• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.67-72
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• 2017

BACKGROUND:Cultivation of alternative crops in paddy fields is necessary because of the decrease in rice consumption and the increase in excess stock of rice. The study was conducted to investigate the effects of alternative crops cultivation in paddy fields on soil physico-chemical characteristics and crop yield. METHODS AND RESULTS: Soybean (Glycine max), red-clover (Trifolium pratense), and water convolvulus (Ipomoea aquatica) were selected for alternative crops in the first and/or second year and rice was planted in the third year. When alternative crops were cultivated in the previous year, soil bulk density, soil hardness, and water content were lower than those for rice cultivation. Water-depth decreasing rate and aggregate content were greater for the upland-upland-paddy cropping system than upland-paddy-paddy cropping system. Cultivation of red-clover and water convolvulus for two years resulted in the high soil organic matter content. In the third year, available phosphate, exchangeable potassium, and soil cation exchange capacity were relatively high when soybean was cultivated in the previous year. In the first year, water convolvulus cultivation showed greater productivity than red-clover cultivation while the opposite pattern was found in the second year. Rice yield in the third year was greater for soybean or red-clover as a previous crop than for water convolvulus as a previous crop. CONCLUSION: The results suggest that cultivation of alternative crops in paddy fields can improve soil physical properties including bulk density, hardness, water content, and aggregate content as well as rice productivity.

• Geomechanics and Engineering
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• v.3 no.2
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• pp.131-151
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• 2011

The electrical conductivity of a soil-water system is related to its engineering properties. By measuring the soil electrical conductivity, one may obtain quantitative, semi-quantitative, or qualitative information to estimate the in-situ soil behavior for site characterization. This paper presents the results of electrical conductivity measured on compacted kaolin clay samples using a circular two-electrode cell in conjunction with a specially designed compaction apparatus, which has the advantage of reducing errors due to sample handling and increasing measurement accuracy. The experimental results are analyzed to observe the effects of various parameters on soil electrical conductivity, i.e. porosity, unit weight, water content and pore water salinity. The performance of existing analytical models for predicting the electrical conductivity of saturated and unsaturated soils is evaluated by calculating empirical constants in these models. It is found that the Rhoades model gives the best fit for the kaolin clay investigated. Two general relationships between the formation factor and soil porosity are established based on the experimental data reported in the literature and measured from this study for saturated soils, which may provide insight for understanding electrical conduction characteristics of soils over a wide range of porosity.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.5
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• pp.59-69
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• 2000

Sludge is generated in the process of water and wastewater treatment, and it has been causing various environmental problems. From this point of view, recycling of sludge appears to be the best way. The firing technology in pottery industry is applied to the sludge treatment , and the final product is called artificial soil. The effect of mixed artificial soil with upland soil was investigated through the crop growth experiment and the physical & chemical characteristics of the mixed soils were analyses. After the growth experiment , mixed soil plots contained more CEC, OM, TN, TP than upland soil plots. This result shows that the artificial soil produced form sludge can be mixed with upland soil, and crop can be increased. From the growth analysis, growth of soybean and corn in the mixed soil plots was better than that in the original upland soil plots. Heavy metals contents in the mixed soil plots were within the quality standard. This is a promising result since in most cases heavy metals are the most concern in the application of sludge product to farmland.

• The Korean Journal of Pesticide Science
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• v.17 no.3
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• pp.168-177
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• 2013

This experiment was carried out to estimate leaching potential of thirteen endocrine disruptor-suspected pesticides in upland soils using soil columns (5 cm I.D. ${\times}$ 35 cm H.) packed with soil A (sandy loam) and soil B (loam). When 12.6 mL of water, average precipitation in Cheongju area during the period from June to August, 2001-2010, was percolated through soil column packed with soil A every day for 21 days, no pesticides were detected from leachate, with the exception of metribuzin which was detected with negligible. Also, when 2 L of water was percolated consecutively five times through soil columns packed with soil A and B, irrespective of soil types, cypermethrin, endosulfan, fenvalerate, parathion and trifluralin, which were very low water solubilities and high soil $K_{oc}s$, were not detected from leachate and were distributed mostly in the depth of 0-5 cm, representing that water solubility and soil $K_{oc}$ are major contributing factors to their leaching behavior. Despite high average leaching rates in carbaryl and methomyl, actual possibilities of ground water contamination in the agricultural environment by them would be very low, considering that the negligible amount of pesticide was percolated through a lysimeter with an undisturbed soil core simulating the field conditions, while most of pesticide was percolated through a soil column with the disturbed soil profile.

