• Journal of the Korean GEO-environmental Society
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• v.15 no.8
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• pp.13-21
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• 2014

The Plastic Board Drain is used to improve soft soils deposited in container terminal area at a port. This paper describes settlement behavior of soft ground in this area from PBD installation to the time of operating facilities. Previous researches focused on soil improvement effect of PBD, that is, the settlement occurred during ground improvement period. The residual settlement occurred during operating the facility is very important from the maintenance and management point of view. However, the study of this residual settlement has been rarely conducted. In this study, by analyzing the measured settlement data obtained from the container terminal area at the port, it was verified that the residual settlement induced during operating facilities occurred in a layer with PBD improvement. In addition, by comparison the settlement predicted by a numerical analysis with the settlement measured in the field, it was confirmed that the actual settlement is in the range of predicted settlement.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.31-40
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• 2005

This study proposed a new yield function considering the spacing ratio of the critical state to predict the undrained shear behavior of anisotropic field ground. We have suggested a nonassociated constitutive model that used a newly modified plastic potential function in order to apply the yield function of the modified Cam-Clay model to the anisotropic consolidation. In this paper, we predicted undrained shear behavior of the remolded weathered mudstone soils in Phohang isotorpically and anisotropically consolidated using the suggested model. To evaluate the reliability of proposed model, we predictied undrained shear behavior of Bankok Clay isotropically, nomally consolidated and Drammen Clay Ko consolidated. The predicted results are consistent with the observed behavior.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1444-1449
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• 2006

Korea is about 70% of all country to mountain, and basin is consisted of various terrain, soil, vegetation, land use etc. because use land as intensive. Also, need basin hydrologic model that can analysis base outflow as well as outflow directly for calculation of discharge to establish irrigation plan. Inconvenient in use method and user interface offer side is causing by way that existing USGS WEASEL runs in PC Arc/Info, and ArcGIS with development of present GIS technology is applied in many fields offering convenience in analysis that use GIS. In this research, wished to develop suitable outflow parameter extraction system, For this, develop pre-processor and post-processor that effectively draw of hydrologic model input data from water resources DB through van example benchimarking, and developed input/output component of GIS base applicable to various hydrologic and water quality model.

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.1097-1107
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• 2003

The DAWAST model was originally developed to consider the variation of water storage in the unsaturated soil zone and it is a conceptual lumped model. Return flows from agricultural, domestic and industrial water were included to the original result of model simulation to calibrate model parameters of watershed runoff. Agricultural water demand was estimated only in paddy fields supposing that return flow responded at stream was originated from paddy fields. Domestic and industrial water demand was estimated by average daily water demand multiplied monthly variation coefficient. Daily inflow to the Daechung multipurpose dam was applied to verify the DAWAST model considered return flows. On annual average from 1983 to 2001, inflows were simulated to 652.5 mm with return flows considered, which was approached more closer to observed inflow of 667.3 mm, compared with case of 606.8 mm with return flows not considered.

• Journal of Korea Water Resources Association
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• v.45 no.11
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• pp.1081-1091
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• 2012

SWAT model is applied to simulate rainfall-runoff and pollutant loadings in the Nakdong River basin as the condition for extreme droughts and floods. The year 1994 and 2002 are chosen as the drought and flood year, respectively, through the analysis of past rainfall data for 30 years. The simulation results show decreases in both runoff and pollutant loadings for the drought year but increases for the flood year. However, the pollutant loadings on some upper sub-basins increase for drought year due to highly-regulated dam discharge and soil moisture change. Collectively, extreme droughts and floods have negative impacts on water quality, showing elevated SS loadings during wet season and concentrated T-P concentrations during low flow season. The extent of these impacts is highly influenced by antecedent dry days and precipitation patterns.

• Journal of the Korean Geosynthetics Society
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• v.8 no.4
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• pp.27-34
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• 2009

In this paper, characteristics of shear strength and deformation of geosynthetics-reinforced slag materials are described. In order to investigate the effect of geosynthetics on shear strength and deformation behavior of slags, when they are reinforced with geosynthetics or geomat such as PET mat, large triaxial tests were performed under consolidated-drained condition. The materials used in the study are real ones as they are in the field, so that the scale effect of samples disappeared. From the large triaxial tests, it was observed that the stress-strain relationship of geosynthetics-reinforced slags shows relatively small dilatancy and weak tendency of strain hardening, compared with that of slags without reinforcement. The shear strength parameters such as apparent cohesion and internal friction angle increase with PET mat reinforcement, consequently result in about 1.2 (for low confining pressure) to 1.4 (for high confining pressure) times of shear strength of un-reinforced sample. Therefore, the adoption of geomat-reinforced slag layers leads to an increase in the factor of safety for embankment design on soft soil formations.

