• Earthquakes and Structures
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• v.16 no.6
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• pp.727-741
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• 2019

A reinforced concrete water tank is a typical functional liquid storage structure and cracks are the greatest threat to the liquid storage structure. Tanks are readily cracked due to seismic activity, thereby leading to the leakage of the stored liquid and a loss of function. In order to study the effect of cracks on liquid storage tanks, self-healing and leakage tests for bending cracks and through cracks in the walls of a reinforced concrete water tank were conducted. Material performance tests were also performed. The self-healing performance of bending cracks in a lentic environment and through cracks in a lotic environment were tested, thereby the self-healing width of bending micro-cracks in the lentic environment in the short term were determined. The through cracks had the capacity for self-healing in the lotic environment was found. The leakage characteristics of the bending cracks and through cracks were tested with the actual water head on the crack. The effects on liquid leakage of the width of bending cracks, the depth of the compression zone, and the acting head were determined. The relationships between the leakage rate and time with the height of the water head were analyzed. Based on the tests, the relationships between the crack characteristics and self-healing as well as the leakage were obtained. Thereby the references for water tank structure design and grading earthquake damage were provided.

• Journal of the Korea Institute of Building Construction
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• v.10 no.6
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• pp.97-107
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• 2010

This study outlines a successful and effective plan for repairing water-leakage cracks in concrete structures. The lack of adequate solutions for water-leakage cracks often results in unnecessarily high repair costs, and as such this remains a problem that requires constant attention. Unfortunately, despite the availability of a vast number of different materials and methods, it is often difficult to attain a perfect waterproof sealing The reason for the difficulties in the repair of water-leakage cracks can be attributed to an insufficient knowledge and understanding of the negative factors (i.e., chemical and physical (mechanical) conditions) that cause water-leakage cracks, and of the properties of the repair materials and methods. In this study, guidelines and methods for the selection of adequate materials for the repair of water-leakage cracks in concrete structures were developed for countries that do not already have general guidelines on this subject, and for local regulatory authorities elsewhere.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.343-344
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• 2018

This study proposes a standard method of diagnosis and repair to prevent and maintain the problem of durability deterioration caused by leakage cracks in apartment basement structures in Korea. Following the announcement of the previous maintenance plan section, this is the second part of the study, focusing on inspection of methods for diagnosing and repairing leakage cracks in apartment basement structures. In this thesis, the matters required for the procedures, types, times and equipment of the inspection plan and the inspection methods, records, and decisions required for the actual inspection are described.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.191-192
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• 2018

This study presents the standard methods of diagnosis and repair to prevent and maintain the durability degradation caused by leakage cracks in underground structures in Korea. The third part after the announcement of the existing maintenance plan, The environmental characteristics and leakage condition of underground structures, the causes of deterioration of underground concrete structures, and countermeasures and leakage equipment were described.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1085-1090
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• 2000

It is socially increasing the need to maintenance of building's durability and management for building's safety. It has happened in waterproofing field, especially in case of water leakage in expansion joint and cracks, lacking basic design for waterproofing. After the completed of construction, there are many troubles something like this. Therefore it need for development to prevent from water leakage, using oakum and urethane in expansion joint and cracks as a method for waterproofing.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.197-202
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• 2003

The leakage quantity through concrete facing of Concrete Face Rockfill Dam(CFRD) is very small due to its low permeability of intact concrete. Even though the concrete facing is well designed and constructed, fine cracks can be generated due to effects of thermal and drying shrinkage. Therefore, it can be said that the leakage from the CFRD is subjected to not permeability of intact concrete but poor joints, cracks and foundation rocks. The Safety of a dam on leakage was evaluated based on the comparison between apparent permeability estimated and leakage quantity measured. The above method can be concluded to give a good direction for the evaluation of safety on CFRD in maintenance aspects as design and construction technology is improved with the accumulation of leakage data.

