• Tunnel and Underground Space
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• v.32 no.5
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• pp.285-297
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• 2022

We report results of Extended Leak-Off Test (XLOT) conducted in a large diameter borehole, which is drilled for installation of deep borehole geophysical monitoring system to monitor micro-earthquakes and fault behavior of major fault zones in the southeastern Korean Peninsula. The borehole was planned to secure a final diameter of 200 mm (or more) at a depth of ~1 km, with 12" diameter wellbore to intermediate depths, and 7-7/8" (~200 mm) to the bottom hole depth. We drilled first the 12" borehole to approximately 504 m deep and installed American Petroleum Institute standard 8-5/8" casing, then annulus between the casing and bedrock was fully cemented. XLOT was carried out for several purposes such as confirming casing and cementing integrity, measuring rock stress states. To that end, we drilled additional 4 m long open hole interval to directly inject water and pressurize into the rock mass using the upper API casings. During the XLOT, flow rates and interval pressures were recorded in real time. Based on the logs we tried to analyze hydraulic conductivity of the test interval.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.33-36
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• 2009

This study suggests manufacturing and cleaning the feeding system of hydrogen peroxide to use oxidizer of liquid rocket. We established the process of cleaning and passivation in order to minimize the pollution of Hydrogen Peroxide feeding system. And, we verified stability of the manufactured feeding system by leak test & hot test.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.145-150
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• 2020

Water wall tube is one of the major factors consisting of a fluidized bed boiler and it plays very important role for the generation of electricity within the boiler. But these water wall tubes within the fluidized bed boiler are subject to the ware and corrosion caused by the high temperature gas and the flowing medium. If water leak is occurred, the secondary damage by the water leak will occur. As a result of that, the power generation efficiency decreases noticeably. Therefore, the maintenance of the water wall tube is very important. In this study, we designed a exciter sensor based on simulation and composed a remote field eddy current system for the defect evaluation of the outer water wall tube. Starting from the shape design of exciter, we conducted simulations for various design factors such as the water wall tube size, material, frequency, lift-off and so on. Based on the results, we designed the optimum exciter sensor for the water wall tube test within the fluidized bed boiler.

• 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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.92-93
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• 2020

The test method to be developed is to determine whether the waterproof layer applied to the leak-prone part such as cracks and joints has defects such as tearing or lifting of the waterproof layer due to the influence generated from the behavior of the structure under complex deterioration conditions. This is to evaluate the performance of the waterproofing method afterwards. Therefore, by notifying only the pass or fail, the unique mechanical properties of the material or method used are notified to the test client to limit the physical properties of the test body, thereby determining and supplementing the weaknesses of the user material in advance to improve the high quality. We want to prevent damage from water leakage through production and distribution of materials.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1177-1192
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• 2018

The objective of this study is to develop the existing drainage system for catching the partial leakage of tunnel structures operating in cold region. The drainage system consists of drainage board, Hotty-gel as a waterproofing material, cover for preventing protrusion of Hotty-gel, air nailer, fixed nail, pipe for collecting ground leak, pipe for conveying ground leak, wire-mesh, and sprayed cement mortar. The drainage systems were installed in conventional concrete lining tunnels to evaluate the site applicability and constructability. The performances of waterproof and the drainage in the drainage system were evaluated by injecting 1,000 ml of red water in the back of the drainage system at 7 days, 14 days, 21 days, 28 days, 2 months, 3 months, 4 months, 5 months, 6 months, 7 months and 8 months. During 8 months of field test, the average daily temperature of the tunnel site was measured from $-16.0^{\circ}C$ to $25.6^{\circ}C$. The daily minimum temperature was $-21.3^{\circ}C$ and the daily maximum temperature was $30.8^{\circ}C$. There was no problem in waterproof and drainage performance of the drainage board in the drainage system. However, the pipe for conveying ground leak had the leakage problem from 14 days. It is considered that the leakage of the pipe for conveying ground leak was caused by the deformation of the pipe of the flexible plastic material having a thickness of 0.2 cm by using the high pressure air nailer and the fixing pin and the insufficient thickness and width of the hotty-gel for preventing the leakage.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.4
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• pp.573-585
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• 2019

