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유한요소법에 의한 VCB 접속부의 대전류에 대한 전열해석
강우종,허훈,강경록,Kang, Woo-Jong,Huh, Hoon,Kang, Kyeong-Rok 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.4
A large electric system of a vacuum circuit breaker(VCB) has been studied for the electro-thermal analysis by finite element methods. Since the heat generation in VCB causes not only energy loss but deterioration of the VCB system with oxidization of parts, the overheating of the system must be prevented. For the analysis, a finite element formulation is derived for both electric analysis and thermal analysis that are coupled together. Two sets of formulations are uncoupled after finite dimensional approximation. First, the electric potential is obtained for the entire field and scaled to the given electric current. The electric field obtained is then used to calculate the heat generation in the VCB system including contacts and connections for the calculation of the temperature distribution in the entire domain. The finite element analysis is carried out to study the effect of shapes and locations of contacts and connections. From the results, the existing VCB has been modified to enhance its capacity with reduction of heat generation and temperature elevation.
새로운 Tension Split Hopkinson Bar를 이용한 박판의 고속 인장시험
강우종,조상순,허훈,정동택,Kang, Woo-Jong,Cho, Sang-Soon,Huh, Hoon,Jung, Dong-Taek 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.12
A split hopkinson bar could be used for obtaining the high strain rate material properties of sheet metals for an autobody. In high speed tensile tests of sheet matals, a new design of a tension split Hopkinson bar apparatus is needed. The design of grips and an anvil length are numerically analyzed with ABAQUS/Explicit for the new apparatus of split Hopkinson bars. From the experiments with the new apparatus, the material properties of SPCEN in the high strain rate state have been acquired and compared with quasi-static experimental results. The material properties of SPCEN as well as other sheet metals in an autobody are indispensible for the analysis of crashworthness. Nevertheless the experiment of sheet metal in the high strain rate state has not been done or reported.
자동차 프론트엔드모듈 캐리어용 경량 복합소재의 고속인장 시험
강우종 ( Woo Jong Kang ),김성태 ( Sung Tae Kim ) 한국복합재료학회 2011 Composites research Vol.24 No.3
경량복합소재의 고속인장시험을 수행하여 변형률속도에 따른 강도변화를 측정하고자 한다. 준 정적 시험인 경우 섬유강화 복합소재의 인장시험은 ASTM D3039에 따른 시편 형상이 사용되지만 고속 인장시험인 경우 표준화된 시편 형상에 대한 연구가 진행되어 있지 않다. 본 연구에서는 ASTM D638에 나타난 시편 형상을 기본으로 몇 가지 변형된 형태의 시편을 가지고 고속인장 시험을 수행하여 변형률 속도에 따른 경량복합소재의 강도 변화를 측정하였다. 낙하방식의 고속인장 시험기를 제작하여 변형률 속도 15/s, 100/s에서 시편의 형상에 따른 섬유강화 복합소재의 인장거동을 측정하였으며 시편의 폭이 6mm, 8mm, 10mm인 경우에 대하여 시험을 수행하였다. 측정 결과 시편의 폭이 8mm인 경우 섬유강화 복합소재의 강도를 정확하게 평가할 수 있는 것으로 나타났다. High strain rate tensile tests were performed to measure the strain rate sensitivity of fiber reinforced composite material. The composite material was developed for the light weight design of an automotive FEM(front end module) carrier. Standard specimens for quasi-static tests of fiber reinforced composites can be found in ASTM D3039. However, in case of high strain rate tests, it was hard to find standard specimen shapes. In this study, three kinds of tensile specimens designed based on ASTM D638 were investigated to determined the adequate gauge width of tensile specimen for fiber reinforced composite. A drop tower type of high speed tensile apparatus was developed for strain rates of about 15/s and 100/s. Gauge width of 6mm, 8mm and 10mm were investigated. Test results showed the specimen of 8mm width was adequate for the high strain rate tensile tests of fiber reinforced composite. It was found the strength of the composite material increased as the strain rate increased.
강우종(Woo-Jong Kang),김충원(Choong-Won Kim),이준(joon Lee) 한국멀티미디어학회 2010 한국멀티미디어학회 학술발표논문집 Vol.2010 No.2
교육환경 패러다임의 변화로 우리나라의 교육환경은 전통적인 면대면 수업인 교실 수업과 여러 가지 디지털 매체를 사용하여 시·공간의 제약을 받지 않는 사이버 교육의 두 가지 방법에 의해 이루어지고 있다. 이 두 가지 방법은 따로 존재하는 것이 아니라 상호 보완적인 관계에서 병행되어야 할 필요가 있다고 생각한다. 모든 학생들이 만족할 수 있는 교수학습방법을 교수자가 올바른 교수학습방법을 해당 학생들과 충분히 논의한 후 강의를 해야한다고 본다.
Tension Split Hopkinson bar를 이용한 자동차 성형용 금속 박판의 고속인장 시험
강우종(Woo-Jong Kang),조상순(Sang-Soon Cho),허훈(Hoon Huh),정동택(Dong-Taek Jung) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_2
A split Hopkinson bar could be used for obtaining high strain rate material properties of sheet metals for an autobody. In high speed tensile test of sheet metals, a new tension split Hopkinson bar is needed. From the experiments with the new apparatus, the material properties of SPCEN, SPCC, SPRC in the high strain rate state have been acquired and compared with quasi-static experimental results. The experimental results are used to obtain the constants of Johnson-Cook constitutive relation.<br/>
[구조강도부문] 인장형 홉킨슨 바의 오차 분석 및 자동차용 냉연강판의 고속인장 특성 연구
강우종(Woo-Jong Kang),허훈(Hoon Huh),한수식(Soo-Sik Han) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The dynamic behavior of vehicle body materials is dependent on material strain rates. In high speed tensile test of sheet metals, a new tension split Hopkinson bar specially designed for sheet metals is used. The tension split Hopkinson bar has some sources of errors such as grips and the plate type specimen. In this paper, these errors estimated and minimized. The results from both quasi-static and dynamic tests show that the strain rate hardening effect for sheet metals can not be described by the original Johnson-Cook constitutive relation. This relation has been modified to include a higher-order term for the hardening effect.
허훈(Woo-Jong Kang),강우종(Hoon Huh) 한국자동차공학회 1998 한국자동차공학회 학술강연초록집 Vol.1998 No.4
Identification of dynamic response of the auto-body is important to evaluate the crash worthiness of a car. A split Hopkinson bar could be used for obtaining high strain rate material properties of sheet metals. In this paper, experiments have been carried out with a new split Hopkinson bar apparatus specially designed for the dynamic tensile test of sheet metals. The experimental results are used to construct a dynamic constitutive relation of sheet metals as the Johnson-Cook model. The conventional Johnson-Cook model has a linear term for strain hardening of the semi-logarithmic scale, which must be modified to a higher-order term to satisfy the experimental results. The constructed constitutive relations are applied to simulating the crashworthiness of a simplified car body.
김경진,신재호,강우종,Kim, Kyung Jin,Shin, Jaeho,Kang, Woo Jong 한국자동차안전학회 2016 자동차안전학회지 Vol.8 No.3
Braking system is directly related to the safety of a vehicle and the brake discs are essential part of the braking system. Due to the repeated frictional forces and torque during braking, brake discs are always works at high temperature and high pressure. Furthermore, the brake disc is one of major tuning components in aftermarket, the braking performance of the brake disc should be evaluated for establishing the certification standards of tuning components. This paper proposes the test method to evaluate the performance of tuning brake discs.