• Korean Journal of Environmental Agriculture
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• v.17 no.4
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• pp.362-367
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• 1998

To investigate the effects of simulated acid rain(SAR) on the downward movement of mineral nutrients, SARs of different pH were applied to the soil. SAR of pH 2.0 decreased the soil pH greatly, while SAR of pH 4.0 and 6.0 did not change the soil pH to compare to that of SAR of pH 2.0. Decrease in soil pH was in the order of sandy loam > loam > clay loam. The amoumt of leached exchangeable and soluble bases from the soil due to the penetration of SAR was in the order of Ca >Mg > K. After application of 1200mm SAR of pH 2.0 in to the soil downward mean movements of the exchangeable and soluble bases was in the order of Mg > Ca > K in sandy loam and loam soil and Ca > Mg > K in clay loam soil. Downward movements of the those bases under pH 4.0 into the soil was in the order of Mg > K > Ca in sandy loam and clay loam, and K > Mg > Ca in loam soil. Available phosphorus moved slightly downward with increasing acidity of the SAR.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.341-346
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• 2016

This study was conducted to analyze soil physico-chemical properties of agricultural land composed from the river-bed sediments. We investigated the changes of soil physico-chemical properties at 30 different sampling sites containing paddy, upland and plastic film house from 2012 to 2015. pH, exchangeable calcium and magnesium decreased gradually in paddy soils during the four years, whereas the available $P_2O_5$, exchangeable Ca, Mg and EC increased in upland and plastic film house soil. For the soil physical properties, bulk density and hardness of topsoil were $1.47g\;cm^{-3}$ and 21.5 mm and those of subsoil were $1.71g\;cm^{-3}$ and 25.7 mm in paddy soils. In upland soils, bulk density and hardness of topsoil were $1.48g\;cm^{-3}$ and 15.9 mm and those of subsoil were $1.55g\;cm^{-3}$ and 16.9 mm. In plastic film house soils, bulk density and hardness of topsoil were $1.42g\;cm^{-3}$ and 14.4 mm and those of subsoil were $1.40g\;cm^{-3}$ and 18.5 mm, respectively. The penetration hardness was higher than 3 MPa below soil depth 20 cm, and it is impossible to measure below soil depth 50 cm. As these results, in agricultural anthropogenic soils dredged from river basins, the pH, amount of organic matter and exchangeable cations decreased and soil physical properties also deteriorated with time. Therefore, it is needed to apply more organic matters and suitable amount of fertilizer and improve the soil physical properties by cultivating green manure crops, deep tillage, and reversal of deep soils.

• Korean Journal of Environmental Agriculture
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• v.17 no.1
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• pp.59-64
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• 1998

The environmental problem of the rural area has been accelerated in soil as well as water. Soil contamination is usually caused by improper operation of landfills, abandoned mine fields, accidental spills, and illegal dumpings. Once soil contamination is initiated, pollutants migrate and may cause groundwater contamination which takes much effort for remediation. Early detection, therefore, is important to prevent further contamination. Electrical resistivity method was used to detect soil contamination, but it was not effective to the heterogeneous condition. Static cone penetrometer test (CPT) has been used widely to investigate geotechnical properties of the underground. In this study, electrical resistivity method and CPT are combined to improve the applicability of it. The pilot test was performed to examine the variation of electrical resistivity with different soil minerals and pore fluid characteristics. Soil samples used were poorly graded sand, silty sandy soil, and weathered granite soil. For all the cases, electrical resistivity decreased with increasing of moisture content. Soil mineral also affected the electrical resistivity significantly. Above all, leachate addition in the pore fluid was very sensitive and caused decreasing of electrical resistivity markedly. It implies that electrical resistivity method can be applied to investigate pollutant plume effectively. This is specially sure when the sensors contact the contaminated soils directly. The CPT method involves cone penetration to the ground, therefore, underground contamination around the cone could be investigated effectively even for heterogeneous condition as it penetrates if electrical resistivity sensors are attached on the cone.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.3
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• pp.235-241
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• 2016

