• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.135-139
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• 2010

A construction technique to install the soil-bentonite (SB) cut-off wall for in-situ geoenvironmental containment by employing the trench cutting and re-mixing deep wall method is first presented in this paper. The laboratory test results on the hydraulic barrier performance of SB in relation to the chemical compatibility are then discussed. Hydraulic conductivity tests using flexible-wall permeameters as well as swell tests were conducted for SB specimens exposed to various types and concentrations of chemicals (calcium chloride, heavy fuel oil, ethanol, and/or seawater) in the permeant and/or in the pore water of original soil. For the SB specimens in which the pore water of original soil did not contain such chemicals and thus the sufficient bentonite hydration occurred, k values were not significantly increased even when permeated with the relatively aggressive chemical solutions such as 1.0 mol/L $CaCl_2$ or 50%-concentration ethanol solution. In contrast, the SB specimens containing $CaCl_2$ in the pore water had the higher k values. The excellent linear correlation between log k and swelling pressure implies that the swelling pressure can be a good indicator for the hydraulic barrier performance of the SB.

• Journal of the Korean Geotechnical Society
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• v.33 no.4
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• pp.25-34
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• 2017

The soil-water characteristics is the most important state parameter for understanding changes in suction and water contents of unsaturated soil slopes. In the field, the hysteretic behaviors of drying and wetting soil-water characteristic curve are real and the adoption of path-dependent suction-water content is needed to predict the hydro-mechanical analysis of unsaturated soils. In this study, in-situ monitored hydraulic behavior of various soil slopes are compared with the data from numerical analysis with the laboratory soil water characteristic curve. Then, the verifications are performed based on the field monitored data respectively. Therefore, the use of path-dependent soil-water characteristic curves could be more rational for design and analysis of unsaturated soil slopes under rainfall conditions.

• Journal of Korea Soil Environment Society
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• v.4 no.3
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• pp.3-15
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• 1999

This paper includes the basic experimental results performed for developing an innovative and technologically feasible process wherein gaseous ozone, a powerful oxidant. is injected directly into vadose zone by which in-situ chemical degradation of semi- or, non-volatile petroleum product such as diesel fuel is derived. As ozone gas injected continuously(50mL/min, 119.0$\pm$6.1mg/L) into soil packed columns artificially contaminated with diesel fuel(initial concentration 1,485mg-DRO/kg/soil), the removal rates at the inlet and outlet point of 14hrs-operated column are 87.9% and 100.0%, respectively. On the other hand, soil vapor extraction system showed less than 30% of removal rates of residual diesel both at the inlet and outlet samples under the same experimental conditions which confirms the limited treatability of SVE in diesel contaminated soil.

• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.44-50
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• 2012

A new type of chemical oxidation technology utilizing micro bubble ozone oxidizer and a pneumatic fracturing equipment was developed to enhance field applicability of a traditional chemical oxidation technology using hydrogen peroxide as an oxidizer for in-situ soil remediation. To find an efficient way to dissolve gaseous ozone into hydrogen peroxide, ozone was injected into water as micro bubble form then dissolved ozone concentration and its duration time were measured compared to those of simple aeration of gaseous ozone. As a result, dissolved ozone concentration in water increased by 31% (1.6 ppm ${\rightarrow}$ 2.1 ppm) and elapsed time for which maximum ozone concentration decreased by half lengthened from 9 min to 33 min. When the developed pneumatic fracturing technology was applied in sandy loam, cracks were developed and grown in soil for 5~30 seconds so that the radius of influence got longer by 71% from 392 cm to 671 cm. The remediation system using the micro bubble ozone oxidizer and the pneumatic fracturing equipment for field application was made and demonstrated its remediation efficiency at petroleum contaminated site. The system showed enhanced remediation capacity than the traditional chemical oxidation technology using hydrogen peroxide with reduced remediation time by about 33%.

• Korean Journal of Agricultural Science
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• v.39 no.3
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• pp.407-412
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• 2012

Soil texture has an important influence on agriculture such as crop selection, movement of nutrient and water, soil electrical conductivity, and crop growth. Conventionally, soil texture has been determined in the laboratory using pipette and hydrometer methods requiring significant amount of time, labor, and cost. Recently, in-situ soil texture classification systems using optical diffuse reflectometry or mechanical resistance have been reported, especially for precision agriculture that needs more data than conventional agriculture. This paper is a part of overall research to develop an in-situ soil texture classification system using image processing. Issues investigated in this study were effects of sensor travel speed and light source and intensity on image quality. When travel speed of image sensor increased from 0 to 10 mm/s, travel distance and number of pixel were increased to 3.30 mm and 9.4, respectively. This travel distances were not negligible even at a speed of 2 mm/s (i.e., 0.66 mm and 1.4), and image degradation was significant. Tests for effects of illumination intensity showed that 7 to 11 Lux seemed a good condition minimizing shade and reflection. When soil water content increased, illumination intensity should be greater to compensate decrease in brightness. Results of the paper would be useful for construction, test, and application of the sensor.

