• 한국가스학회:학술대회논문집
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• 1997.09a
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• pp.127-132
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• 1997

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.108.1-108
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• 2003

Soil metagenome is untapped total microbial genome including that of the majority of unculturable bacteria present in soil. We constructed soil metagenomic library in Escherichia coli using DNA directly extracted from two different soils, pine tree rhizosphere soil and forest topsoil. Metagenomic libraries constructed from pine tree rhizosphere soil and forest topsoil consisted of approximately 33,700 clones and 112,000 clones with average insert DNA size of 35-kb, respectively. Subsequently, we screened the libraries to select clones with antimicrobial activities against Saccharomyces cerevisiae and Agrobacterium tumefaciens using double agar layer method. So far, we have a clone active against S. cerevisiae and a clone active against A. tumefaciens from the forest topsoil library. In vitro mutagenesis and DNA sequence analysis of the antifungal clone revealed the genes involved in the biosynthesis of antimicrobial secondary metabolite. Metagenomic libraries constructed in this study would be subject to search for diverse genetic resources related with useful microbial products.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.805-812
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• 1989

An efficient diagnostic approach for real-time operation aiding expert system in chemical process plants is discussed. The approach is based on the hybrid of the simplified symptom tree(SST) and the fault consequence digraph(FCD), representation of propagation patterns of fault states. The SST generates fault hypothesis efficiently and the FCD resolve the real fault accurately. Frame based knowledge representation and object-oriented programming make diagnostic system general and efficient. Truth maintenance system enables robust pattern matching and provides enhanced explain facilities. A prototype expert system for supports operation of naphtha furnaces process, called OASYS, has been built and tested to demonstrate this methodology. Utilization of diversified process symbolic data, produced using dynamic normal standards, overcomes the problem of qualitative Boolean reasoning and enhance the applicability.

• Journal of the Korean Society of Safety
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• v.10 no.1
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• pp.56-63
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• 1995

Two methods of the numerical method of CPQRA(Chemical Process Quantitative Risk Analysis) and the manual method of IAEA(International Atomic Energy Agency) were used to estimate the individual risk and societal risk around the chemical plant. Where, the CPQRA is introduced to verify the theoritical background of the manual of international atomic energy agency. The Gaussian plume model which has a weather stability class D with velocity of 5m/s was applied to calculate dispersion of hazard material. Also, 8-point method was employed to the effects of accidents for wind distribution. Furthermore, historical record, FTA(Fault Tree Analysis) and ETA(Event Tree Analysis) were used to estimate the probability or frequency of accidents. Eventually, the individual risk shows isorisk contour and the societal risk shows F-N curve around hazard facility, especially in chemical plants. Caulculated results, which both individual and societal risk, by using IAEA manual show simillar results to those of calculation by numerical method of CPQRA.

• Macromolecular Research
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• v.17 no.7
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• pp.469-475
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• 2009

We investigated the feasibility of dispersion polymerization without any stabilizer, which has been considered essential for ensuring colloidal stability. By employing small amounts of a lyophilic comonomer, 4-vinyl pyridine, styrene was successfully polymerized by dispersion polymerization in aqueous alcohol without stabilizer to afford stable poly(styrene-co-4-vinyl pyridine) copolymer microspheres. The stable microspheres were produced in the 4-vinyl pyridine range of 2-15 wt% to styrene. Without 4-vinyl pyridine, severely coagulated particles were obtained, implying that the poly(4-vinyl pyridine) moiety endowed colloidal stability. The polymerization kinetics, behavior, and properties of the ultimate particles showed general features of dispersion polymerization. The study results suggest that stabilizer- tree dispersion polymerization is possible, thereby facilitating the synthesis of impurity(stabilizer)-tree polymer particles.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.748-756
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• 2006

We propose a genome-scale clustering approach to identify whole genome relationships using the functional groups given by the Kyoto Encyclopedia of Genes and Genomes Orthology (KO) database. The metabolic capabilities of each organism were defined by the number of genes in each functional category. The archaeal, bacterial, and eukaryotic genomes were compared by simultaneously applying a two-step clustering method, comprised of a self-organizing tree algorithm followed by unsupervised hierarchical clustering. The clustering results were consistent with various phenotypic characteristics of the organisms analyzed and, additionally, showed a different aspect of the relationship between genomes that have previously been established through rRNA-based comparisons. The proposed approach to collect and cluster the metabolic functional capabilities of organisms should make it a useful tool in predicting relationships among organisms.

