• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1885-1889
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• 2012

Among 23 cytochrome P450s, CYP125A4 was proposed as a putative monooxygenase based on the high level of amino acid sequence homology (54% identity and 75% similarity) with the well characterized C27-steroid $Mycobacterium$ $tuberculosis$ CYP125A1. Utilizing MTBCYP125A1 as a template, homology modeling of SPCYP125A4 was conducted by Accelrys Discovery Studio 3.1 software. The modeled SPCYP125A4 structure with lowest energy value was subsequently assessed for its stereochemical quality and side-chain environment. The final model was generated by showing its active site through the molecular dynamics. The docking of steroids showed broad specificity of SPCYP125A4 with different orientation of ligand within active site facing the heme. One poses of C27-steroid with C26 facing the heme with distance of 3.734 ${\AA}$ from the Fe were predominant.

• 환경생물
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• 제29권2호
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• pp.98-106
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• 2011

마산만의 수질변화와 chlorophyll-$a$의 관계를 밝히고자 이 해역을 대표할 수 있는 4개 정점에서 2010년 2월부터 2010년 11월까지 강우와 기온을 포함한 기후학적 요인, 물리 화학적 요인, 그리고 chlorophyll-$a$의 변화를 집중 조사하였다. 그 결과, 수온, 염분, SS, 규산염은 정점별 차이를 보이지 않았으며, COD 및 DIN은 마산만 내만으로 갈수록 증가하였다. 시계열적으로는 여름철 집중 강우 시 마산만 지류 하천 및 낙동강을 통해 담수가 유입되면서 염분의 급강하 및 SS량과 COD의 증가가 나타났다. 영양염류 중 DIN은 여름철 집중강우 시 일시적으로 증가하는 양상을 제외하고는 낮은 농도를 보였고 DIP와 규산염 또한 DIN과 유사한 양상을 보였다. 마산만에서 식물플랑크톤 성장에 영향을 주는 영양염류는 봄철 중반까지 규소와 인이 성장제한인자로 작용하고, 늦봄부터 가을까지는 질소원이 주 성장제한요인으로 작용할 것으로 판단된다. 다중회귀분석을 실시한 결과, 늦겨울부터 봄철까지 chlorophyll-$a$ 농도는 수온, 염분, COD, DIP의 변화에 의해 영향을 받고 있었다. 여름철에는 봄철과 달리, 염분 및 COD, 강수량이 영향을 주고 있어, 여름철 집중강우에 따른 영향인자들에 의해 chlorophyll-$a$가 빠르게 변화됨을 알 수 있었다. 따라서 마산만 해역의 chlorophyll-$a$의 변화는 영양염류와 같은 화학적 인자의 영향과 함께, 수온 및 강수와 같은 물리적 인자에 의해 크게 영향을 받고 있다.

• 생태와환경
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• 제42권4호
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• pp.422-431
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• 2009

This study was to provide basic data for aquatic ecosystem research using fishes. Field sampling was carried out at five selected sites of Gap Stream, and fish samples, especially for a selection of sentinel species were collected three times in June, September, and October 2007. We analyzed total length distribution of Zacco platypus in relation with the season and the sampling sites, and then compared with total body weight, condition factor (K), and age distribution of the fish. The fish population data were compared with physico-chemical water quality, obtained from the Ministry of Environment, Korea. Water quality analysis showed a significant nutrient enrichment, based on total nitrogen (TN) and total phosphorus (TP), and organic matter pollution, based on biological oxygen demand (BOD) and chemical oxygen demand (COD) in the Site 5, which is directly influenced by wastewater disposal plant (WDP). Population analysis of the sentinel species showed that the total number of individuals, age distribution, and the population size-structure were influenced by the effluents from the WDP, and that reproductive failure of young-age population were evident in Site 5. According to the relation analysis of total weight to K, the disturbed population was mainly attributed to combined effects of habitat modifications and chemical degradations. Regression analysis of K values against water quality parameters showed significant (p<0.05) positive relations with nutrient and organic matter contents. Our data suggest that the population structure using a sentinel fish species reflected the ambient water quality in the stream and that diagnosis of aquatic ecosystem health using Z. platypus population may be practical for water resource and ecosystem conservations.

