• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.242-243
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• 2005

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.888-892
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• 2008

If gas hydrate dissociates due to natural and/or human activities, it generates large amount of gas and water. Upon gas hydrate dissociation, a generated pore water pressure between soil particles increases and results in the loss of an effective stress and degradation of soil stiffness and strength. In order to predict the generated excess pore water pressure due to gas hydrate dissociation, two methods based on small hydrate concept (SHC) and large hydrate concept (LHC) are proposed. An excess pore water pressure generated by the gas hydrate dissociation in the Storegga Slide was calculated using two proposed methods.

• 한국가스학회:학술대회논문집
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• 2001.10a
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• pp.58-68
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• 2001

Microbiologically influenced corrosion (MIC) of carbon steel gas pipeline in soil environments was investigated at field and laboratory MIC is very severe corrosion and it is not easy to distinguish this corrosion from Inorganic corrosion because of its localized, pitting-type character Therefore, it is important to provide proper assessment techniques for the prediction, detection, monitoring and mitigation of MIC. It is possible to predict the MIC risk, i.e., the activity of sulfate-reducing bacteria (SRB) through the analysis of soil environments. Chemical, microbiological and surface analysis of corrosion products and metal attacked could reveal the possibility of the occurrence of MIC. Various electrochemical and surface analysis techniques could be used for the study of MIC. Among these techniques, thin-film electrical resistance (ER) type sensors are promising to obtain localized corrosion rate of MIC induced by SRB. It is also important to study the effect of cathodic protection (CP) on the MIC In case of coated pipeline, the relationship between coating disbondment and the activity of SRB beneath the disbanded coating is also important.

• Journal of Soil and Groundwater Environment
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• v.20 no.4
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• pp.51-65
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• 2015

Indoor inhalation of vapors intruded into buildings is an important exposure pathway in volatile organic compoundscontaminated sites. Site-specifically measured indoor air concentration is preferentially used for risk assessment. However, when indoor air concentration of VOC is not measured, the indoor air concentration needs to be estimated from soil concentration or measured soil gas concentration of the VOC. Some risk assessment guidance (e.g., Korea Ministry of Environment (KMOE) and American Society for Testing and Materials (ASTM) International guidance) estimate the indoor air concentration from soil concentration while other guidances (e.g., United States Environmental Protection Agency (USEPA) and Dutch National Institute for Public Health (RIVM)) estimate it from measured soil gas concentration. This study derived indoor inhalation risks of intruded benzene in two benzene-contaminated residential areas with four different risk assessment guidances (i.e., KMOE, USEPA, ASTM, and Dutch RIVM) and compared the derived risks. The risk assessment results revealed that indoor air estimation approach from soil concentration could either underestimate (when the contaminant is not detected in soil) or overestimate (when the contaminant is detected in soil even at negligible concentration) the indoor air inhalation risk. Hence, this paper recommends to estimate indoor air concentration from soil gas concentration, rather than soil concentration. Discussions about the various indoor air concentration estimation approaches are provided.

• Journal of Soil and Groundwater Environment
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• v.16 no.5
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• pp.42-52
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• 2011

In this laboratory study, the changes in gas-exposed perchloroethene (PCE) saturation in sand during a PCE removal process were measured using gaseous tracers. The flux of fresh air through a glass column packed with PCEcontaminated, partially water-saturated sand drove the removal of PCE from the column. During the removal of PCE, methane, n-pentane, difluoromethane and chloroform were used as the non-reactive, PCE-partitioning, water-partitioning, and PCE and water-partitioning tracers, respectively. N-pentane was used to detect the PCE fraction exposed to the mobile gas. At water saturation of 0.11, only 65% of the PCE was found to be exposed to the mobile gas prior to the removal of PCE, as calculated from the n-pentane retardation factor. More PCE than that detected by n-pentane was depleted from the column due to volatilization through the aqueous phase. However, the ratio of gas-exposed to total PCE decreased on the removal of PCE, implying gas-exposed PCE was preferentially removed by vaporization. These results suggest that the water-insoluble, PCE-partitioning tracer (n-pentane in this study), along with other tracers, can be used to investigate the changes in fluid (including nonaqueous phase liquid) saturation and the removal mechanism during the remediation process.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.199-201
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• 2005

