• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.211-214
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• 2001

Electronic Speckle Pattern Interferometry(ESPI) is one of optical technique to measure displacement precisely, uses CCD camera to show result image in real time. General ESPI system measures in-plane or out-of-plane displacement. Shearography is one of electronic speckle pattern interferometric methods which allow full-field observation of surface displacement derivatives and it is robust in vibration. The shearography provides non-contacting technique of evaluating defects nondestructively. In this study, the shearography was used to evaluate defects in Carbon Fiber Reinforced Plastic(CFRP). Various sizes of artificial defects were embedded in various depths of woven CFRP plate. Effects due to the variation of size and depth of defects were evaluated in this study.

• 한국결정성장학회지
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• 제8권4호
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• pp.539-543
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• 1998

초크랄스키로 성장한 Si 단결정에서 결정 성장 속도를 달리한 sample을 이용하여 COP, FPD 및 LSTD등의 grown-in 결함 밀도와 한 웨이퍼 내에서의 분포를 정확하게 측정하여 이들 결함들간의 상호 관계를 고찰하였다. 이들 결함의 밀도와 한 웨이퍼 내에 발생하는 영역의 크기는 결정 성장 속도가 빠를수록 증가하였다. 또한 한 웨이퍼 내에서 이들 결함의 발생 영역이 일치하는 것으로 보아 이들 결함은 동일한 origin에 의해 생성된 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1101-1104
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• 1995

Through welding fabrication, user can feel an surficaial and capable unsatisfaction because of welded defects, Generally speaking, these are called weld defects. For checking these defects effectively without time loss effectively, weldability estimation system setup isan urgent thing for detecting whole specimen quality. In this study, by laser vision camera, catching a rawdata on welded specimen profiles, treating vision processing with these data, qualititative defects are estimated from getting these information at first. At the same time, for detecting quantitative defects, whole specimen weldability estimation is pursued by multifeature pattern recognition, which is a kind of fuzzy pattern recognition. For user friendly, by weldability estimation results are shown each profiles, final reports and visual graphics method, user can easily determined weldability. By applying these system to welding fabrication, these technologies are contribution to on-line weldability estimation.

• 전기학회논문지
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• 제56권5호
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• pp.876-883
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• 2007

The magnetic flux leakage(MFL) type nondestructive testing(NDT) method is widely used to detect corrosion, defects and mechanical deformation of the underground gas pipelines. The object pipeline is magnetically saturated by the magnetic system with permanent magnet and yokes. Hall sensors detect the leakage fields in the region of the defect. The defects are sometimes occurred in group. The accuracy of the detecting signals in this defect cluster become lowered because of the complexity of the defect cluster. In this paper, the effects of the multi -defects are analyzed. The detecting signals are computed by 3-dimensional finite element method and compared with real measurement. The results say that, rather than the size of the defects, the effects of the relative position of the multi-defects are very important on the detecting signals.

• 한국해양공학회지
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• 제24권1호
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• pp.140-145
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• 2010

This study presents a detection method for mechanically fabricated defects on underwater steel pipes, using ultrasonic guided waves. Three different diameters (60, 90, and 114 mm) of 1000-mm long steel pipes were considered, along with several experimental design factors such as incident angles, incident distances, and the degrees of defects, to investigate how these factors affected the experimental results - the detectability of the mechanical defects. From the experimental results, we determined that the amplitude and arrival time of the first received wave signals gave a promising clue for distinguishing the existence of the defects and their severities. Between the amplitude and arrival time, the arrival time gave a more promising indication since it was affected by the experimental factors in a constant manner. Therefore, it was shown that the use of ultrasonic guided waves for underwater pipe inspection is feasible.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2002년도 정기학술대회
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• pp.245-251
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• 2002

Electronic Speckle Pattern Interferometry(ESPI) is one of optical technique to measure displacement precisely, uses CCD camera to show result image in real time. General ESPI system measures in-plane or out-of-plane displacement. Shearography is one of electronic speckle pattern interferometric methods which allow full-field observation of surface displacement derivatives and it is robust in vibration. The shearography provides non-contacting technique of evaluating defects nondestructively In this study, the shearography was used to evaluate defects in Carbon Fiber Reinforced Plastic(CFRP). Various sizes of artificial defects were embedded in various depths of woven CFRP plate. Effects due to the variation of size and depth of defects were evaluated in this study.

• 한국안전학회지
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• 제10권4호
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• pp.9-12
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• 1995

Detection of small defects by medical ultrasonic testing when the thermal sprayed coating by $MoSi_2$ on the metal is done. The defects may occur at the bonded surface. So, the detecting method of the defects by non-destructive in spection is desired. Here, in order to examine the possibility of the detection of the small defects by the ultrasonic. The electronic scanning ultrasonic equipment using an array probe developed as the medical ultrasonic diagnostic equipment is applied for the detection of the metal material defects. It's validity is investigated.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.278-279
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• 2017

Result from Amendment of Apartment Houses Decree Customer Service, Recently, the starting point of Defects Liability changed "Criteria of Completion date" to "Delivery date to Divided property". Through the Law amended, There are some inconsistency between "Claim for repairing defects" and "Period of security deposit for repairing defects claim". If someone bought a house after Completion date, Purchasing period of "Claim to security deposit for repairing defects" lapsed without renewal. This research is to identify problems and solutions for improving the system.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.293-295
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• 2007

The thixoforming process become important for forming automobile parts. But, the thixoforming process cannot still prevent to forming defects such as pores and shrinkage which reduce mechanical properties of automobile parts. Therefore, it is necessary to analyze the correlation between forming defects and mechanical properties. However, it is difficult to get data about relations between mechanical properties and forming defects in thixoformed aluminum alloy parts. In this study, three parts of aluminum thixoformed knuckle have been analyzed using tensile test and computer tomography(CT scan). Experimental results showed that the elongation properties of thixoformed aluminum parts were significantly dependent on size and number of forming defects.

• 대한기계학회논문집
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• 제18권11호
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• pp.3098-3107
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• 1994

The central burst defects, so-called chevroning, in wire drawing are analyzed by the rigid-plastic finite element method. The occurrence of central burst defects in wire drawing is estimated by the distribution of the hydrostatic pressure around the central part of the workpiece. It has been possible to obtain numerical boundaries which, in reduction in area vs. semicone angle plane, divide the safe and the danger zones, depending on friction factors and material properties. Based on the results of the analysis, it is suggested that the previous criterion derived from the upper bound analysis should be modified for better prediction of the defects. The back tension and the billet with a spherical hole on the central axis are also included in the analysis of the defects.