The objective of this study is to propose the drainage system that has been improved the workability, waterproofing and drainage performance to treat the leakage from the cement concrete structures in underground. It is improved that the pipe for conveying ground leak in the existing drainage system had the problem in workability and waterproof. The drainage systems with the improved pipe for conveying ground leak were constructed in conventional concrete lining tunnels to evaluate the workability, waterproofing and drainage. The waterproof and the drainage performance of the drainage system was evaluated by injecting 1,000 ml of red water in the back of the drainage system at 3 weeks, 6 weeks, 9 weeks, 11 weeks, 14 weeks, 17 weeks and 23 weeks. During 6 months of field performance test, the average daily temperature of the tunnel site was measured from $-12.4^{\circ}C$ to $19.7^{\circ}C$. The daily minimum temperature was $-17.2^{\circ}C$ and the daily maximum temperature was $26.7^{\circ}C$. There was no problem in waterproof and drainage performance on the pipe for conveying ground leak and the drainage system during 6 months for field performance test. It is concluded that the improved drainage system can be applied to various cement concrete underground structures where leakage occurs, and has little seasonal effect.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.274-277
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• 2004

The most important mode of subcritical crack growth is primary water stress corrosion crack, which was the reported mechanism from the root cause analysis of the crack in the bimetallic welds. Stress corrosion crack growth evaluations was carried out for several flaw shapes of both axial and circumferential flaws, using the steady-state stresses including residual stresses. This evaluation considered the possibility of additional flaws in the primary loops of nuclear power plant, even though no such flaws have been identified by Ultrasonic Test. Consequently, Results show that the predicted flaw sizes will determine acceptability for continued service and maintenance.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.70-78
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• 2022

The trenchless entire repair technology (TERT) have many different names depending on the companies, and they have the same or similar methods as well as materials. In addition, there was quiet difficulty in application of field working and even confuse to classify for new TERT, while application criteria of TERT is not listed systematically. This study proposed standardization and method for TERT affecting by pipe condition, working materials, working method, specification/quantity per unit according to field condition, strange affairs and others. Determination criteria of defective sewer pipe has proposed to effective method which modify a criteria between Ministry of Environment and Seoul Metropolitan City. A Cured-in-place pipe (CIPP) is suitable for TERT, and the design criteria for the entire broken pipe are proposed when the pipe itself deforms more than 10%. A check lists are specimen preparing, hardening site made by clamped mold, numbers, flexural and tensile property, water leak and desquamation test, and have to use material property of minimum CIPP value depend on ISO 11296-4, ISO 11297-4, KS M3550-7 and KS M3550-9.

• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.266-271
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• 2014

Chemical sensors are used in various industrial facilities such high-risk and prevent the leakage of substances, important in life and environmental protection and the safe use of industry, used for management. In particular, high-temperature environments such as power generation equipment of the rotating part due to leakage generated by the various oil, power plants Shut Down, fire, work environment (exposure to various chemical solution and gas leak) and various water, air and soil pollution causes. Thus, over the long term through various channels such as crops and groundwater contamination caused by the slow, serious adverse effect on the ecosystem. In this paper, synthetic lube oil and high pressure hydraulic fluid leakage and immediately detect a new Printed Electronic implementation of technology-based film-type sensors, and its performance test. Thus, industrial accidents and environmental pollution and for early detection of problems, large accidents can be prevented. Experimental results of the synthetic lube oil and high pressure hydraulic fluid solution after the contact time depending on the experiment and the oil solution of the sensor material of the conductive porous PE resistance value by a chemical reaction could be confirmed that rapid increase. Also implemented in the film-type oil sensor electrical resistance change over time of the reaction rate and the synthetic lube oil is about 2 minutes or less, the high pressure hydraulic fluid is less than about 1 minute was. Therefore, more high-pressure hydraulic fluid such as a low volatility synthetic lube oils are the resistance change and the reaction rate was confirmed to be the slowest.