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보론 강의 스폿 용접 시 발생하는 스패터 감소에 관한 연구
지성환(Sung Hwan Jee),김진아(Jin A Kim),안광우(Kwang Woo Ahn),전정도(Jung Do Jeon),전언찬(Eon Chan Jeon) (사)한국CDE학회 2012 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2012 No.2
When assemble automotive steel that produced by stamping, it is widely used the resistance spot welding which is relatively easy to work with and has an outstanding bond force. Spot welding results in different features in welding zone depending on current, weld time and change of welding force, and therefore determine weld quality. If the spatter which generated in spot welding adheres to the surface of steel, it can have a bad influence on the quality of automotive exterior and needs additional work for removal. It can cause the rising of prime costs, irregular workload and the exterior with bad images. Thus, this study will examine the optimal welding condition in order to decrease the spatter through comparison of changes in the spatter according to welding current, welding force and welding time while resistance spot welding.
A Study on the deep hole machining by BTA drill
조명제(Myoung Je Jo),이해수(Hae Soo Lee),지성환(Sung Hwan Jee),한민식(Min Sik Han),전언찬(Eon Chan Jeon) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4
Among drilling operation, the most difficult machining method is deep hole drilling. And deep hole drilling is difficult by using conventional drilling operation because it has problems such as chip removal, cooling and lubrication for the cutting tip and vibration problem and strength requirement of the tool. To solve these problems, the most adequate drilling method is to use tool which can supply high pressure cutting fluid. And the typical method for this application is the BTA drill. This study is related to the fuel oil supply pipe for the large ship and machining of it.
Inconel 718합금의 시효열처리가 기계적 성질에 미치는 영향
강희재(Hee Jae Kang),김정민(Jung Min Kim),지성환(Sung Hwan Jee),성지현(Jie Hyun Sung),김영희(Young Hee Kim),성장현(Jang Hyun Sung),전언찬(Eon Chan Jeon) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.3
Inconel 718 super alloy was aging heat treated at the temperature range from 675°C to 785°C for 5~40 hours after solution annealing at 1025°C for 1 hour. The aging treated specimens were investigated microstructure, mechanical properties and thermal expansion/contraction. Precipitates appeared for a long time aging treatment were niobium carbide and also γ’ phase. For the aging treatment time of 10 hours, the changes in strength and hardness with increasing aging treatment temperature showed the maximum value at the temperature of 725°C. This maximum value is to be related with the precipitation of γ’ and γ’’ phases. The decrease in strength, elongation and hardness during long time aging at 725°C were thought to be induced from the coarsening of the grain size and the transformation of γ’’ phase to γ’ phase. For the specimens treated for 10 hours, impact energy showed constant value of ~105 J with increasing the aging temperature, however this value continuously decreased with elapsing time at the aging temperature of 725°C. It was found that the decrease in impact value was induced from the coarsening of grain size and the carbide coarsening. The coefficient of thermal expansion of aging treated Inconel 718 alloy increased with raising test temperature, and the coefficient was appeared 11.57~12.09 ㎛/m?°C and 14.28~14.39 ㎛/m?°C, respectively, after heating to 150°C and 450°C.