• Journal of Korean Society on Water Environment
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• v.36 no.2
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• pp.109-115
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• 2020

Recently, since impervious areas have increased due to urban development, the water cycle system of urban watersheds has been destructed. Hence, researches on LID (Low Impact Development) technique have been conducted to solve such problems environmentally. In order to verify suitability with the scale and arrangement of LID technique, the runoff reduction effect of the LID technique should be analyzed per small watershed unit. In this study, pre-post difference of the runoff by applying the LID was estimated using the rational method and rainwater treatment capacity equation. As a result, the runoff before and after the application of LID were estimated as 22,533.5 ㎥ and 14,992.1 ㎥, respectively. In addition, rainfall-runoff simulations were carried out using SWMM to evaluate the efficiency of the LID technique. The SWMM simulation results showed that the runoff before and after the application of LID were 21,174 ㎥ and 15,664 ㎥, respectively. Based on the results of the two methods, the scale and arrangement of the LID technique were revised in order to maximize the effect of the water cycle improvement. Rainfall-runoff simulations were carried out using the SWMM with the revised LID techniques. As a result, despite 34.8 % reduction of pervious pavement area, the rate of runoff reduction increased by 2.1 %. These results indicate that designing the scale and arrangement of LID technique, while considering the total amount of inflow entering into each LID techniques, is essential to effectively achieve the goals of runoff reduction in urban development.

• Journal of Korean Society on Water Environment
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• v.32 no.4
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• pp.367-374
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• 2016

In this study, the RDII impact on sewer designing in the upstream monitoring area (A site) was considered. Based on the long-term (1/1/2011~12/31/2011) rainfall and flow data consisting of 10-min interval sampling in the nearby design area (B site), the maximum RDII/DWF ratio was selected. The sewer network system at B site was evaluated by the Manning equation. Scenario 1 considering the hourly maximum flow with respect to the flow velocity showed that none of the sewer pipes satisfied the minimum flow velocity condition (0.6 m/s), and 40 pipes did not achieve half of the velocity condition. In scenario 2 considering I/I, 1 the pipes satisfied 0.6 m/s, and 35 pipes showed 0.3 m/s. Scenario 3 reflected the effect of RDII. Velocities in 26 pipes were less than 0.3 m/s, and 4 pipes satisfied the velocity condition. With respect to the allowance rate, 17 pipes were shown to have more than 99%, and none of the pipes satisfied less than 95% of the allowance rate in scenario 1. In scenario 2, 17 Ed: Per the Table pipes showed more than 99% and one pipe showed less than 95%. In scenario 3, 16 pipes showed more than 99% of the allowance rate, and 19 pipes showed less than 95%. Based on these results, it is predicted that deposition would occur due to the slow flow velocity; however, capacity would not be a problem.

• Journal of Wetlands Research
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• v.13 no.2
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• pp.199-208
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• 2011

Scarcity of water worldwide, increasing greenhouse gas emissions, increased energy consumption due to the Earth is threatened. Existing in the process of urban planning and development of forests, rivers and other natural ecosystems have been destroyed and that there was increased impervious pavement. Impervious pavement increase water circulation system to destroy the natural and urban water retention, infiltration and decreased evaporation. Nonpoint source pollution(NPS) occurs when rainfall impervious pavement and appeal directly to the river water inflow is adversely impacts of the situation. In this study, rainfall occurs impervious pavement NPS pollution reduction and temperature increase due to the increase in urban areas, and to solve heat island phenomenon is to develop small HSSF constructed wetland technology. The small HSSF constructed wetland sedimentation, filtration, adsorption, absorption by vegetation, including such mechanisms. Techniques for verification of the pilot-scale test was conducted. In the future domestic urban heat island phenomenon and restore the natural water cycle for the facilities will be used as a basis to develop.

• Journal of Korea Water Resources Association
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• v.47 no.6
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• pp.513-522
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• 2014

Climate change and urbanization have affected a increase of peak discharge and water pollution etc. In a view of these aspects, the LID(Low Impact Development) technology has been highlighted as one of adjustable control measures to mimic predevelopment hydrologic condition. Many LID technologies have developed, but there is a lack of studies with verification of LID technology efficiency. Therefore this study developed a rainfall-runoff simulator could be possible to verify LID technology efficiency. Using this simulator, this study has experimented the rainfall verification through the rainfall distribution experiment and the experiment to show the relation between inflow and effective rainfall in order to sprinkle the equal rainfall in each unit bed. As a result, the study defined the relation between allowable discharge range and RPM by nozzle types and verified the hydrologic cycle such as the relation between infiltration rate, surface runoff and subsurface runoff at pervious area and impervious area through the rainfall-runoff experiment.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1559-1570
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• 2008

A new grouting material named 3S is developed that can be used effectively for reinforcing cut surface of weathered rock in processing of tunneling. The new material is composed of mostly micro slag cement and general Portland cement, but the material is foundered again upto $8,000\;cm^2/g$ of specific area so that it can be easily infiltrated in to the ground. For verifying technical and engineering quality of the material several laboratory tests with specially designed test apparatus were performed including compression tests, infiltration tests and resonant column tests. It was verified that the newly developed grouting material at early age of 1 or 3 days generates 200~1500% higher compressive strength and 400~560% larger elastic modulus than those of the LW(LW-1) or micro-cement(LW-2) grouting materials in the market. In addition, the new 3S grouting material could be so easily infiltrated into the model ground in the lab tests that it produces 4 times larger grouted roots in average compared to the usual water glass type grouting material(LW-1). Thus, it can be said that the newly developed grouting material can effectively prevent inflow water into tunnel compared to LW grouting materials.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.424-431
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• 2018

