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현상학,유홍희,Hyun, Sang-Hak,Yoo, Hong-Hee 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.4
In this paper, an infinite determinant method is presenstd for stability analysis of parametrically excited systems. Unstable regions of the combination parametric resonance as well as principal resonance can be identified with the method. A numerical problem of relatively large amplitude of excitation is solved, and the results of the presented method are compared to those of the multiple scales perturbation method. It is found that the presented method obtains more accurate transition curves which divide stable and unstables in the parameter plane than those of the multiple scales perturbation method.
Torsion Beam Axle 현가장치 설계전용 프로그램 개발을 위한 연구
현상학(Sang-Hak Hyun),이치범(Chi-Bum Lee),최동환(Dong-Hwan Choi),신상하(Sang-Ha Shin),유홍희(Hong Hee Yoo) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
Due to the low production cost and space availability which are originated from the structural simplicity of the<br/> torsion beam axle suspension, the suspension has been frequently used for sedan and SUV style vehicles. The design<br/> procedure of the suspension, however, requires significant amount of time which prohibits more efficient design of<br/> the suspension. In this paper, an integrated procedure and constituting modules are explained and the performance of<br/> the corresponding program is exhibited. The integrated procedure enables one to save the design time and cost<br/> tremendously.
열차 주행안전성 해석을 위한 분기기 모델링 툴킷 개발 및 적용
김만철(Man-chul Kim),현상학(Sang-Hak Hyun) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10
분기기를 통과하는 열차의 주행안정성과 승차감 해석을 위해서는 분기기의 동역학 특성을 정밀하게 묘사하는 모델링 작업이 선행되어야 한다. 일반 궤도 구간에 비해, 분기기 궤도 모델링은 과정이 복잡하고 많은 시간을 소요한다. 왜냐하면 선형이 복잡하고, 위치별로 기하학적 레일 형상 및 궤도 강성이 다르기 때문이다. 본 연구에서는 분기기 선형, 텅레일/노즈레일 단면, 그리고 궤도 강성 모델링을 자동화하는 모델링 툴킷을 개발하고 실제 분기기 시스템에 적용하였다. 개발된 모델링 툴킷을 사용하여 분기기 선형 변화, 레일단면 변화, 그리고 궤도 강성에 변화에 따른 주행안전성 특성 변화를 분석하였다. 특히, 스위칭부와 크로싱부에서의 레일 단면 정밀도와 궤도 강성이 접촉력 크기에 미치는 영향을 분석하였다. To analyze the running safety and comfort of the train passing the turnout, modeling the dynamic characteristics of the turnout shall be preceded. Turnout track modeling requires complex process and time, comparing to plain track because of complex alignment and different profile of rail cross section and track stiffness depending on location. In this study, tool kit designed for modeling the turnout alignment, tongue rail/nose rail section and track stiffness was developed and applied to real turnout system. Using developed modeling tool kit, analysis of the changes to the characteristics of running safety depending on changes to turnout alignment, rail section and track stiffness was carried out. Particularly, among others, analysis of the effect of the accuracy of rail section on swing part and crossing part and track stiffness on contact force was carried out.
김만철(Man-Cheol Kim),황성호(Sung-Ho Hwang),황광하(Kwang-Ha Hwang),현상학(Sang-Hak Hyun) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
In this paper a flexible track modeling of turnout was developed and dynamic characteristics of turnout rails were analyzed when a vehicle passed through the turnout. The flexible track modeling is effective to the stiffness and durability design of turnout because it can capture the deformation and dynamic stress due to the collision of between wheels and rails when the vehicle move to the tongue rail. Also a more accurate running safety can be obtained by considering the interaction between wheel and rail deformation. Solid finite elements were used for variable cross-sections of rails and the variation of rubber stiffness was modeled. The proposed flexible track modeling in this paper was verified to be valid by comparison with the experiment of the turnout system.