• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1051-1060
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• 2010

In this study, the pressuremeter test (PMT) and the standard penetration test (SPT) were performed on the lateral pile loading tests site to evaluate the coefficient of subgrade reaction, which is used for load-deformation behavior analysis of laterally loaded piles by elastic subgrade reaction method. As a result, widely used empirical formulas of the coefficient of subgrade reaction by N values of SPT is evaluated conservatively lateral behavior of piles. While the method of directly used PMT results and evaluation method of the coefficient of subgrade reaction considering deformation moduli of soil and a pile diameter that is able to estimate very similar to actual load-deformation behavior of laterally loaded piles in deformation range of 0.5%-1.0% of a pile diameter.

• Environmental Engineering Research
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• v.17 no.4
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• pp.217-225
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• 2012

In this study, the treatability of two target contaminants during the Fenton reaction, n-hexadecane and 1-methylnaphthalene, was evaluated as a function of the amounts of $FeCl_2$ and $H_2O_2$ injected into open and closed reaction systems. In the Fenton reaction of n-hexadecane and 1-methylnaphthalene, the mass recovery of the target contaminants was above 95% in the closed system. However, when the Fenton reaction was performed with high amounts of $H_2O_2$ and $FeCl_2$ injected in the open system, a reduction of approximately 40% of the initial mass of 1-methylnaphthalene was observed. This trend may be explained by the unique physical properties of 1-methylnaphthalene, which has higher volatility than n-hexadecane. Further, this trend was well correlated with the rise in high temperature at the initial reaction stage. Considering the mass recovery of the two target contaminants, the reaction temperature, and the residual concentration of $H_2O_2$ at different amounts of $FeCl_2$ and $H_2O_2$ injected, it can be suggested that the Fenton reaction should be performed with controlled conditions that can provide a suitable reaction environment between oxidant and contaminants.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.19-22
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• 2004

Two-dimensional modeling studies using TOUGHREACT were conducted to investigate the coupling between flow and transport developed as a consequence of differences in density, dissolution/ precipitation, and medium heterogeneity. The model includes equilibrium reactions for aqueous species, kinetic reactions between tile solid phases and aqueous constituents, and full coupling of porosity and permeability changes resulting from precipitation and dissolution reactions in porous media. Generally, the evolutions in the concentrations of the aqueous phase are intimately related to the reaction-front dynamics. Plugging of the medium contributed to significant transients in patterns of flow and mass transport.

• Food Science and Biotechnology
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• v.18 no.4
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• pp.1038-1041
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• 2009

Aflatoxins are secondary metabolites produced by the aflatoxigenic fungi in suitable conditions. Saffron, Crocus sativus, is the most expensive spice in the world. Saffron is normally contaminated with soil and hand microflora during harvest and post-harvest operations. In this study, rapid assessment of aflatoxigenic fungi in saffron was accomplished using polymerase chain reaction. In total, 37 market samples were assayed in order to isolate aflatoxin-producing fungi. The 18.9% of the total samples were contaminated with aflatoxigenic fungi. Our results also show that most of the isolated fungi were saprophytes which are normally originated from soil during harvest and postharvest process.

• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.664-670
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• 1996

The aim of the present research program was to develop a strain of actinomycetes producing antifungal substance. Soil samples were collected from various sites in Korea and a number of actinomycetes were isolated from the soil samples by applying selective agar for actinomycetes. Among over 440 isolates, a strain (NA-4803) producing antifungal substance against Trichophyton spp. Nannizzia otae and Pyricularia oryzae was selected. The strain NA-4803 was identified as strain similar to Streptoverticillium blastmyceticum with respect to morphological and physiological characteristics, lecithinase and lipolytic activity, degradation of organic compounds, resistance to antibiotics and utilization of carbon and nitrogen sources. But it showed some differences such as positive reaction of nitrate reduction, negative reaction of L-tyrosine degradation, resistance to cephaloridine, and utilization of I -rhamnose and inulin. The strain NA-4803 was named as Streptoverticillium sp. NA-4803.

