• Title, Summary, Keyword: 표면균열

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Cracks Detection of Concrete Slab Surface using ART2 based Quantization (ART2 기반 양자화를 이용한 콘크리트 슬래브 표면의 균열 검출)

  • Kim, Kwang-Baek;Cho, Jae-Hyun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.10
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    • pp.1897-1902
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    • 2008
  • In computer vision analysis of detecting concrete slab surface cracks, there are many difficulties to overcome. Target images often have defamations due to the light condition and other external environment. Another difficulties in detecting concrete crack image is that there is no clear distinction in intensity between the crack and the surface since the surface is often irregular. In this paper, we apply ART2 based quantization in order to classify target concrete slab surface images into several areas with respect to the light intensity. From those quantized areas, we investigate the distribution of real cracks and noises. Then, we extract candidate crack areas after applying noise removal process to areas which have be th oracle and noises. Finally, crack areas are recognized by using morphological features of cracks from such candidate areas. In experiment with real world concrete slab structure images, our algorithm has advantage in recognizing accuracy of cracks to other algorithms especially in relatively brighter areas of concrete surface.

Plastic and Drying Shrinkage Cracking Reduction by the Bubble Sheet Curing (버블시트 피복양생법에 의한 소성 및 건조수축 균열저감)

  • Lee, Joung-Gyo;Han, Cheon-Goo
    • Journal of the Korea Institute of Building Construction
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    • v.16 no.3
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    • pp.211-217
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    • 2016
  • In this research, the performance of surface covering technique using a white-colored bubble sheet on reducing the cracking due to the plastic, and drying shrinkages for high rise building construction were evaluated by comparing the exposed surface without any surface treatment. From the results of the experiment conducted during fall season, desired results of decreased numbers, length, maximum width, and area of cracking were obtained without a significant difference on heat of hydration and cumulative temperature. Therefore, it is considered that the surface covering technique using bubble sheet is an appropriate method for preventing plastic and drying shrinkage cracking at fall season concrete construction.

Effect of Temper-Embrittlement on Surface Crack Growth and Fatigue Life Prediction (재질열화가 표면 균열 진전에 미치는 영향과 수명 예측에 관한 연구)

  • 권재도
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.5
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    • pp.921-927
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    • 1989
  • One of the most important problems in recent life prediction is to introduce the degradation effects into life prediction procedure. In the present paper, the effect of the material degradation on the fatigue surface crack growth and fatigue life prediction in a 2 1/4 Cr-1Mo steel were investigated. The 2 1/4 Cr-1Mo steel has been used in a plant having operated for over 60000hours and subjected to material degradation due to temper-embitterment. A Monte-Carlo simulation was made on the basis of the data obtained in the experiment in order to determine the P-S-N diagrams of surface crack growth for the degraded and recovered steels.

The Fatigue Life and Crack Penetration Behavior of High-Strength Steel (고장력강의 피로수명과 균열관톤 거동에 관한 연구)

  • 남기우
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.6
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    • pp.1990-2001
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    • 1991
  • The fatigue life and crack penetration behavior of high strength steel have been studied in detail both experimentally and analytically. The fatigue crack shape of a smooth specimen is almost semicircular, while a specimen with stress concentration becomes semielliptical according to stress concentration shape. The aspect ratio of smooth specimens calculated using the Newman-Raju's formular is smaller than the value obtained from the experiment. On the other hand, the aspect ratio of the stress concentration specimen shows a good agreement with experimental results. It is found that the crack growth behavior on the back surface after the penetration is unique and can be divided into three stages ; rapid growth region, constant growth region and acceleration growth region. By using the K value suggested in this study, the particular crack growth behavior and crack shape can be estimated quantitatively.

Development of Multi-Channel DCPD System for Surface Crack Measurement (표면균열 형상측정을 위한 다채널 DCPD 시스템의 개발)

  • Shim D.J.;Park H.L.;Choi J.B.;Kim Y.J.
    • Journal of the Korean Institute of Gas
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    • v.4 no.1
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    • pp.49-54
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    • 2000
  • The DCPD(Direct Current Potential Drop) method has been adopted for the crack measurement of a structure. The objective of this paper is to develop a multi-channel DCPD system not only for detecting crack depth, but also for determining the accurate shape of the surface crack. For this purpose, an exclusive software was also developed. In order to verify the developed DCPD system it was initially tested on a CT specimen, and subsequently was applied to a wide plate specimen. The developed multi-channel DCPD system was proven to provide an efficient and accurate measurement of a surface crack during the crack growth.

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Analysis of mixed mode surface crack in finite-width plate subjected to uniform tension and bending by boundary element method (경계요소법에 의한 등분포인장과 굽힘을 받는 유한폭 판재의 혼합 모드 표면균열에 대한 해석)

  • 박성완;홍재학
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.6
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    • pp.1592-1602
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    • 1990
  • Mixed mode surface crack in finite-width plate subjected to uniform tension and bending has been analyzed in 3-D problem by using boundary element method. The calculations were carried out for the surface crack angles(.a/pha.) of 0.deg., 15.deg., 30.deg., 45.deg., 60.deg., and 75.deg., and for the aspect ratio(a/c) of 0.2, 0.4, 0.6 and 1.0 to get stress intensity factors at the boundary points of the surface crack. For the aspect ratio of 1.0 and the surface crack angles, finite element method was used to check the results in this study. Comparison of the results from both methods showed good agreement.

