• Textile Coloration and Finishing
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• v.17 no.3 s.82
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• pp.43-48
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• 2005

시료는 POY사 104/192로 Draw-Winder(독일, Zinser)를 이용하여 기존의 태세사 제조장치의 부분적인 개조를 통하여 길이방향으로 강제적인 태세사가 형성되도록 하는 제조기술을 이용하여 Thin-thick yam(T&T사) 6종류를 제조하였으며 제조 조건에 따른 구조변화와 물성에 대하여 연구 검토한 결과 다음과 같다. 결정화도의 변화는 Draw-winder의 R2 roller 온도가 상온인 경우보다 $100^{\circ}C$인 경우가 높게 나타났으며 태세사의 세(thin)부분의 복굴절률은 연신비가 높고 Draw winder의 roller(R2)의 온도가 높을수록 복굴절 값은 선형적으로 증가하였다. T&T사 제조시 연신 온도가 상온인 경우는 Thin부분만 연신이 진행되고 Thick 부분은 원사인 POY사의 성질이 그대로 유지하고 있음을 알 수 있고 R2 roller 온도가 상온에서 제조된 시료의 초기탄성률은 약1.5-2.0kgf/denier 정도로 높게 나타났으나 $100^{\circ}C$로 제조된 시료는 약 0.2-0.8kgf/denier 정도로 낮게 나타났다.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.112-117
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• 1999

In this paper, the creep properties and creep life prediction by Larson-Miller Parameter method for Udimet 720 to be used for aircraft gas turbine engines or other high temperature components were presented at the elevated temperatures of 538, 649 and $704^{\circ}C$. It was confirmed experimentally and quantitatively that a creep life predictive equation at such various high temperatures was well derived by LMP.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.325-330
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• 2004

Several kinds of low voltage cables have been used in nuclear power plants for the supply of electric power, supervision, and the propagation of control signals. These low voltage tables must be inspected for safe and stable operation of nuclear power plants. In particular, the degradation diagnosis to estimate the integrity of low voltage rabies has recently been emphasized according to the long use of nuclear power plants. In order to evaluate their degradation, the surrounding temperature, hardness of insulation material, elongation at breaking point (EAB), etc. have been used. However, the measurement of temperature or hardness is not useful because of the absence of quantitative criteria; the inspection of a sample requires turning off of the power plant power; and, the electrical inspection method is not sufficiently sensitive from the initial through the middle stage of degradation. In this research, based on the theory that the ultrasonic velocity changes with relation to the degradation of the material, we measured the ultrasonic velocity as low voltage cables were degraded. To this end, an ultrasonic degradation diagnosis device was developed and used to measure the ultrasonic velocity with the clothing on the cable, and it was confirmed that the ultrasonic velocity changes according to the degradation of low voltage cables. The low voltage cables used in nuclear power plants were degraded at an accelerated rate, and EAB was measured in a tensile test conducted after the measurement of ultrasonic velocity. With the increasing degradation degree, the ultrasonic velocity decreased, whose potential as a useful parameter for the quantitative degradation evaluation was thus confirmed.