• Journal of the Korean Applied Science and Technology
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• v.22 no.2
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• pp.136-141
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• 2005

This paper presents applicability of Fenton oxidation to perchloroethylene(PCE) contaminated soil. The initial concentration of PCE was 187mg/kg and Fenton oxidation conditions were 1.0M $H_2O_2$ and 0.5M $Fe^{2+}$. More than 97% of PCE decomposition and 98% of dechlorination were obtained within 5 hrs. It was found that the decomposition of PCE by Fenton oxidation was followed pseudo first order and its reaction coefficient was 0.78 $hr^{-1}$. GC-MS and GC-ECD analysis of reaction intermediates confirmed only the presence of trichloroacetic acid(i.e., 1.0% of initial PCE concentration). Under Fenton oxidation conditions, it was proposed that PCE was decomposed not simultaneously but one by one.

• Journal of Korean Institute of Fire Investigation
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• v.11 no.1
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• pp.139-144
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• 2007

The fires were occasionally occurred by the quicklime, used in soil conditioners and stall disinfectant, in the stables and shed especially during the rainy season. Accordingly, we observed that spontaneous ignition by the exothermic reaction was happened through the revival experiments. As a results of revival experiments, we confirmed that fire had been occurred by exothermic energies in the case of heat accumulation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.136-139
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• 2000

Fenton-like oxidation of para-nitrophenol(PNP) was studied using hydrogen peroxide iii combination with steeler's dust substituted for ferrous iron in Fenton's reaction. Various factors critical in the degradation of PNP were studied, including hydrogen peroxide dosage, concentration of steeler's dust. and initial pH. Experimental results showed that 1,000mg/L PNP and its oxidation intermediate could be mostly decomposed within 30m1n by 10g/L steeler's dust, 0.25% hydrogen peroxide, and initila pH of 3.0. The reaction rate constant (k) of CODcr concentration were calculated with the addition of steeler's dust(0.0059 min$^{-1}$ (g/L)$^{-1}$ ) and hydrogen peroxide(0.2965 min$^{-1}$ (%)$^{-1}$ ), respectively.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.428-435
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• 2011

In general, thickness of the sublayers under track is designed based on concept of vertical soil reaction value or vertical stiffness. However, this design method cannot take consideration into soil-track interaction under repetitive load, traffic condition and velocity of the train. Furthermore, the reinforced roadbed soils experience complex behavior that cannot be explained by conventional stress-strain relation expressed as soil reaction value k. The reinforced roadbed soils also can produce cumulative permanent deformation under repetitive load caused by train. Therefore new design method for the sublayers under track must be developed that can consider both elastic modulus and permanent deformation. In this study, a new design concept, a rule-of-thumb, is proposed as the form of design monograph that is developed using elastic multi-layer and finite element programs by analyzing stress and deformation in the sublayers with changing the thickness and elastic modulus of the sublayers and also using data obtained from repetitive triaxial test. This new design concept can be applied to design of the reinforced roadbed before developing full version of design methodology that can consider MGT, axial load and the material properties of the layers. The new design monograph allows the user to design the thickness of the reinforced roadbed based on permanent deformation, elastic modulus and MGT.

• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.51-57
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• 2012

The purpose of study is to understand the possibility of biogrout of soil induced by bacteria. Microbial Calcium Carbonate Precipitation(MCP) has been analysed using the microorganism Bacillus Pasteurii. In order to understand the biogrout of soft ground treated with microbial calcium carbonate precipitation, four types of specimens(sterilization soil, non-sterilization soil, reaction solution and microorganism solution with pre-treatment mix and reaction solution and microorganism solution with post-treatment mix) were made. Scanning Electron Microscope(SEM), EDX and X-ray diffraction(XRD) analyses were performed on the soft ground specimens. On the basis of the preliminary results, it appears that microbial treatment methods using calcium carbonate precipitation may be possible to improve property of biogrout.