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김동수(Dongsoo Kim),정현철(Hyunchul Jung),장호섭(Hosub Chang),김경석(Kyeongsuk Kim) 한국생산제조학회 2010 한국공작기계학회 추계학술대회논문집 Vol.2010 No.-
This study shows the variation of poisson’s ratio acoording to tensile speed by UTM(Unversal Testing Machine). To make a experiment, used CCD cameras and measured a volume change at real-time. According to tensile speed consider the change of the Poisson’s ratio, Confirmed the functional relation of the Poisson’s ratio which follows in tensile speed. Generally Poisson’s ratio has been consider as one of properties, but the test result shows Poisson’s ratio changed by external conditions(Tensile speed). And Poisson’s ratio increase in Fracture zone.
적외선열화상을 이용한 원자력발전소 감육 배관의 결함 검출
김경석(Kyeongsuk Kim),장호섭(Hosub Chang),홍동표(Dongpyo Hong),박찬주(Chanjoo Park),나성원(Sungwon Na),김경수(Kyungsu Kim),정현철(Hyunchul Jung) 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.2
절대온도(OK) 이상의 온도를 가지고 물체는 표면온도에 대응하는 적외선 파장대역에서 적외선 에너지를 방출하게 된다. 적외선열화상은 적외선 파장대역에 반응하는 검출기를 이용하여 검출된 적외선 량을 온도로 변환하고 사용자에게 적외선영상을 실시간으로 제공하는 비파괴검사 방법이다 원자력발전소의 배관은 부식, 피로 등으로 인해 두께가 얇아져 큰 사고로 이어질 수 있는 결함이 발생하므로 이를 위한 효율적인 비파괴검사 시스템이 요구되고 있다. 따라서 본 연구에서는 적외선열화상 카메라로 측정한 온도와 배관의 결함 깊이 및 크기와의 상관관계를 알아보고 이를 원자력발전소 배관에 적용하여 결함을 검출하는 연구를 수행하였다. The infrared energy is emitted in the infrared wavelength range that corresponds to the surface temperature of a object which has temperature that is over the absolute the temperature(OK). The infrared thermography (IRT) is a non-destructive testing method that provides thermal video for the user in real-time by converting the infrared quantity that is detected by the infrared detector into temperature. The pipes of nuclear power plant(NPP) could be thinned by the corrosion and fatigue and the defect could lead to a big accident. For this reason, the effective non-destructive testing method is necessary. In this study, the relationship between the measured temperature and the defect depth or size of NPP pipes were recognized and that was applied to detect the wall thinning defects of NPP pipes.
김경수(Kyungsu Kim),김경석(Kyeongseok Kim),정현철(Hyunchul Jung),장호섭(Hosub Chang),정성욱(Seongwok Jung) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The objective of this paper is to investigate the roughness of fracture crack surfaces of CT specimens. In the test, the CT specimens were loaded by a fatigue testing machine with changing loads until they were broken. The roughness of the fracture crack surfaces thereafter were measured by digital holographic interferometer (DHI), high. From the results, it was confirmed that DHI could measure the roughness of the various types of the crack surface. In this paper, finally a possibility to predict the magnitude of loads by roughness measurement of the fracture crack surface was proposed.
김경석(Kyeongsuk Kim),정현철(Hyunchul Jung),박찬주(Chanjoo Pack),김동수(Dongsoo Kim),정덕운(Dukwoon Jung),장호섭(Hosub Chang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
In this study, the method of measuring stress non-contact and non-destructive using Lock-in infrared thermography(IRT) is introduced. A object under load emit a part of energy as a thermal energy with variation. The stress was measured based on the thermoelastic theory that the emitted infrared light could be converted to the stress. In experiment, The surface temperature measured by Lock-in infrared thermography is calculated to the stress based on thermoelastic equation. Also, the reliability of those data were verified by comparing with the finite element analysis. The infrared thermography technique has merits that it can show the distribution of stress of the specimen in a short time and real-time without destructing and contacting the specimen.
적외선 열화상 기술을 이용한 원자력 배관의 온도측정과 보정에 관한 연구
김경석(Kyeongsuk Kim),정현철(Hyunchul Jung),박찬주(Chanjoo Pack),김동수(Dongsoo Kim),정덕운(Dukwoon Jung),장호섭(Hosub Chang) 한국비파괴검사학회 2009 한국비파괴검사학회지 Vol.29 No.5
열화상 카메라와 대상물의 측정 위치에 따른 방사각도에 따라 방사율은 달라지게 된다. 이로 인해 열화상 시스템을 이용한 온도 측정시 나타나는 온도 분포는 절대적 온도로 볼 수 없다. 대상체의 실제 표면온도가 일정하더라도 열화상 카메라로 측정된 온도는 방사율 값에 따라 오차를 가지게 된다. 본 논문에서는 동일 온도로 가열된 원통 형태를 가지는 대상체와 평면 형태를 가지는 대상체의 온도를 열화상 카메라를 이용하여 측정하였다. 측정된 표면 온도값을 통하여 화각에 의한 방사율 보정표와 방사각도의 영향에 의한 반사율 보정식을 구하였으며 이를 바탕으로 측정 온도의 오차보정을 수행하였다. 그리고 방사 각도와 화각에 따른 온도 영향을 원자력 배관의 결함 검출에 적용하여 더욱 신뢰성 있는 표면 온도값을 획득하였다. The emissivity is different because the emitted angle changes according to the position of the infrared thermography camera and object. Because of this, the temperature distribution expressed when measuring the temperature by using the infrared thermography system is not the accuracy temperature. Although the real surface temperature is constant, the temperature measured by using infrared thermography camera have error in accordance with the value of emissivity. In this paper, the temperatures of the round cylindrical object and the flat square object that heated to the equal temperature were measured by infrared thermography camera. The emissivity calibration formula and correction table are made with the affect of the view angle and emission angle form the surface temperature value. The error of measured temperature values are corrected by using the emissivity calibration formula and correction table, and apply to defect detection of the nuclear power plant pipe. From the calibration method, reliability surface temperature values were obtained.