• Korean Journal of Remote Sensing
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• v.30 no.5
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• pp.587-596
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• 2014

Soil moisture is one of the most important interests in hydrological response and the interaction between the land surface and atmosphere. Estimation of Antecedent Wetness Conditions (AWC) which is soil moisture condition prior to a rainfall in the basin should be considered for rainfall-runoff prediction. In this study, Soil Wetness Index (SWI), Antecedent Precipitation Index ($API_5$), remotely sensed Soil Moisture ($SM_{rs}$), and 5 days ground Soil Moisture ($SM_{g5}$) were selected to estimate the AWC at four study area in the Korean Peninsula. The remotely sensed soil moisture data were taken from the AMSR-E soil moisture archive. The maximum potential retention ($S_{obs}$) was obtained from direct runoff and rainfall using Soil Conservation Service-Curve Number (SCS-CN) method by rainfall data of 2011 for each study area. Results showed the great correlations between the maximum potential retention and SWI with a mean correlation coefficient which is equal to -0.73. The results of time length representing the time scale of soil moisture showed a gap from region to region. It was due to the differences of soil types and the characteristics of study area. Since the remotely sensed soil moisture has been proved as reasonable hydrological variables to predict a wetness in the basin, it should be continuously monitored.

• Journal of the Korean Geotechnical Society
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• v.21 no.6
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• pp.137-146
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• 2005

299 railroad slopes were investigated and the failure characteristics and reinforcement patterns were analyzed. Stability analyses on the 14 cut-off soil slopes were carried out. Surficial failures were predicted by infinite slope analyses assuming the temporarily perched ground water table at soil surface during rainfall period. Limit equilibrium analyses were also carried out and the influences of rainfall infiltration on the slope stabilities were taken Into account by seepage analyses using finite element method and by assuming ground water tables to be located adjacent to soil surface. The adequacy of those analyses was evaluated by comparing the slope failure characteristics between analysis results and the past failure records. From the comparison results, it was deduced that the limit equilibrium analyses were not appropriate to estimate the shallow failure that occurred at most of the railroad cut-off soil slopes. For the better estimation of the surficial failure, not only the increase of pore-water pressure (reduction of matric suction), but also the influence of water flows over slope surface which erode soil mass, should be evaluated and considered.

• Journal of Soil and Groundwater Environment
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• v.24 no.1
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• pp.1-9
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• 2019

This study presents a technical perspective to the fate characteristics of phenol and m-cresol, which represent some of the most common organic chemicals found in chemical spill accidents, and likely to persist in soil and groundwater due to their highly stable physicochemical properties. Some cases of domestic and foreign chemical accidents linked to phenol and m-cresol contamination were compiled. Due to their low organic carbon-water partitioning coefficient (Koc), phenol and m-cresol tend to migrate into groundwater and remained as dissolved phase. On the other hands, phenol and m-cresol can be readily decomposed by microbes in soil and groundwater under appropriate conditions. Therefore, the fate characteristics of these chemicals are highly contingent on environmental conditions. Thus, if a great quantity of leakage is occurred by chemical accidents, the up-to-date and correct information about fate characteristics taking into account both the chemical and environmental conditions is greatly needed to minimized the potential hazards from these chemicals.

• Journal of the Korean Geographical Society
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• v.39 no.1
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• pp.45-55
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• 2004

The paper describes the rainfall-runoff. soil moisture distribution and subsurface flow of 'U-shaped Goll' valley head slope to evaluate quantitatively the interaction between the water circulation system and geomorphic development. The findings are as follows: The fissure and the pipe entrance in front of 'U-shaped Goll' introduce a lot of direct runoff into either the soil pipe or the soil layer to accelerate the erosion of the soil layer, so that they are likely to contribute to the expansion and development of the soil pipe. Most of soil water is to be drained in pipe flow, while some of remaining soil water is to be fed into groundwater. Therefore, low rainfall intensity is thought to let both the groundwater level and the pipe flow react sensitively by the effects of the precedent rainfall even at events: As a result, the soil pipe is said to be an important factor having influence upon the material balance of 'U-shaped Goll' valley head slope. On the other hand, the groundwater shows greater specific flux at the top than at the bottom, and relatively larger specific flux is applied to the top to make 'U-shaped Goll' valley head slope go back to the top.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.341-347
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• 2006

Geographically Imha basin is adjacent to Andong basin, but the occurrence of turbid water in each reservoir by storm events shows big differences. Hence, it is very important to identify the reason for these large differences. This study compared and analyzed soil erosion using the semi-empirical soil erosion model, RUSLE for both Imha and Andong basin, especially with emphasis on high-density turbid water. The agricultural district, which is the most vulnerable to soil erosion, was intensively analyzed based on land cover map produced by Ministry of Environment. As a result, the portion of the agricultural area is 11.88% for Andong basin, while it is 14.95% for Imha basin. Also all RUSLE factors excepts practice factor turned out to be higher for Imha basin. This means that the basin characteristics such as soil texture, terrain, and land cover for Imha basin is more vulnerable to soil erosion. Estimation of soil erosion by RUSLE for Andong and Imha basin is 1,275,806 ton and 1,501,608 ton, respectively, showing higher soil erosion by 225,802 ton for Imha basin.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.26-43
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• 2010

To determine the effect of draining for the drainage layer in CFGD(Concrete Faced Gravel Dam) body, centrifuge model tests were performed. Also, soil compaction works are essential to construction of dams in order to avoid unexpected settlement of superstructures. Taking advantage of oscillating accelerometer, this research was made to complement existing methods for assessment of soil stiffness. In order to examine the validity of compaction-degree suggested in the study, tests on vibration characteristics using accelerometers was also performed.