• 한국도로학회논문집
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• 제15권3호
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• pp.45-52
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• 2013

PURPOSES : This study is to construct the regression models of drainage asphalt concrete specimens and to provide the appropriate coefficients of hydraulic conductivity prediction models. METHODS: In terms of easy calculation of the hydraulic conductivity from porosity of asphalt concrete pavement, the estimation model of hydraulic conductivity was proposed using regression analysis. 10 specimens of drainage asphalt concrete pavement were made for measurement of the hydraulic conductivity. Hydraulic conductivity model proposed in this study was calculated by empirical model based on porosity and the grain size. In this study, it shows the compared results from permeability measured test and empirical equation, and the suitability of proposed model, using regression analysis. RESULTS: As the result of the regression analysis, the hydraulic conductivity calculated from the proposal model was similar to that resulted from permeability measured test. Also result of RMSE (Root Mean Square Error) analysis, a proposed regression model is resulted in more accurate model. CONCLUSIONS: The proposed model can be used in case of estimating the hydraulic conductivity at drainage asphalt concrete pavements in fields.

• 방사성폐기물학회지
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• 제21권2호
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• pp.225-234
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• 2023

In the design of HLW repositories, it is important to confirm the performance and safety of buffer materials at high temperatures. Most existing models for predicting hydraulic conductivity of bentonite buffer materials have been derived using the results of tests conducted below 100℃. However, they cannot be applied to temperatures above 100℃. This study suggests a prediction model for the hydraulic conductivity of bentonite buffer materials, valid at temperatures between 100℃ and 125℃, based on different test results and values reported in literature. Among several factors, dry density and temperature were the most relevant to hydraulic conductivity and were used as important independent variables for the prediction model. The effect of temperature, which positively correlates with hydraulic conductivity, was greater than that of dry density, which negatively correlates with hydraulic conductivity. Finally, to enhance the prediction accuracy, a new parameter reflecting the effect of dry density and temperature was proposed and included in the final prediction model. Compared to the existing model, the predicted result of the final suggested model was closer to the measured values.

• 한국환경과학회지
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• 제24권7호
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• pp.939-946
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• 2015

Hydraulic conductivity is an important parameter in the analytical model of groundwater. This study analyzed the groundwater movement characteristics by estimating optimal parameters according to hydraulic conductivity input methods with the MODFLOW model which is widely used. It first estimated the optimal parameters by dividing hydraulic conductivity zones by attitude. Next, it estimated optimal parameters by geological characteristic. It analyzed the groundwater movement characteristics by applying the recharge quantity and amount of evapotranspiration of drought periods and flood years with the estimated parameters. As the result was analyzed that there are differences of observation water level values according to hydraulic conductivity input methods but there is no big differences of overall groundwater movement characteristics by hydraulic conductivity input method, the two methods have found to be applicability in analyses of groundwater. So, it is judged that studies on more exact application of hydraulic conductivity and the application methods are needed.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.99-101
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• 2003

Unsaturated hydraulic conductivity models have been widely used for the numerical modeling of water flow and contaminant transport in soils. In this study, a simple hydraulic conductivity model is developed by using information of particle-size distribution from the lognormal distribution model and its results are compared with those from the Kosugi-Mualem (KM) model. The accuracy of the proposed model is verified for observed data chosen from the international UNSODA database. Results showed that the proposed model produces adequate predictions of hydraulic conductivities. Performance of this model is generally better than the KM function.

• 한국환경과학회지
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• 제28권12호
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• pp.1157-1169
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• 2019

We used numerical models to reliably analyze the groundwater flow and hydraulic conductivity on Jeju Island. To increase reliability, improvements were made to model application factors such as hydraulic watershed classification, groundwater recharge calculation by precipitation, hydraulic conduction calculation using the pilot point method, and expansion of the observed groundwater level. Analysis of groundwater flow showed that the model-calculated water level was similar to the observed value. However, the Seogwi and West Jeju watersheds showed large differences in groundwater level. These areas need to be analyzed by segmenting the distribution of the hydraulic conductivity. Analyzing the groundwater flow in a sub watershed showed that groundwater flow was similar to values from equipotential lines; therefore, the reliability of the analysis results could be improved. Estimation of hydraulic conductivity distribution according to the results of the groundwater flow simulation for all areas of Jeju Island showed hydraulic conductivity > 100 m/d in the coastal area and 1 - 45 m/d in the upstream area. Notably, hydraulic conductivity was 500 m/d or above in the lowlands of the eastern area, and it was relatively high in some northern and southern areas. Such characteristics were found to be related to distribution of the equipotential lines and type of groundwater occurrence.

