• Journal of Life Science
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• v.21 no.8
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• pp.1083-1093
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• 2011

A microorganism utilizing rice hulls as a substrate for the production of carboxymethylcellulase (CMCase) was isolated from seawater and identified as Bacillus lincheniformis by analyses of its 16S rDNA sequences. The optimal carbon and nitrogen sources for production of CMCase were found to be rice hulls and ammonium nitrate. The optimal conditions for cell growth and the production of CMCase by B. lincheniformis LBH-52 were investigated using the response surface method (RSM). The analysis of variance (ANOVA) of results from central composite design (CCD) indicated that a highly significant factor ("probe>F" less than 0.0001) for cell growth was rice hulls, whereas those for production of CMCase were rice hulls and initial pH of the medium. The optimal conditions of rice hulls, ammonium nitrate, initial pH, and temperature for cell growth extracted by Design Expert Software were 48.7 g/l, 1.8 g/l, 6.6, and 35.7$^{\circ}C$, respectively, whereas those for the production of CMCase were 43.2 g/l, 1.1 g/l, 6.8, and 35.7$^{\circ}C$. The maximal production of CMCase by B. lincheniformis LBH-52 from rice hulls under optimized conditions was 79.6 U/ml in a 7 l bioreactor. In this study, rice hulls and ammonium nitrate were developed to be substrates for the production of CMCase by a newly isolated marine microorganism, and the time for production of CMCase was reduced to 3 days using a bacterial strain with submerged fermentation.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.654-659
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• 2013

This study was conducted to identify an optimal ratio of carbon to nitrogen (C/N ratio) for denitrification of nitrate using molasses as an external carbon source. A series of batch and column tests was conducted using an indigenous bacterium Pseudomonas sp. KY1 isolated from a nitrate-contaminated soil. For the initial nitrate-nitrogen concentration of 100 mg-N/L, batch test results indicated that C/N ratio of 3/1 was the optimal ratio with a relatively high pseudo-first-order reaction constant of $0.0263hr^{-1}$. At C/N ratio of 3/1, more than 80% of nitrate-nitrogen concentration of 100 mg-N/L was removed in 100 hrs. Results of column tests with a flow velocity of 0.3 mL/min also indicated that the C/N ratio of 3/1 was optimal for denitrification with minimizing remaining molasses concentrations. After 172 hrs of column operation (35 pore volumes) with an influent nitrate-nitrogen concentration of 100 mg-N/L, the effluent met the drinking water standard (i.e., 10 mg $NO_3$-N/L).

• Applied Biological Chemistry
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• v.40 no.2
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• pp.134-138
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• 1997

The objective of this study was to examine the effect of phosphorus deficiency on nitrogen fixation and photosynthesis of nitrogen fixing soybean plant under $CO_2$ enrichment condition. The soybean plants(Glycine max [L.] Merr.) inoculated with Bradyrhizobium japonicum MN 110 were grown with P-stressed(0.05 mM-P) and control(1 mM-P) treatment under control$(400\;{\mu}l/L\;CO_2)$ and enrichment$(800\;{\mu}l/L\;CO_2)$ enviromental condition in the phytotron equipped with high density lamp$(1000\;{\mu}Em^{-2}S^{-1})$ and $28/22^{\circ}C$ temperature cycle for 35 days after transplanting(DAT). At 35 DAT, phosphorus deficiency decreased total dry mass by 64% in $CO_2$ enrichment condition, and 51% in control $CO_2$ condition. Total leaf area was reduced significantly by phosphorus deficiency in control and enriched $CO_2$ condition but specific leaf weight was increased by P deficiency. Phosphorus deficiency significantly reduced photosynthetic rate(carbon exchange rate) and internal $CO_2$ concentration in leaf in both $CO_2$ treatments, but the degree of stress was more severe under $CO_2$ enrichment condition than under control $CO_2$ environmental condition. In phosphorus sufficient plants, $CO_2$ enrichment increased nodule fresh weight and total nitrogenase activity(acetylene reduction) of nodule by 30% and 41% respectively, but specific nitrogenase activity of nodule and nodule fresh weight was not affected by $CO_2$ enrichment in phosphorus deficient plant at 35 DAT. Total nitrogen concentrations in stem, root and nodule tissue were significantly higher in phosphorus sufficient plant grown under $CO_2$ enrichment, but nitrogen concentration in leaf was reduced by 30% under $CO_2$ enrichment. These results indicate that increasing $CO_2$ concentration does not affect plant growth under phosphorus deficient condition and phosphorus stress might inhibit carbohydrate utilization in whole plant and that $CO_2$ enrichment could not increase nodule formation and functioning under phosphorus deficient conditions and phosphorus has more important roles in nodule growth and functioning under $CO_2$ enrichment environments than under ambient condition.

