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서용위(Yongwie Seo),신영삼(Young-Sam Shin) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Aluminum matrix composite A1356/SiCp(Vol. 15%)(Al MMC) material has been cut under various cutting conditions using abrasive waterjet (AWJ) machining process. The experimental cutting was carried out using three different material thicknesses of 10, 20, 30㎜ with a 0.33㎜ diameter orifice. The pump pressure, traverse rate, standoff distance(SOD) were taken as process parameters. After cutting the quality of the specimen in terms of kerf width, kerf taper, and surface finish were measured to characterize machinability of the material. As a result of the study, the maximum traverse rate for 30㎜ thick Al MMC under the pump pressure of 350 ㎫ reached up to 70 ㎜/min and the surface roughness of the material showed surface finish Ra in the range of 2.3~23.4㎛.
Waterjet Peening에 의한 SUP9강의 압축잔류응력 유발 최적조건
서용위(Yongwie Seo),조지룡(Ji Ryong Cho),임익섭(Ik-Sub Lim),여명헌(Myeong-Heon Yeo) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.11
Waterjet peening of spring steel SUP9 was conducted in-air to investigate the optimum peening conditions for the induced compressive residual stress which is beneficial to improve the endurance limit. The erosion-peening transition was identified as a critical standoff distance within the experimental envelope. Using X-ray diffraction technique the residual stresses generated by the waterjet peening was measured and analyzed to characterize the optimum peening conditions for the maximum compressive stress on the specimen surface. Also the surface roughnesses of peened specimen were measured at the non-eroded surfaces and the results represented the superior surface quality with minimal changes in surface topography before and after the peening process.
구조용강의 Waterjet Peening에 의한 압축잔류응력 유발조건
서용위(Yongwie Seo),신영삼(Young-Sam Shin),윤호섭(Ho-Sup Yoon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
Widely used structural steel SM45C was waterjet peened in air to investigate the optimum peening conditions for the induced compressive residual stress which is beneficial to improve the fatigue strength of the material. After peening the residual stresses generated by the waterjet peening on the surface were measured using X-ray diffraction technique and the results were analyzed to characterize the peening conditions for the maximum compressive stress. Also, the surface roughnesses of peened specimen were measured and the results showed the superior surface quality with minimal changes in surface topography before and after the waterjet peening process.
Abrasive Waterjet Machining Characteristics of Epoxy Plastics
서용위(Yongwie Seo) 한국자동차공학회 2007 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
Engineering epoxy plastic material was machined with abrasive waterjet (AWJ) to investigate its machinability under various cutting conditions. Maximum traverse rates for a couple of thicknesses of the material were experimentally determined. The characteristics of kerf width and surface quality generated by the AWJ machining were investigated. The kerf width was comparable with the focus tube size at the jet entry and the surface roughness was ranged several micrometers near the jet entrance region, and was observed to increase at the jet exit of the workpiece. The overall range of the AWJ machined surface roughness was identified in the scope of the experimental study, and some of the operating conditions were recommended for acceptable surface quality.
클러스터 시스템에서 3차원 강소성 유한요소법의 병렬처리
최영(Young Choi),서용위(Yongwie Seo) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.1
On the cluster system, the parallel code of rigid-plastic FEM has been developed. The cluster system, Simforge, has 15 processors and the total memory is 4.5GBytes. In the developed parallel code, the distributed data of the column-wise partitioned stiffness are stored as the compressed row storage and the diagonal preconditioned conjugate gradient solver is applied. The analysis of block upsetting is performed with the parallel code on Simforge cluster system. In this paper, the analysis results are compared and discussed.
나선형 홈이 있는 벤틸레이티드 브레이크 디스크의 열방출 성능
최영(Young Choi),최주원(Joo-Won Choi),김형만(Hyung-Man Kim),서용위(Yongwie Seo) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.3
A brake disc with helical grooved vent in radial direction is proposed for the improvement of thermal dissipation. The heat transfer phenomenon is analyzed for both the proposed disc and the conventional one using finite element method. The thermal dissipation is considerably influenced by the geometrical differences of the brake discs. The results of the analysis show that the proposed brake disc with helical grooved vent has the improved performance to dissipate the thermal energy more effectively.
Waterjet Peening에 의해 생성된 표면특성의 변화에 관한 연구
서용위 인제대학교 2010 仁濟論叢 Vol.25 No.1
Structural carbon steel SM45C was waterjet peened in air to investigate the induced residual stresses and resulting surface characteristics of the material, Experimental works were carried out under the pump pressure of 100-300 MPa, standoff distance(SOD) of 20-60 mm, traverse rate from 40 to 100 mm/min using fanjet nozzle with 0,33 mm in inner diameter and diffusion angles of 10, 15 and 20 °. After the peening the erosion-peening transition in terms of SOD, characteristics of the surface topography, and resulting residual stresses were evaluated using surface roughness tester and X-ray diffraction equipment. The erosion-peening transition was revealed to occur in the range of 10-58 mm SOD and erosion was generated at higher pressures, slower traverse rates and shorter SODs on the surface of the material. The peened surface topography appeared to have deep valleys and high peaks relative to the rounded shapes before peening, also the average increase in surface roughness Ra before and after the peening was measured to have less than 0,2 ㎛ for all the peening conditions. The maximum compressive residual stress of -406.9 MPa were induced, which corresponds to about 68% of the ultimate tensile strength of the material, The result of superior surface quality along with high compressive residual stress generated by the in-air waterjet peening showed a feasible application of this process for the precise surface treatment of machine elements.
Abrasive Waterjet에 의한 원형절단 Kerf 형상의 특성
서용위 인제대학교 2012 仁濟論叢 Vol.27 No.1
A 10 mm thick A15052 was machined straightly and circularly using abrasive waterjets to investigate the machined quality. Experimental works were carried out under the pump pressure of 300 MPa and 0.3 mm orifice inner diameter with #80 garnet abrasives. The ranges of traverse rate applied were from 200 to 760 mm/min for straight cut and 100 to 460 mm/min for 10 mm diameter circular cut. After machining kerf widths at jet entry and exit, tapers and surface roughness of the surfaces were measured and compared each other for both the cuttings. The ratio of kerf width at jet entry for circular cut with respect to straight cut over the overlapped traverse rate of 200≤ v ≤ 480 mm/min was 1.15 and that at jet exit was 1.24, hence the kerf width for circular cut was appeared greater than that for straight cut. On the contrary, the taper generated at the identical range of traverse rate was rather smaller for circular cut by 90% compared with that of straight cut. Also the average surface roughness of circular cut surface was appeared to have about 96.7% of the straight cut surfaces over the overlapped traverse rate, indicated a little smoother surfaces for circular cut. Though not pronounced the surface topography of circular cut revealed to have more regular and repeating peaks and valleys in general within the range of current experimental study.