• Geomechanics and Engineering
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• 제14권5호
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• pp.467-477
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• 2018

Estimation of hydraulic parameters is a critical step during design of foundation dewatering works. When many piles are installed in an aquifer, estimation of the hydraulic conductivity should consider the blocking of groundwater seepage by the piles. Based on field observations during a dewatering project in Shanghai, hydraulic conductivities are back-calculated using a numerical model considering the actual position of each pile. However, it is difficult to apply the aforementioned model directly in field due to requirement to input each pile geometry into the model. To develop a simple numerical model and find the optimal hydraulic conductivity, three scenarios are examined, in which the soil mass containing the piles is considered to be a uniform porous media. In these three scenarios, different sub-regions with different hydraulic conductivities, based on either automatic inverted calculation, or on effective medium theory (EMT), are established. The results indicate that the error, in the case which determines the hydraulic conductivity based on EMT, is less than that determined in the automatic inversion case. With the application of EMT, only the hydraulic conductivity of the soil outside the pit should be inverted. The soil inside the pit with its piles is divided into sub-regions with different hydraulic conductivities, and the hydraulic conductivity is calculated according to the volume ratio of the piles. Thus, the use of EMT in numerical modelling makes it easier to consider the effect of piles installed in an aquifer.

• 한국농공학회논문집
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• 제55권4호
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• pp.1-11
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• 2013

Unsaturated hydraulic conductivity function is one of key parameters to solve the flow phenomena in problems of landslide. Prediction models for hydraulic conductivity function related to soil-water retention curve equations in many geotechnical applications have been still used instead of direct measurement of the hydraulic conductivity function since prediction models from soil-water retention curve equations are attractive for their fast and easy use and low cost. However, many researchers found that prediction models for the hydraulic conductivity function can not predict the hydraulic conductivity exactly in comparison with experimental outputs. This research introduced an inverse analysis to evaluate the hydraulic conductivity function corresponding to experimental output from the flow pump system. Optimisation process was carried out to obtain the hydraulic conductivity function. This research showed that the inverse analysis with flow pump system was suitable to assess the hydraulic conductivity in unsaturated soil, and the prediction models for the hydraulic conductivity were led to the significant discrepancy from actual experimental outputs.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권4호
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• pp.87-97
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• 2020

In this study, the applicability of the geostatistical evolution strategy as an inverse analysis method of estimating hydraulic properties of small-scale basin was tested. The geostatistical evolution strategy is a type of data assimilation method that can effectively estimate aquifer hydraulic conductivity by combining a global optimization model of the evolution strategy and a local optimization model of the ensemble Kalman filtering. In the applicability test, the geometry, hydraulic boundary conditions, and the distribution of groundwater monitoring wells of Hanlim-Eup were employed. On the other hand, a synthetic hydraulic conductivity distribution was generated and used as the reference property for ease of estimation quality assessment. In the estimations, two different cases were tested where, in Case I, both groundwater levels and hydraulic conductivity measurements were assumed to be available, and only the groundwater levels were available, in Case II. In both cases, the reference and estimated hydraulic conductivity fields were found to show reasonable similarity, even though the prior information for estimation was not accurate. The ability to estimate hydraulic conductivity without accurate prior information suggests that this method can be used effectively to estimate mathematical properties in real-world cases, many of which little prior information is available for the aquifer conditions.

• 한국환경과학회지
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• 제28권9호
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• pp.737-749
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• 2019

In this study, the sensitivity analysis of hydraulic conductivity and separation distance (distance between injection well and pumping well) was analyzed by establishing a conceptual model considering the hydrogeologic characteristics of facility agricultural complex in Korea. In the conceptual model, natural characteristics (topography and geology, precipitation, hydraulic conductivity, etc.) and artificial characteristics (separation distance from injection well to pumping well, injection rate and pumping rate, etc.) is entered, and sensitivity analysis was performed 12 scenarios using a combination of hydraulic conductivity ($10^{-1}cm/sec$, $10^{-2}cm/sec$, $10^{-3}cm/sec$, $10^{-4}cm/sec$) and separation distance (10 m, 50 m, 100 m). Groundwater drawdown at the monitoring well was increased as the hydraulic conductivity decreased and the separation distance increased. From the regression analysis of groundwater drawdown as a hydraulic conductivity at the same separation distance, it was found that the groundwater level fluctuation of artificial recharge aquifer was dominantly influenced by hydraulic conductivity. In the condition that the hydraulic conductivity of artificial recharge aquifer was $10^{-2}cm/sec$ or more, the radius of influence of groundwater level was within 20 m, but In the condition that the hydraulic conductivity is $10^{-3}cm/sec$ or less, it is confirmed that the radius of influence of groundwater increases sharply as the separation distance increases.

• Environmental Engineering Research
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• 제7권3호
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• pp.159-167
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• 2002