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냉연 압연 강판의 레이저 용접 공정 시 발생하는 응력 평가
이철구,이우람,Lee, Chulku,Lee, Wooram 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.1
Residual stress caused in the weldments with high restraint force are often observed during welding in the weldments of Inner and outdoor materials or radial tanks. The reason is that quantitative analysis about thermal stresses during laser welding is lacking for this weldments. To verify Finite Elements Method (FEM) theory, the temperature was measured with thermocouple in a real time in this paper. Also analysis of the thermal stress for welding condition is performed by Comsol program package on various welding condition in SCP1-S butt welding. The principal stress in laser welding process is seen through the width direction. Also, it was confirmed that a change in base metal by thermal expansion made the stress in width direction stronger. Base metal close to the weld bead as the process progresses to the tensile stress in the compressive stress was varied. It was shown that the change of stress was quantitative from the bead at a certain distance.
[가솔린엔진부문] 원추 환형림을 이용한 촉매변환기내의 유동분포 개선
이철구(Chulku Lee),이은호(Eunho Lee),유재석(Jaisuk Yoo) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The steady flow effects of an underbody catalytic converter(UCC) are investigated. When individual flow coming from manifold entered UCC, the flow distribution at the front of UCC was affected by routing in manifold and exhaust pipe. In general, the flow passing through the monolith was concentrated in the center of monolith. In this study, by installing the cone type circular ring in diffuser, the flow distributed more uniformly under the limited length of converter, but there was minor increasement of pressure drop.
이철구(Chulku Lee),이은호(Eunho Lee),유재석(Jaisuk Yoo),목재균(Jaikyun Mok),황석렬(Sukryul Hwang) 한국자동차공학회 2001 한국 자동차공학회논문집 Vol.9 No.3
An experimental investigation has been performed on the steady flow in exhaust system. When individual flow coming from exhaust manifold entered UCC, the inlet conditions at entry to the diffuser in UCC were affected by the upstream pipe and manifold works. But those effects of the inlet condition on flow through monolith are negligible because the flows are concentrated on the center of monolith regardless of inlet flow distribution. To improve the flow distribution, we installed the cone type circular ring in diffuser of UCC. This led to increasement of flow uniformity, but there was minor increment of pressure drop.<br/> <br/>
입ㆍ출구 형상변화에 따른 촉매변환기 내의 유동특성에 관한 연구
이은호(Eunho Lee),이철구(Chulku Lee),유재석(Jaisuk Yoo),이종화(Jonghwa Lee) 한국자동차공학회 1999 한국 자동차공학회논문집 Vol.7 No.7
In the design of catalytic converter, velocity distribution is more important than pressure drop because monolith pressure drop is about SO% of overall pressure drop. For the catalytic converter with single diffuser, pressure drop is decreased as the angle of diffuser decrease, but when the angle is below 18˚ , the effect is almost negligible. For the catalytic converter with double diffuser, variation of the angle of the first diffuser shows the same trend as the catalytic converter with single diffuser. The angle of diffuser gives significant influence on the pressure drop while the shape of diffuser gives little influence on that. The outlet shape gives negligible effect on the pressure drop and velocity distribution. Results show that recirculation region of commercial model is about 30% of the total area in the front of monolith. For the catalytic converter with Model 11 that was presented in the study, recirculation region was not detected. more uniform velocity distribution was obtained, and pressure drop was also decreased.<br/>
[가솔린엔진부문] 촉매변환기 내의 속도분포와 압력강하에 대한 연구
이은호(Eunho Lee),이철구(Chulku Lee),유재석(Jaisuk Yoo) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1999 No.11_1
Monolithic catalytic converters have been widely used to satisfy the regulations of pollutant emissions in automobiles. The optimum design of inlet and outlet header in catalytic converter can decrease the pressure drop, make the flow distribution uniformed and improve the lifetime of catalytic converter against thermal stress<br/> In the design of catalytic converter ‘ velocity distribution is more important than pressure drop because pressure drop of the monolith contributed about 80~85% of overall pressure drop. The function of diffuser in catalytic converter is to diffuse the flow and recover the static pressure<br/> The efficiency of diffuser is increased by rounding the diffuser shape and extending the diffuser length. On the other hand ‘ if the diffuser has equal length but different shapes the velocity distribution in the front of the monolith is almost same. However as the length of diffuser increased, velocity distribution becomes uniform.