• Structural Engineering and Mechanics
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• v.52 no.6
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• pp.1257-1271
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• 2014

The hydraulic deterioration of the drainage system in tunnel linings is one of the main factors governing long-term lining-ground interactions during the lifetime of tunnels. Thus, in the design procedure of a tunnel below the groundwater table, the possible detrimental effects associated with the hydraulic deterioration should be addressed. Hydraulic deterioration in double-lined tunnels can occur because of reasons such as clogging of the drainage layer and drain-pipe blockings. In this study, the coupled mechanical and hydraulic interactions between linings due to drain-pipe blockings are investigated using the finite-element method. A double-lined structural model incorporating hydraulic behavior is developed to represent the coupled structural and hydraulic behavior between the linings and drainage system. It is found that hydraulic deterioration hinders flow into the tunnel, causing asymmetric development of pore-water pressure and consequent detrimental effects to the secondary lining.

• Proceedings of the KIEE Conference
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• summer
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• pp.1364-1366
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• 2004

When an underground pipeline runs parallel with DC-powered railways, it suffers from electrolytic corrosion caused by the stray current leaked from the railway negative returns. Perforation due to the electrolytic corrosion may bring about large-scale accidents even cathodically protected systems. Traditionally, bonding methods such as direct drainage, polarized drainage and forced drainage have been used in order to mitigate the damage on pipelines. In particular, the forced drainage method is widely adopted in Seoul. In this paper, we report the analysis of the stray current conditions in Seoul subway DC electrification system.

• Journal of the Korean GEO-environmental Society
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• v.24 no.10
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• pp.33-39
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• 2023

As interest in the use of underground spaces increases, safety against water pressure acting on underground structures is required. In Korea, various buoyancy prevention methods are used to control such underground water pressure, and among them, the vertical drainage method with excellent economic efficiency, constructionability and stability has recently been introduced and applied. However, in the case of the vertical drainage method designed and constructed in the field, it is often designed and constructed depending on numerical analysis, making it difficult to expect practical stability judgment. Accordingly, in this study, an experiment was conducted to measure both pressure by installing a vertical drainage system using a model soil. Based on the measured value by the experiment and the numerical analysis value, we intend to compare and analyze the action positive pressure and use it as basic data for field application.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.449-455
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• 2019

The increase in impermeable pavement from recent urbanization has resulted in an increase in surface runoff. The surface runoff has also increased the burden of the existing drainage system. This drainage system has structural limitations in that the catchment area is reduced by the waste particles transported with the surface runoff. In addition, the efficiency of the drainage system is decreased. To overcome these limitations, a new type of drainage system with a drainage layer was developed and applied. In this study, various volume porosity and permeability of the lower drainage layer were simulated using ANSYS CFX, which is a three dimensional computational fluid dynamics program. The results showed that the outlet velocity of the 35% volume porosity was faster than that of the 20% and 50% cases, and there was no relationship between the volume porosity and drainage performance. The permeability of the drainage layer can be determined from the particle size of the material, and a simulation of five conditions showed that 2 mm sand grains are most suitable for workability and usability. This study suggests appropriate values of the volume porosity and particle size of the drainage layer. This consideration can be advantageous for reducing and preventing flood damage.

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.85-90
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• 2014

Dewaterability, one of the important properties of wastewater sludge, was investigated using a simple capillary suction time (CST) measurement method. CST and SRF have a very close co-relation. It was convinced that CST method was quite effective, and compensating the time-consuming SRF of conventional drainage measuring method. It turned out that one could use the results of CST to find optimum flocculants ratio to improve drainage in wastewater treatment for the tissue paper production at a mill. Since the optimum ratio of flocculants could be determined with the value of CST and COD removal efficiency could be improved with precise ratio of flocculants. Thus, using CST for determining the optimum ratio of flocculants could be economical by reducing the amount of flocculants. Dewaterability might be measured within several seconds using the values of CST in a precise way. The dewaterability could also be useful in investigating the optimum ratio of flocculants.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.324-329
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• 2008

A coal mine drainage sludge(designated as CMDS) is mainly generated during physicochemical treatment or electrical purification of the drainage abandoned mine that include dissolved heavy metal. To understand the possibility of an application of the dehydrated CMDS as the landfill cover medium of hygienic a reclaimed ground, an laboratory experiment was performed to investigate the physicochemical and geoengineering characteristics of the dehydrated CMDS. To improve the geoengineering characteristics of the dehydrated CMDS, the liquid limit, plasticity limit test, compaction method test, strength test, and hydraulic conductivity test ware performed with the lithification material mixed sludge. When the mixed ratio of the sludge and the lithification material was more than 1:06, the compaction method was A method, the moisture content less than 33.5%, the strength of mixed sludge was $8.2kg\;cm^{-2}$, the hydraulic conductivity was $2.7\times10^{-6}cm\;sec^{-1}$, the sludge was up to the landfill standard of US Environmental Protection Agency (US EPA).

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.31-36
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• 2014

In this study, the methodologies for evaluating the low-flow at the ungauged watershed are reviewed and assessed. The ungauged watershed can be classified into different situations such as the partially recorded watershed and the completely ungauged watershed. The extension method and the percentile method are used to evaluated the low-flow at the partially recorded watershed. The drainage-area ratio method and the regional regression method are used at the completely ungauged watershed. These four methods are applied and validated based on the hydrological and geometric data acquired from unit watersheds in Han River basin for TMDLs. In case of partially recorded watershed, the values of low-flow evaluated by the extension method are in better agreement with measured flow-rate rather than those by the percentile method. In case of completely ungauged watershed, the drainage-area method is broadly used to estimate the low-flow. It must be paid attention to consider the treated sewage discharge produced at watersheds when applying the method.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.133-138
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• 2011

This study aims to compare hydraulic & hydrologic design characteristics by examining generated on weak points for road drainage poor sites. More appropriated methodology of rainfall-intensity calculated is to consider minutely rainfall-intensity decision method for road drainage basins. To use non-uniform flow analysis methodology for road surface drainage facilities inlet spacing decision methods is better than present experience inlet spacing decision equations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.34-43
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• 2017

Large amounts of household water are required as common households change from the single-residence types of the past to group-residence types. Therefore, the management of reservoirs is urgently required to ensure the supply of clean household water to users. Important considerations for household water include the duration for which the water is stored in the reservoir, the disinfectant's dilution capacity, and the size of the reservoir to allow for the amount of water required for emergencies and firefighting. The drainage efficiency was analyzed in this study using computational fluid analysis for existing rectangular reservoirs and the newly proposed hexagonal reservoir. Thus, it was determined that the centrifugal force generated at the inlet was maintained until the outlet due to the approximately circular shape of the hexagonal reservoir. The findings of this study verified that the centrifugal force improved the flow rate by approximately 35% compared to existing rectangular reservoirs and that drainage was performed efficiently without stagnation zone.

• Proceedings of the KIEE Conference
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• summer
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• pp.1367-1369
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• 2004

When an underground pipeline runs parallel with subway DC electrification system, it suffers from stray current corrosion caused by the stray current from the rails negative returns. Perforation due to the stray current corrosion may bring about disastrous accidents such even in cathodically protected systems. Traditionally, bonding methods such as direct drainage, polarized drainage and forced drainage have been used in order to mitigate the damage on pipelines. In particular, the forced drainage method is widely adopted in Busan. In this paper, we report the real-time measurement data of the pipe-to-soil potential variation in the presence and absence of the IR compensation. The drainage current variation was also measured using the Stray Current Logger developed. By analyzing them, the problems of current countermeasures for stray current corrosion are discussed.