A Technique for Image Processing of Concrete Surface Cracks (콘크리트 표면 균열의 영상 처리 기법)

  • Kim Kwang-Baek;Cho Jae-Hyun;Ahn Sang-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.7
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    • pp.1575-1581
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    • 2005
  • Recently, further study is being done on the affect of crack on concrete structure and many people have made every endeavor not to leave it unsettled but to minimize it by repair works. In this paper we propose the image processing method that do not remain manual but automatically process the length, the direction and e width of cracks on concrete surface. First, we calibrate light's affect from image by using closing operation, one of morphology methods that can extract the feature of oracle and we extract the edge of crack image by sobel mask. After it, crack image is binarized by iteration binarization. And we extract the edge of cracks using noise elimination method that use an average of adjacent pixels by 3${\times}$3 mask and Glassfire Labeling algorithm. on, in this paper we propose an image processing method which can automatically measure the length, the direction and the width of cracks using the extracted edges of cracks. The results of experiment showed that the proposed method works better on the extraction of concrete cracks. Also our method showed the possibility that inspector's decision is unnecessary.

A study on the Surface Cracks in the West Stone Pagoda of Gameunsa Temple Site, Gyeongju, Korea: Examples from the second story stone body and the third story capstone (경주 감은사지 삼층석탑(서탑)에 발달한 표면균열에 대한 연구: 2층 탑신과 3층 옥개석의 사례)

  • Jwa, Yong-Joo;Kim, Jae-Hwan;Park, Sung-Cheol
    • The Journal of the Petrological Society of Korea
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    • v.17 no.4
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    • pp.238-244
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    • 2008
  • The west stone pagoda of Gameunsa temple site(National Treasure No. 112) has been seriously damaged by surface weathering, and conservation treatment is needed. In the second story body stone, vertical cracks developed parallel to the main compressional axis. The vertical cracks seem to grow much more with the compression. Chemical and biological weathering along the vertical cracks could have enhanced the crack growth. In the third story capstone, the surface cracks strike toward NE and NW directions, which are intersecting each other. In the eastern and southern parts of the third story capstone, lots of vertical cracks develop along the lines from the axial center to outer rim, whereas horizontal cracks are easily observed at the outer rim of the capstone. On the other hand, a few horizontal cracks develop in the western and northern parts of the third story capstone. This fact indicates that the compression along the vertical axis is not uniform in direction. The west stone pagoda leans toward the east and the south, so it is considered that compression by deviatoric stress prevailed at these directions.

A Length and Width Extraction of Concrete Surface Cracks using Image Processing Technique (영상 처리 기법을 이용한 콘크리트 표면 균열의 폭 및 길이 추출)

  • Her Joo-Yong;Kim Kyung-Ran;Lim Eun-Kyung;Ahn Sang-Ho;Kim Kwang-Baek
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.346-351
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    • 2006
  • 본 논문은 콘크리트 표면 균열 영상에서 균열의 특징을 추출하기 위해, 영상 처리 기법을 적용하여 균열의 특징(길이, 폭, 방향)을 자동으로 추출 및 처리 할 수 있는 기법을 제안한다. 본 논문에서 적용된 영상 처리 기법으로는 균열 영상의 빛을 보정하기 위하여 모폴로지 기법인 채움(Closing)기법을 적용한다. 균열의 경계를 명확히 추출하기 위하여 고주파 강화 필터링을 적용한 후, 8가지 색상(검정, 빨강, 파랑, 초록, 노랑, 자주, 주황, 하늘)으로 명암 값을 분류하고 그 중 빈도수가 가장 높은 색상을 가진 명암 값을 제거한 후에 추출한 영상을 이진화한다. 이진화된 영상에서 콘크리트 표면 균열의 실거리 측정을 위한 임의의 선을 제거하기 위하여 위치 히스토그램을 적용하여 임의의 선을 제거한다. 임의의 선이 제거된 균열 영상에서 $5\times5$ 마스크를 적용하여 균열을 확대시키고, 3차례에 걸쳐 잡음 제거연산을 수행하여 균열의 후보 영역을 선택한 후, 후보 영역으로부터 특정 균열들을 추출한다. 추출된 특정 균열을 모폴로지 기법인 제거(Opening) 연산을 수행하여 균열의 특징이 일정하게 유지되게 하고 미세하게 끊어진 부분을 보정하여 균열의 특징(길이, 방향, 폭)을 측정한다. 실제 콘크리트 표면 균열영상을 대상으로 실험한 결과, 특정 균열이 효율적으로 추출되었고, 특정 균열의 길이, 방향, 폭의 등이 정확히 추출 및 계산되었다.

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Develpment of Automated Stress Intensity Factor Analysis System for Three-Dimensional Cracks (3차원 균열에 대한 자동화된 응력확대계수해석 시스템 개발)

  • 이준성
    • 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.

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