• Nuclear Engineering and Technology
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• 제30권5호
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• pp.435-443
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• 1998

Leak-before-break(LBB) approach has been shown to be both cost effective and risk reductive when applied to high energy Piping in nuclear Power Plants. For the Korean Next Generation Reactor (KNGR) development, LBB application is considered for the Main Steam Line(MSL) piping inside containment. Unlike the primary system leakages, the MSL leak detection systems must be based on principles other than radioactivity measurements. Among humidity, heat and acoustic noise currently being considered as indicators of leakage, we explored humidity as an effective one and developed ceramic-based humidity sensor which can be qualified for LBB applications. The ceramic material, sintered and annealed MgCr$_2$O$_4$-TiO$_2$, is shown to increase its electrical conductivity drastically upon water vapor adsorption over the entire temperature range of interest. With this ceramic sensor specimen, we suggested installation-inside-the-piping method by which we can detect leakage more rapidly and sensitively. In this paper, we describe the progress in the development and characterization of ceramic humidity sensor for the LBB application to the MSL of KNGR.

• 대한화학회지
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• 제43권3호
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• pp.294-301
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• 1999

제미널 비스포스폰에이트기를 포함하는 화합물들은 칼슘과 관련된 다양한 질병들 즉 Paget's disease, 악성칼슘과다증, 골다공증등에 약효가 있는 것으로 잘 알려져 있다. 이러한 화합물을 합성하기 위하여 먼저 methylvhyl ketone과 triethylphosphite를 가지고 5배 위된 옥사포스포린 화합물을 합성하였다. 이렇게 합성된 5배위 결합된 옥사포스프린을 bromination, 응용된 Westheimer반응, 그리고 가수분해를 통해서 Y-keto-bisphosphonates를 얻을 수 있었다. 그리고 이 Y-ketobisphosphonates 화합물들은 환원성아민화를 이용해서 N-알킬화된 Y-aminobisphosphonates로 전환하였다. 이렇게 합성된 2차아민 형태의 N-알킬화된 Y-aminobisphosphonates는 N-알킬화반응으로 3차아민을 만든 후 N,N디알킬화된Y-aminobisphosphonates 화합물로 합성할 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제10권6호
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• pp.737-752
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• 2000

Wood-rotting basidiomycetous fungi are the most efficient degraders of lignin on earth. The white-rot fungus Phanerochaete chrysosporium has been used as a model microorganism in the study of enzymology and its application. Because of the ability of the white-rot fungus to degrade lignin, which has an irregular structure and large molecular mass, this fungus has also been studied in relation to degrading and mineralizing many environmental pollutants. The fungus includes an array of enzymes, such as lignin peroxidase (LiP), manganese-dependent peroxidase (MnP), cellobiose:quinone oxidoreductase, and $H_2O_2$-producing enzymes and also produces many other components of the ligninolytic system, such as veratryl alcohol (VA) and oxalate. In addition, the fungus has mechanisms for the reduction of degradation intermediates. The ligninolytic systems have been proved to provide reductive reactions as well as oxidative reactions, both of which are essential for the degradation of lignin and organopollutants. Further study on the white-rot fungus may provide many tools to both utilize lignin, the most abundant aromatic polymer, and bioremediate many recalcitrant organopollutants.

• Environmental Engineering Research
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• 제25권3호
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• pp.274-280
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• 2020

The marine sediment sustains from the anoxic condition due to increased nutrients of external sources. The nutrients are liberated from the sediment, which acts as an internal source. In hypoxic environments, anaerobic respiration results in the formation of several reduced matters, such as N₂ and NH₄⁺, N₂O, Fe²⁺, H₂S, etc. The experimental results have shown that nitrogen and sulfur played an influential, notable role in this biogeochemical cycle with expected chemical reductions and a 'diffusive' release of present nutrient components trapped in pore water inside sediment toward the bulk water. Nitate/ammonium, sulfate/sulfides, and ferrous/ferric irons are found to be the key players in these sediment-waters mutual interactions. Organonitrogen and nitrate in the sediment were likely to be converted to a form of ammonium. Reductive nitrogen is called dissimilatory nitrate reduction to ammonium and denitrification. The steady accumulation in the sediment and surplus increases in the overlying waters of ammonium strongly support this hypothesis as well as a diffusive action of the involved chemical species. Sulfate would serve as an essential electron acceptor so as to form acid volatile sulfides in present of Fe³⁺, which ended up as the Fe²⁺ positively with an aid of the residential microbial community.

• 약학회지
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• 제42권5호
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• pp.500-506
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• 1998

Steroidal 2${\beta},\;3{\beta}$--epoxy compound was prepared from asiaticoside via six steps and reduced regioselectively with lithium aluminum hydride. Epoxide ring opening furnished 9 as a sole product at reflux condition through axial hydride attack at C-3.

