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마이크로 박판 미세 패턴 성형공정에 대한 해석 효율성 연구
차성훈(S. H. Cha),신명수(M. S. Shin),김종호(J. H. Kim),김종봉(J. B. Kim),이혜진(H. J. Lee),송정한(J. H. Song) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
Roll forming process is one of important metal processing technology because the process is simple and economical. These days, roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate for productivity. However, it is difficult to apply to the forming of micro scale or sub-micro scale pattern. In this study, the roll forming processing for the micro scale is designed and analyzed. In this study, the forming of micro pattern for solar cell plate by incremental roll forming process is analyzed. The solar cell plate may have thousands of patterns, and the analysis of forming considering all the patterns is impossible due to the computational costs. In this study, analyses are carried out for various numbers of patterns and the results are compared. It is shown that the analyses results with four row patterns and twelve row patterns are same. So, it is considered that the analysis can be carried out for only four rows of pattern for the design of incremental roll forming process.
브레이크 제어 방식에 기초한 차량 스핀 제어 시스템의 시뮬레이션
차성훈(S.H.Cha),송재복(J.B.Song) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_2
In this research, “spin control systems” has been developed that reduce the vehicle’s spin occurred by high speed cornering or disturbances. Here, the spin means the unwanted yawing motion about the vertical axis of the vehicle’s weight center. This system determines the driver’s desired yaw rate from the information on the steering angle and other driving conditions and compares it with the actual yaw rate from the yaw rate sensor. When the spin is detected, the proper brake control action is applied, thus leading to the reduction on the excessive spin of the vehicle. To this end, the driver model and yaw rate estimation scheme has been developed. Based on simulations for various driving situations, it is shown that the proposed spin control systems stabilize the vehicle’s behavior by reducing the excessive spin and help the driver perform the stable steering operation.<br/>
차성훈(S.-H. Cha),신명수(M.-S. Shin),김종호(J.-H. Kim),나승우(S.-W. Ra),김종봉(J.-B. Kim) 한국소성·가공학회 2009 소성가공 : 한국소성가공학회지 Vol.18 No.2
A shaft for laser printers has to be produced with high dimensional accuracy of a few micrometers. Most companies produce the shaft, therefore, by machining. These days, forging process is tried to be employed in manufacturing the shaft for productivity. In this study, the dimensional inaccuracy of straightness is studied and the underfill is not focused because the shaft shape is simple and the load capacity of press is sufficient. The straightness and concentricity of the shaft is important for the operation of a laser printer. Many design parameters such as preform shapes, tooling dimensions, forging load, and billet geometries may affect on the dimensional accuracy. In the forging process of shafts, a billet which is cut from wires is used. The billet, therefore, may be a little bit curved but not always straight. The elastic recovery is considered to cause the dimensional inaccuracy. Therefore, the effect of the forging load on the elastic recovery and straightness is investigated through the finite element analyses using DEFORM-3D and ABAQUS.
수치해석을 이용한 SHPB 시험의 마찰영향 분석과 보정에 대한 연구
차성훈(Sung-hoon Cha),신현호(Hyunho Shin),김종봉(Jong-Bong Kim) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.5
SHPB시험은 입력봉과 출력봉 사이에 시편을 위치시키고 고속으로 변형하여 동적 응력-변형률 선도를 추출하는 것이다. 그렇기 때문에, 소재와 입력봉 사이 또는 소재와 출력봉 사이의 마찰이 측정되는 응력-변형률 선도에 영향을 주게 된다. 이것은 측정되는 응력이 유동응력이 아니고 축방향 응력이기 때문임을 확인 하였다. 본 연구에서는 측정되는 축방향 응력을 보정하여 정확한 유동응력을 구하기 위해 새로운 보정식을 제안하였다. 소재가 업셋팅 형태로 변형한다고 가정하고, 에너지 보존에 기초하여 보정식을 제안하였다. ABAQUS를 이용한 수치적 실험을 통해 마찰계수 0.3까지 보정한 결과 보정식이 유용함을 확인하였다. The split Hopkinson pressure bar (SHPB) has been widely used to determine the mechanical properties of materials at high loading rates. However, to ensure test reliability, the source of measurement error must be identified and eliminated. During the experiment, specimens were placed between the incident and the transmit bar. Contact friction between the test bars and specimen may cause errors. In this study, numerical experiments were carried out to investigate the effect of friction on the test results. In the SHPB test, the stress measured by the transmitted bar is assumed to be the flow stress of the test specimen. However, performing numerical experiments, it was shown that the stress measured by the transmit bar is axial stress components. When the contact surface is frictionless, the flow stress and axial stress of the specimen are approximately equal. On the other hand, when the contact surface is not frictionless, the flow stress and axial stress are no longer equal. The effect of friction on the difference between the flow stress and axial stress was investigated.
차성훈(S.-H. Cha),신명수(M.-S. Shin),김종호(J.-H. Kim),이혜진(H. J. Lee),김종봉(J.-B. Kim) 한국소성가공학회 2009 금형가공 심포지엄 Vol.2009 No.11
Roll-to-roll forming process is one of important metal processing technology because the process is simple and economical. These days, with these merits, roll-to-roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate. However, it is difficult to apply to the forming of micro scale or sub-micro scale pattern. In this study, the roll forming processing for the micro scale is designed and analyzed. The forming of micro pattern for photovoltaic plate of a solar cell by incremental roll forming process is analyzed. The solar cell plate may have millions of patterns, and the analysis of forming considering all the patterns is impossible due to the computational costs. In this study, analyses are carried out for various numbers of patterns and the results are compared. It is shown that the analyses results with four row patterns and twelve row patterns are same. So, it is considered that the analysis can be carried out for only four rows of pattern for the design of incremental roll-to-roll forming process. Also formability is analyzed for various protrusion shapes at various forming temperatures.
마이크로 박판 미세 패턴 성형공정의 성형성에 대한 해석적 연구
차성훈 ( Sung Hoon Cha ),신명수 ( Myung Soo Shin ),김종호 ( Jong Ho Kim ),이혜진 ( Hye Jin Lee ),김종봉 ( Jong Bong Kim ) 한국고무학회 2009 엘라스토머 및 콤포지트 Vol.44 No.4
롤-롤(Roll to roll) 성형은 공정이 비교적 간단하고 생산 효율이 높은 중요한 금속 성형 공정이다. 이러한 이유로 롤-롤 성형 공정은 최근에 솔라셀 집전판, 디스플레이 격벽구조, 그리고 회로기판 성형 등 넓은 범위에서의 활용이 검토되고 있다. 본 연구에서는 솔라셀 집전판에 수십만 개의 홈을 성형하는 공정에 대해 유한요소해석을 수행하였다. 수백만 개 홈에 대한 성형을 해석하는 것은 컴퓨터 용량과 시간의 문제로 불가능하기 때문에 공정 설계를 가능하게 하는 최소의 문제 영역을 해석 결과를 바탕으로 설정하였다. 그리고, 홈의 형상과 온도에 따른 해석을 수행하여 그 결과를 분석함으로서 공정 설계의 방향성을 제시하였다. Roll-to-roll forming process is one of important metal processing technology because the process is simple and economical. These days, with these merits, roll-to-roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate. The solar cell plate may have millions of patterns, and the analysis of forming considering all the patterns is impossible due to the computational costs. In this study, analyses are carried out for various numbers of patterns and the results are compared. It is shown that the analyses results with four row patterns and twelve row patterns are same. So, it is considered that the analysis can be carried out for only four rows of pattern for the design of incremental roll-to-roll forming process. Also formability is analysed for various number of mesh, protrusion shapes and forming temperature.