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정성훈(Sunghoon Jeong),류성희(Sung Hee Yoo),정대현(Dae Hyeon Joung),이희범(Heui Bom Lee) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
The quenched and tempered steel is usually treated by heat treatment. But micro-alloyed steel including alloying elements such as vanadium, boron and so on is applied without overall heat treatment. The surface of crankshaft made with micro-alloyed steel is locally processed by induction hardening. The process can cause a crack on grinded surfaces when residual tensile stress is higher than strength of the material. Therefore crack inspection is required. Various inspection methods such as magnetic testing and eddy current testing have been used for detecting surface defects of shaft in automobile engine and transmission. Magnetic testing is to see fluorescent lines by condensed magnetic particles on defects and can have an error because of worker’s subjective judgment. Eddy current testing is difficult to be flexible because it should have many sensors to detect surface defects. Also, it has limitation in detection ability because the higher sensor sensitivity is the more noise is included. The eddy current sensor can detect cracks above a depth of 0.1mm. In this paper, it is investigated that vision inspection method is valid in ability of detection, classification, measurement of surface defects such as crack, contamination, scratch, and pores.
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고속전철 Catenary/Pantograph계의 동적응답에 대한 수치해석
최연선,정대현 成均館大學校 科學技術硏究所 1991 論文集 Vol.42 No.1
To increase the velocity of high speed train, electric power collection through pantograph from trolley wire of should be guaranted. As the velocity increase, there are lots of possibility of separation between pantograph and trolley wire due to the mutual dynamic behaviors. However, the complexity of actual Catenary system makes almost impossible to find dynamic responses analytically. In this respect a numerical method is developed to calculate the dynamic responses of Catenary/Pantograph system using central difference method. And the dynamic characteristics of Catenary/Pantograph are investigated as the design parameter variation.
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고속 전철 Catenary/Pantograph계의 동특성 해석
최연선,정대현 成均館大學校 科學技術硏究所 1990 論文集 Vol.41 No.2
The vibrations in Catenary/Pantograph system should be avoided to assure the power collection in High-Speed train. Contacts between pantograph and trolley wire depend on various design parameters. To select good design parameters, analytical and numerical simulation were performed for a simplified model. The dynamic characteristics of tensioned wire subject to moving force was calculated using Laplace transform. And, a simulation program was developed to calculate the displacement of trolley wire using Euler method. The numerical results showed good agreements between two methods.
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