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- 저자 : 김규만(G. M. Kim) (검색결과 120 건)
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볼엔드밀 경사면 가공에서 절삭력 맵을 이용한 평균절삭력 예측
김규만(G. M. Kim),주종남(C. N. Chu) Korean Society for Precision Engineering 1998 한국정밀공학회지 Vol.15 No.12
During machining of dies and molds with sculptured surfaces, the cutter contact area changes continuously and results in cutting force variation. In order to implement cutting force prediction model into a CAM system, an effective and fast method is necessary. In this paper, a new method is proposed to predict mean cutting force. The cutter contact area in the spherical part of the cutter is obtained using Z-map, and expressed by the grids on the cutter plane orthogonal to the cutter axis. New empirical cutting parameters were defined to describe the cutting force in the spherical part of cutter. Before the mean cutting force calculation, the cutting force density in each grid is calculated and saved to force map on the cutter plane. The mean cutting force in an arbitrary cutter contact area can be easily calculated by summing up the cutting force density of the engaged grid of the force map. The proposed method was verified through the slotting and slanted surface machining with various inclination angles. It was shown that the mean force can be calculated fast and effectively through the proposed method for any geometry including sculptured surfaces with cusp marks and holes.
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김규만(G.M. Kim),최덕기(D.K. Choi),주종남(C.N. Chu) Korean Society for Precision Engineering 1998 한국정밀공학회지 Vol.15 No.12
Recently, the needs of machining technologies of very small parts have been increasing with advent of micro-revolution. These technologies have mostly used the method applied to semi-conductor production process such as LIGA, etc. But they have serious difficulties to settle down in terms of workpiece materials, machining thickness, 3-dimensional structure. Therefore, micro-machining technology using EDM(Electrical Discharge Machining) was proposed. It is very difficult to machine the micro-parts (microshaft, microhole) using conventional machining. Micro-machining using EDM can machine the micro-parts easily because it requires little machining force. This MEDM(Micro-EDM) need the capabilities to move a electrode and control a discharge energy precisely, and the gap control strategy to maintain the optimal discharge condition is necessary. Therefore, in this study, the new EDM machine with high precision motion stage and high-performance EDM device was developed. Using this MEDM machine, we have machined microshaft and microhole with various shapes and sizes.
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김규만(G. M. Kim),정성일(S.I. Chung),오현석(H.S. Oh) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
Fabrication of a high-resolution shadow mask, or called nanostencil, is presented. This high-resolution shadowmask is fabricated by a combination of MEMS processes and focused ion beam (FIB) milling. 500 ㎚ thick and 2x2 mm large membranes are made on a silicon wafer by micro-fabrication processes of LPCVD, photolithography, ICP etching and bulk silicon etching. Subsequent FIB milling enabled local membrane thinning and aperture making into the thinned silicon nitride membrane. Due to high resolution of FIB milling process, nanoscale apertures down to 70 ㎚ could be made into the membrane.
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Z map 을 이용한 임의의 절삭영역에서 볼엔드밀의 절삭력예측
김규만(G. M. Kim),조필주(P. J. Cho),김병희(B. H. Kim),주종남(C. N. Chu) Korean Society for Precision Engineering 1997 한국정밀공학회지 Vol.14 No.3
In this study, a cutting force in the Ball-end milling process is calculated using Z-map. Z-map can describe any type of cutting area resulting from the previous cutting geometry and cutting condition. Cutting edge of a ball-end mill is divided into infinitesimal cutting edge elements and the position of the element is projected to the cutter plane normal to the Z axis. Also the cutting area in the cutter plane is obtained by using the Z-map. Comparing this projected position with cutting area, it can be determined whether it engages in the cutting. The cutting force can be calculated by numerical integration of cutting forces acting on the engaged cutting edge elements. A series of experiments such as contouring and upward/downward ramp cutting was performed to verify the calculated cutting force.
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G. M. Kim(김규만),H. Khan(칸하룬),H. J. Choi(최혜진) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
Microfluidic enzymatic biofuel cells (μEBFCs) have received significant research attention due to their feasibility to power implantable medical devices. However, typical two-streamflow channel in μEBFC limit their practicality. We propose a new approach to design the single-stream μEBFC based on their performance by placing electrodes at different positions in the microchannel. Multiwalled carbon nanotube (MWCNT) electrodes were produced by stencil method which were modified with glucose dehydrogenase and laccase via direct covalent bonding, for bioanode and biocathode, respectively. The best results were attained by placing the cathode at the top and anode at the bottom of the microchannel in a Y-shaped two streamflow μEBFC. With a single stream, we achieve more practicality, but the performance was reduced by 40%. However, 20% of this loss was recovered by applying a new design of electrodes i.e., anode at bottom and cathode at the top facing each other in the microchannel. This corresponds to maximum current and power density of 216 ± 12 μA.cm<SUP>-2</SUP> and 69.2 ± 9.2 μW.cm<SUP>-2</SUP>, respectively. When two devices were stacked, the maximum power density reached 160 μW.cm<SUP>-2</SUP> at 0.3 V. This study validates the feasibility of using single-stream μEBFCs to power microelectronics more simply and practically.
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