• Asian Journal of Turfgrass Science
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• v.11 no.4
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• pp.289-294
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• 1997

The cycles of heavy metals, mercury, lead and cadmium, were investigated on in dynamic grassland ecosystems at a steady state in Zoysia japonica and Miscanthus sinensis in Mt. Kwanak, Korea. Estimates of decay constants of heavy metals based on experimental and methomatical model, were Hg 0.14, Pb 0.17 and Cd 0.41 of Z. japonica grassland, and Hg 0.33, Pb 0.13 and Cd 0.56 of M sinensis grassland. The durations of reaching half of initial amounts in Z. japonica and M. sinensis grassland, were Hg 4.95, Pb 4.07 and Cd 1.69 years, and Hg 2.10, Pb 5.33 and Cd 1.24 years respectively. Times needed for 99% decomposed were longer in Z. japonica than M. sinensis grassland. Decay velocity of constituents of surface soil layers were more rapidly in M. sinensis than Z. japonica grassland. Key words: Cycles of heavy metals, Mercury, Lead, Cadmium, Zoysia japonica. Miscanthus sineusis, Mt. Kwanak, Decay constants.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.393-396
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• 2003

Soil contains the several kinds of metal oxides. Magnetite in soil may contribute the generation of secondary waste during the decontamination of soil by citric acid. Dissolution of magnetite powders by citric acid was investigated in the pH range between 2.0 and 5.0. The dissolution behaviour of magnetite was well described by the equation, A[1 - $e^{-B(x-c)}$]. The parameters of the equation were optimized by the iteration method, and the physical meaning of each parameter was explained. Concentration of each of the dissociated chemical species of citric acid was calculated using the ionization constants. The dissolution reaction was explained by the concentration of the dissociated chemical species of citric acid.d.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.42-49
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• 1997

In this paper, the method for soil-structure interaction analyses in the time domain is proposed. The far field soil region which is the outside of the artificial boundary is modeled by using explicit frequency-dependent two dimensional infinite elements which can include multiple wave components propagating into the unbounded medium. Since the dynamic stiffness matrix of the far field soil region using the proposed infinite elements is obtained explicitly in terms of exciting frequencies and constants in the frequency domain, the matrix can be easily transformed into the displacement unit-impulse response matrix, which corresponds to a convolution integral of it in the time domain. To verify the proposed method for soil-structure interaction analyses in the time domain, the displacement responses due to an impulse load on the surface of a soil layer with the rigid bed rock are compared with those obtained by the method in the frequency domain and those by models with extend finite element meshes. Good agreements have been found between them.

• Structural Engineering and Mechanics
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• v.15 no.2
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• pp.249-267
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• 2003

In this study, circular plates subjected to general type of loads and supported on a two-parameter elastic foundation are analysed. The stiffness, elastic bedding and soil shear effect matrices of a fully compatible ring sector plate element, developed by Saygun (1974), are obtained numerically assuming variable thickness of the element. Ring sector soil finite element is also defined to determine the deflection of the soil surface outside the domain of the plate in order to establish the interaction between the plate and the soil. According to Vallabhan and Das (1991) the elastic bedding (C) and shear parameters ($C_T$) of the foundation are expressed depending on the elastic constants ($E_s$, $V_s$) and the thickness of compressible soil layer ($H_s$) and they are calculated with a suitable iterative procedure. Using ring sector elements presented in this paper, permits the generalization of the loading and the boundary conditions of the soil outside the plate.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.223-226
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• 2004

