• Journal of the Korean GEO-environmental Society
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• v.17 no.6
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• pp.33-41
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• 2016

This study attempted to investigate drain capacity and vegetation potential of made-planting soil via finite element simulations. Engineering drain capacity of made-planting soil can be evaluated by an analysis of unsaturated soils. In a perspective for vegetation landscape, it is necessary to check whether the minimum amount of water in the made-planting soil can be supplied for the survival of plants. Herein, 1-m high soil column covered by made-planting soil were numerically simulated. Numerical results showed that how the coefficient of permeability of saturated soil and soil-water characteristics of unsaturated soil are considered significantly influences the drain capacity of soils. Variation in the volumetric water content within the Least Limiting Water Range (LLWR) provides us with information on whether the soil can contain a sufficient amount of water for the plants to survive the drought.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.1
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• pp.51-55
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• 1997

Three soils, sandy loam, loam and silty clay loam, were selected and three inches soil cores with 4 bulk density(BD) levels were made by compressing the soils wetted with 3 levels water. Mechanical and water characteristics were measured and analyzed the mechanical resistance limiting water, available water and least-limiting water range. Mechanical resistance limiting water(MRLW) were appeared at higher bulk density than $1.6Mg/m^3$ in sandy loam, and $1.4Mg/m^3$ in loam and silty clay loam. The least-limiting water ranges were sharply decreased at the bulk density $1.6Mg/m^3$ in sandy loam and loam, $1.4Mg/m^3$ in silty clay loam. There were big deferences between available water contents and least limiting water ranges in finer texture and higher bulk density soils.

• Journal of Soil and Groundwater Environment
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• v.11 no.1
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• pp.45-53
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• 2006

This study was performed to evaluate the heating characteristics of soils for the application of electrical resistance heating process combined with soil vapor extraction. Laboratory tests were conducted to find out optimum heating conditions by the adjustment of electrical supply and electrode. Results show that fine soil particles are more efficient for electrical heating. As water content of soil increases, more efficient electrical heating is observed. However, as the soil is saturated with water above the soil porosity, decrease in the heating efficiency is observed. The higher the voltage, is and the shorter the distance between the electrodes is, the better the heating efficiency is. The soil contaminated by fuel is also more efficient than non-contaminated soil in electrical resistance heating. From the relationship between the intial electrical current and the conductivity obtained in this study, soil temperature by electrical heating can be estimated.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.98-105
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• 2009

This paper presents the characteristics of soil ionization for different water contents, and the parameters associated with the dynamic properties of a simple model grounding system subject to lightning impulse currents. The laboratory experiments for this study were carried out based on factors affecting the soil resistivities. The soil resistivities are adjusted with water contents in the range from 2 to 8% by weight. A test cell with a spherical electrode buried in the middle of the hemispherical container was used. As a result, the electric field intensity $E_c$ initiating ionization is decreased with the reduction of soil resistivities. Also, as the water content increased, the pre-ionization resistance $R_1$ and the post-ionization resistance $R_2$ became lower with increasing current amplitude. The time-lag to ionization $t_1$ and the time-lag to the second current peak $t_2$ at high applied voltages were significantly shorter than those of low applied voltages. It was found that the soil ionization behaviors are highly dependent on the water content and the applied voltage amplitude.

• Journal of The Geomorphological Association of Korea
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• v.23 no.1
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• pp.77-85
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• 2016

To understand the difference of runoff discharge processes between Gwangneung deciduous and coniferous forest catchments, we collected hydrological data (e.g., precipitation, soil moisture, runoff discharge) and conducted hydrochemical analyses in the deciduous and coniferous forest catchments in Gwangneung National Arboretum in the northwest part of South Korea. Based on the end-member mixing analysis of the three storm events during the summer monsoon in 2005, the hillslope runoff in the deciduous forest catchment was higher 20% than the coniferousforest catchment during the firststorm event. Howerver, hillslope runoff increased from the second storm event in the coniferous catchment. We conclude that low soil water contents and topographical gradient characteristics highly influence runoff in the coniferous forest catchment during the first storm events. In general, coniferous forests are shown high interception loss and low soil moisture compared to the deciduous forests. It may also be more likely to be a reduction in soil porosity development when artificial coniferous forests reduced soil biodiversity. The forest soil porosity is an important indicator to determine the water recharge of the forest. Therefore, in order to secure the water resources, it should be managed coniferous forests for improving soil biodiversity and porosity.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.8-13
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• 1998

