• Journal of Industrial Technology
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• v.25 no.A
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• pp.67-73
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• 2005

In this research, centrifuge model experiments and numerical approach of finite element method to analyze experimental results were performed to investigate the behavior of improved ground with sand compaction piles. One of typical clay minerals, kaolinite powder, were prepared for soft ground in model tests. Jumunjin standard sand was used to sand compaction pile installed in the soft soil. In order to investigate the characteristics of mechanical behavior of sand compaction piles with low replacement ratios, centrifuge model experiments with the replacement ratio of 40%, changing the width of improved area with respect to testing results the width of surcharge loads, were carried out to obtain of bearing capacity, characteristics of load-settlement, vertical stresses acting on the sand pile and the soft soil failure mechanism in improved ground.

• Journal of Soil and Groundwater Environment
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• v.22 no.6
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• pp.22-28
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• 2017

The accuracy of analytical results in response to the use of different additives ($NH_4Cl$, KCl, $LaCl_3$) and oxidant gases was evaluated and compared by using Atomic Absorption Spectrometry (AAS). Identification of spectroscopic interferences and possible improvements in Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) analysis were also discussed. The average accuracies of total chromium using Certified Reference Materials (CRMs) were found to be 72.1~94.2% in air/acetylene flame condition by AAS, and they were improved to 100.5~110.5% when the oxidants was changed to nitrous oxide rather than adding the additives. The field samples showed similar trends to CRMs, but chromium concentrations were highly variable depending on analytical conditions. The average accuracies using CRMs were estimated to be 89.3~166.1% by ICP-AES, and improved to below 121.7% after eliminating iron interference. Field samples with low chromium and high iron concentration were measured to be > 30% lower in total chromium concentrations by ICP-AES than AAS in nitrous oxide/acetylene flame. Total chromium concentrations in soil could be analyzed with better accuracy under nitrous oxide/acetylene flame by AAS because it was more effective to increase the temperature of the flame than to eliminate the chemical interference for maximizing atomization of chromium. When using ICP-AES, interference substances, total chromium levels, and analytical conditions should be also considered.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.2
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• pp.158-165
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• 2014

The enormous quantity of 'Bayer-Process by-products' (BP by-products) discharged by industries producing alumina from bauxite represents an environmental and economical problem. As it is mainly composed of $Fe_2O_3$, $Al_2O_3$, $SiO_2$, CaO and $Na_2O$, it is thought that using BP by-products as a construction material is an effective way to consume such a large quantity of alkaline waste. In this study, This study evaluates the effect of alkali-activated binder based on recycling BP by-products on soil improvement through the evaluation of slope stability and seepage flow numerical analysis. The results of analysis of ground slope safety at dry season and wet season meet standard (Ministry of Land, Infrastructure and Transport, 2006) Especially, when wet season, the ground used soil improving material meet standard, while the ground used soil-nailing method doesn't. Also, permeability coefficient of improved soil is smaller than that of natural soil and saturation depth of reinforced ground surface with improve soil is lower than that of natural soil.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.302-305
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• 2003

The electrokinetic remediation tests for natural soil contaminated by lead are performed on unsaturated conditions, in which the degree of saturation is controlled through the changes in water content and the constant unit weight. At the degree of saturation of 70% the small acid range and electrical potential is developed. The changes in the water content are little above the saturation of 90%. But it is increased by 1.7 times at the degree of saturation of 70%. Finally, the efficiency of extraction is improved at 70% than 100%.

• Textile Coloration and Finishing
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• v.26 no.3
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• pp.209-217
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• 2014

Detergency and soil redeposition of wool fabric in drycleaning solvents, i.e. petroleum solvent, perchloroethylene (PCE), decamethylcyclopentasiloxane($D_5$), with commercial detergents were studied. The detergency of wool soiled cloth in drycleaning solvents without detergents were the order of PCE > petroleum solvent > $D_5$. When commercial detergents were added to the system, the detergency were greatly improved. When 1.0% water was added to solvents/commercial detergents system, the detergency of petroleum solvent and PCE improved whereas that of $D_5$ decreased. The soil redeposition prevention effects of solvents were the same order of detergency, i.e. PCE > petroleum solvent > $D_5$. When commercial detergents were added to the system, the soil redeposition changed depending on solvents and detergents. The soil redeposition in $D_5$ became higher with a commercial detergent, therefore it is important to develop appropriate detergents for $D_5$. Three silicone surfactants were tested for detergency and soil redeposition in $D_5$ to find candidate surfactants for drycleaning detergent formulations. Silicone surfactant PEG/PPG-19/19 Dimethicone was found to be the best surfactant for $D_5$ drycleaning detergents.

