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구정서(J. S. Koo),노규석(K. S. Rho),조현직(H. J. Choi),권태수(T. S. Kwon),최성규(S. K. Choi) 한국철도학회 2000 한국철도학회 학술발표대회논문집 Vol.- No.-
In this paper, numerically evaluated is the regulations for crashworthy design of the Korean standard urban train suggested by KRRI. The 4-car consist of K-EMU(Korean Electric Multiple Unit) train developed in recent is analyzed under various collision conditions such as normal coupling, heavy shunt, light and heavy collisions. The collision conditions are assumed as K-EMU collides against another stationary one at 5 kph, 10 kph, 25 kph and 32 kph. According to the numerical results and bibliographical study, it is necessary that the regulations by KRRI be complemented from crashworthy point of view. Furthermore, the K-EMU train is recommended to adopt a new coupler with an additional energy absorber or a mechanical fuse.
장기 저장연료의 열안정성 및 연료접촉 고무오링의 수명예측 연구
정근우(K. W. Chung),홍진숙(J. S. Hong),김영운(Y. W. Kim),한정식(J. S. Han),정병훈(B. H. Jeong),권태수(T. S. Kwon),서동욱(D. O. Suh),성민준(M. J. Sung),권영일(Y. I. Kwon) 한국트라이볼로지학회 2018 한국윤활학회지(윤활학회지) Vol.34 No.5
Thermal deterioration of fuel due to long-term storage influences engine performance and causes malfunctions. Fuel stability is usually evaluated via heat resistance and thermal stability during a brief heat shock at high temperature; storage stability in this scenario means that there is very little change in the quality of the fuel during long-term storage. In addition, rubber-based products such as oil seals, O-rings, and rubber hoses can influence the quality of the fuel. When these rubber products are in contact with fuel, they can swell, mechanically weaken, and occasionally crack, thus leaking low molar weight rubber and additives including plasticizer and antioxidant into the fuel to degrade its properties and shorten its useful lifetime. This study determines the thermal stabilities of three kinds of synthetic fuels by evaluating their low temperature kinematic viscosities, chemical composition changes via GC analyses, gross heat of combustion, and color changes. We evaluate the compression set of O-rings by immersing one NBR and two FKM rubber O-rings in the three synthetic fuel samples in airtight containers at variable storage temperatures for six months; from this, we estimate the lifetimes of the O-rings using the Power law model. There were very little changes in the chemical compositions and gross heat of combustion after six months of the experiment. The lifetimes are thus dependent on the materials of the rubber products, and in particular, the FKM O-ring was calculated to have a theoretical lifetime of 200 to 5,700 years. These results indicate that the synthetic fuels maintain their physical properties even after long-term storage at high temperatures, and the FKM O-ring is suitable for long-term sealing of these fuels.
이장욱(J.W. Lee),정지호(J.H.Jeong),김승택(S.T.Kim),이강운(K.W.Lee),권태수(T.S.Kwon),정현승(H.S.Jeong) 한국철도학회 2015 한국철도학회 학술발표대회논문집 Vol.2015 No.10
철도차량 충돌안전도에 대한 법규 및 규격이 전세계적으로 발효되어 이에 대한 철도차량의 충돌안전 설계가 요구되고 있다. 본 연구의 목적은 기관차에 적용되는 대용량 충돌에너지 흡수부재를 개발하여 차량의 단부에 설치하므로서 국내 철도안전법 및 유럽의 충돌안전 규격을 만족할 수 있도록 하는 것이다. 기관차는 차체의 강도가 강하여 차체 끝단부에 설치된 흡수부재가 모든 충돌에너지를 받도록 설계하는 것이 합당한 방법이다. 본 연구를 통해 충돌 시 차체의 변형 없이 충돌흡수부재에서 모든 충돌에너지를 받는 개념의 흡수부재를 개발하였고 실물 제작을 통한 충돌시험 입증까지 완료하였다. 끝으로 실제 기관차에 본 흡수부재를 모델링하여 적정성을 최종충돌해석을 통하여 검증하였다. Recently, the crashworthiness requirements and standards are variously released world widely and the passive crashwothiness design are requested. In this paper, the high capacity of crash energy absorbing element which is to be applied to the locomotives has been studied and developed. As the strength requirement for the proof load is severe for the locomotives, the side buffer type is needed to be attached on the car extreme end .This concept is to protect the carbody structure with buffer to absorb all the required energy. The absorbers are developed by real crash test and finally the crashworthiness analysis with full carbody structure has been analyzed according to EN15227 C-I standard.