DAWAST model considering the meteorologic and geographic characteristics of the Korean watersheds was newly developed to simulate the daily streamflow. From the condition of soil water storage just before the storm event from DAWAST model, realtime flood can be forecasted by FLOCON model. The purpose of study is that Umax and FC of DAWAST model parameter is obtained by the soil physical characteristics.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.227-229
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• 2004

The corrosion rate of buried steel pipes for water works was investigated under soil environment. Steel pipe shows various characteristics caused by complicated environment condition of underground and especially the corrosion rate of it depends on the resistivity of soil controlled by content of water. In this paper, the corrosion behavior of steel pipe was observed by polarization test under soil and the silica sand in the water content range of 0-50%. Generally it is well known that the resistivity of soil decreased rapidly over 15% water content. In fact the corrosion rate, corrosion potential, and corrosion consumption (MPY) of steel pipe were shown very different aspects within 20% water content.

• Geomechanics and Engineering
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• v.34 no.5
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• pp.577-595
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• 2023

A dynamic triaxial discrete element numerical model of lightweight soil was established using the discrete element method to study the microscopic mechanism of expanded polystyrene (EPS) particles in the soil under cyclic loading. The microscopic parameters of the discrete element model of the lightweight soil were calibrated depending on the dynamic triaxial test hysteresis curves. Based on the calibration results, the effects of the EPS particles volume ratio and amplitude on the contact force, displacement field, and velocity field of the lightweight soil under different accumulated strains were studied. The results showed that the hysteresis curves of lightweight soil exhibit nonlinearity, hysteresis, and strain accumulation. The strain accumulated in remolded soil is mainly tensile strain, and that in lightweight soil is mainly compressive strain. As the volume ratio of EPS particles increased, the contact force first increased and then decreased, and the displacement and velocity of the particles increased accordingly. With an increase in amplitude, the dynamic stress of the particle system increased, and the accumulation rate of the dynamic strain of the samples also increased. At 5% compressive strain, the contact force of the particles changed significantly and the number of particles deflected in the direction of velocity also increased considerably. These results indicated that the cemented structure of the lightweight soil began to fail at a compressive strain of 5%. Thus, a compressive strain of 5% is more reasonable than the dynamic strength failure standard of lightweight soil.

• Journal of Soil and Groundwater Environment
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• v.24 no.6
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• pp.26-32
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• 2019

An analysis of groundwater quality is significant for monitoring and managing water contamination and groundwater system. For the purpose of those, the geochemical characteristics of groundwater were studied over the concern for water quality, water type and origin of nitrate nitrogen. Total colony counts were detected in 11 out of 20 samples, and the average value was 31.73 CFU/ml. Range and average of NO₃-N concentrations were 0.9~24.0 mg/L and 8.3 mg/L. All groundwater types were found to be Ca²⁺-HCO₃^-. The range and average of NO₃-N were 0.2~17.4 mg/L and 8.7 mg/L, and those of δ¹⁵N were 1.7~8.9‰, and 5.0‰. Careful consideration is required for evaluating the origin of nitrogen when NO₃-N concentration is low. In general, noticeable difference between rockbed and alluvial water was not found. The ranges of nitrate origins by chemical fertilizer, livestock manure and domestic sewage, and natural soil were 29.6~76.4%, 14.2~58.9% and 2.6~7.0%, and the average values of those were 57.4%, 37.4%, and 5.3%, respectively. Origin of nitrate was affected by more chemical fertilizer than the other parameters. Rockbed water was more affected by chemical fertilizer than alluvial water.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.417-425
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• 2013

This study investigated the runoff from rice paddy located on reclaimed fine sandy loam soil to provide data for the development of policies to protect water quality of estuaries. Total N (TN), Total P (TP) concentrations and runoff loads at outlet were monitored from 2006 to 2008. Soil phosphate adsorptivity was measured and compared with typical paddy soil in watersheds. TP concentration of the paddy water and TP runoff loads were much greater than those of typical paddy field in watershed because phosphate adsoptivity in reclaimed paddy field of fine sandy loam appeared to be a third of those of typical paddy soils by relatively low soil OM and high sand content of the reclaimed soil. Thus, nutrient runoff, particularly phosphate from the reclaimed paddy field needs to be managed more thoroughly to protect estuarine water quality.