• KSBB Journal
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• v.26 no.1
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• pp.1-6
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• 2011

Contamination of soils, groundwater, air and marine environment with hazardous and toxic chemicals is major side effect by the industrialization. Bioremediation, the application of microorganism or microbial processes to degrade environmental contaminant, is one of the new environmental technologies. Because of low water solubility and volatility of diesel, bioremediation is more efficient than physical and chemical methods. The purpose of this study is biodegradation of diesel in sand by using Rhodococcus fascians, a microorganism isolated from petroleum contaminated soil. This study was performed in the column containing sand obtained from sea sides. Changes in biodegradability of diesel with various flow rates, inoculum sizes, diesel concentrations, and pH were investigated in sand column. The optimal condition for biodegradation of diesel by R. fascians in sand column system was initial pH 8 and air flow rate of 30 mL/min. Higher diesel degradation was achieved at larger inoculum size and the diesel degradation by R. fascians was not inhibited by diesel concentration up to 5%.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.263-270
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• 2016

Recent Engineered nanoparticles were increasingly exposed to environmental system with the wide application and production of nanomaterials, concerns are increasing about their environmental risk to soil and groundwater system. In order to assess the transport behavior of silver nanoparticles (AgNPs), a saturated packed column experiments were examined. Inductively coupled plasma-mass spectrometry and a DLS detector was used for concentration and size measurement of AgNPs. The column experiment results showed that solution chemistry had a considerable temporal deposition of AgNPs on the porous media of solid glass beads. In column experiment, comparable mobility improvement of AgNPs were observed by changing solution chemistry conditions from salts (in both NaCl and $CaCl_2$ solutions) to DI conditions, but in much lower ionic strength (IS) with $CaCl_2$. Additionally, the fitted parameters with two-site kinetic attachment model form the experimental breakthrough curves (BTCs) were associated that the retention rates of the AgNPs aggregates were enhanced with increasing IS under both NaCl and $CaCl_2$ solutions.

• Journal of Soil and Groundwater Environment
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• v.27 no.4
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• pp.49-62
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• 2022

The magnesium and iron-based layered double hydroxide (Mg-Fe LDH) was synthesized by the co-precipitation process and the bead type LDH (BLDH, 5~6 mm in diameter) was manufactured by using the Mg-Fe LDH and the starch as a binder. To evaluate the feasibility of the BLDH as the As stabilizer in the soil, various experiments were performed and the As stabilization efficiency of the BLDH was compared to that of powdered type LDH (PLDH, <149 ㎛ in diameter). For the As sorption batch experiment, the As sorption efficiency of both of the PLDH and the BLDH showed higher than 99%. For the stabilization experiment with soil, the As extraction reducing efficiency of the PLDH was higher than 87%, and for the BLDH, it was higher than 80%, suggesting that the BLDH has similar the feasibility of As stabilization for the contaminated soil, compared to the PLDH. From the continuous column experiments, when more than 7% BLDH was added into the soil, the As stabilization efficiency of the column maintained at over 91% for 7 pore volume flushing (simulating about 21 months of rainfall) and slowly decreased down to 64% after that time (to 36 months) under the non-equilibrium conditions. Results suggested that more than 7% of BLDH added in As-contaminated soil could be enough to stabilize As in soil for a long time. The main As fixation mechanisms on the LDH were also identified through the X-ray fluorescence (XRF), the X-ray diffraction (XRD), and the Fourier transform infrared (FT-IR) analyses. Results showed that the LDH has enough of an external surface adsorption capacity and an anion exchange capability at the interlayer spaces. Results of SEM/EDS and BET analyses also supported that the Mg-Fe LDH used in this study has sufficient porous structures and outer surfaces to fix the As. The reduction of carbonate (CO₃^2-) and sulfate (SO₄^2-) anions in the LDH after the reaction between As and the LDH was observed through the FT-IR, the XRF, and the XRD analyses, suggesting that the exchange of some of these anions with the arsenate (H₂AsO₄^- or HAsO₄^2-) occurs at the LDH interlayers during the stabilization process in soil.

• Korean Journal of Environmental Agriculture
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• v.11 no.3
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• pp.201-208
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• 1992

Municipal landfill leachate, a major source of soil contamination and ground water pollution, causes serious environmental problems. To investigate the removal efficiency of pollutants in the leachate by sand, briquet ash, fly ash, and activated carbon columns, COD and some pollutants in the leachate passed through each column for 8 weeks were examined. Average COD removal efficiency for 8 weeks was 83%, 45%, and 43% by activated carbon, briquet ash and fly ash columns, respectively. COD was not effectively reduced by sand column. Average ${NH_4}\;^+$ removal efficiency for 8 weeks was more than 60% by ail columns. Hardness was effectively removed for 8 weeks by fly ash and activated carbon columns. Anoins including $PO_4\;^{3-}$, $CI^-$ and $SO_4^{2-}$ were not removed by all columns.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.162-163
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• 2005