In this paper, removal of diesel hydrocarbons (C$_{10}$-C$_{22}$) for dry and moist soil was investigated so that microwave-enhanced soil vapor extraction(SVE) reduced soil treatment time and raised remediation efficiency. Kinetic constants of diesel hydrocarbons with microwave energy were 7 times on dry soil and 1580 times on moist soil as much as those of SVE process without microwave energy. The diesel removals were 67.7～78.4% for $C_{10}$ and $C_{12}$, and 0～18.5% for $C_{14}$～C$_{22}$ for dry and moist soil with SVE process only. On the other hand, dry soil with microwave-enhanced SVE process showed 89.3～99.4% removal for $C_{10}$ and $C_{12}$ and 35.6～67.0% for hydrocarbons over $C_{14}$. All hydrocarbons(C$_{10}$～C$_{22}$) studied were significantly removed (93.6～99.8%) for moist soil with microwave-enhanced SVE process. Almost all diesel hydrocarbons were usually considered as semi-volatile compounds(SVOCs). Microwave-enhanced SVE process might have a great potential for remediation of soils contaminated with SVOCs.OCs.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.92-95
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• 2002

Bioavailability study was conducted to elucidate the relationship between sorption/desorption and biodegradation of sorbed phenanthrene in seven different soils. Mineralization kinetics was determined for phenanthrene-sorbed soil slurries inoculated with Pseudomonas putida (ATCC strain 17484). Two biodegradation models were used to fit mineralization kinetics; (i) a first-order degradation model and (ii) a coupled degradation-desorption model. The biodegradation rates were in order of vermicompost >Bion peat > 50% organoclay > Pahokee > blank (no soil, medium only) > montmorillonite > Ohio shale. The mineralization rate constants increased as desorption-resistance of phenanthrene increased. Among the tested sorbents, active biodegradation of phenanthrene was observed in vermicompost and Bion peat. Biodegradation in these two sorbents exhibited little lag time and a high maximum mineralized capacity. The role of sorption/desorption in bioavailability of phenanthrene sorbed in soils was discussed.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.5
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• pp.227-236
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• 2017

This study reviews concepts, theories and formulas included in standards on soil-structure interaction and also shows practical example of application for engineers. Real structures are 3 dimensional and multi degree of freedom but they are often idealized to single degree of freedom for convenience. In this study, detailed procedures to calculate soil spring constants and damping coefficients and method to model soil-structure system are explained. Additionally, case studies to judge fixed base condition and evaluation of applicability of simple analysis method based on response spectra are performed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.5
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• pp.133-139
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• 2003

Dredged soil from sea has much higher water content than liquid limit of clay and even if small loads apply, it will suffer a great settlement. Therefore it is very difficult to perform a consolidation test with general consolidation apparatus because of high water content. In this study Rowe Cell Apparatus consolidation tests have been performed with 1 remolding clay of water content 56% and 4 slurry clays of a water content of 100%, 120%, 133% and 150%. From the test results the consolidation characteristics such as compression index, secondary compression index and consolidation coefficient have been investigated with a variation of water content of dredged soil. The equations to get consolidation constants such as a compression index, a consolidation coefficient have been proposed with the field water content.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.91-94
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• 2003

A field pilot-scale demonstration of an enhanced SVE using hot air injection and extraction was conducted to remove diesel range compounds from subsurface soils at a site in J-city, Korea. The objective of demonstration was to evaluate field ISR by intrinsic microorganism after an application study of hot air-SVE technology and to calculate each first-order kinetic with soil temperature. TPH concentration of contaminated soil at the site was approximately 2, 000~11, 000 mg/kg (average 6, 900 mg/kg) with depths greater than 5 m bgs. The 1st-order reaction rate constants, k were 0.0438(@about5$0^{\circ}C$), 0.0564(@4$0^{\circ}C$), and 0.0685(@33$^{\circ}C$) d-1 respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.5
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• pp.63-72
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• 2008

This study was conducted to define a characteristics of Electrical Resistivity of weathered soil against volumetric water content and frequency. It is essential to analyze and understand a characteristics of the Electrical Resistivity for evaluation of soil as subsurface contaminant detection. Before the test, an effect of pore water and ion were checked using four liquids(distilled water, tap water, potassium chloride 1.8mM, and 3.7mM). As a result, the correlation between the volumetric water content and the Electrical Resistivity was estimated. The Electrical Resistivity decreases with increasing frequency and water content. Also, Electrical Resistivity could be described by an exponential function of volumetric water content with the constants.