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김찬일(C.I. Kim),안대철(D. C. Ahn),샤오샤오(X. Xiao),인정훈(J. H. In),전재성(J. S. Jeon),양승한(S. H. Yang),김영석(Y. S. Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Incremental sheet forming has been used for producing a prototype and customized product instead of conventional press forming. However most of previous studies are confined into regular-shaped like cone, rectangle, etc. In this study, incremental sheet forming is applied to the medical product for orthopedic application substituting for common plaster cast of damaged human ankle. It has the merit of easy assembly and disassembly and reusable.
김찬일(Chan Il Kim),샤오샤오(Xiao Xiao),도반크옹(Van Cuong Do),김영석(Young Suk Kim) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.3
점진 판재 성형은 금형을 제작하지 않고 판재를 가공하는 방법으로써 빠른 시제품 제작과 소량 생산에 적합한 성형법이다. 이러한 점진 판재 성형의 공정 변수로 공구 직경, 매 스탭당 z-방향 깊이, 공구 이송 속도, 공구 회전 속도 등은 성형품의 품질에 크게 영향을 미친다. 본 연구에서는 Al5052-O(0.8mm) 판재를 사용하여 Varying Wall Angle Conical Frustum 모델의 점진성형을 실시하였으며, 각각의 변수들의 조합에서 성형성을 판단하였다. 다구찌 기법을 사용하여 점진성형 변수들의 조합을 찾아내고, 그레이 관계형 최적화를 통하여 최적 성형 변수 값의 조합을 찾아 내였다. 최종 성형물의 품질은 성형성, 스프링 백, 두께 감소량을 측정하여 판단하였다. 본 연구의 실험 조건에서의 최적의 변수 조합은 공구직경 6 mm, 회전속도 60rpm, 매 스탭당 z-방향 깊이 0.3 mm, 이송속도 500 mm/min으로 판단되었다. Single point incremental forming (SPIF) is a sheet-forming technique. It is a die-less sheet metal manufacturing process for rapid prototyping and small batch production. The Critical parameters in the forming process include tool diameter, step depth, feed rate, spindle speed, etc. In this study, these parameters and the die shape corresponding to the Varying Wall Angle Conical Frustum(VWACF) model were used for forming 0.8mm in thick Al5052-O sheets. The Taguchi method of Experiments of Design (DOE) and Grey relational optimization were used to determine the optimum parameters in SPIF. A response study was performed on formability, spring back, and thickness reduction. The research shows that the optimum combination of these parameters that yield best performance of SPIF is as follows: tool diameter, 6mm; spin speed, 60rpm; step depth, 0.3mm; and feed rate, 500mm/min.
이중 방식에 의한 독립적 폐환기에 적용한 고빈도 Jet 환기법 및 지속적 기도
김찬,엄대자,박윤곤,임현교,최령 대한마취과학회 1990 Korean Journal of Anesthesiology Vol.23 No.3
The effects of oxygenation of differential independent lung ventilation using HFJV (High Frequency Jet Ventilation) and CPAP (Continuous Positive Airway Pressure) on PaO₂ and Qs/Qt were studied during one lung anesthesia in 11 mongrel dogs in left semilateral position with pentobarbital anesthesia. The dogs were divided into two groups. In group A(N = 7), following the conventional two lung ventilation, one lung ventilation, HFJV, one lung ventilation, cpap 5 cmH₂O, and CPAP 10 cmH₂0 were applied sequentially. In group B(N =4), following the conventional two lung ventilation the above applications were reversed. In group A PaO₂ revealed a similar increase among a two lung ventilation, CPAP 5 cmH₂O, CPAP 10 cmH₂O and HFJV. Intrapulmonary shunt showed the similar decrease among two lung ventilation, HFJV and CPAP 10cmH₂O, but CPAP 5 cmH₂O was higher than CPAP 10cmH₂O. Although there were no statistically significant differences in PaO₂ and shunt among each step in group B, HFJV showed a greate increas and shunt than one lung ventilation, CPAP 5 cmH 20) 20, and CPAP 10 cmH₂O. In conclusion, HFJV proved to be more effective than CPAP 5 cmH₂O in increasing PaO₂ and decreasing shunt in differential independent lung ventilation. Both CPAP and JFJV should be applied in the deflation phase of the nondependent lung to cause an effective increase in PaO₂. HFFV proved to be more effective than CPAP in recruiting the small airway closure.
Analysis of forming limit in tube hydroforming
김찬일,양승한,김영석 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12
The automotive industry has shown increasing interest in tube hydroforming. Despite many automobile structural parts being produced from cylindrical tubes, failures frequently occur during tube hydroforming under improper forming conditions. These problems include wrinkling, buckling, folding back, and bursting.We perform analytical studies to determine forming limits in tube hydroforming and demonstrate how these forming limits are influenced by the loading path. Theoretical results for the forming limits of wrinkling and bursting are compared with experimental results for an aluminum tube.
김찬일,Seung Han Yang,Young Suk Kim 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.6
Molecular dynamics simulations are performed to verify the deformation characteristics of grain boundaries on the AFM-based nanolithography. The model used has about 750,000 (Cu) atoms and is composed of two different crystal orientations. The grain boundaries are located in the center of model and have 45, 90, 135, and -135 degree angles in the xz-plane. The tool is made of rigid diamond-like carbon and is in the shape of the Berkovich indenter. The simulation has four different stages: relaxation, indentation, re-relaxation, and lithography. The simulation results reveal that the lithography deforms the grain boundary shape by the tool. The deformation of grain boundary’s angle proceeds to minimize the total potential energy of whole system. Consequently, the grain boundary angle is changed about 90 degrees.