This paper describes a simple procedure for the quantitative analysis of 7 PCBs (polychlorinated biphenyls) in soils on the waste reclaimed land, The procedure involved sample clean up using silicagel column, acetonitrile partition and sulfuric acid procedures. The instrumental technique is applied GC/PDD(gas chromatography/pulsed discharge detector) and GC/ECD(gas chromatography/electron capture detector). Concentration of $sub-{\mu}g/g$ level was attainable with 20g soils on the waste reclaimed land.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2C
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• pp.109-117
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• 2010

Gas hydrate dissociation can generate large amounts of gas and water in gas hydrate bearing sediments, which may eventually escape from a soil skeleton and form voids within the sediments. The loss of fine particles between coarse particles or collapse of cementation due to water flow during heavy or continuous rainfall may form large voids within soil structure. In this study, the effect of void formation resulting from gas hydrate dissociation or loss of some particles within soil structure on the strength of soil is examined. Glass beads with uniform gradation were used to simulate a gas hydrate bearing or washable soil structure. Glass beads were mixed with 2% cement ratio and 7% water content and then compacted into a cylindrical sample with five equal layers. Empty capsules for medicine are used to mimic large voids, which are bigger than soil particle, and embedded into the middle of five equal layers. The number, direction, and length of capsules embedded into each layer vary. After two days curing, a series of unconfined compression tests is performed on the capsule-embedded cemented glass beads. Unconfined compressive strength of cemented glass beads with capsules depends on the volume, direction and length of capsules. The volume and cross section formed by voids are most important factors in strength. An unconfined compressive strength of a specimen with large voids decreases up to 35% of a specimen without void. The results of this study can be used to predict the strength degradation of gas hydrate bearing sediments in the long term after dissociation and loss of fine particles within soil structure.

• Journal of Soil and Groundwater Environment
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• v.15 no.5
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• pp.40-45
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• 2010

In this study, methane production by reuse of screened soil of landfill was estimated and the effect of application of landfarming for the reduction of methane was investigated. The study soil sampled from S closed landfill contains VS 9.8~12.8% and its BOD/COD is 0.31~0.33 which is more than three times over 0.1, the BOD/COD stabilization criteria of Ministry of Environment. The effective remediation technology for the reduction of organics of soil, landfarming was applied to the screened soil for 60 days. VS and TPH removal showed 5.2~8.3% and 67~74% respectively, and the reduction of VS until 30 day charged 70% of the total reduction. BMP test showed 27.77~30.46 mL $CH_4$/g VS and total methane production from total screened soil for remediation is expected about 260.4 $CH_4$ ton. Expected amount of methane production of the screened soil by landfarming application is 12.9 $CH_4$ ton, which shows 95% gas reduction effect and landfarming is effective for the reduction of methane production from screened soil of landfill.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1693-1698
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• 2012

A headspace gas chromatographic mass spectrometric (GC-MS) assay method was developed for the simultaneous determination of methyl tertiary butyl ether (MTBE), $tert$-butyl alcohol (TBA) and benzene, toluene, ethyl benzene and xylene (BTEX) in soil contaminated with gasoline. 2 g of soil sample were placed in a 10 mL headspace vial filled with 5 mL of phosphoric acid solution (pH 3) saturated with NaCl, and the solution was spiked with fluorobenzene as an internal standard and sealed with a cap. The vial was heated in a heating block for 40 min at $80^{\circ}C$. The detection limits of the assay were 0.08-0.12 ${\mu}g$/kg for the analytes. For five independent determinations at 10 and 50 ${\mu}g$/kg, the relative standard deviations were less than 10%. The method was used to analyze fifty six soil samples collected from various regions contaminated with gasoline in Korea. The developed method may be valuable for the monitoring of the analytes in soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.577-583
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• 2010

In this study, the effect of void formation resulting from gas hydrate dissociation or loss of some particles within soil structure on the strength of soil is examined. Beag-ma river sands with uniform gradation were used to simulate a gas hydrate bearing or washable soil structure. Empty capsules for medicine are used to mimic large voids, which are bigger than soil particle. Beag-ma river sand was miced with 8% cement ratio and 14% water content and compacted into a shear box. The number and direction embedded into a specimen. After 4 hours curing, a series of direct shear test is performed on the capsule embedded cemented sands. Shear strength of cemented sands with capsules depends on the volume and direction. The volume and direction formed by voids are most important factors in strength. A shear strength of a specimen with large voids decreases up to 39% of a specimen without void. The results of this study can be used to predict the strength degradation of gas hydrate bearing sediments after dissociation and loss of fine particles within soil structure.