• Journal of the Korean Geotechnical Society
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• v.34 no.2
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• pp.5-17
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• 2018

In this study, the in-situ stress, strength and stress-strain characteristics with shear parameters (UU, CU, ${\bar{CU}}$) are analytically evaluated and the stability analyses are carried out under loading/unloading conditions. The in-situ stress and the stress-strain behaviour may become different according to input shear parameters in finite element analyses with construction step, Especially, if the internal friction angle in Mohr-Coulomb model is set to zero, the in-situ stress and the stress-strain behaviour might not be properly predicted. The results from CU parameter of total stress analysis have no significant difference with the results from CU of effective stress analysis. Therefore, in the numerical analysis for soft ground, CU parameters can be applied to predict in-situ stress and stress-strain behaviors. In addition, the calculation method was proposed to determine the shear parameter of Mohr-Coulomb model, which is corresponding to the shear strength equivalent to that of in-situ soil.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.435-444
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• 2009

In situ stabilization of heavy metals through adsorption onto indigenous bacterial biofilm developed on soil particles was investigated. Biofilms were developed in soil columns by supply of various carbon sources such as acetate, lactate and glucose. During development of biofilms, acetate, lactate, and glucose solutions were flew out from the soil columns with volume ratios of 98.5%, 97.3%, and 94.7%, respectively, when compared with soil column supplied with deionized water. Decrease in effluent amounts through the soil columns amended with carbon sources over time indicated the formation of biofilms resulting in decrease of soil porosity. Solutions of Cd, Cr(VI), Cu, Pb, and Zn were injected into the biofilms supported on soil particles in the columns, and the dissolved heavy metals in effluents were determined. Concentrations of dissolved Cd, Cr(VI), Cu, and Zn in the effluents through biofilm columns were lower than those of control column supplied with deionized water. The result was likely due to enhanced adsorption of the metals onto biofilms. Efficiency of metal removal by biofilms depended on the type of carbon sources supplied. The enhanced removal of dissolved heavy metals by bacterial biofilms in this study may be effectively applied to technical development of in situ stabilization of heavy metals in natural soil formation contaminated with heavy metals.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.69-81
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• 2011

The soil moisture data of the National Aeronautics and Space Administration(NASA) and the Vrije Universiteit Amsterdam(VUA) in collaboration with NASA, retrieved from Advanced Microwave Scanning Radiometer-Earth observing system(AMSR-E) brightness temperature, were collected to evaluate the applicability of the remote sensed soil moisture in South Korea. The averages of the soil moisture by in-situ sensors, by NASA and by VUA-NASA are approximately 0.218, 0.119, and $0.402m^3/m^3$, respectively. This indicates that the soil moisture of NASA was underestimated and that of VUA-NASA was overestimated. The soil moisture products of VUA-NASA showed a better relationship with the in-situ data than that of NASA data. However, there are still limitations of C-band soil moisture measurements. To improve the applicability of satellite soil moisture measurements, bias correction and other post processings are essential using in-situ soil moisture measurements at various surface conditions.

• Journal of the Korean Geotechnical Society
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• v.28 no.2
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• pp.15-21
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• 2012

It is difficult to determine the strength and the permeability of a soil levee quantitatively because the damages of a levee have been evaluated only by visual inspection in Korea. Therefore, it is necessary to develop a simplified measurement device for measuring the strength and permeability of a levee. In this paper, a new in-situ permeability measuring device which can measure strength and permeability based on GWP is developed and its applicability to the field permeability test of a soil levee is introduced. From the laboratory and in-situ experiments, the new measuring device has the potential of measuring the soil permeability simply and accurately.

• Geomechanics and Engineering
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• v.28 no.5
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• pp.493-503
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• 2022

Cavity expansion is a classical problem in the field of solid mechanics with a wide range of applications in geotechnical and petroleum engineering. A drained solution is developed for cylindrical cavity expansion in anisotropic soils under biaxial in-situ stresses using a K0-based anisotropic modified Cam-clay model (K0-AMCC). The problem is formulated by solving differential equations using an auxiliary variable, which provides analytical expressions for the volume and four stress components of the soil around the cylindrical cavity. The solution is validated by comparisons with existing well-developed solutions. The results show that the present solution well captures the cavity expansion responses in anisotropic soils under biaxial in-situ stresses, and removes limiting assumptions that the cylindrical cavity expands under uniform in-situ stress in isotropic soils. The elastic-plastic boundary of the expanding cylindrical cavity in K0-consolidated anisotropic soils under biaxial in-situ stresses is a circle rather than an ellipse in isotropic soils, and the mathematical proof is provided in detail.