• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.77-84
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• 2007

A fungus, Aspergillus sp. PS-104, with the high phosphate-solubilizing activities was isolated from Korean upland soil and formulated into a solid powder type with various additives. For the long-time preservation of conidia, some additives (Tween 80, SDS, Triton X-100, glucose, glycerol, corn oil, bio-ceramic, PEG 200, $Cu^{++}$, $Mo^{+++}$, $Fe^{++}$, $Ca^{++}$ and $Zn^{++}$) were supplemented in the rice-cooked hard medium with various concentrations (0, 0.001, 0.01, 0.1, 1.0 and 5.0%). In case of surfactants. the highest relative viability of the Aspergillus sp. PS-104 conidia was recorded nearly to 80% by the addition of 0.01 to 0.1% Tween 80, while 50% in control. The number of conidia were found to be about 100 times higher when treated at 0.01 to 0.1% Tween 80 as compared to control. Relative viability of the conidia was decreased in order of Tween 80 $\geq$ SDS > Triton X-100 during the storage at $25^{\circ}C$. As regards the organic additives, the relative viability of Aspergillus sp. PS-104 conidia was also recorded nearly to 80% by the addition of 1.0% bio-ceramic, and 5.0% glucose and sucrose during the storage at $25^{\circ}C$. In case of metal ions, the relative viability of Aspergillus sp. PS-104 conidia was decreased in order of $Cu^{2+}>Ca^{2+}>Mo^{3+}>Zn^{2+}>Fe^{2+}$ during the storage at $25^{\circ}C$.

• Korean Journal of Environmental Agriculture
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• v.19 no.3
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• pp.234-241
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• 2000

For the recycling of sludge as soil conditioner, the firing technology in pottery industry was applied to the sludge treatment, and produced artificial media with many voids. To produce artificial media using sludge, chabazite and lime were used as additives, and the mixture of sludge and additives was thermally treated in the firing kiln at about $800{\sim}1,100^{\circ}C$ for about ten minutes. The effect of mixed artificial media into upland soil was investigated through the crop growth experiment and the physical & chemical characteristics of the mixed soils were analysed. The pH of artificial media was higher than that of the control soils. After the plant growth experiment, artificial media plots almost contained more CEC, OM, TN, TP and $AV.P_2O_5$ than upland soil plots. From the growth analysis, growth of soybean and corn in the artificial media plots was better than that in the original upland soil plots. The yield of soybean and corn in the artificial media plots were about 46kg/10a, 194kg/10a, respectively, which is higher than that in the control. Heavy metals in the artificial media plots were lower than the standard regulation. Therefore, the artificial media produced from sludge can be mixed into farmland, and crop production can be increased additionally.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.59-65
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• 2012

Solidification/Stabilization(S/S) is one of the remediation technologies that have been applied for treating inorganic hazardous wastes. This study investigated the reduction of arsenic concentration of arsenic-contaminated soil using by S/S. The binder plays a role in controlling the mobility and solubility of the contaminants in S/S process, so it is important to determine the optimum binder content. Therefore, this study evaluated the effectiveness of S/S using four different binders(cement, zero valent iron, and monosulfate and ettringite(cement-based synthesized materials) at the binder content ranged between 5%(wt.) and 20%(wt.). The leachability of arsenic in 1 N HCl was different depending on the types of binders: cement(71.41%) > monosulfate(47.45%) > ettringite(46.36%) > ZVI(33.08%) at the binder content of 20%. Additionally, three kinds of a mixture binder were prepared using cement and additives(monosulfate, ettringite, calcium sulfoaluminate(CSA)) and tested for arsenic reduction. The highest arsenic removal capacity was found at the mass ratio of cement to the additive, 4:1 in all experiments using a mixture binder, regardless of the additives types. A mixture binder(cement and additives) resulted in higher arsenic removal relative to the arsenic removal when cement was used alone.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.360-367
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• 2020

In this study, the accumulation and distribution routes of microplastics in soil environment were examined, and their analytical methodologies were summarized. Density separation and removal process of inhibition materials were introduced for the separation of microplastics in soil and the basic principles and limitations of quantitative and qualitative analyses including pyrolysis gas chromatography mass spectrometry, µ-Raman spectrometry, fourier transform infrared spectrometry, and microscopes were investigated. Chemical extraction methods for the analysis of mediated hazardous substance (additives and sorbed matters) in microplastics were also discussed with focusing on in vitro bioaccessibility assay for the human oral exposure route. Based on the described methodologies for the analysis of microplastics in soil, it is expected that these methods enable to select appropriate analysis techniques in consideration of medium state, contamination level and sample quantity.

