• The Journal of Engineering Geology
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• v.26 no.2
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• pp.251-260
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• 2016

Groundwater flow due to hydraulic gradients across a geologic barrier surrounding a dam reservoir can cause swamps or wetlands to form on the downstream side of the dam, thereby restricting land use. The difference in head between the reservoir level and the downstream groundwater level creates a hydraulic gradient, allowing water to flow through the geologic barrier. We constructed a drainage system at the Daecheong dam to study the effects on groundwater levels and soil moisture contents. The drainage system consisted of a buried screened pipe spanning a depth of 1-1.5 m below a land surface. Groundwater levels were monitored at several monitoring wells before and after the drainage system was installed. Most well sites recorded a decline in groundwater level on the order of 1 m. The high-elevated site (monitoring well W1) close to the reservoir showed a significant decline in groundwater level of more than 2 m, likely due to rapid discharge by the drainage system. Soil moisture contents were also analyzed and found to have decreased after the installation of the drainage system, even considering standard deviations in the soil moisture contents. We conclude that the drainage system effectively lowered groundwater levels on the downstream side of the dam. Furthermore, we emphasize that water seepage analyses are critical to embankment dam design and construction, especially in areas where downstream land use is of interest.

• Journal of Korea Water Resources Association
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• v.52 no.4
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• pp.301-312
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• 2019

The importance of the dual drainage system model has increased as the urban flood damage has increased due to the increase of local storm due to climate change. The dual drainage model is a model for more accurately expressing the phenomena of surface flow and conduit flow. Surface runoff and pipe runoff are analyzed through the respective equations and parameters. And the results are expressed visually in various ways. Therefore, inundation analysis results of dual drainage model are used as important data for urban flood prevention plan. In this study, the applicability of the COBRA model, which can be interpreted by combining the dual drainage system with the natural watershed and the urban watershed, was investigated. And the results were compared with other dual drainage models (XP-SWMM, UFAM) to determine suitability of the results. For the same watershed, the XP-SWMM simulates the flooding characteristics of 3 types of dual drainage system model and the internal flooding characteristics due to the lack of capacity of the conduit. UFAM showed the lowest inundation analysis results compared with the other models according to characteristics of consideration of street inlet. COBRA showed the general result that the flooded area and the maximum flooding depth are proportional to the increase in rainfall. It is considered that the COBRA model is good in terms of the stability of the model considering the characteristics of the model to simulate the effective rainfall according to the soil conditions and the realistic appearance of the flooding due to the surface reservoir.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.131-142
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• 2003

The characteristics of electroosmosis drainage in clayey soil were investigated, when an electrokinetic technique was applied for the purpose of separating heavy metals in contaminated ground. A series of laboratory tests, considering voltage, zeta potential, pH distribution, and current, were performed for a lead-contaminated kaolin. The results of laboratory tests were compared with numerical analysis of finite difference method. The 1311owing conclusions were obtained: The flow velocity in electroosmosis was very sensitive to the chemical and electrical characteristics of the clay. As the concentration of ion increases, the flow rate decreases and the amount of drainage also decreases as time elapses.

• Fire Science and Engineering
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• v.22 no.5
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• pp.83-89
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• 2008

Using the high expansion foam generator of ISO 7203-2 which spray 6 liter at 5 bar, foam generation characteristics was studied. Wind flow rate, foam screen, concentration of foam agent solution and concentration of salt of water were varied to find the effect of the parameters on foam generation. Research result showed that expansion ratio of foam was increased with wind flow rate. The expansion ratio of foam in the perforated type standard screen was higher than the wire mesh screen. Expansion ratio and drainage time were increased with increase of foam solution concentration. But a increase of salt concentration in solution showed the decrease of expansion ratio and drainage time.

