• Microbiology and Biotechnology Letters
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• v.21 no.5
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• pp.486-493
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• 1993

A gram(+) bacteria that produced microbial flocculant was isolated from soil and classified as a Bacillus species and named as Bacillus sp. A56. The culture conditions of the strain for fluocculant production were studied in a shake flask. Optimum temperature and initial pH for flcculant production were 30C and 6.5, respectively. The optimized medium has gollowing composition: glucose 20g/l, NH4NO3 0.5g/l, K2HPO4 1.0g/l, KH2PO4 0.8g/l, MgSO4.7H2O 0.2g/l, MnSO4.4-6H2O 0.3g/l, CaCO3 0.5g/l, yeast extract 0.3g/l, tryptone 0.3g/l in tap water.

• Microbiology and Biotechnology Letters
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• v.24 no.2
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• pp.185-190
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• 1996

Some microorganisms including yeasts produce surface tension-decreasing biosurfactants. The strain G-1, the best producer of biosurfatants was isolated from the soil and identified as Rhodotorula sp., which was not discribed any report. The Rhodotorula sp. G-1 produced biosurfactant from vegetable oils, but failed to produce it from n-alkane or carbohydrate. Yeast extract was found to be more effective for the biosurfactant production as nitrogen source than any other inorganic nitrogen source. The composion of the optimal medium contained the following conponents: soybean oil 4%, glucose 2%, yeast extract 0.5%, KH$^{2}$PO$^{4}$ 0.1%, K$^{2}$HP0$^{4}$ 0.l%, MgSO$^{4}$ 5%, CaCl$^{2}$ 0.01%, NaCl 0.01%, pH 6.0. The surface tension activity was increased to 14% when, at first, the culture broth was fermented with only soybean oil as carbon sourse, and after 90 hours, feeded glucose, than that Of glucose and soybean oil added to it simultaneously. The maxium yield of the biosurfactant was about 15 g/l by after 90 hours, the feeding method of glucose.

• Korean Journal of Organic Agriculture
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• v.12 no.2
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• pp.183-196
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• 2004

This study was carried out to screen and select the effects of antifungal bacterial strains which inhibit the growth of plant pathogen, Fusarium oxysporum(fusarium wilt) occurred in carnation plants in greenhouse. We isolated an effective bacterial strains and investigated into the antifungal activity of the antagonistic microorganism and it's identification. Twenty bacterial strains which strongly inhibited Fusarium oxysporum were isolated from roots of carnation plants and the soil in greenhouse, and the best antifungal bacteria designated as C121, was finally selected. Antagonistic bacterial strain, C121 was identified to be the genus Bacillus sp. based on the morphological, biochemical and cultural characterizations. The Bacillus sp. C121 showed 58.1% of antifungal activity against the growth of Fusarium oxysporum. By the bacterialization of the cultural broth and the heat bacterialization culture filtrate of it, Bacillus sp. C121 was shown 92.1% and 21.0% of antifungal activity, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.105-111
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• 2010

It is very important to select carefully backfill materials and build for the structural integrity of abutment in bridge. In general, backfill materials of unbound crushed stones (SB-1) are used to provide the safety of abutment structure and to reduce differential settlement around abutment that is significantly related with performance of road pavement under working conditions. In this study, to evaluate the compatibility of backfill materials at abutment and to develop the abutment design program, i) basic properties of subgrade soils in Korea, ii) evaluation of deformational characteristics of backfill materials from RC/TS tests, cyclic TX tests and Creep tests were accomplished.

• Journal of Applied Biological Chemistry
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• v.42 no.2
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• pp.57-61
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• 1999

Seven numerically dominant 2-methyl-4-chlorophenoxyacetic acid (MCPA)-degrading bacteria were isolated from agricultural soils. The isolates utilized the herbicide MCPA as a sole carbon source, producing significant biomass in MCPA mineral medium. They exhibited diverse herbicide degradation capabilities, but most of them grew very slowly in mineral medium containing herbicide. The chromosomal DNA patterns of the isolates obtained by polymerase chain reaction amplification of repetitive extragenic palindromic sequences were distinct from each other. One isolate, SH3, which was identified as Sphingomonas species by fatty acid methyl ester analysis, was able to degrade 5 different phenoxyacetic acid herbicides within 4 days. This strain contains two plasmids, and the smaller one has a crucial role in herbicide degradation. MCPA treated into agricultural soils without indigenous MCPA-degraders persisted for a long time, but the application of the isolate SH3 resulted in rapid decline of MCPA concentration in the soil.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.264-268
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• 1997

Microbial metabolites from rhizosphere soil samples mainly inhabitated by Streptomyces are selectively uptaken into plants. The culture broth of a Streptomyces strain K9301 showed a major metabolite which disappeared in the medium 24hrs after planting of seedlings. This metabolite was selectively uptaken in the rice plants as well as the wheat plants. We identified the targeted metabolite showing a strong UV-absorbing spot at Rf 0.6 on TLC to be 2-aminobenzamide.

