cant, which corresponds to 47.5 % of current actual cant. This effect could be explained by the fact that 1.34 m, which is the height of gravitational center of tilting car from the rail level, is much lower than that of locomotive and thus guarantees much higher level of safety in curve. The equivalent amount of cant due to the lateral displacement of gravitational center followed by tilting in curve was 2.4 mm. It was small but not enough to be neglected and must be included in calculating the maximum speed in curve. It could be concluded that the 15 % speed-up of the conventional line is reasonable under the current condition of alignment.
틸팅특성과 승차감을 고려한 틸팅열차의 곡선부 제한속도 평가
엄기영(Ki-Young Eum),엄주환(Ju-Hwan Um),여인호(In-Ho Yeo),유영화(Young-Hwa You) 한국철도학회 2004 한국철도학회 학술발표대회논문집 Vol.- No.-
For the purpose of speed-up of conventional lines with many curves, the introduction and operation of tilting train is under process. Those are Joong-Ang, Jang-Hang and Ho-nam lines etc. Tilting trains can run a curve section faster than existing trains without a significant violation of passenger"s comfort and enable to reduce operating time in the lines with many curves. In this study, the trains speeds are evaluated, based on the alignment of conventional line, criteria for passenger"s comfort and investigated field conditions of the sections where the curves exist. Decision on whether the alignment(transition line) needs to be modified or not is also made. Relative efficiency on curve sections of tilting train to existing trains is approximately 50 % in average.
엄기영(Ki-Young Eum),엄주환(Ju-Hwan Um),유영화(Young-Hwa You),최정호(Jung-Ho Choi) 한국철도학회 2004 철도저널 Vol.7 No.4
The investigation of running stability of the train for curved track is necessary in view of preventing the train from derailment caused by unbalanced forces transferred from the wheel and guaranteeing moderate level of running safety in curve sections. This paper carried out an analysis of running stability of tilting trains in conventional line which the test operation of tilting trains under development are scheduled. For this purpose, the wheel load and lateral pressure to the rail are evaluated. The criteria for the calculated wheel load and derailment coefficient are compared to the design criteria for running stability. It is founded that the running stability of tilting trains for curved track is guaranteed to have sufficient safety and the train speed in curve is governed by the geometric lay out of track rather than the criteria for running stability.
엄주환(Ju-Hwan Um),유영화(Young-Hwa You),엄기영(Ki-Young Eum) 한국철도학회 2003 철도저널 Vol.6 No.4
In this paper, the track impact factor of conventional line was evaluated using the data for wheel load measured in field and the properties of current operating trains. The equation for track impact factor was presented through the statistical analysis of variational ratio in wheel load and compared with other design equations in domestic and foreign countries. A review on the safety of track system in conventional line was made from the relationship between the velocity and the corresponding impact factor It was found that the impact factor from the proposed equation is a little less than the values from the equations adopted in both AREA and domestic railway, while it is same as the equation for continuous welded rail(CWR) in Japan. Therefore it could be said that the track satisfies a criteria for dynamic load caused by the train and the corresponding level of safety is guaranteed for dynamic load of the train
기존선 완화곡선부의 승차감을 고려한 틸팅차량의 곡선부 제한속도 평가
엄주환(Ju-Hwan Um),엄기영(Ki-Young Eum),여인호(In-Ho Yeo),유영화(Young-Hwa You) 한국철도학회 2004 철도저널 Vol.7 No.4
The purpose of this paper is to present the alignment layout and the way of modifying transition curve for better operation of tilting trains. It is based on data from field investigation of all curves in conventional line. In general, all curves have transition parts in the beginning and end of the main curve in order to improve the passenger s comfort. The speed-up of conventional line may need an extention of transition curves. This paper checked out whether the transition curve should be modified or not and how to lengthen it. Then the maximum train speeds in curve prior to and after the modification of transition curve were evaluated.
김운학,유영화,박문식 안성산업대학교 2002 論文集 Vol.34 No.-
Several considerations on structural safety of connection part in Finger-Type expansion joint system were presented in this paper. Special considerations were focused on the compressive strength of sealant concrete, the stress of anchor bolt through introducing prestressing force and he reasonability on the magnitude of prestressing force. Tow-and three-dimensional finite element analyses using MIDAS have been performed to check the structural safety of the expansion joint system. The analysis results showed that the excessive compressive stress acting on concrete can be dispersed or reduced only when over 40% of maximum tensile stress acting on bolt obtained by hand calculation is added to the prestressing force. And the design compressive strength of sealant concrete over 400 kgf/㎠ is reasonable, but more attention should be paid to quality control and construction management even though he design value of 500 kgf/㎠ in original design can improve a structural safety.
시간이력 해석법을 사용한 교량의 지반-구조물 상호작용해석
김운학,유영화,김남창 안성산업대학교 2002 論文集 Vol.33 No.-
A response analysis of bridge subjected to seismic forces is performed by applying seismic input motion at the base defined in Free Field to the footing, under the usual assumptions that the base is rigid body and the superstructure is rigidly connected to the base. Seismic design of bridge is required to consider the facts that the base has flexibility and this property may give an effect on the seismic response of superstructure. In this paper, the effects specified above have been considered in soilstructure interaction(SSI) time history analysis by SAP2000, where instead of conventional seismic design concept which uses a site coefficient and a assumption of rigid footing, substructure method has been incorporated into the analysis after evaluating the equivalent spring constant representing those properties. An artificial earthquake simulated from the design spectrum specified in Guideline for Highway Bridges was used throughout the 3-D analysis. Using equivalent spring constant representing the base footing makes it possible to predict more realistic behavior, which was not found in conventional analysis.