• Geomechanics and Engineering
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• v.14 no.3
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• pp.247-255
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• 2018

Soil stabilization can make the soils becoming more stable by using an admixture to the soil. Lime stabilization enhances the engineering properties of soil, which includes reducing soil plasticity, increasing optimum moisture content, decreasing maximum dry density and improving soil compaction. Silica fume is utilized as a pozzolanic material in the application of soil stabilization. Silica fume was once considered non-environmental friendly. In this paper, the materials required are kaolin grade S300, lime and silica fume. The focus of the study is on the determination of the physical properties of the soils tested and the consolidation of kaolin mixed with 6% silica fume and different percentages (3%, 5%, 7% and 9%) of lime. Consolidation test is carried out on the kaolin and the mixtures of soil-lime-silica fume to investigate the effect of lime stabilization with silica fume additives on the consolidation of the mixtures. Based on the results obtained, all soil samples are indicated as soils with medium plasticity. For mixtures with 0% to 9% of lime with 6% SF, the decrease in the maximum dry density is about 15.9% and the increase in the optimum moisture content is about 23.5%. Decreases in the coefficient of permeability of the mixtures occur if compared to the coefficient of permeability of kaolin soft clay itself reduce the compression index (Cc) more than L-SF soil mix due to pozzolanic reaction between lime and silica fume and the optimum percent of lime-silica fume was found to be (5%+6%) mix. The average coefficient of volume compressibility decreases with increasing the stabilizer content due to pozzolanic reaction happening within the soil which results in changes in the soil matrix. Lime content +6% silica fume mix can reduce the coefficient of consolidation from at 3%L+6%SF, thereafter there is an increase from 9%L+6%SF mix. The optimal percentage of lime silica fume combination is attained at 5.0% lime and 6.0% silica fume in order to improve the shear strength of kaolin soft clay. Microstructural development took place in the stabilized soil due to increase in lime content of tertiary clay stabilized with 7% lime and 4% silica fume together.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.5
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• pp.355-374
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• 2022

Soil conditioning improves the performance of EPB (earth pressure balance) shield TBMs (tunnel boring machines) by reducing shear strength, enhancing workability of the excavated soil, and supporting the tunnel face during EPB tunnelling. The mechanical and rheological behavior of the excavated muck mixed with additives should be properly evaluated to determine the optimal additive injection condition corresponding to each ground type. In this study, the laboratory pressurized vane test apparatus equipped with a vane-shaped rheometer was developed to reproduce the pressurized condition in the TBM chamber and quantitively evaluate rheological properties of the soil specimens. A series of the pressurized vane tests were performed for an artificial sand soil by changing foam injection ratio (FIR) and polymer injection ratio (PIR), which are the injection parameters of the foam and the polymer, respectively. In addition, the workability of the conditioned soil was evaluated through the slump test. The peak and yield stresses of the conditioned soil with respect to the injection parameters were evaluated through the rheogram, which was derived from the measured torque data in the pressurized vane test. As FIR increased or PIR decreased, the workability of the conditioned soil increased, and the maximum torque, peak stress, and yield stress decreased. The peak stress and yield stress of the specimen from the laboratory pressurized vane test correspond to the workability evaluated by the slump tests, which implies the applicability of the proposed test for evaluating the rheological properties of excavated soil.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.153-164
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• 1999