The soil does not only serve as a medium for plant growth but also for engineering construction purposes. It is very weak in tension, very strong in compression and fails only by shearing. The behaviour of the soil under any form of loading and the interactions of the earth materials during and after any engineering construction work has a major influence on the success, economy and the safety of the work. Soils and their management have therefore become a broad social concern. A limitless variety of soil materials are encountered in both agronomy and engineering problems, varying from hard, dense, large pieces of rock through gravel, sand, silt and clay to organic deposits of soft compressible peat. All these materials may occur over a range of physical properties, such as water contents, texture, bulk density and strength of soils. Therefore, to deal properly with soils and soil materials in any case requires knowledge and understanding of these physical properties. The desired value of bulk density varies with the degree of stability required in construction. Bulk density is also used as an indicator of problems of root penetration,soil aeration and also water infiltration. This property is also used in foundation engineering problems. While not conforming to standard test procedures, this work attempts to add to the basic information on such important soil parameters as water content, bulk density.

• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.963-974
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• 2015

This study was conducted to determine the effects of organic vegetable cultivation on the soil physical properties in 33 farmlands under plastic greenhouse in Korea. We were investigated 5~8 farms per organic vegetable crops during the period from August to November 2014. The main cultivated vegetables were leafy lettuce (Lactuca sativa L.), Perilla leaves (Perilla frutescens var. Japonica Hara), cucumber (Cucumis sativus L.), strawberry (Fragaria ananassa L.) and tomato (Lycopersicon spp.). We have analyzed soil physical properties. The measured soil physical parameters were soil plough layer, soil hardness, penetration resistance, three soil phase, bulk density and Porosity. The measurement of the soil plough layer, soil hardness and penetration resistance were carried out direct in the fields, and the samples for other parameters were taken using the soil core method with approximately 20 mm diameter core collected from each organic vegetable field. Soil plough layer was average 36 cm and ranged between 30 and 50 cm, and slightly different depending on the sorts of vegetable cultivation. The soil hardness was $0.17{\pm}0.15{\sim}1.34{\pm}1.02$ in the topsoil, $0.55{\pm}0.34{\sim}1.15{\pm}0.62$ in the subsoil. It was not different between topsoil and subsoil, but showed a statistically significant difference between the leafy and fruit vegetables. Penetrometer resistance is one of the important soil physical properties that can determine both root elongation and yield. The increase in density under leafy vegetables resulted in a higher soil penetrometer resistance. Soil is a three-component system comprised of solid, liquid, and gas phases distributed in a complex geometry that creates large solidliquid, liquid-gas, and gas-solid interfacial areas. The three soil phases were dynamic and typically changed in organic vegetable soils under greenhouse. Porosity was characterized as range of $54.2{\pm}2.2{\sim}60.3{\pm}2.4%$. Most measured soils have bulk densities between 1.0 and $1.6gcm^{-3}$. To summarize the above results, Soil plough layer has been deepened in organic vegetable cultivation soils. Solid hardness (the hardness of the soil) and bulk density (suitable for the soil unit mass) have been lowered. Porosity (soil spatial content) was high such as a well known in organic farmlands. Important changes were observed in the physical properties according to the different vegetable cultivation. We have demonstrated that the physical properties of organic cultivated soils under plastic greenhouse were improved in the results of this study.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.557-575
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• 2020

Plasma blasting which is generated by high voltage arc discharge of electricity is applied to soil mass to improve permeability of soil and cleaning efficiency of oil contamination. A new high voltage generator was manufactured and three types of soil including silty sand, silty sand mixed with lime and silty sand mixed with cement were prepared. Small and large soil columns were produced using these types of soil and plasma blasting was performed within soil columns to investigate the variation of soil volume penetrated by fluid and permeability. Soil volume penetrated by fluid increased by 11~71% when plasma blasting was applied in soil. Although plasma blasting with low electricity voltage induced horizontal fracture and fluid penetrated along this weak plane, plasma blasting with high voltage induced spherical penetration of fluid. Plasma blasting increased the permeability of soil. Permeabilty of soils mixed with lime and cement increased by 450~1,052% with plasma blasting. Permeability of soil increased as discharge voltage increased when plasma blasing was applied once. However, several blastings with the same discharge voltage increase or decrease permeability of soil. Oil contaminated soil was prepared by adding diesel into soil artificially and plasma blasting was performed in these oil contaminated soil. Cleaning efficiency increased by average of 393% for soil located nearby the blasting and by average of 239% for soil located far from the blasting. Cleaning efficiency did not show any correlation with discharge voltage. All these results indicated that plasma blasting might be used for in-situ cleaning of oil contaminated soil because plasma blasting increased permeability of soil and cleaning efficiency.