• 한국유기농업학회지
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• 제28권2호
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• pp.235-250
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• 2020

작물 재배 방법이 토양의 미생물 군집 특성과 화학성에 미치는 영향을 검토하였다. 이를 위해서 다섯 곳의 고추 관행 재배지와 다섯 곳의 유기농 재배지 토양을 채취한 후, 16S rRNA 유전자 기반의 파이로시퀀싱 기법으로 미생물 군집을 조사하였다. 분석 결과 총 22개의 세균 문으로 구성되었으며 Proteobacteria 문(33.0 ± 5.7%), Actinobacteria 문(19.9 ± 9.7%) 및 Firmicutes 문(13.6 ± 5.0%)이 우점하였고, 이들은 전체 상대풍부도의 66%를 차지하였다. 고추 관행 재배지와 유기농 재배지의 미생물 군집 분포를 비교했을 때 전반적으로 서로 다른 군집 특성을 나타내었다. 또한 관행 재배 토양에서는 Actinobacteria 문과 Chloroflexi 문이 상대적으로 풍부하였고, 유기 재배 토양에서는 Proteobacteria 문과 Firimicutes 문이 상대적으로 풍부하였다. 특히 Streptomyces 속과 Bacillus 속의 상대풍부도는 관행 재배 토양과 유기 재배 토양 간에 상당한 차이를 보였다. 또한 토양 화학 성에 의하여 세균 군집 변화가 관찰되었는데, Proteobacteria 문의 Rhizobiales 목과 Actinobacteria 문의 Streptomyces 속은 pH에 의해 세균 군집이 바뀌었고, Firimicutes 문의 Bacillus 속은 유기물 함량에 의해 군집 분포가 바뀌었다. 본 연구결과는 재배관리에 따른 토양의 물리-화학성의 변화가 미생물 군집 분포에 뚜렷하게 관련(p<0.05)되어 있다는 것을 보여주었다.

• 한국약용작물학회지
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• 제8권3호
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• pp.274-282
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• 2000

사람주나무 (Sapium japonicum) 종실유의 물리 화학적 특성과 구성성분을 다양한 분석법으로 구명하였다. 사람주나무의 종실유를 구성하는 지질은 중성지질이 93% 로 가장 높고 , glycolipid 가 4.9%, phospholipid가 1.3%로 나타났다. GC 분석 결과 사람주나무의 종실에는 9종의 지방산이 존재하였다. 종실유에서 지방산의 함량은 저장기간 등에 따라 약간의 차이를 보였다. 종실유 중 3종의 지질은 silica open column을 통해 분획하고, 이들의 지방산 성분을 조사하였다. 3종의 지질 중 주요 지방산은 linoleic acid와 linolenic acid로 나타났다. 채취직후의 종실유에서 지방산의 함량은 저장된 종실유의 지방산에 비해 전반적으로높았다. 이상의 결과로 보아 사람주나무의 종실유는 화장품, 세정제, 의약품 등으로의 이용이 기대된다.

• Journal of the Korean Wood Science and Technology
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• 제50권5호
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• pp.325-337
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• 2022

Grewia serrulata fibres were chemically treated with 3%, 6%, and 9% NaOH for the duration of 4 h. Additionally, the NaOH-treated fibres were also treated with 3 - (trimethoxysilyl) propyl methacrylate (silane). Properties such as density and tensile strength of the treated fibres were compared against the untreated fibres. The highest density was obtained in the case of 9% NaOH + silane treated fibres, which was 26.47% higher than untreated fibres, implying effective removal of hemicellulose. Likewise, the highest tensile strength was also obtained in the case of 9% NaOH + silane treated fibres. The increment observed in the tensile strength of the natural fibres was related to the removal of impurities, hemicellulose, and stress-raisers as well as deposition over the fibre surface that smoothed it. These observations were further validated by estimating changes in chemical constituents due to chemical treatment along with characterization techniques such as scanning electron microscopy and thermogravimetric analysis.

