• KIEAE Journal
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• v.5 no.3
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• pp.17-24
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• 2005

Until today, rainwater management was processed without disposing the peak discharge, which was due to rainfall, to provide stability against flood damage. In this process, the natural hydrologic cycle changed quickly, and because of this, some problems that could harm human beings and the environment arose. These problems need to be addressed accordingly. One of the proposals was to carry out decentralized rainwater management through a natural hydrologic cycle on site, including utilization, infiltration, detention, and retention of rainwater. This study aims to set the direction of applicable decentralized rainwater management to housing complex in Korea. Therefore, spacial properties in urban housing complexes were analysed such as the impervious area-to-land ratio, the green area-to-land ratio, artificial land-to-land ratio etc. As the result of this study, when a housing complex was small and developed by reconstruction, the impervious area, artificial land, the green area in the artificial land-to-land ratio were high. So, direction of decentralized rainwater management of these housing complexes is available to utilize and detain rainwater. On the other hand, those of big housing complexes in land development district were low relatively. So, direction of decentralized rainwater management of these housing complexes is available to infiltrate and evaporate rainwater.

• Economic and Environmental Geology
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• v.45 no.6
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• pp.697-707
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• 2012

The quantitative landslide susceptibility assessment methods can be divided into statistical approaches and geomechanical approaches based on the consideration of the triggering factors and landslide models. The geomechanical approach is considered as one of the most effective approaches since this approach proposes physical slope model and considers geomorphological and geomechanical properties of slope materials. Therefore, the geomechanical approaches has been used widely in landslide susceptibility analysis using the infinite slope model as physical slope model. However, the previous studies assumed constant groundwater level for broad study area without the consideration of rainfall intensity and hydraulic properties of soil materials. Therefore, in this study, landslide susceptibility assessment was implemented using the coupled infinite slope model with hydrologic model. For the analysis, geomechanical and hydrualic properties of slope materials and rainfall intensity were measured from the soil samples which were obtained from field investigation. For the practical application, the proposed approach was applied to Jinbu area, Gangwon-Do which was experienced large amount of landslides in July 2006. In order to compare to the proposed approach, the previous approach was used to analyze the landslide susceptibility using randomly selected groundwater level. Comparison of the results shows that the accuracy of the proposed method was improved with the consideration of the hydrologic model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.683-690
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• 2008

The objectives of this study are to provide an observation-based urban flood prediction model and to evaluate their performance on a restored Cheonggye stream. The study area, which has its own unique hydrologic and flooding conditions that can be characterized the standard of flood occurrence by watergate opening and walk lane inundation, measured stream discharges at the 5 sites and watergate opening and walk lane inundation through the main stream since 2006. This study derived the relationship between precipitation intensity and watergate opening and walk lane inundation time by using the observations of 2006 and verified their performance on 2007 flood events. The result showed that the coefficients of determination are ranged on 0.57-0.75, which would be acceptable if considering the complexity of the area and the proposed model simplicity. It also suggested the continuous observation of these properties is required for further improvement of the models.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.439-439
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• 2015

The temporal and spatial relationship of the weather elements such as rainfall and temperature is closely linked to the streamflow simulation, especially, to the flood forecasting problems. For the study area, Imjin river basin, which has the specific characteristics in geography with river cross operation between North and South Korea, the meteorological information in the northern area is totally deficiency, lead to the inaccuracy of streamflow estimation. In the paper, this problem is solved by using the combination of global (such as soil moisture content, land use) and local hydrologic components data such as weather data (precipitation, evapotranspiration, humidity, etc.) for the model-driven runoff (surface flow, lateral flow and groundwater flow) data in each subbasin. To compute the streamflow in Imjin river basin, this study is applied the hydrologic model SURR (Sejong Univ. Rainfall-Runoff) which is the continuous rainfall-runoff model used physical foundations, originally based on Storage Function Model (SFM) to simulate the intercourse of the soil properties, weather factors and flow value. The result indicates the spatial variation in the runoff response of the different subbasins influenced by the input data. The dependancy of runoff simulation accuracy depending on the qualities of input data and model parameters is suggested in this study. The southern region with the dense of gauges and the adequate data shows the good results of the simulated discharge. Eventually, the application of SURR model in Imjin riverbasin gives the accurate consequence in simulation, and become the subsequent runoff for prediction in the future process.

• Journal of Korea Water Resources Association
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• v.32 no.4
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• pp.479-488
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• 1999

The flood damage has being increased because of urbanization due to the industrialization and the growth of population. Therefore, the hydrologic properties such as increasing the peak flow and decreasing the concentration time of the peak flow have been changed. Hence, the interest of an urban prevention against flood disasters has been centralized at the present day. The objectives of this study is to develop the suitable models to calculate the runoff characteristics from an urban basin. This study describes the properties of each urban hydrologic model and to determine suitable basin model using the ILLUDAS and SWMM models in the urban runoff models in the Yong-Ahm area at Chungju. The peak flow, concentration time and total runoff value of this area are compared and analyzed with regard to calculated and real values. After obtaining values appropriated from the ILLUDAS and SWMM models using 5 rainfall events in this areas, the peak flows, concentration times and total runoff values are compared with real values. As a result of this study, the Transport block of the SWMM is closely shown to real values.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2B
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• pp.163-171
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• 2009