• Proceedings of the Korean Geotechical Society Conference
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• 1998.10a
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• pp.359-366
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• 1998

• Geomechanics and Engineering
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• v.23 no.3
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• pp.275-287
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• 2020

Rectangular barrettes have been increasingly used as foundations for many infrastructure projects, but the vertical vibration of a barrette has been rarely addressed theoretically. This paper presents an analysis method of dynamic response for a rectangular barrette subjected to a time-harmonic vertical force with the aid of a modified Vlasov foundation model in multilayered viscoelastic soil. The barrette-soil system is modeled as a continuum, the vertical continuous displacement model for the barrette and soil is proposed. The governing equations of the barrette-soil system and the boundary conditions are obtained and the vertical shaft resistance of barrette is established by employing Hamilton's principle for the system and thin layer element, respectively. The physical meaning of the governing equations and shaft resistance is interpreted. The iterative solution algorithm flow is proposed to obtain the dynamic response of barrette. Good agreement of the analysis and comparison confirms the correctness of the present solution. A parametric study is further used to demonstrate the effects of cross section aspect ratio of barrettes, depth of soil column, and module ratio of substratum to the upper soil layers on the complex barrette-head stiffness and the resistance stiffness.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.161-189
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• 2015

Soil-pile raft-structure interaction is recognized as a significant phenomenon which influences the seismic behaviour of structures. Soil structure interaction (SSI) has been extensively used to analyze the response of superstructure and piled raft through various modelling and analysis techniques. Major drawback of previous study is that overall interaction among entire soil-pile raft-superstructure system considering highlighting the change in design forces of various components in structure has not been explicitly addressed. A recent study addressed this issue in a broad sense, exhibiting the possibility of increase in pile shear due to SSI. However, in this context, relative stiffness of raft and that of pile with respect to soil and length of pile plays an important role in regulating this effect. In this paper, effect of relative stiffness of piled raft and soil along with other parameters is studied using a simplified model incorporating pile-soil raft and superstructure interaction in very soft, soft and moderately stiff soil. It is observed that pile head shear may significantly increase if the relative stiffness of raft and pile increases and furthermore stiffer pile group has a stronger effect. Outcome of this study may provide insight towards the rational seismic design of piles.

• Applied Biological Chemistry
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• v.36 no.6
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• pp.510-516
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• 1993

The degradation and leaching pattern of benzoylurea insecticide teflubenzuron and flucycloxuron in soil environment and their effect on urease activity were investigated. The half-life of teflubenzuron was 39.1 days and 20.9 days in Chilgok and Ansim soil of nonsterilized condition, respectively, and that of flucycloxuron was 102.3 days and 50.1 days. Teflubenzuron and flucycloxuron were degraded more rapidly in Ansim soil with rich organic matter than Chilgok soil, and were degraded very slowly under sterilized condition. Their degradation seemed to be mainly mediated by microorganisms in soil. Teflubenzuron was degraded 63.2 days and 29.2 days faster than flucycloxuron under nonsterilized condition of Chilgok and Ansim soil. The inhibition of urease by the pesticides in two kinds of soil was strongly affected $(37.6{\sim}42.4%)$ in the early stage of their treatment but hardly affected or increased a little after 120 days. The teflubenzuron and flucycloxuron remained in the upper 5 cm of the soil column after elution with 1,000 ml of water, and they were not detected in leachate.

• Journal of Korea Soil Environment Society
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• v.3 no.2
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• pp.101-114
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• 1998

Soil vapor extraction (SVE) is known to be an effective process to remove the contaminants from the soils by enhancing the vaporization of organic compounds using forced vapor flows or applying vacuum through soils. Experiments are carried out to investigate the effects of the organic contaminants, types of soils, and water contents on the removal efficiency with operating time. In the study, simulated soils include the glass bead which has no micropore, sand and molecular sieve which has a large volume of micropores. As model organic pollutants, toluene, methyl ethyl ketone, and trichloroethylene are selected. Desorption experiments are conducted by flowing nitrogen gas. Under the experimental conditions, it is found that there are linear relationships between logarithm of removal efficiency and logarithm of number of pore volumes. The number of pore volumes are defined as the total amount of air flow through the soil column divided by the pore volume of soil column. For three organic compounds studied, the removal rate is slow for no water content, while the number of pore volumes for removal of organic compounds are notably reduced for water contents up to 37%. For the removal of dense organic compound, such as trichloroethylene, a large number of pore volumes are needed. Also, the effects of the characteristics of simulated soils on the removal efficiency of organic compounds are studied. After the characterization of soil surface, porosity of soil columns and types of contaminants, the results could provide a basis for the design of SVE process.