• Advances in Traditional Medicine
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• 제3권1호
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• pp.29-33
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• 2003

Sense-line (SL), a dietary functional food, is our invention for weight loss. To evaluate such an effect of SL, we analyzed the plasma levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and weight changes after rats were fed on high fat diet with SL for 20 days. Plasma total cholesterol level and LDL-cholesterol level was decreased by 52% and 91.89% in 5% SL treated group and by 13% and 51.45% in 10% SL treated group, respectively. But HDL-cholesterol was not changed. In addition, the weight was significantly lower in SL group than in high-fat diet group (P<0.05). Our findings indicate that SL may contain compounds with actions, which can treat blood circulatory trouble as well as overweight.

• 대한화학회지
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• 제37권1호
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• pp.136-140
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• 1993

새로운 methotrexate 중간체인 diethyl N-[4-{[(2,4-diamino-6-yl)methyl]-amino}benzoyl]-L-glutamate(10)를 합성하기 위하여 p-nitrobenzoic acid를 chlorination한 다음 L-glutamic acid와 coupling하고 이를 esterification한 후, 환원과 methylation시켜 diethyl N-(4-methylaminobenzoyl)-L-glutamate(7)를 합성하였다. 이 화합물(7)을 DMF 존재하에서 NaH와 allyl chloride를 가하여 allylation한 다음 여기에 $IN_3$ addition 반응으로 diethyl-p-[N-(2-azido-3-iodopropyl)-N-methyl]aminobenzoyl-L-glutamate(9)를 합성하였다. 이 화합물(9)을 2,4,5,6-tetraaminopyrimidine hydrochloride와 cyclization시켜 methotrexate diethylester를 얻었다.

• Bulletin of the Korean Chemical Society
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• 제26권10호
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• pp.1533-1538
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• 2005

We have determined the contents of monosaccharides in the hydrolysates of some yogurt and orange juice products by derivatizing monosaccharides with p-aminobenzoic acid ethyl ester (ABEE). The separation of the ABEE-derivatized monosaccharides was efficiently carried out by HPLC using a microcolumn packed with the Alltima $C_{18}$ stationary phase. The concentrations of monosaccharides were determined based on the measured peak area/height counts. ABEE derivatization of fructose and its detection have never been successfully carried out before this work. In this study, two peaks were observed in a fixed ratio for ABEE-fructose, and the ratio was maintained over a wide range of fructose concentration. In order to prove the validity of the above method, we compared the concentrations of glucose, galactose and fructose determined by ABEE derivatization and UVD (ultraviolet detector) chromatography with those determined by RID (refractive index detector) chromatography without derivatization. The determined concentrations of monosaccharides obtained from the two chromatographic methods were found close to each other within acceptable error ranges.

• Macromolecular Research
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• 제11권5호
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• pp.382-386
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• 2003

Reductive amination of N-succinyl-chitosan (1) and lactose using sodium cyanoborohydride in 1/15 M phosphate buffer (pH 6.0) for 6 d was suitable for the preparation of lactosaminated N-succinyl-chitosan (2). At 8, 24 and 48 h after i.v. administration of fluorescently labeled 1 (1') or 2 (2'), Peyer's patch, mesenteric lymph nodes, testes, prostate, preputial grand, intestine (small intestine plus cecum), femoral muscle, backbone and peritoneum were taken. Peyer's patch and mesenteric lymph nodes were put together as lymph nodes. Over 10% of dose/g tissue was distributed to the prostate and lymph nodes at 48 h post-administration in both l' and 2'.2' was easily distributed into not only the liver but also prostate, intestine, preputial gland and lymph nodes. Although galactose receptors are known to exist not only on the liver parenchymal cells but also on prostate and testes, the selective distribution of 2' into the prostate and the testes were not observed clearly. This study suggested that 1 and 2 should have possibilities for both the prevention and cure of lymph node metastasis as drug carriers.

• Archives of Pharmacal Research
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• 제21권4호
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• pp.429-435
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• 1998

Lectins and its A- and B-chains from Korean mistletoe (Viscum album var. coloratum) were isolated by affinity chromatography on the Sepharose 4B modified by lactose-BSA conjugate synthesized by reductive amination of ligand (lactose) to .epsilon.-amino groups of lysine residues of spacer (BSA) after reduction by $NaCNBH_3$. The lactose-BSA conjugate was coupled to Sepharose 4B activated by cyanogen bromide. The molecular weight determined by SDS-PAGE were a 31 kD of A-chain and a 35kD of B-chain. Amino acid analysis and N-terminal sequencing were performed. The effects of pH, temperature and guanidine chloride on the conformation of the lectin were investigated by measuring its intrinsic fluorescence and compared with its hemagglutinating activities. Blue shift was detected on the acidic pH and there was a close relationship between activities and conformation of the lectin. Under denaturing conditions, the tryptophan emission profile of lectin showed typical denaturaiional red shift which also correspond to the conformations and activity of lectin.