• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4302-4309
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• 2012

Underground structures without the expansion joint in the settled intervals, the underground structures may suffer from structural crack and the water leakage thereby resulting in the occurance of the efflorescence. In this study, the performance of new expansion joint used in underground structures were verified. The spacing of expansion joint was defined by the finite element analysis. Expansion length, resistance and waterproofing performance of developed expansion joint were confirmed by experiment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.533-549
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• 2017

In this study, drainage systems were proposed to drain the leakage of groundwater in the existing underground concrete structures. The system consists of drainage board, wire mesh, fixed nail, and mortar with mineral. In order to increase constructability, the drainage board and wire mesh were attached on the surface of cement concrete using the air nailer and fixed nail. The mortar with 30% of blast furnace slag was sprayed on the drainage board and wire mesh using the spray mortar equipment. The field test construction was carried out in a conventional concrete lining tunnel and concrete retaining wall for performance verification of the drainage system in the field. There was no problem with performance degradation in the drainage system for three years after construction. The bond strength tests were performed on the sprayed mortar at 14 days and about 3 years after field test construction. In case of attaching the wire mesh on the drainage board, the bond strengths of the sprayed mortar were 1.04 MPa at 14 days and 1.46 MPa about 3 years. In case of the drainage board without the wire mesh, the bond strengths of the sprayed mortar were 1.13 MPa at 14 days and 0.89 MPa, less than 1 MPa of bond strength criteria, about 3 years.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.102-113
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• 2021

The deterioration environments caused by de-icing salt and airborne chlorides in the seashore, evaluated in the "Detailed guideline for safety and management practice of facilities (performance evaluation)", were reviewed in terms of penetrated chlorides into concrete on various road facilities. Target concrete structures, in this study, were 4 concrete barriers in Gangwon area, 3 concrete barriers and 1 retaining wall in Busan area, and 4 bridges in Gangwon-do, Seoul, Gyeonggi-do, and Busan. The deterioration environments were classified into three categories: direct and indirect de-icing salt attack, and airborne salt attack depending on the distance to seashore and the height of pier, and the penetrated chlorides in to concrete were analyzed. The results showed that (1) the regional deterioration environments were clearly classified by de-icing salt sprayed days (snowfall days), (2) the penetrated chlorides increased significantly when leakage occurred through slabs or expansion joints, and (3) the airborne chlorides affected to a height of 20 m concrete in the seashore, Busan. From these, it could be confirmed that the chloride ion penetration properties depend on the exposed aging environment, member location and height, and deterioration status, even on the same structure, so the selection of target members and location is very important in the inspection and maintenance. If the database of penetrated chlorides properties in various deterioration environments is constructed, it is expected that the proactive durability management on concrete structures will be possible in the field.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.45-52
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• 2007

Maintenance of structural and hydrological safety of the superannuated fill dam is very important subject on the viewpoint of disaster prevention. Mainly, the core of the superannuated fill dams have been damaged continuously by the various harmful external forces such as the typhoons, flash floods and earthquake, and these can be connected to the large scaled general dam failure. Therefore, the research on the repair, remediation and reinforcement of dam is necessary. In this study, the permeable grouting method for the remediation of fill dam was examined by the electrical resistivity survey and the change of permeability of core front. As a result, the permeable grouting method can be useful remediation method for the superannuated fill dam, the leakage from the core front decreased greatly before and after the construction of grouting. Furthermore, it can be said that the turbidity of fill dam may not be greatly increased by grouting.

• Journal of the Korean Geotechnical Society
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• v.33 no.12
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• pp.115-125
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• 2017

PHC-W earth retaining wall could be constructed continuously. Various retaining wall methods such as C.I.P. etc. method require separate waterproof method. However, the PHC-W retaining wall method prevents leakage of groundwater by inserting a waterproofing material at connection part between 2 PHC piles. In this study, the experimental study on 3 waterproofing method for PHC-W retaining wall was conducted at the model pressure chamber. In the method using textile with 1-liquid type and 2-liquid type urethane, rapid leak occurred at the pressure of 120 kPa and 140 kPa or more. In the method of textile with grouting, rapid leak occurred at the pressure of 120 kPa or more, however, in this method, the rapid leakage happened at the top part and the bottom part reinforced with urethane.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.396-403
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• 2016

This study is based on the evaluation of a single component injection type adhesive repair material and a new 2 component type used in leakage of underground concrete structures. The studies showed that based on different mix ratio of the 2 component type adhesive sealant comprised of an asphalt main and latex mixture agent the viscosity of the material compound differed significantly. Based on a permeability testing, injection and economic efficiency, and performance, the appropriate ratio was determined to be 6:1 and was proceeded to the KS F 4935 evaluation method. The 2 component type adhesive sealant uses a static mixer and a cartridge type container for the injection procedure and was able to satisfy the evaluation criteria outlined in the KS F 4935 standard.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.169-172
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• 1990

본 논문에서는 모달해석을 통해 불안정성을 제거 할 수 있는 메카니즘 (mechanism)으로 만든 씨일(Anti-Swirl Injection type Seal: ASIS)의 등록 성 및 누수량, 압력 강하등을 평씨일, 댐퍼씨일 등과 비교, 해석하여 본질의 역할 및 안정성을 동시에 향상시킬수 있는 씨일을 연구해보고자한다.

• Journal of the Korea Society of Computer and Information
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• v.19 no.4
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• pp.25-33
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• 2014

This paper proposes a power-efficient scheduling scheme that stochastically minimizes the power consumption of real-time tasks while meeting their deadlines on multicore processors. In the proposed scheme, uncertain computation amounts of given tasks are translated into probabilistic computation amounts based on their past completion amounts, and the mean power consumption of the translated probabilistic computation amounts is minimized with a finite set of discrete clock frequencies. Also, when system load is low, the proposed scheme activates a part of all available cores with unused cores powered off, considering the leakage power consumption of cores. Evaluation shows that the scheme saves up to 69% power consumption of the previous method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.127-128
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• 2017

Tests are conducted according to the ISO TS 16774, Part 3 standard for quality management of leakage repair materials used in cracks in underground concrete structures. These test methods are performed indirectly using a nonwoven fabric on a chalet containing leak repair materials. However, it is considered that it is appropriate to verify the resistance of the repair material, which is required to be applied directly to the cracks in the actual field and to exhibit the resistance of the flow velocity. In this study, mass change was measured by using nonwoven fabric and nonwoven fabric. As a result, both methods showed an increase in mass, which indicated that the maintenance material itself contained a large amount of water, and that the mass change occurred depending on the drying state. Also, depending on the use of nonwoven fabric, the error due to the indirect test could not be ruled out. Therefore, further verification is needed, and it is considered that the test for change of mass reduction measurement is necessary according to the drying time of other types of the same series.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.9-17
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• 2012

Concrete sewage culvert shows degradation with time since it is always exposed to various harmful ions, and deterioration of concrete culvert propagates to structural safety problems. After reclamation, maintenance for concrete sewage culvert is very difficult so that high durable and structural performance are essential for the sewage concrete culvert. Recently polymer concrete has been used to improve mechanical properties and durability performance. In this paper, engineering properties are evaluated for sewage culvert made with polymer concrete, and leakage and adhesive strength between joints are evaluated with small-scale models. The polymer sewage culvert shows high compressive strength over 100MPa with low water permeability and chloride penetration. Furthermore, high resistances to chemical and biological attack are evaluated. Through tests for leakage and adhesive, unification of joints is verified with evaluation of no leakage and high adhesive strength. Precast polymer sewage culvert in this paper can be actively used for severe conditions like sewage lines.