• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.101-110
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• 2005

In Seoul, structural deterioration is severe in the private masonry buildings which have been built since 1906s. But most of these structures remain without any repair works. As a result, the rate of deterioration is getting faster and these dangerous structures may cause hazardous circumstances to the adjacent structures and neighborhood. The purpose of this study is to investigate the actual conditions of wall cracks among the defect types which occur in private masonry buildings and to analyze the correlation between safety grades and wall cracks for offering the fundamental data. Using these date we can establish basic criteria for safety grades of structures and improve the quality of masonry buildings. The result of this study indicate that there are high correlations between safety grades and the width of crack but much less so with the length. Furthermore, with regard to crack patterns, vertical cracks much more negatively effected the safety grades.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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• pp.1361-1368
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• 2005

The structural and leakage integrity of steam generator tubes should be sustained all postulated loads with appropriate margin even if a crack is present. During the past three decades, for effective integrity evaluation, several limit load solutions have been used world-widely. However, to predict accurately load carrying capacities of specific components under different conditions, the solutions have to be modified by using lots of experimental data. The purpose of this paper is to propose a new burst pressure estimation scheme based on fracture mechanics analyses for steam generator tube with an axial or circumferential through-wall crack. A series of three dimensional elastic-plastic finite element analyses were carried out and, then, closed-form estimation equations with respect to both J-integral and crack opening displacement were derived through reference stress method. The developed engineering equations were utilized for structural integrity evaluation and the resulting data were compared to the corresponding ones fiom experiments as well as limit load solutions. Thereafter, since the effectiveness was proven by promising results, it is believed that the proposed estimation scheme can be used as an efficient tool for integrity evaluation of cracked steam generator tubes.

• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.593-604
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• 2021

In this study, a comparative test was conducted on a specially developed elastic waterproof paint and general water-based paint for the purpose of responding to cracks occurring on the outer wall of concrete structures and improving watertightness. Through the comparative experiment, it was confirmed that the watertightness could be improved by securing the crack shielding property, and it was also confirmed that about 10 times more crack responsiveness was secured compared to general water-based paint. In addition, it was confirmed that the adhesion performance of at least 1.3MPa and resistance to a water permeation pressure of 0.1MPa were possible, confirming that stability was secured from a waterproofing perspective.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1143-1148
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• 2001

Experimental programs were accomplished to improve and evaluate the structural performance of test specimens, such as hysteretic behavior, maximum horizontal strength, crack propagation, and ductility etc. Test variables are restraining factors of frame, with or without masonry infilled wall, and masonry method. Six reinforced concrete rigid frame and masonry infiiled wall were constructed and tested in one-third scale size under vertical and cyclic loads simultaneously. Based on the test results, the following conclusions can be made. For masonry infilled walls with restraining factors of frame, maximum horizontal capacities were increased by 1.26~2.24 times in comparision with that of rigid frame. For masonry infilled wall with restraining factors of frame(IFWB-1), cumulated energy dissipation capacities wear increased by 1.60 times in comparision with that of masonry infilled wall(IFB-1) at final stage of testing.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.202-205
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• 2006

Three reinforced concrete shear wall and infilled shear wall using retrofitting system were constructed and tested under both vertical and cyclic loadings, Experimental programs were carried out to evaluate and improve the seismic performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility etc. under load reversals. All the specimens were modeled in one-third scale size. For specimens(RWAHC, RWXHC) designed by the improving of seismic performance using the high ductile fiber composite mortar, anchoring, and advanced detailing system for the reinforced concrete shear wall load-carrying capacities were increased $1.1{\sim}1.22$ times in comparison with the standard specimen(SRW).

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.478-481
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• 2006

Reinforced concrete shear wall is composed of wall, horizontal and vertical flanges. Due to the abrupt change in its geometry, it is difficult to predict the ultimate behaviour of shear wall in the action of lateral forces. For the better understanding of ultimate state, the propagation of crack and inelastic compressive zone are simulated reasonably. In this study, for the improvement of analysis result for shear wall with flanges, analyses are fulfilled with the application of some modelling methods including various material and geometrical models and numerical methods. The results from various modelling methods are compared and the advisable model is proposed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.1006-1013
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• 2004

Operating experience of steam generators shows that the tubes are degraded by stress corrosion cracking, fretting wear and so on. These defected tubes could stay in service if it is proved that the tubes have sufficient structural margin to preclude the risk of tube bursting. This paper provides detailed plastic limit pressure solutions for through-wall cracks in the steam generator tubes. These are developed based on three dimensional(3D) finite element analyses assuming elastic-perfectly plastic material behavior. Both axial and circumferential through-wall cracks in free span and in u-bend regions are considered. The resulting limit pressure solutions are given in a polynomial form, and thus can be simply used in practical integrity assessment of the steam generator tubes.

• Journal of the Korean housing association
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• v.8 no.3
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• pp.219-230
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• 1997

Lack of technical standards, specification and inadequate execution in masonry wall construction in Korea lead to produce serious flaw problems such as crack, efflorescene, and upset etc.. The purpose of this paper is to present the practical details for Masonry cavity wall construction to prevent rain penetration and to accommodate differential movement between the inner and outer wythes of cavity walls. Considering rain penetration and differential movement of both wythes of cavity walls, provision of an adequate air space, an airtight back-up wall, clean cavity with weepholes and vents, properly positioned flashing, tie and shelf angle etc. depend on the cavity wall types will help ensure good performance. The present details included noncorrosive hot dip galvanized steel or stainless steel for metal components, plastic and ultra violet resistant polypropylene Copolymer for other components was taken into account the construction method and several types of cavity walls in Korea

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.120-125
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• 2007

Put Abstract text here The strain distribution measurement for wall thinned pipe bends by ESPI is presented. Defect types observed in the steel piping in the nuclear power plants (NPP) are the crack at the weld part and the wall thinning defect in the pipe bends. Especially, the wall thinning defects in the pipe bends due to the flow-accelerated corrosion (FAC) is a main type of defects observed in the carbon steel piping system. ESPI is one of the optical non-destructive testing methods and can measure the stress and the strain distribution of the object subjected by the tensile loading or the internal pressure. In this paper, the strain distribution of the wall thinned pipe bends due to the internal pressure will be measured by ESPI technique and the results are discussed. From the results, the size of the wall thinning defect can also be measured approximately.

• Nuclear Engineering and Technology
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• v.42 no.5
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• pp.546-551
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• 2010

The objective of this research is to estimate the crack location and size of a carbon steel pipe by using a laser ultrasound guided wave for the wall thinning evaluation of an elbow. The wall thinning of the carbon steel pipe is one of the most serious problems in nuclear power plants, especially the wall thinning of the carbon steel elbow caused by Flow-Accelerated Corrosion (FAC). Therefore, a non-destructive inspection method of elbow is essential for the nuclear power plants to operate safely. The specimens used in this study were carbon steel elbows, which represented the main elements of real nuclear power plants. The shape of the wall thinning was an oval with a width of 120mm, a length of 80mm, and a depth of 5mm. The L(0,1) and L(0,2) modes variation of the ultrasound guided wave signal is obtained from the response of the laser generation/air-coupled detection ultrasonic hybrid system represent the characteristics of the defect. The trends of these characteristics and signal processing were used to estimate the size and location of wall thinning.