• 한국지형학회지
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• 제24권3호
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• pp.27-45
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• 2017

At the upper part of terrace deposits at Jeongdongjin area, there is a structure in which reddish brown and grayish white layers laying horizontally. Previous studies have reported the existence of these structures within the deposits and suggested the theoretical background related to the formation process. However, the analysis of physical properties and chemical composition such as particle size, classification, etc. of the materials constituting the reddish brown and grayish white layers is scarcely done. In this study, the physico - chemical properties of gray - white and reddish brown beds are investigated. The mean grain size of the particles was less than $4{\varphi}$ in both layers and the reddish brown layer was more coarse. The results shows that the sorting of the grayish white layer is better. The chemical composition of both layers shows that the average concentration of $SiO_2$, $Al_2O_3$ and $K_2O$ of the grayish white layer was higher than those of the reddish brown layer. The concentration of $Fe_2O_3$ of reddish brown lyaer was 3 times higher than those of the grayish white layer. The degree of chemical weathering (CIA) is 90 or so in both the reddish brown and grayish white layers, indicating a significant level of chemical weathering. In conclusion, reddish brown layers had been formed by the processes related to the migration of iron and the migration of water that induced aggregation after the formation of sediments (psudo-gleization). In this study area, a vertical layer of grayish white which cuts off horizontal reddish brown and grayish white color was found. The vertical layer or wedge similar to a ice-wedge or columnar structure that in a cold environment, and there is a difference in shape and size. The vertical layer appears to have occurred three or more cycles. The vertical layers begin to form at a certain height within the outcrop and descend downwards, which of course is difficult to see as directing certain times.

• Nuclear Engineering and Technology
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• 제35권5호
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• pp.378-386
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• 2003

Recently failures of nuclear fuel rods in Korean nuclear power plants were reported and their failure causes have been investigated by using PIE techniques. Destructive and physico-chemical examinations reveal that the clad hydriding phenomena had caused the rod failures primarily and secondarily in each case. In this study, the basic mechanisms of the primary and the secondary hydriding failures are reviewed, PIE data such as cladding inner and outer surface oxide thickness and the restructuring of the fuel pellets are analyzed, and they are compared with the predicted behaviors by a fuel performance code. In addition, post-defected fuel behaviors are reviewed and qualitatively analyzed. The results strongly support that the hydriding processes, primary and secondary, played critical roles in the respective fuel rods failures and the secondary hydriding failure can take place even in the fuel rod with low linear heat generation rate.

• 생약학회지
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• 제25권3호
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• pp.293-304
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• 1994

In order to estimate accurate originality of the important crude drugs, Gastrodia, Dendrobium, Bletilla and Cremastra spp. were investigated comparing their morphological, anatomical and physicochemical characteristics and antibacterial, antifungal activities. The results of the studies as follows: 1. In morphological and anatomical studies, Korean Gastrodia contained more mucilage duct and symbiotic fungi than imported Gastrodia. Korean Dendrobium contained starch grains but without starch grains in the imported Dendrobium from China enclosed with thicken silicified wall. The corm of Cremasta appendiculata contained raphides of bundles with mucilage while the bulbs of Tulipa edulis contained several various starch grains form. 2. In physiological and TLC analysis, crude drugs in Orchidaceae contained common constituents with fluorescence and much mucilage. 3. The EtOH extracts of Gastrodia, Dendrobium, Bletilla, Cremastra showed antibacterial activities against B. subtilis and E. coli (Dendrobium>Gastrodia>Bletilla>Cremastra). But, no antifungal activities against C. albicans, A. niger were observed.

• 생약학회지
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• 제2권3호
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• pp.121-123
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• 1971

In series of the the development of domestic natural products, the studies were conducted to evaluate the pharmacologically active substances of the roots of Pursatilla koreana, which is a specific plant, widely distributed in this country and known to be effective as antiinflammatory, hemostatic and antidysentric agents in oriental remedies. From the hydrolysis of methanol extract of the root, a triterpenic substance was isolated. It was identified as $hederagenin\;C_{30}H_{48}O_4,\; m.p.\;333^{\circ}{\sim}334^{\circ}$, by the m.m.p. with authentic sample, elemental analysis, IR, mass spectra and the other physico-chemical experimentations.