• Textile Coloration and Finishing
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• v.24 no.2
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• pp.138-144
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• 2012

Detergency and soil redeposition of wool fabric in 8 nonionic surfactants (Span 20, 40, 60, 80/Tween 20, 40, 60, 80) and 4 solvents (water, petroleum, perchloroethylene(PCE), decamethylcyclopentasiloxane($D_5$)) were studied. Detergency of wool fabric in water was very low with and without surfactants due to the low wetting and difficulty in penetration of water into the fabric. Lipophilic surfactants improved the detergency of wool fabric in petroleum solvent and PCE. The detergency of wool fabric in $D_5$ was similar to that in petroleum solvent without surfactants. When water was solubilized, Span 20 addition to petroleum solvent and PCE increased the detergency of wool fabric. The detergency for $D_5$ was improved with solubilized water, however, it was lowered when the surfactants were added to the system. Therefore, it is important to formulate appropriate detergents which have good solubility and affinity to silicone for $D_5$ charge system. Hydrophilic surfactants were effective for water and lipophilic surfactants were effective for petroleum solvent and PCE in soil redeposition prevention of wool fabric. The soil redeposition prevention effects are not found in $D_5$ with both Span 20 and Tween 20. The same tendency of results in soil redeposition of wool fabric is observed when water is solubilized.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.2
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• pp.34-43
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• 2007

To investigate the restoration procedure on soil physical properties and vegetation at the surface of strip road affected by timber harvesting operation. This study was carried out at strip roads constructed between 1989 and 1994 in Mt. Baekun, Kwangyang, Chollanam-Do. Soil hardness of the surface layer was improved with change of time after strip road construction, but that of 7.6~15 cm depth from the surface was not improved. According to linear regression analysis, it was estimated 16.6 years in 0~7.5 cm and 16.9 years in 7.6~15 cm soil depth to be restored to natural forest lands. The amount of surface soil erosion was 0.045$m^3$/km/yr on strip roads constructed in 1989 and 1990, and road constructed in 1994 showed the highest value (4.5$m^3$/km/yr). Vegetation coverage rates of road surface were 96.7% in strip roads constructed in 1990. Those of cutslope and fillslope were highest in roads constructed in 1990. The results indicated that strip roads were restored with change of time after road construction.

• Journal of Applied Biological Chemistry
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• v.44 no.4
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• pp.177-179
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• 2001

Traditional wet chemical methods for testing of soil properties require extensive time and labor, and cause the discharge of pollutants, making them undesirable for routine soil analyses. This research was conducted to improve the accuracy of soil properties in soil fertility assessments. A total of 140 finely ground soil samples were used to obtain accurate calibrations and validation for estimating soil moisture, OM, and T-N. Finely ground soil samples satisfied the improved accuracy for routine NIR measuring of the field soils. The results indicated that NIR spectroscopy could be used as a routine method for quantitatively determining OM, moisture, and T-N of field soil, although this technique requires many combinations of sample pretreatments and data manipulations to obtain optimal predictions.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.1
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• pp.30-35
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• 2015

This study was conducted to investigate investigated the effect of nitrogen fertilizer on nitrate concentration in soil solution and to determine the relationship between yield and nitrate concentration in soil solution for cucumber cultivation under plastic film house. Nitrogen as urea was applied at rates of 0, 120, 240, 360, and $480kg\;N\;ha^{-1}$ as an additional fertilizer by trickle irrigation during cucumber cultivation. Monitoring of nitrate concentration in soil solution was investigated using porous cups at 25 cm depth under soil surface. Nitrate concentration in soil solution increased with increasing the rate of additional nitrogen. Correlation coefficient between EC value and nitrate concentration was positive in soil and soil solution (p<0.05). An additional nitrogen of about $300kg\;ha^{-1}$ was shown the highest yield of cucumber, and improved yield by 5% compared to N recommendation of $240kg\;N\;ha^{-1}$. The highest yield was determined at nitrate concentration of $82mg\;L^{-1}$ in soil solution by regression equation ($Y=74.2+0.73X+0.000504X^2$, $R^2=0.629^*$). These results means indicate that nitrate concentration in soil solution would be useful method to rapid determination for additional nitrogen during cucumber cultivation under plastic film house.

• Geomechanics and Engineering
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• v.28 no.5
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• pp.505-520
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• 2022

In recent years, geotextile-encased gravel columns (usually called stone columns) have become a popular method to increasing soil shear strength, decreasing the settlement, acceleration of the rate of consolidation, reducing the liquefaction potential and increasing the bearing capacity of foundations. The behavior of improved loose base-soil with gravel columns under shear loading and the shear stress-horizontal displacement curves got from large scale direct shear test are of great importance in understanding the performance of this method. In the present study, by performing 36 large-scale direct shear tests on sandy base-soil with different fine-content of zero to 30% in both not improved and improved with gravel columns, the effect of the presence of gravel columns in the loose soils were investigated. The results were used to predict the shear stress-horizontal displacement curve of these samples using support vector machines (SVM). Variables such as the non-plastic fine content of base-soil (FC), the area replacement ratio of the gravel column (Arr), the geotextile encasement and the normal stress on the sample were effective factors in the shear stress-horizontal displacement curve of the samples. The training and testing data of the model showed higher power of SVM compared to multilayer perceptron (MLP) neural network in predicting shear stress-horizontal displacement curve. After ensuring the accuracy of the model evaluation, by introducing different samples to the model, the effect of different variables on the maximum shear stress of the samples was investigated. The results showed that by adding a gravel column and increasing the Arr, the friction angle (ϕ) and cohesion (c) of the samples increase. This increase is less in base-soil with more FC, and in a proportion of the same Arr, with increasing FC, internal friction angle and cohesion decreases.