The solubilization of BTEX was evaluated in aqueous surfactant solutions with and without several additives. Anionic surfactant(Sodium Dodecyl Sulfate, SDS) and nonionic surfactants (NEODOL(equation omitted)25-3 and $SOFTANOL\circledR-90$ were used as test surfactants. The effects of surfactant HLB(Hydrophile-Lipophile Balance) Number and hydrocarbon molar volume and polarity of BTEX on the MSR(Molar Solubilization Ratio), micelle-water partition coefficient of BTEX, and CMC(C,itical Micelle Concentration) were investigated. Optimizing treatment conditions applicable to enhanced solubilization was also studied by manupulating salinity or electrolyte control with additives of ethyl alcohol, hydrotrope, and electrolyte solution. The most effective surfactant for solubilization was found $SOFTANOL\circledR-90$, since HLB number of 13.6 is similar to those values of BTEX ranging between 11.4 and 12.2, which was also proved experimentally. Ethyl alchohol of 3% was the most effective additives in reducing CMC and improving solubilization among the conditions using SDS, NEODOL(equation omitted)25-3, and $SOFTANOL\circledR-90$ with three additives. The partitioning of BTEX between surfactant micelles and aqueous solutions was characterized by a mole fraction micelle-phase/aqueous phase partion coefficient, $K_m$. Values of log $K_m$. for BTEX compounds in surfactant solutions of this study range from 2.95 to 3.76(100mM SDS) and 2.95 to 3.49(117mM $SOFTANOL\circledR-90$. Log $K_m$ appears to be a linear function of log $K_{ow}$ for SDS and $SOFTANOL\circledR-90$. A knowledge of partitioning of BTEX in aqueous surfactant system can be a prerequisite for the understanding of the behavior of hydrophobic organic compounds in soil-water systems in which surfactants play a role in remediation of contaminated soil and facilitated transport.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.95-107
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• 2004

In this paper, the rheological characteristics of slurry used fur slurry-shield tunnels were studied with emphasis on penetration characteristics. The slurry penetration was modeled by soil-filter clogging theory. The coefficient of particle deposition was suggested as an indicator of sin clogging during tunnel construction and calculated through model tests. The measured slurry weight, clogged in the base soil, was compared with the value obtained from clogging theory. Based on the testing results, a stability analysis of a tunnel face was performed to pinpoint the most influential factor affecting stability of slurry-shield tunnels. It was found that the stability of tunnel face is dependent on the ratio of infiltration velocity to the coefficient of particle deposition, and the penetration distance of slurry increases with the ratio of infiltration velocity to the coefficient of particle deposition. Since the stability of tunnel face decreases with the slurry penetration distance, it was necessary to add some additives in order to reduce the slurry penetration distance. It was found that the ground condition needs additives when the soil has the effective particle diameter$(D_{10})$ larger than 0.75mm. It was also found that the tunnel face stability due to slurry penetration is significantly affected by the tunnel advance rate.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.291-300
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• 1999

Surfactant flushing for enhancing the removal of BTEX from contaminated sand/clay mixtures was investigated. Eight soil columns packed with relatively undisturbed BTEX contaminated soils, were leached with water, methyl alcohol and then flushed with surfactant with or without several additives. Initial concentrations of BTEX mixture range from 278mg/kg to 1975mg/kg. Initial BTEX removal efficiency was 98% when the contaminated soil was flushed with water of 850 pore volumes. Because of tailing effect, water flushing could not remove below 8mg/kg concentrations during the experimental period. Eventually, the most effective surfactant for flushing was turned out to be 4% SOFTANOL(equation omitted)-90 with 3% ethyl alcohol and 3% SXS. In interrupted flow conditions, the removal efficiency was 99.5% with the flushed water of 95 pore volumes. The BTEX mixture removed from the soil columns during the surfactant flushing ranges from 84.5% to 99.5% of the initial amount for both water leaching(850 pore volumes) and surfactant flushing(95-165 pore volumes), respectively. Test results indicated that surfactant flushing could enhance the removal of BTEX mixture from contaminated soils and could reduce the aqueous phase BTEX mixture concentration in leachate.

• Applied Biological Chemistry
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• v.45 no.2
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• pp.97-100
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• 2002

Phthalate esters are used as additives in plastics to improve mechanical properties, particularly flexibility. The contamination of soil samples by phthalate esters around four tributaries to the nm river was analyzed based on gas chromatography-mass spectrometry (GC-MS). All soil samples collected from the four tributaries, which include Anyangcheon and Seohocheon (expected polluted areas), and Gapyeongcheon and Namhan river (expected clean areas), were found to be contaminated by his(2-ethylhexyl) phthalate (DEHP). Soil around Anyangcheon was the most contaminated (113 ppb), about twofold higher than the ones around Seohpcheon (64 ppb), Gapyeongcheon and Namhan river (50 ppb). Based on the fact that DEHP contamination in sediments of the river tributaries around the country is as high as 2.04 ppm, it was concluded that DEHP contamination of the soils around the tributaries to the Han river is relatively low.