• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1353-1358
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• 2010

In this paper, we propose a detection method that automatically detects concrete surface cracks using fuzzy method in the image of concrete surface cracks. First, the proposed method detecting concrete surface cracks detects the candidate crack areas by applying R, G, B channel values of the concrete crack image to fuzzy method. We finally detect cracks by the density information about the detected candidate areas after we remove the detailed noises on the image of the concrete surface cracks. The experiments using real concrete images showed that the proposed method is greatly improved of crack detection compared with the conventional methods.

• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.251-253
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• 1999

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.2
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• pp.38-43
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• 2012

It is necessary to measure cracks on concrete slab surface accurately in concrete structure maintenance for the stability of the structure. However, in real world, the process is done by time consuming and ineffective manual inspection. Although there have been some studies to provide computerized inspection methods, they are vulnerable to rugged surface or noise due to the influence of the light or environmental reasons. In this paper, we propose a new method that extracts not only undistorted cracks but minute cracks that were often regarded as noise. We extract candidate crack areas by applying fuzzy method with R, G, and B channel values of concrete slab structure. Then further refinement processes are performed with SOM algorithm and density based cutoff to remove noise. Experiment verifies that the proposed method is sufficiently useful in various crack images.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.3
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• pp.111-119
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• 1999

The purpose of this study is the simulation of discontinuous rockmass and identification of characteristics of discontinuity network as a branch of the study on characteristics of groundwater system in discontinuous rockmass for evaluation of safety on disposal site of radioactive waste. In this study the site for LPG underground storage was selected for the similarities of the conditions which were required for disposal site of radioactive waste. Through the identification of hydraulic properties. characteristics of discontinuities and selection of discontinuity model around LPG underground storage facility. the applications of discrete fracture network model were evaluated for the analysis of pathway. The orientation and spatial density of discontinuities are primarily important elements for the simulation of groundwater and solute transportation in discrete fracture network model. In this study three fracture sets identified and the spatial intensity (P$_{32}$) of discontinuities is revealed as 0.85 $m^2$/㎥. The conductive fracture intensity (P$_{32c}$) estimated for the simulation area around propane cavern (200${\times}$200${\times}$200) is 0.536 $m^2$/㎥. Truncated conductive fracture intensity (T-P$_{32c}$) is calculated as 0.26 $m^2$/㎥ by eliminating the fracture with the iowest transmissivity and based on this value the pathway from the water curtain to PC 2. PC 3 analyzed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.268-272
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• 2009

본 논문에서는 형태가 왜곡되지 않은 균열뿐만 아니라, 잡음과 유사한 미세 균열까지 효과적으로 추출하고 분석할 수 있는 방법을 제안한다. 본 논문에서 제안하는 균열 검출 방법은 콘크리트 슬래브 표면의 R, G, B 채널 값을 퍼지 기법에 적용하여 후보 균열 영역을 추출한 후, 추출한 후보 균열 영역에 SOM 기법을 적용하여 1차적으로 잡음 영역을 제거한다. 잡음이 제거된 후보 균열 영역에서 밀도 정보를 이용하여 2차적으로 세부적인 잡음 영역을 제거하여 최종적으로 균열 영역을 검출한다. 실제 콘크리트 균열 영상을 대상으로 실험한 결과, 다양한 콘크리트 균열 영상에서 기존의 균열 추출 방법보다 균열 검출 성능이 개선되었음을 확인하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1155-1162
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• 2001

Sihs minimum strain energy density criterion(SED) often used in the mixed mode problem has the ambiguity of the choice of minimum values. In this paper, as the method to solve the problem of SED, maximum minimum strain energy density criterion is proposed that the crack propagates in the direction of having the maximum among the minimum values of modified strain energy density factor(MS), i.e., sign($\sigma$(sub)$\theta$).Smin.

• Tunnel and Underground Space
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• v.9 no.4
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• pp.364-372
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• 1999

In this paper, mechanical characteristics of micro-defects in granitic rock was studied. Crack spacing and length were investigated by scanline survey in specimen of granite. To estimate the direction and distribution of potential microcrack in granite, thin sections were made for three direction of Rift, Grain and Hardway axis of the rock specimen. The density and length of microcrack were investigated quantitatively. Three directions of microcracks are comparatively perpendicular. Crack density varies as direction differs, but crack length doesn't show influence of direction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1281-1287
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• 2000

The studies of probability distribution of the fatigue crack growth life have been somewhat reported. But the study on the probability distribution of the fatigue crack growth life considering the crack coalescence for three dimensional surface fatigue crack has apparently not been reported to date. In this study, the computer program has been developed to predict the probability distribution of the fatigue crack growth life considering the crack coalescence. The effects of parameters for the distribution of the fatigue crack propagation life were evaluated by using the program.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.379-385
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• 2008

콘크리트 건물의 보수 작업은 표면에 발생하는 균열을 정확하게 계측함으로써 비용적인 측면과 안전성이 결정된다. 하지만 표면에 발생한 균열은 대부분 점검자에 의해 수작업으로 계측되기 때문에 시간적 측면에서 비효율적이다. 따라서 본 논문에서는 콘크리트 슬래브 표면에 발생한 균열의 밝기와 밀도 그리고 면적 특징을 이용한 균열 검출 기법을 제안한다. 제안된 균열 검출 방법은 콘크리트 슬래브 표면의 명암도와 위치 정보를 ART2 기반 양자화에 적용한 후, 균열과 인접한 배경간의 명암도 차이를 이용하여 균열과 인접한 배경을 분리한다. 균열과 인접한 배경이 분리된 영상에서 형태학적인 정보를 이용하여 세부적인 잡음을 제거한 후에 최종적으로 균열 영역을 검출한다. 실제 콘크리트 균열 영상을 대상으로 실험한 결과, 다양한 콘크리트 균열 영상에서 기존의 방법보다 균열 검출 성능이 개선되었음을 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.6
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• pp.64-73
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• 1997

솔리드 모델러, 자동요소분할 기법, 4면체 특이요소, 응력확대계수의 해석 기능을 통합하여, 3차원 균열의 응력확대계수를 효율적으로 해석할 수 있는 시스템을 개발하였다. 균열을 포함하는 기하모델을 CAD 시스템을 이용하여 정의하고, 경계조건과 재료 물성치 및 절점밀도 분포를 기하모델에 직접 지정함으로써, 퍼지이론 에 의한 절점발생과 데로우니 삼각화법에 의한 요소가 자동으로 생성된다. 특히, 균열 근방에는 4면체 2차 특이요소를 생성시켰으며, 유한요소 해석을 위한 입력 데이터가 자동으로 작성되어 해석코드에 의한 응력 해석이 수행된다. 해석 후, 출력되는 변위를 이용하여 변위외삽법에 의한 응력확대계수가 자동적으로 계산되어 진다. 본 시스템의 효용성을 확인하기 위해, 인장력을 받는 평판내의 표면균열에 대해 해석하여 보았다.