• Journal of Life Science
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• v.6 no.2
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• pp.79-86
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• 1996

A bacterium producing pullulanase was from soil, and was identified Bacillus cereus and named as Bacillus cereus JK36. The optimal culture conditions for the efficident production of pullulanase from B. cereus JK36 was obtained by cultivating with the medium composed of 1% pullulan, 1% teast extract, 1% bactopeptone, 0.1% NaH$_{2}$PO$_{4}$, 2H$_{2}$O, 0.02% MgSO$_{4}$\ulcorner7H$_{2}$O at 40$\circ$C, initial pH 6.5 for 70 hours. Using the culture supernatant as crude enzyme, the optimal pH and temperature of the pullulanase of this strain were 6.5 and 50$\circ$C. In effect of pH and temperature on the stability of the enzyme, the enzyme was stable in the range of pH6.0$\sim$9.5 and up to 40$\circ$C, respectively. The hydrolysis product on pullulan was mainly maltotriose.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.117-125
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• 2000

자가굴착식 프레셔미터 시험(Self-Boring Pressuremeter Test, SBPT)은 지반의 교란을 최소화할 수 있기 때문에 점성토의 비배수 전당강도($S_{u}$ )를 비교적 정확하게 평가할 수 있는 방법 중의 하나로 알려져 있으며, 많은 연구자들에 의하여 SBPT 결과로부터 $S_{u}$ 를 산정하는 여러 가지 방법들이 제안되었다. 본 연구에서는 국내 5개지역에서 총 33회의 SBPT를 수행한후, 기존에 제안된 여러 가지 방법들을 이용하여 $S_{u}$ 를 산정하고, 그 중 변형률 경화 거동을 보이는 지반에서의 $S_{u}$ 를 동일 현장에서 수행한 현장베인시험 결과와 비교. 분석하여 각 방법들의 적용성과 신뢰성을 분석하였다. 그리고, $S_{u}$ 산정 결과에 대한 프레셔미터 멤브레인의 유일한 길이의 영향을 수치해석으로 분석하였으며, 그 결과를 이용하여 기존의 접선영 방법(Subtangent method)을 보정하는 식을 제안하였다. 새로이 보정된 방법으로 산정한 $S_{u}$ 를 현장베인시험 결과와 비교하여 개선 효과를 확인하였다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.3
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• pp.97-106
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• 2000

The study is closely relevant to Lade's single work hardening model. This model has been shown to have good applicability to cohesive soils. However the validation of this model on the clayey soils has not been satisfactorily reported. To scrutinize the applicability of this model on clayey foundation the laboratory tests for Kwangyang clayey soils were performed using the improved cubical triaxial test apparatus designed originally by Lade. A computer program was developed by which soil parameters for the single work-hardening model can be rationally determined by deleting some dispersed test data generated usually at the initial stage of laboratory tests. And using the program numerical analysis of the cubical clayey specimens using intermediate principal stress was carried out and a good agreement between observed values and numerical results was found.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.1
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• pp.39-53
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• 1994

To investigate the behaviour of the embankment on very soft foundation reinforced geotex- files,the laboratory model test in order to analyze the elementary effects of geotextile reinfor- cement and the finite element program analyzing the stresses and deformations characteristics was carried out. A two-dimensional nonlinear finite element program called GEOTEXT(a modification of ISBILD) for the static analysis of embankment on very soft foundation reinforced geotextiles has been developed. Both linear and nonlinear hyperbolic stress-strain soil models are inclu- ded, and incremental and stage construction can be simulated. However, the program GEO- TEXT is not developed herein as an adaptable design tool for practicing engineer. It was found that the geotextile reinforcement significantly reduced the shear stresses in the foundation and decreased the vertical differential settlements at the top of the embank- ment. This influence was more pronounced as the tensile strength of the geotextile was increased.