• Journal of the Korean Chemical Society
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• v.15 no.6
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• pp.370-377
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• 1971

The Carbon-14 content in surface air at Seoul, Korea, was measured from February 1970 to August 1971 and a Larix Leptolepis, Gordon tree (Ip-Gal Namu) grown at Kwang-Nung, Kyunggi-Do, Korea, having 37 growth rings, was assayde for $^{14}C$. From the results of the surface air study, it was calculated that during the above period the inventory of excess $^{14}C$ in the atmosphere decreased with a half-time of 4.6 years. The overall yearly decrease was also checked. The tree-ring study showed that the tree's atmosphere was affected by $^{14}C$ from nuclear tests after 1956. In one study, atmospheric $CO^2$ samples were collected bi-monthly by the absorption of $CO^2$ in alkaline hydroxide solution. In the other, 5 year annual growth rings were assayed for radiocarbon. For the radioactivity measurement, carbon atoms in samples were converted to carbon atoms of benzene. The resulting benzene was taken as primary solvent for liquid scintillation counting.

• Journal of the Korean Chemical Society
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• v.65 no.5
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• pp.327-332
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• 2021

Shiranuhi is a fruit of Citrus species widely cultivated in Jeju Island, Korea. From an extract of Shiranuhi tree branches were identified five polymethoxyflavones possessing anti-inflammatory effects; nobiletin (1), sinensetin (2), tetramethylscutellarein (3), 6-hydroxy-5,7,3',4'-tetramethoxyflavone (4) and 5-desmethylsinensetin (5). Evaluation of the activities was conducted by monitoring the production of nitric oxide (NO), prostaglandin E₂ and pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) as well as the levels of iNOS and COX-2 protein expression in LPS-induced RAW264.7 cells. Among the isolates, the compound 4 exhibited the most significant NO inhibition, and suppressed the levels of iNOS and related cytokines. Therefore, it was suggested that the extract and constituents from Shiranuhi tree branches could be useful as anti-inflammatory ingredient.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.267-267
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• 2019

The purpose of this study is to understand the risk of chemical product, Styrene Monomer(SM), shipped in a vessel. SM is harmful chemical product which can make injury, explosion and/or fire in a vessel. The understand of SM risk is very important to protect seafarer's body and vessel safety. This research can be expected that the understanding of SM risk by a seafarer's to prevent accidents by SM explosion/fire. In this study we used event tree analysis method using chemical reaction cased by explosion. As a result, we founded various chemical reaction and visualization for explosion path.

• Journal of Climate Change Research
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• v.6 no.3
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• pp.249-256
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• 2015

This study was conducted to investigate the effects of different levels and types of nitrogen fertilizer on seedlings and soil chemical properties in a semi-arid area, Mongolia. 2-year-old Populus sibirica and 4-year-old Ulmus pumila seedlings were planted in May 2014. Six treatments with three levels of nitrogen (low-level: urea $5g\;tree^{-1}$; medium-level: urea $15g\;tree^{-1}$, ammonium sulfate $33g\;tree^{-1}$, urea $15g\;tree^{-1}$ with potassium phosphate $10g\;tree^{-1}$; high-level: urea $30g\;tree^{-1}$) were applied and for the medium-level of nitrogen, different types of fertilizer were treated. Survival rate, root collar diameter (RCD) growth rate, leaf nitrogen concentration of seedlings, and soil chemical properties were determined in August 2014. The seedling survival rate of both species decreased as the level of nitrogen increased. This result can be explained by water stress caused by nitrogen fertilization in arid regions. The RCD growth rate of P. sibirica was significantly decreased by the treatment of high-level of nitrogen due to excessive nitrogen fertilization, and was increased by the treatment of ammonium sulfate due to sulfur which might promote nitrogen uptake. The leaf nitrogen concentration of P. sibirica did not change by the treatment of low-level of nitrogen, and was increased by the treatment of medium-level of nitrogen. There were no significant differences in the RCD growth rate and the leaf nitrogen concentration of U. pumila among the six treatments. None of soil chemical properties was affected by nitrogen fertilization. Overall, the low-level of nitrogen showed no effect on seedlings and soil chemical properties, except on survival rate of U. pumila and the high-level of nitrogen was considered excessive fertilization. Continuous monitoring of medium-level nitrogen fertilization including the ammonium sulfate, which increased early growth of seedlings, would be needed to elucidate the effect of fertilization on seedling growth and soil properties in a semi-arid region.