구병춘(B. C. Goo),이찬우(C. W. Lee),권태수(T. S Kwon) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
용접구조물은 대부분 용접 토우에서 균열이 발생하여 성장하고 어느 크기에 도달하여 구조물이 작용하중을 더는 지탱하지 못하게 되면 파손에 이르게 된다. 용접부의 용접금속과 모재의 열영향부가 만나는 부위는 용접열에 의해 미세조직이 변하고 용접 비드의 표면에 요철이 생겨 응력집중이 발생하기 쉽고, 표면층에는 용접으로 인장 잔류응력이 작용하므로 피로강도 측면에서 매우 취약하다. 용접부의 피로강도를 향상하기 위해 용접 토우 주위를 고주파 가진 액추에이터를 진동시켜 충격 핀이 용접 토우 부위를 타격하면 소성변형이 발생하여 인장 잔류응력이 압축 잔류응력으로 변한다. 그리고 피닝은 조직을 미세하게 하고, 거친 표면을 매끄럽게 하여 응력집중을 완화해 피로강도를 향상한다. 본 연구에서는 독자적으로 초음파 피닝 장비를 개발하고, SM490A 강판으로 용접시편을 제작하고 개발 장비로 용접 토우에 피닝을 하여 피닝이 용접부의 피로수명에 미치는 영향을 평가하였다. Most cracks in the weld structure occur and grow on the weld toe, reaching a certain size, resulting in breakage if the structure no longer supports the working load. The area where weld metal and parent metal meet each other is very weak in terms of fatigue strength due to microstructural change and tensile residual stress. To improve the fatigue strength of the weld joint, ultrasonic impact peening is widely used. Peening makes the microstructure fine, smoothes the rough surface, and relieves stress concentration. In this study, we developed ultrasonic peening equipment, manufactured welded specimens with SM490A steel plate, and investigated the effect of ultrasonic impact peening on the fatigue lifetime of the welded specimens.
철도 차량용 티어링 튜브의 충돌 에너지 흡수 능력 예측 기법
고윤기(Y. K. Ko),안광현(K. H. Ahn),허훈(H. Huh),최원목(W. M. Choi),정현승(H. S. Jung),권태수(T. S. Kwon) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
This paper deals with the numerical prediction of energy absorbing capacity of a tearing tube, which can absorb the crash energy through expanding and axial splitting process. It is important to consider the dynamic material behavior and fracture characteristics of tube material in order to simulate accurately the deformation behavior of tearing tube. Therefore, uniaxial tensile tests are performed in order to obtain the flow stress curve and fracture strain of tube material according to strain rate. Quasi-static tensile tests were carried out in the range of strain rate from 0.001/sec to 0.01/sec using the static tensile testing machine. Dynamic tensile tests were conducted at the strain rate ranged from 0.1/sec to 300/sec using the high speed material testing machine. These dynamic material properties are applied to finite element analysis through user material subroutine of ABAQUS/Explicit. Especially, ductile fracture criterion is applied in order to describe the fracture characteristics of tube material during axial splitting process. Dynamic tearing cases are simulated and the reliability of the numerical results is verified by comparing with the experimental result in dynamic tearing test. The simulated results predict accurately the onset of fracture in axial splitting process and the energy absorption capacity has a good agreement with experimental result.