Classical linear models have been generally used to analyze and forecast hydrologic time series. However, there is growing evidence of nonlinear structure in natural phenomena and hydrologic time series associated with their patterns and fluctuations. Therefore, the classical linear techniques for time series analysis and forecasting may not be appropriate for nonlinear processes. In recent, the BDS (Brock-Dechert-Scheinkman) statistic instead of conventional techniques has been used for detecting nonlinearity of time series. The BDS statistic was derived from the statistical properties of the correlation integral which is used to analyze chaotic system and has been effectively used for distinguishing nonlinear structure in dynamic system from random structures. DVS (Deterministic Versus Stochastic) algorithm has been used for detecting chaos and stochastic systems and for forecasting of chaotic system. This study showed the DVS algorithm can be also used for detecting nonlinearity of the time series. In this study, the stochastic and hydrologic time series are analyzed to detect their nonlinearity. The linear and nonlinear stochastic time series generated from ARMA and TAR (Threshold Auto Regressive) models, a daily streamflow at St. Johns river near Cocoa, Florida, USA and Great Salt Lake Volume (GSL) data, Utah, USA are analyzed, daily inflow series of Soyang dam and the results are compared. The results showed the BDS statistic is a powerful tool for distinguishing between linearity and nonlinearity of the time series and DVS plot can be also effectively used for distinguishing the nonlinearity of the time series.

• Current Research on Agriculture and Life Sciences
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• v.29
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• pp.29-35
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• 2011

The relationship between hydrologic processes and scale is one of the more complex issues in surface water hydrology. Disturbances that change vegetation and/or soil properties have been known to subsequently alter the landscape. The primary objective of this study was to estimate the grain size of soils with different properties from the hydraulic conductivity using pedotransfer functions. The double ring infiltrometer method was used to measure the vertical hydraulic conductivity of three soils under different soil planar surface treatments. Seven selected pedotransfer functions were used to estimate percentile diameters and the reduction in infiltration caused by compaction was misconstrued as caused by changes in percentile diameter. Results showed that compaction on the sandy loamy foot paths reduced the hydraulic conductivity by about 50%. The study showed that perceptual models of infiltration processes and appreciation of scale problems in modeling are far more sophisticated than normally presented in texts. Hydraulic measurement methods are still relevant and will provide significant information of grain size of the soils.

• Geomechanics and Engineering
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• v.10 no.6
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• pp.727-736
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• 2016

Excessive rainfall can cause runoff flows over the soil surface and as a consequence some amount of water will infiltrate into the soil. From a hydrologic modeling perspective it is necessary to estimate infiltration rate in order to calculate the actual runoff discharge. There are many parameters that can affect the infiltration rate such as soil texture, moisture and compaction. However, the most common equations used in hydrological calculations for estimating the infiltration rate do not consider the soil properties directly and estimate infiltration rate without any soil properties expressions. The purpose of this research was to investigate the relations between infiltration rate and soil texture, moisture and compaction. To achieve this purpose an experimental study was performed to show the effect of soil properties and their relations on infiltration rate by using non-linear regression.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.3
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• pp.251-268
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• 1986

Selecting a site for the safe disposal of radioactive waste requires the evaluation of a wide range of geologic, mineralogic, hydrologic, and physicochemical properties. Although highly diverse, these properties are in fact interrelated. Site requirements are also diverse because they are influenced by the nature of the radionuclides in the waste, for example, their half-lives, specific energy, and chemistry. A fundamental consideration in site selection is the mineralogy of the host rock, and one of the most ubiquitous mineral groups is clay minerals. Clays and clay minerals as in situ lithologic components and engineered barriers may playa significant role in retarding the migration of radionuclides. Their high sorptivity, longevity (stability), low permeability, and other physical factors should make them a very effective retainer of most radionuclides in nuclear wastes. There are, however, some unanswered questions. For example, how will their longevity and physicochemical properties be influenced by such factors as radionuclide concentration, radiation intensity, elevated temperatures, changes in redox condition, pH, and formation fluids for extended periods of time? Understanding of mechanisms affecting clay mineral-radionuclide interactions under prevailing geochemical conditions is important; however, the utilization of experimental geochemical information related to physicochemical properties of clays and clay-bearing materials with geohydrologic models presents a uniquely challenging problem in that many assessments have to be based on model predictions rather than on experiments. These are high-priority research investigations that need to be addressed before complete reliance for disposal area performance is made on clays and clay minerals.

• The Journal of Engineering Geology
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• v.30 no.3
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• pp.303-314
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• 2020

Bottled water companies submit monthly hydrologic data including periodical environmental effects investigation, daily water production capacity, water production, water level, water chemistry (pH, EC, temperature) per hour and strictly manage groundwater by periodical analyses. Thus few problems concerning drawdown due to excess intake of groundwater take place. Nevertheless, bottled water companies are imprinted as a contribution to civil affairs resulted regarding groundwater near the companies. Therefore, a new method is required during water balance analysis in environmental effects evaluation, which should be compatible with the evaluation by hydrologic experts as well more accessible to non-experts. In this study, water level of surface water and recharge rate in subcatchment where water production wells are located were measured and monthly baseflow rates were separated from normal streams. Besides, recharge properties of groundwater and surface water in the same catchment area were estimated using analyses of oxygen and hydrogen isotopes in groundwater (production well), surface water, and rainfall.