Stormwater runoff containing considerable amounts of pollutants such as particulates, organics, nutrients, and heavy metals contaminate natural bodies of water. At present, best management practices (BMP) intended to reduce the volume and treat pollutants from stormwater runoff were devised to serve as cost-effective measures of stormwater management. However, improper design and lack of proper maintenance can lead to degradation of the facility, making it unable to perform its intended function. This study evaluated an infiltration trench (IT) that went through a series of maintenance operations. 41 monitored rainfall events from 2009 to 2016 were used to evaluate the pollutant removal capabilities of the IT. Assessment of the water quality and hydrological data revealed that the inflow volume was the most relative factor affecting the unit pollutant loads (UPL) entering the facility. Seasonal variations also affected the pollutant removal capabilities of the IT. During the summer season, the increased rainfall depths and runoff volumes diminished the pollutant removal efficiency (RE) of the facility due to increased volumes that washed off larger pollutant loads and caused the IT to overflow. Moreover, the system also exhibited reduced pollutant RE for the winter season due to frozen media layers and chemical-related mechanisms impacted by the low winter temperature. Maintenance operations also posed considerable effects of the performance of the IT. During the first two years of operation, the IT exhibited a decrease in pollutant RE due to aging and lack of proper maintenance. However, some events also showed reduced pollutant RE succeeding the maintenance as a result of disturbed sediments that were not removed from the geotextile. Ultimately, the presented effects of maintenance operations in relation to the pollutant RE of the system may lead to the optimization of maintenance schedules and procedures for BMP of same structure.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.119-128
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• 2008

Sewer rehabilitation is performed to improve the problem for urban drainage sewer system recently. However the data for the sewer system is not stored enough so that the sewer system is difficult to be managed systematically. In this study, a maintenance management system for urban drainage system is developed to store the data efficiently and manage the system systematically. In the developed system, a hydraulic and hydrologic analysis module is included to test the carrying capacity of a sewer pipe and estimate the amount of combined sewer overflows. The I/I and superannuation evaluation module is included in this system. The module distribute the total inflow/infiltration observed at the several sampling points in a drainage area to the individual pipes of the entire sewer system. Then the superannuation of a sewer pipe is evaluated according to the amount of I/I of the pipe. And in the developed system, the optimal rehabilitation priority module is included to determine the optimal priority and support the decision making for the sewer rehabilitation. The maintenance management system which is developed in this study is constructed by the association with the developed modules and the system is formed as graphical user interface system.

• Journal of the Korean GEO-environmental Society
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• v.1 no.1
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• pp.79-85
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• 2000

The environmental assessment on the open dumping landfill of small scale which was situated in local small city was carried out to reuse the landfill site as the residental, commercial and other purposes through the analysis of the leachate of landfill, extracted solution from landfill waste. The waste was landfilled at 5.5~8m depth and the covered layer so poor as 20~50cm thickness. The biodegradable organic matters were almost degraded and the result of the leachate of landfill showed that the BOD/COD ratio were measured as 0.079, pH 7.2~7.6, SS 47736mg/L, COD 6193.8mg/L, T-N 596mg/L, and T-P 123.9mg/L respectively. These results were higher than those of extracted solution of landfill waste as the COD and BOD were measured as low values and T-N 7.77mg/L and T-P as 0.20mg/L lower concentrations the landfill appears the maturation phase. As the result of the assessment on the open dumping landfill of small scale, if appears that this landfill is maturation phase and the formation leachate is reduced. If the treatment facility of leachate from landfill and the layer which protects the inflow/infiltration is prepared, it can be safely used as this landfill site.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.911-916
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• 2005

In this study, variations of water quality, sediment size and contaminant substances are analyzed at upstream and downstream in sewer systems in order to evaluate the characteristics of wastewater transformation by physico-chemical and biological reactions. The differences of DOC concentration between up and down stream showed the range of $-5.8{\sim}18.6$ from the result of continuous measurement at up and down stream. About 8.4% of DOC concentration was reduced and reduction rate was 2.3 mg/L/km. SS reduction rate was measured by 5.5 mg/L/km, 0.22 mg/L/min from upstream to downstream, which was twice than DOC reduction rate. When pollution load reduction was evaluated considering infiltration/inflow effect, DOC load was eliminated from 1,230 ka/d to 1,167 kg/d by physi-chemical and biological reaction in a sewer and 7.8% of the SS in upstream station was reduced under dry weather condition. The results showed that the characteristics of transformation process of wastewater in sewer should be considered for design and operation of wastewater treatment plant.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.4 s.23
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• pp.37-47
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• 2006

Urban development results in increased runoff volume and flowrates and shortening in time of concentration, which may cause frequent flooding downstream. Flow retardation structures to limit adverse downstream effects of urban storm runoff are used. There are various types of flow retardation measures include detention basins, retention basins, and infiltration basins. In basic planning phase, a number of planning models of detention ponds which decide storage volume by putting main variables were used to design detention ponds. The characteristics of hydrological parameters $\alpha,\;\gamma$ which are used in planning models of detention pond were analyzed. In this study, detention ponds data of Disaster Impact Assessment report at 22 sites were analyzed in order to investigate correlation between characteristic of urban drainage basin parameter and characteristics of detention pond parameter due to urbanization effects. The results showed that storage volume was influenced by peak discharge ratio $\alpha$ more than runoff coefficient ratio $\beta$ and peak discharge ratio $\alpha$ was influenced by runoff coefficient ratio $\beta$ less than regional parameter n. Storage ratio was mainly influenced by duration of design rainfall in the case of trapezoidal inflow hydrograph such as Donahue et al. method.