• KCID journal
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• v.18 no.1
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• pp.4-17
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• 2011

The standard design methodology was suggested to construct wetland system for reducing non-point source pollution from Saemangeum reclaimed paddy land. To set for the design flow and concentrations, runoff and water quality survey were conducted during the irrigation period in 2008 at Gyehwa reclaimed paddy land located at near Saemangeum lake. It is rational that 1ha is the optimum constructed wetland size. To meet this size, the moderate drainage area of reclaimed paddy field was 50ha under the conditions that rainfall is 30mm, average runoff coefficient is 0.83, and runoff capture ratio is 0.6. At these condition, the runoff volume from 50ha was 10,520 $m^3/d$ including base flow during irrigation period. To select the optimum wetland system, several case studies were conducted by focusing on the tidal reclaimed land areas having wetland systems in Seokmun. Pond-Wetland system was selected as the standard model because of showing the highest reduction efficiency. Single variable regression equation were delivered to estimate effluent water concentrations from the designed wetland by using long-term monitoring data from the Seokmun experiment site. The effluent concentration from the designed wetland using these equation were showed moderately range.

• Journal of Korea Water Resources Association
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• v.45 no.4
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• pp.419-430
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• 2012

Due to the calculation difficulty on the hydraulic and hydrologic analysis for road drainage facilities design, these analysis techniques are not applicable. This study's result are development of minutely rainfall-intensity equation suitable for road drainage area, verification of rainfall-runoff model joining kinematic wave theory for road drainage area, computational model based GUI for road surface drainage facilities spacing and culvert's size decision and various road drainage channel design. Applicable test on the developed model is proceed, result that in case of road surface dranage facilities spacing is narrower 6~65% than present spacing calculation method, in other case of road cross dranage facilities size is bigger 6~140% than present size decision method.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.6
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• pp.1-10
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• 2008

The study was aimed at analyzing the relationship between the characteristics of urban green infrastructure and stormwater runoff in a small urban watershed composed of 22 drainage basins. The green areas of which soils are not sealed and allow water infiltrate, were examined for different types of green spaces. In a comparative study for drainage basins of which green spaces are 15.5% and 34.4%, respectively, runoffs were not different with the size of green space. It was attributed to that the increase of runoff by greater road area offset the advantage of greater green area. Another comparative measurement of runoff for drainage basins with similar green area size showed that runoff decreased with greater permeable area (school ground area) and smaller road area. The runoff measurements could address that runoff rates are affected not only by green area size but also by the type of green area and other land covers related to permeability and flow into drainage. It implicated that the improvement of urban green infrastructure as a functional unit for water infiltration and interception is important for stormwater runoff management.

• Journal of the Korean GEO-environmental Society
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• v.5 no.4
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• pp.65-72
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• 2004

Within a country, owing to the restriction of aggregate which have been supplied to construction sites, applicability of byproducts such as the copper slag is expected to be more reasonable. In this study, on the basis of characteristics, grain distribution and environmental stability of copper slag, its engineering application was estimated as the vertical and horizontal drainage material. As a results of laboratory tests, it was shown that the permeability of the copper slag was similar to that of sands under vertical drainage condition. In addition, the copper slag showed higher critical hydraulic gradient than that of sand under upward vertical flow state. The copper slag has potential safety against piping and it that the copper slag is suitable for drainage and filter material.

• 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.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.619-625
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• 2008

Urban sewer systems are designed to operate in open-channel flow regime and energy loss at square manholes is usually not significant. However, the energy loss at surcharged manholes is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze the head loss associated with manholes, especially in surcharged flow. Hydraulic experimental apparatus which can change the manhole inner profile(CASE I, II, III, and IV) and the invert types(CASE A, B, C) were installed for this study. The experimental discharge was $16{\ell}/sec$. As the ratio of b/D(manhole width/inflow pipe diameter) increases, head loss coefficient increases due to strong horizontal swirl motion. The head loss coefficients for CASE I, II, III, and IV were 0.46, 0.38, 0.28 and 0.37, respectively. Side covers increase considerably drainage capacity at surcharged square manhole when the ratio of d/D(side cover diameter/inflow pipe diameter) was 1.0. The head loss coefficients for CASE A, B, and C were 0.45, 0.37, and 0.30, respectively. Accordingly, U-invert is the most effective for energy loss reduction at surcharged square manhole. This head loss coefficients could be available to evaluate the urban sewer system with surcharged flow.