• Journal of the Korean Magnetics Society
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• v.22 no.2
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• pp.49-57
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• 2012

From among the NDT (Non-Destructive Testing) methods, the MFL (Magnetic Flux Leakage) PIG (Pipeline Inspection Gauge) is especially suitable for testing pipelines because the pipeline has high magnetic permeability. MFL PIG showed high performance in detecting the metal loss and corrosions. However, MFL PIG is difficult to detect the crack which occured by exterior-interior pressure difference in pipelines and the shape of crack is very long and narrow. Therefore, the new PIG is needed to be researched and developed for detecting the cracks. The CMFL (Circumferential MF) PIG performs magnetic fields circumferentially and can maximize the magnetic flux leakage at the cracks. In this paper, CMFL PIG is designed and the distribution of the magnetic fields is analyzed by using 3 dimensional nonlinear finite element method (FEM). By Simulating and Measuring the magnetic leakage field, it is possible to detect of axial cracks in the pipeline.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.3
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• pp.13-20
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• 2013

In this paper, we propose a multi-scale crack detection method. This method uses decomposition, composition, and shape properties. It is based on morphology algorithm, crack features. We use a morphology operator which extracts patterns of crack. It segments cracks and background using opening and closing operations. Morphology based segmentation is better than existing integration methods using subtraction in detecting a crack it has small width. However, morphology methods using only one structure element could detect only fixed width crack. Thus, we use decomposition and composition methods. We use a decimation method for decomposition. After decomposition and morphology operation, we get edge images given by binary values. Our method calculates values of properties such as the number of pixels and the maximum length of the segmented region. We decide whether the segmented region belongs to cracks according to those data. Experimental results show that our proposed multi-scale crack detection method has better results than those of existing detection methods.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.93.2-93.2
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• 2015

플라즈마를 포함한 반응성 가스 공정 분석용 사중극자 질량분석기의 필라멘트의 파손양상을 조사하였다. 또한 유전체 증착층이 이온원 성능에 미치는 영향을 분석하기 위하여 이온원의 일반적인 가동 전압 조건에서 Poisson방정식을 이용하여 전위를 수치 해석으로 구하였다. 사용중 파손된 필라멘트의 파단면을 주사전자현미경으로 관찰결과, 수직으로 절단되는 양상과 직경이 점차 작아지면서 erosion되는 두가지 양상을 보였다. 또한 파단면은 표면균열과 패시팅(faceting) 현상을 보였다. 필라멘트 사용시 가장 큰 문제는 패시팅(faceting)이다. 대부분의 결정에서는 다른 결정면보다 에너지 준위가 낮은 결정면이 존재한다. W 원자는 고온에서 확산 또는 증발하여 표면에서 다시 응축할 때 표면 에너지를 최소화하기 위한 독특한 평형 형상이 만들어 지는데 이것이 패시팅의 구동력이다. 이때 국부적으로 단면적이 감소하는 곳이 생기는데, 이 지점이 집중적으로 가열되고 증발이 가속화하여 파손된다. 파단면을 EDS 분석결과, 산화물을 포함한 F, Fe 및 C이 검출되었다. 이 F과 C는 공정중 사용된 CF4의 분해에 의한 것으로 생각되며, 파손된 필라멘트를 Ar 유도결합 플라즈마로 처리한 결과 이 F, Fe 및 C의 양이 감소하였다.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.2
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• pp.21-25
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• 2011

Although many defects in PZR heater sleeve have been reported continually from operating experiences in oversea nuclear power plant, utilities get into difficulties in finding appropriate methods for diagnostics of the components due to the limited access or high radiation problems. Recently, as an alternative, diagnostics using Guided Wave Testing(GWT) are proposed and the attention of the methods has been growing gradually because of their long range inspection capability. This study is to investigate the effectiveness of GWT to detect PWSCC in welding points of PZR heater sleeve. Moreover, mode sensitivity analysis of GWT and optimal frequency for the diagnostics of PWSCC are presented by testing the mock-ups specimens that contain artificial flaws.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.642-646
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• 2008