• Journal of Korean Society of Forest Science
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• v.84 no.2
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• pp.218-225
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• 1995

In this paper, a mechanical analysis model for steep-slope log-skidding operations of a rubber-tired tractor is discussed and the applicability of the model is investigated. The model largely consists of mathematical analysis models for log drag, dynamic vehicle weight distributions and soil-vehicle traction. For the case study, a theoretical data set for log skidding operations is used in investigating the effect of the factors influencing the results of mechanical analysis or the productivity of skidding operations. The analyses include 1) the effect of log choking methods on tangential log-skidding force, 2) the effects of the change in travel speed and log load on the required input power to the wheels and 3) the log skidding performance of a two-wheel drive compared with that of a four-wheel drive.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.417-426
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• 2016

SWAT model usually underestimates daily peak discharges. To resolve this problem, in this study, the algorithm related with the surface flow simulation was modified by partitioning excessive infiltration based on the relative length between overland flow time of concentration and percolation travel time in soil water zone and by computing time of concentration varying with the amount of surface flow. The modified SWAT was applied to the Chungju dam watershed to assess the increasing effects of daily peak discharges. The daily peaks simulated by the modified SWAT were on average 10% higher than those by original SWAT for the peaks above $5,000m^3/s$. The modified SWAT was found to be able to more accurately reproduce daily peaks, particularly showing increase rates of 9.9%, 18.6% and 12.6%, respectively, for top three peaks that occurred in the years of 1990, 2002, and 2006.

• KCID journal
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• v.13 no.2
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• pp.262-273
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• 2006

The Soil and Water Assessment Tool (SWAT) model has been widely used in hydrology and sediment simulation worldwide. In most cases, the SWAT model is first calibrated with adjustments in model parameters, and then the validation is performed. However, very little study regarding the effects on SWAT estimation of subwatershed delineation was performed. Thus, the SWAT model was applied to the Doam-dam watershed with various threshold values in subwatershed delineation in this study to examine the effects on the number of subwatershed delineated on SWAT estimation. It was found the flow effect of subwatershed delineation is negligible. However there were huge variations in SWAT estimated sediment, T-N, and T-P values with the use of various threshold value in watershed delineation. Sometimes these variations due to watershed delineation are beyond the effects of parameter adjustment in model calibration and validation. The SWAT is a semi-distributed modeling system, thus, the subwatershed characteristics are assumed to be the same for all Hydrologic Response Unit (HRU) within that subwatershed. This assumption leads to variations in the SWAT estimated sediment and nutrient output values. Therefore, it is strongly recommended the SWAT users need to use the HUR specific slope length and slope value in model runs, instead of using the slope and the corresponding slope length of the subawatershed to exclude the effects of the number of subwatershed delineated on the SWAT estimation.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.385-385
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• 2011

유역 스케일의 실제 증발산량을 산정하는 대표적인 방법으로 관측 강우량과 유출량의 관계로부터 증발산량을 간접적으로 추정하는 물수지(water balance)법, 증발력과 토양수분량의 변화량 (soil moisture accounting)을 고려한 유역 수문모델링을 이용하는 방법, 잠재 증발산량과 실제 증발산량간 보완관계식(complementary relationship)을 이용하는 방법 등이 있다. 물수지법은 관측치를 기반으로 한다는 점에서 신뢰도가 높다고 할 수 있으나, 기본적으로 유역 저류량의 변화를 무시하기 때문에 연 단위와 같이 긴 시간 스케일에 적용 가능하고 작은 시간 스케일에는 적용성이 떨어진다. 유역 수문모델링을 이용하는 방법은 기상, 토양 및 식물 조건을 모두 고려하는 방법으로 유역의 불균질성을 반영할 수 있고 일 단위 등의 비교적 작은 시간 스케일에 대해서도 증발산량을 산정할 수 있는 장점이 있으나, 수많은 입력자료가 필요하며 간접적인 추정 방식이기 때문에 모형의 정확한 검증과 상당한 숙련도가 뒷받침되어야 한다. 잠재 증발산량과 실제 증발산량간 보완관계식을 이용하는 방법은 토양이나 식물 등의 지표면 조건에 대한 정보를 필요로 하지 않으며 단지 기상자료만을 이용하는 방법으로 적용하기 쉽다는 장점이 있으나 잠재 및 실제 증발산량간의 보완피드벡 매카니즘이 존재한다는 가정이 수반되어 있어 적용시 이를 입증해야 하는 어려움이 있다. 이 처럼 각기 장단점을 가진 여러 방법으로 증발산량을 산정하고 있지만, 각 방법 간의 연결고리를 맺는 연구는 심도 있게 수행되지 못하고 있다. 따라서 본 연구에서는 상기 언급한 증발산량 산정 방법 중 보완관계식을 이용하는 방법과 유역수문모형에 의한 방법 간의 연관성을 평가하고자 하였으며, 이를 위해 충주댐 상류유역에 대해서 SWAT-K에 의한 증발산량 모의치가 보완관계식을 따르는 지에 대해 고찰하였다. 모의기간동안 계산된 잠재 및 실제 증발산량을 습윤지수(humidity index)에 따라 함께 도시해본 결과, 연 단위의 경우에는 건조할수록 잠재 증발산량은 점차 커지고 실제 증발산량은 작아지는 것으로 나타나 보완관계가 성립하였고, 월 단위 경우에는 강우에 비해서 비교적 증발산량이 큰 5, 6월에 가장 명확한 관계가 보여 늦은 봄과 초여름에 보완적 관계가 뚜렷하게 발생하는 반면에 동절기에는 보완관계가 성립하지 않는 것으로 나타나는 등 분석 단위기간별로 보완관계의 성립여부를 판별할 수 있었다.