• Coupled systems mechanics
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• v.3 no.2
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• pp.233-245
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• 2014

Coupled finite element analysis is carried out to study the effect of degree of saturation on the vertical displacements and pore water pressures simultaneously by developing a FORTRAN90 code. The finite element formulation adopted in the present study is based upon Biot's consolidation theory to include partially saturated soils. Numerical methods are applied to a two-dimensional plane strain strip footing (flexible) problem and the effect of variable degree of saturation on the response of excess pore water pressure dissipation and settlement of the footing is studied. The immediate settlement in the case of partly saturated soils is larger than that of a fully saturated soil, the reason being the presence of pore air in partially saturated soils. On the other hand, the excess pore water pressure for partially saturated soil are smaller than those for fully saturated soil.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.4
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• pp.249-254
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• 2007

Inoculation dose of agriculturally important microbes is an important criterion that decides the establishment and hence their effects on plant growth. Effects of the inoculation dose of Azospirillum brasilense strain CW903 on the growth and nutrient absorption of three different crops, tomato, rice and red pepper were assessed under green house condition. Three different concentrations of A. brasilense strain CW903 ($10^5$, $10^6$ and $10^8cfu\;mL^{-1}$) were applied through seed treatment and through the soil near the root zone (1 mL per plant) at 20 and 30 days after sowing. Positive effects on the growth of tomato, rice and red pepper were found at $10^6$ and $10^8cfu\;mL^{-1}$ inoculation doses of A. brasilense strain CW903. The inoculation dose of $10^8cfu\;mL^{-1}$ of A. brasilense strain CW903 recorded the best effects on growth parameters like shoot and root length and the absorption of important nutrients.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.56-62
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• 2008

Two hundred and sixty-eight bacterial strains were isolated from pine mushroom (Tricholoma matsutake) basal soil. In the course of screening for antifungal activity against seven plant pathogenic fungi (Alternaria panax, Botrytis cinerea, Colletotrichum gloeosprioides, Fusarium oxysporum, Phytopthora capsici, Pythium ultimum, Rizoctonia solani) of isolates, strain KM1-15 showed strong antibiotic activity against Alternaria panax and Colletotrichum gloeosprioides. In determining its relationship on the basis of 16S rDNA sequence, KM1-15 strain was most closely related to Bacillus $koguryoae^T$ (AY904033) (99.62%). When assayed with the API 50CHE Kit, unlike Bacillus koguryoae, it is positive for utilization of L-arabinose, cellobiose, inulin, and D-turanose. Results of cellular fatty acid analysis showed that major cellular fatty acids were 15:0 anteiso (35.78%) and 17:0 anteiso (17.97%). In particular, hydroxyl fatty acids such as 13:0 iso 3-OH, 14:0 iso 3-OH, 15:0 iso 3-OH, and 17:0 iso 3-OH were only restricted to strain KM1-15. DNA G+C content was 43.7 mol% and quinone system was MK-7 (100%) in strain KM1-15.

• Journal of the Korean Geotechnical Society
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• v.27 no.11
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• pp.5-15
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• 2011

This paper presents two analysis methods for characterizing the non-linear finite strain consolidation behavior of highly deformable dredged soil deposits along with the fundamental parameters obtained in the companion paper; that is, the zero effective stress void ratio, the non-linear relationships of void ratio-effective stress and void ratio-hydraulic conductivity. The simplified Morris's analytical solution (2002) and the widely recognized numerical program, PSDDF (primary Consolidation, Secondary Compression, and Desiccation of Dredged Fill) for both single and double drainage conditions are adopted in this paper to verify a series of laboratory experiments for self-weight consolidation of the Incheon clay and Kaolinite. The comparisons show that the analysis methods proposed herein can properly simulate the long-term non-linear finite strain consolidation behavior for dredged soils in the field. In addition, a case study for the artificial Craney Island has been conducted to illustrate the importance of obtaining appropriate non-linear finite strain consolidation parameters and the applicability of PSDDF in promoting dredged soil disposal.

• Korean Journal of Food Science and Technology
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• v.38 no.3
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• pp.419-426
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• 2006

A thermophilic microorganism, strain JE 375, which produces a thermostable protease, was isolated from soil and compost in Korea. This gram-positive, rod-shaped, catalase positive, motility positive, and hemolysis ${\beta}$ containing organism was implicated in glucose fermentation, mannitol fermentation, xylose oxidation, aerobic activity and spore formation. The color of the colony was yellowish white. The temperature range for growth at pH 6.5 was between 55 and $70^{\circ}C$, with an optimum growth temperature of $65^{\circ}C$. This result confirmed the strain JE 375 as a thermophilic microorganism. The enzyme was produced aerobically at $65^{\circ}C$ during 20 hr in a medium (pH 6.5) containing 1% trypton. 1% maltose, 0.5% yeast extract and 1% NaCl. The 16S rDNA of strain JE 375 had 97.6% sequence similarity with the 16S rDNA of Bacillus caldoxyloyticus. On the basis of biochemical and physiological properties and phylogenetic analysis, we named the isolated strain as Bacillus sp. JE 375. The thermostable protease from Bacillus sp. JE 375 had been partially purified and characterized. The molecular weight of the enzyme was deduced from SDS-PAGE and gel chromatography as 55 kDa and its optimal temperature was $60^{\circ}C$. The enzyme showed its highest activity at pH 7.5 and was stable from pH 7.0 to 8.0.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.113-120
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• 2008