We have developed a vision based crack detection system and algorithm to inspect base side of bridges. After human operator decides from vision images captured if lines on base side are cracks or dirt, our algorithm finds automatically the length, the width and the shape of cracks. The system has been tested with a robot extender on a truck in real environment and has been proved to be very useful to reduce inspection cost as well as the data management.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.739-744
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• 2000

Concrete structures generally have cracks, so for the safety and durability of structures, studies to detect cracks using nondestructive tests have been treated in great deal. In order to assure the reliability of concrete structure, microscopic fracture behavior and internal damage progress of concrete under the loading should be fully understood. The purpose of this study predicts location of initial crack and measures direction of crack propagation for on-line monitoring before the crack really grows in structures by using two-dimensional Acoustic Emission(AE) source location based on rectangular method with three-point bending test. This will allow efficient maintenance of concrete structure through monitoring of internal cracking based on AE method.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.655-658
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• 2003

The crack of concrete structure plays an important role in the durability and safety of structure. Therefore, the features such as width, length, and direction of that must be measured periodically. The conventional method of measurement of cracks is manually sketched, however. it takes a fairly long time and lacks quantitative objectivity. This study proposes the algorithm to extract and analyze cracks automatically. The proposed algorithm is composed of two sub-algorithms. The extraction algorithm includes elimination of effect due to light, binarization. and noise reduction. The analysis algorithm includes thinning process, labeling, and calculation of crack width, length, and direction. The test to demonstrate the algorithm is fulfilled using the images of cracks on real concrete surface.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.2
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• pp.17-22
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• 2013

In this paper, we propose a concrete crack detection method using shape properties. It is based on morphology algorithm and crack features. We assume that an input image is contaminated by various noises. Thus, we use a morphology operator and extract patterns of crack. It segments cracks and background using opening and closing operations. Morphology based segmentation is better than existing integration methods using subtraction in detecting a crack it has small width. Also, it is robust to noisy environment. The proposed algorithm classifies the segmented image into crack and background using shape properties of crack. This method calculates values of properties such as the number of pixels and the maximum length of the segmented region. Also, pixel counts of clusters are considered. We decide whether the segmented region belongs to cracks according to those data. Experimental results show that our proposed crack detection method has better results than those by existing detection methods.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1501-1502
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• 2015

배전기자재는 오래 사용하다 보면 열적, 전기적, 기계적, 환경적, 복합적 스트레스에 의해 절연성능이 떨어진다. 이때 발생하는 열화현상으로는 발열도 되고, 전자파, 빛, 균열, 침식, 진동음도 발생한다. 따라서 열화된 기자재를 검출하기 위해여 광학장비 또는 과학화 진단장비를 활용하여 고장예방을 하고 있다. 하지만 기자재가 열화되면서 발생하는 증상을 모르고 진단을 하면 투입된 인력과 예산에 비해 초라한 적출실적도 발생할 수 있다. 따라서 한해 동안 배전설비 진단에 가장 많이 활용하고 있는 열화상진단과 초음파 진단의 실적과 적출결과를 분석하여 기자재별 효과적인 진단방식을 제공하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.753-754
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• 2016

스트레스는 매일 살아가면서 사소한 일부터 큰 충격을 받는 삶의 주요한 사건까지 다양한 요인으로 부터 온다. 이는 어느 한 시기에만 나타나는 것이 아니라 인간의 전 생애에 거쳐 나타나므로 지속적으로 스트레스를 관리할 수 있는 연구가 필요하다. 이에 본 논문은 홍채의 형태, 균열, 색깔, 고리, 주름 등의 특징들을 분석하여 환자의 병을 진단하는 홍채진단을 이용하여 스트레스 지수를 측정하는 시스템을 개발하였다. 개발한 시스템은 홍채의 특징인 스트레스 고리를 검출하고, 스트레스 설문지의 결과와 함께 분석하여 안드로이드 어플리케이션을 통해 사용자에게 스트레스 정도를 제공한다. 제안한 시스템은 사용자가 언제 어디서나 쉽게 현재 자신이 느끼고 있는 스트레스 정도를 알 수 있고 이에 상응하는 예측되는 질병에 대해 예방하여 조기 진단 및 질병 예방의 하나의 방법으로 사용할 수 있다.