• Journal of Radiation Protection and Research
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• v.37 no.3
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• pp.149-158
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• 2012

In this paper, we measured the variations of radon concentrations in groundwater using low-level Liquid Scintillation Counter (LSC), an instrument for analyzing the alpha and beta radionuclides at its 10 sites around the Kumjung-Gu, north-western of Busan. Optimization of Pulse Shape Analyzer (PSA) to determinate the highest value of figure of merit (FM) was decided using Quantulus 1200 LSC with radium-226 source, the optimal PSA level was shown in the range of 100 to 110. The results show that the Minimum Detectable Activity (MDA) of radon concentrations is 0.61 $Bq{\cdot}L^{-1}$ for 20 minutes in PSA level. We find that the average radon concentration in groundwater is high in granitic rock area and low in volcanic rock area. (Biotite granite : 191.39 $Bq{\cdot}L^{-1}$, Micro graphic granite : 141.88 $Bq{\cdot}L^{-1}$, Adamellite : 92.94 $Bq{\cdot}L^{-1}$, Andesite (volcanic) : 35.35 $Bq{\cdot}L^{-1}$). No significant seasonal variation pattern is observed from the long-term variation analysis from 10 selected sites. We have not seen the significant correlation of radon concentration to groundwater temperature, atmospheric temperature, atmospheric pressure and rainfall. The concentration variation is probably caused by more complex factors and processes.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.395-402
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• 2017

Overuse of synthetic pesticides caused negative side-effects such as environmental contamination, development of insect pests' resistance, and effects on non-target organisms. Plant origin substances without/or with low mammalian toxicity have been considered as promising alternatives to the synthetic pesticides. Fumigant toxicity of the essential oil of Iranian Yarrow, Achillea millefolium L., was investigated against a cosmopolitan stored-product insect pest: saw-toothed grain beetle (Oryzaephilus surinamensis L.). Chemical profile of this essential oil was studied by Gas Chromatography-Mass Spectrometry. Tested concentrations were significantly effective to the mortality of insect pest. A positive correlation between essential oil concentrations and pest mortality were realized. LC50 value (lethal concentration needed to 50% mortality) was achieved as $17.977(16.195{\pm}20.433){\mu}l/l$ air. The main components were 1,8-Cineole (13.17%), nerolidol (12.87%), ${\alpha}$-cubebene (12.35%), artemisia ketone (6.69%), ${\alpha}$-terpineol (5.27%), alloaromadendrene oxide (4.71%) and borneol (3.99%). Terpenic compounds including monoterpene hydrocarbons (8.19%), monoterpenoids (44.23%), sesquiterpene hydrocarbons (21.69%) and sesquiterpenoids (22.24%) were 96.35% of the total identified compounds. Results indicated that the terpene-rich A. millefolium essential oil may be considered as a safe bio-agent in the O. surinamensis management.

• ETRI Journal
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• v.14 no.4
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• pp.35-42
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• 1992

본 고에서는 X.25 동기 프로토콜(1)을 이용한 KT-MAiL 서비스의 확장 네트워킹의 실현에 대해 기술하고, 많은 사용자에게 서비스를 제공하기 위한 KT-MAiL 호스트 시스팀과의 인터페이스 및 실현후의 패킷 전송 성능에 대해 기술하고자 한다.

• East Asian mathematical journal
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• v.35 no.1
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• pp.77-83
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• 2019

$L^1$-weight functions are investigated to give necessary conditions on the existence of nontrivial solutions for various types of scalar equations and systems of one-dimensional Minkowski-curvature problems.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 1998.08a
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• pp.35-39
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• 1998

• Journal of Korean Society of Environmental Engineers
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• v.35 no.7
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• pp.479-484
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• 2013

This study was performed to examine the effect of copper on the biodegradability, nitrification, denitrification and oxygen uptake rate (OUR) using batch reactor and continuous flow stirred tank reactor (CSTR) of anaerobic/anoxic/oxic ($A_2/O$). The results of this study can be summarized as follows. In the case of the effect of copper on organic treatment, the bad effect initiated when it was above 4.5 mg/L copper with batch reactor and above 2.0 mg/L copper with CSTR. Concerning the case on nitrification and removal of nitrogen, it showed bad effect when copper was above 4.5 mg/L with batch reactor for nitrification and 1.0 mg/L with CSTR for the removal of nitrogen. The bad effect on the removal of phosphorus began when it was 4.5 mg/L copper with batch reactor and 2 mg/L copper with CSTR. In the case of OUR, it decreased as microbial activity was affected when copper concentration was above 1.5 mg/L in both case of batch reactor and CSTR.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1162-1167
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• 2005

Livestock wastewater is known to be very difficult to treat because it contains highly non-biodegradable organic material. Thus the DOF(Dissolved Ozone Flotation) system and the PO2(Pressurized Ozone Oxidation) system were built at the livestock wastewater treatment plant, and characteristics of treatments were investigated in this paper. Suspended Solids(SS) removal efficiency was over 94% by DOF system. 90% of $COD_{Mn}$ was removed, from 620 mg/L down to 63 mg/L by the DOF-PO2 system. During the period of operation, $SCOD_{Cr}$ was removed an average of 82%, from 890 mg/L down to 160 mg/L. 96% of UV-254 absorbance was also removed. TP removal efficiency was over 98%, from 27 mg/L to 0.35 mg/L, and TN was also removed 68% along with suspended solids. It was possible to meet effluent standards of the livestock wastewater treatment plant by the DOF-PO2 system along with biological treatment.