One-dimensional site response analysis is widely used to simulate the seismic site effects. The equivalent linear analysis, which is the most widely used type of site response analysis, is essentially a linear method. The method applies constant shear modulus and damping throughout the frequency range of the input motion, ignoring the dependence of the soil response on the loading frequency. A new type of equivalent linear analysis method that can simulate the frequency dependence of the soil behavior via frequency-strain curve was developed. Various forms of frequency-strain curves were proposed, and all curves were asserted to increase the accuracy of the solution. However, its validity has not been extensively proven and the effect of the shape of the frequency-strain curve is not known. This paper used two previously proposed frequency-strain curves and three additional curves developed in this study to evaluate the accuracy of the frequency-dependent equivalent linear method and the influence of the shape of the frequency-strain curves. In the evaluation, six recordings from three case histories were used. The results of the case study indicated that the shape of the frequency-strain curve has a dominant influence on the calculated response, and that the frequency dependent analysis can enhance the accuracy of the solution. However, a curve that results in the best match for all case histories did not exist and the optimum curve varied for each case. Since the optimum frequency-strain curve can not be defined, it is recommended that a suite of curves be used in the analysis.

• Structural Engineering and Mechanics
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• v.41 no.6
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• pp.711-734
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• 2012

The foundation of a tall building frame resting on settable soil mass undergoes differential settlements which alter the forces in the structural members significantly. For tall buildings it is essential to consider seismic forces in analysis. The building frame, foundation and soil mass are considered to act as single integral compatible structural unit. The stress-strain characteristics of the supporting soil play a vital role in the interaction analysis. The resulting differential settlements of the soil mass are responsible for the redistribution of forces in the superstructure. In the present work, the nonlinear interaction analysis of a two-bay ten-storey plane building frame- layered soil system under seismic loading has been carried out using the coupled finite-infinite elements. The frame has been considered to act in linear elastic manner while the soil mass to act as nonlinear elastic manner. The subsoil in reality exists in layered formation and consists of various soil layers having different properties. Each individual soil layer in reality can be considered to behave in nonlinear manner. The nonlinear layered system as a whole will undergo differential settlements. Thus, it becomes essential to study the structural behaviour of a structure resting on such nonlinear composite layered soil system. The nonlinear constitutive hyperbolic soil model available in the literature is adopted to model the nonlinear behaviour of the soil mass. The structural behaviour of the interaction system is investigated as the shear forces and bending moments in superstructure get significantly altered due to differential settlements of the soil mass.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.103-112
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• 2012

The most of original horizontal bearing capacity theory of the pile is not efficiently to consider interaction between soil and pile because it is only to consider the earth pressure theory and separately the ground form pile. In recent, in order to improve the pile technology, it is necessary to confirm the real behaviour characteristics of pile under lateral load. Hence, to evaluate the behaviour characteristics of the single and group pile under lateral loads using the strain wedge model that could consider the interaction between soil and piles. Primarily, laboratory scale down model tests was carried out to predict the behaviour characteristics on real size piles using the strain wedge model. The comparative analyses between model test and numerical analysis for the evaluation of whole behaviour were conducted.

• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.146-149
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• 2018

BACKGROUND: Selenium is an essential element for all life forms but can be toxic above certain narrow levels. Prevalent forms of selenium in oxic environment are selenium oxyanions such as selenite and selenate, which may be contaminants in soils and water bodies. Bacterial reduction of more mobile selenium species (selenite or selenate) to less mobile elemental selenium may suggest a benign solution for alleviating toxicity and bioavailability of the selenium species. METHODS AND RESULTS: A facultative anaerobic bacterium, Citrobacter strain SE4-1 was isolated from the contaminated stream sediments and found to effectively reduce selenite to elemental selenium. Aqueous phase of selenite was analyzed by inductively couple plasma spectroscopy and the precipitated sphere-shaped elemental selenium was observed by transmission electron microscopy. CONCLUSION: The bacterial strain SE4-1 isolated in this study suggests a potential role in biogeochemical cycle of selenium by the selenite reduction in the stream environment, and potentials for biotechnological applications to reduceselenium concentrations in selenium-contaminated systems such as wastewater, soil, and groundwater.

• Journal of Applied Biological Chemistry
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• v.59 no.1
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• pp.9-12
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• 2016

Strain AP01 was isolated for the biological cypermethrin degradation from soil and sediment in Busan. This strain was identified on the basis of phylogenetic analysis of the 16s rDNA sequence and assigned as Bacillus amyloliquefaciens AP01. AP01 could degrade about 45% of cypermethrin in the mineral medium at $30^{\circ}C$ and 180 rpm for 5 days. Furthermore when 2% glucose was added in the medium, the degradation rate of cypermethrin by strain AP01 was increased upto about 60%. Therefore, AP01 may serve as a promising strain in the bioremediation of soil polluted with cypermethrin.