• Journal of the Korea Institute of Building Construction
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• v.6 no.1 s.19
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• pp.87-91
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• 2006

Since water leakage and cracks are not the source of serious problems such as long-term lowering of performance and durability of a stricture, including damages to operating facilities of a structure, damages to internal finishing materials, exhibition, and goods, and pollution of residential environment, they might have led to development of positive coping skills; however, an instant loss of lives or property due to earthquake, explosion, typhoon, or a fire was indeed neglected. In these days, repair materials for leakage cannot help but being taken in temporary way without any noticeable countermeasure. This kind of repair is socially criticized many times that is defective construction even if this costs a lot. It was not arrange the standard for construction methods of sealer of injection type for leakage maintenance, even it has been used various type of construction methods for leakage part. In conclusion, we suggest that the construction methods of sealer of injection type for leakage maintenance for leakage to establish the leakage repairing technology as increase of structure demand. Therefore, it would be possible to provide a stage-by-stage solution by developing systematic research activities among the industry, schools, and research institutes to spread maintenance management techniques globally through technical solution to water leakage and cracks, acquisition of structural safety with prolonged durability for life cycle, reduction of water leakage repair expense s, and so on.

• Journal of the Semiconductor & Display Technology
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• v.13 no.4
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• pp.15-20
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• 2014

The fracture analysis of $SiN_x$ layers, which were deposited by low-temperature plasma enhanced chemical vapor deposition (LT-PECVD) and could be used for an encapsulation layer of a flexible organic light emitting display (OLED), was performed by an electrical method. The specimens of metal-insulator-metal (MIM) structure were prepared using Pt and ITO electrodes. We stressed MIM specimen mechanically by bending outward with a bending radius of 15mm repeatedly and measured leakage current through the top and bottom electrodes. We also observed the cracks, were generated on surface, by using optical microscope. Once the cracks were initiated, the leakage current started to flow. As the amount of cracks increased, the leakage current was also increased. By correlating the electrical leakage current in the MIM specimen with the bending times, the amount of cracks in the encapsulation layer, generated during the bending process, was quantitatively estimated and fracture behavior of the encapsulation layer was also closely investigated.

• Journal of the Korean Magnetics Society
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• v.21 no.1
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• pp.23-31
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• 2011

From among the NDT (nondestructive testing) methods, the MFL (magnetic flux leakage) method is specially suitable for testing pipelines because pipeline has high magnetic permeability. The system applied to MFL method is called the MFL PIG. The previous MFL PIG showed high performance in detecting the metal loss and corrosions. However, MFL PIG is highly unlikely to detect the cracks which occur by exterior-interior pressure difference in pipelines and the shape of crack is long and very narrow. In MFL PIG, the magnetic field is performed axially and there is no changes of cross-sectional area at cracks that the magnetic field passes through. Cracks occur frequently in the pipelines and the risk of the accident from the cracks is higher than that from the metal loss and corrosions. Therefore, the new PIG is needed to be researched and developed for detecting the cracks. The circumferential MFL (CMFL) 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). In CMFL PIG, cracks, standards of NACE, are detectable. To estimate the shape of crack, the leakage of magnetic fields for many kinds of cracks is analyzed and the method is developed by signal processing.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.591-598
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• 2002

Leakage magnetic flux is occurred in the cracked area of magnetized specimens, and also it changes the magnetic domain area of the magneto-optical film positioned on the specimen. It causes the change of the optical permeability of the magnetic domain on the crack area. So crack images can be obtained easily using this principle. On the other hand, utilizing a laser in this method makes possible to perform a remote sensing by detecting the light intensity contrast between cracked area and normal area. This paper shows the application of non-destructive inspection system taking advantage of magneto-optical method for micro-cracks and presents examples applied to the several types of specimens having fatigue cracks and fabricated cracks using this method. Also the authors prove the possibility of this method as a remote sensing system under the oscillation load considering application to real fields.