• Geophysics and Geophysical Exploration
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• v.17 no.2
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• pp.104-113
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• 2014

Electric resistivity monitoring was applied to evaluate the soft ground in reclaimed land in order to figure out the applicability of physical prospecting. For this, electrical resistivity monitoring data were acquired for total three months and analyzed those data with independent inversion, time-lapse inversion, and 4D inversion methods. The result was compared for various inversion methods so as to figure out what showed the soft soil most properly. Moreover, drilling and CPT(Cone Penetration Test) data were also used in order to find out if each of those inversion methods could distinguish either bed rock or the soft soil clearly. And according to the result, time-lapse inversion showed less inversion artifacts than independent inversion, so it could indicate the soft soil better. If data gained for a longer period than three months are used, 4D inversion has been found to be a more efficient analysis method than the time-lapse inversion method. Electrical resistivity monitoring on the soft soil has been found to be a useful method that can analyze the spatio-temporal electric state of the ground serially.

• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.115-125
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• 2023

In this study, we evaluated the behavior of frozen soil using an electrical resistivity survey method-a nondestructive technique-and examined its characteristics through field experiments. Frozen soil was artificially prepared by injecting fluid to accelerate the freezing process, and naturally frozen soil was selected in a nearby area for comparison. A dynamic cone penetration test (DCPT) was performed to compare the reliability of the electrical resistivity survey, and time-domain reflectometry surveys were performed to assess the moisture content of the ground. Field experiments were conducted in February-when the atmosphere temperature was below freezing-and May-when the temperature was above freezing. This temperature-compensated method was used to determine reliability because the behavior of frozen soil depends on the underlying temperature. In the resistivity survey method, a section of high electrical resistivity was observed under freezing conditions due to the frozen water and converted into porosity. The converted porosity was compared with the porosity inferred from the DCPT, and the results showed that the measured electrical resistivity was valid.

• Journal of the Korean Geotechnical Society
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• v.29 no.10
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• pp.39-48
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• 2013

This paper presents an equation to depict the penetration behavior during the standard penetration test (SPT) in sandy deposits. An energy balance approach is considered and the driving mechanism of the SPT sampler is conceptually modeled as that of a miniature open-ended steel pipe pile into sands. The equation consists of three sets of input parameters including hyperbolic parameters (m and ${\lambda}$) which are difficult to determine. An iterative technique is thus applied to determine the optimized values of m and ${\lambda}$ using three measured values from a routine SPT data. It is verified from a well-documented record that the simulated penetration curves are in good agreement with the measured ones. At a given depth, the increase in m results in the decrease in ${\lambda}$ and the increase in the curvature of the penetration curve as well as the simulated N-value. Generally, the predicted penetration curve becomes nearly straight for the portion of exceeding the seating drive zone, which is more pronounced as soil density increases. Thus, the simulation method can be applied to extrapolating a prematurely completed test data, i.e., to determining the N value equivalent to a 30 cm penetration. A simple linear equation is considered for obtaining similar results.

• Journal of the Korean Geotechnical Society
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• v.29 no.9
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• pp.17-29
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• 2013

The geophysical methods have an advantage for investigating the wide area with low cost, and thus the application of these methods has been increased. The objective of this paper estimates the characteristics of alluvium through the geophysical methods including elastic wave, electrical resistivity and ground penetration radar. And the standard penetration test is also carried out for verifying the geophysical data with comparison. The sources of elastic wave method are divided into hammer and sissy and the electrical resistivity method is applied with different sizes, shapes and arrays of electrode for deciding the effective way. The center frequency is determined to be 270 MHz for considering the characteristics of soil. The results of ground penetration radar are also compared with those of standard penetration test. The high resolution shows when the source is a sissy in elastic wave method, however, the water level is not identified. In the electrical resistivity method, the non-polarizable electrode and schlumberger array show highly reliable data and the resolution of ground penetration radar is low. Thus, the results of this study are widely applied for determining the appropriate method when investigating the characteristics of alluvium.