• 한국작물학회지
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• 제38권3호
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• pp.245-252
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• 1993

광합성 전자전달 억제물질에 대한 빠른 검색 방법을 모색하기 위하여 녹색배양 세포인 광학적 자가 영양세포(PA)를 이용하여 실용화된 제초제 및 4종의 잡초 추출액으로 부터 PA세포의 반응을 조사하였다. 녹색배양 세포인 담배 및 우산이끼 PA세포는 타가 영양세포에 비하여 광합성 전자전달 저해형 제초제들은 700배 이상 높은 감수성을 나타내었으며 호르몬 작용형 제초제인 2, 4-D는 감수성의 차가 8배로 낮게 나타났다. 우산이끼 PA세포는 약제 농도간의 범위(0.01～0.9${\mu}$M)가 좁아 약제선발시 타 배양 세포에 비하여 좋은 재료임을 암시하였으며, 광합성 전자전달 저해약제에 대해서 힐(hill)반응과 동일하게 광합성 산소발생 억제정도인 PI$_{50}$에서 강한 활성을 나타내었다. 잡초 중 여뀌 추출액 10% 처리시 PA배양 세포의 엽록소 함량이 가장 낮았고, 광합성 산소발생 억제율이 가장 높았다. 수용 및 MeOH액으로 추출한 10% 여뀌 추출액을 반응용액 3ml에 300${\mu}$l 반응시 우산이끼 PA배양세포에 대해 각각 60%, 100% 광합성 산소발생 억제효과가 있었다. 이상의 결과에서 PA세포들은 광합성 전자전달 저해형 약제에 대하여 빠르고 민감한 검색수단으로서 좋은 재료가 될 수 있다고 생각한다.다.

• BMB Reports
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• 제31권1호
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• pp.25-30
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• 1998

Kinetic studies of L-Alanine dehydrogenase from Bacillus subtilis-catalyzed reactions in the presence of $Zn^{2+}$ were carried out. The substrate (L-alanine) saturation curve is hyperbolic in the absence of the metal ion but it becomes sigmoidal when $Zn^{2+}$ is added to the reaction mixture indicating the positive cooperative binding of the substrate in the presence of zinc ion. The cooperativity of substrate binding depends on the xinc ion concentration: the Hill coefficients ($n_H$) varied from 1.0 to 1.95 when the zinc ion concentration varied from 0 to $60\;{\mu}m$. The inhibition of AlaDH by $Zn^{2+}$ is reversible and noncompetitive with respect to $NAD^+$ ($K_i\;=\;5.28{\times}10^{-5}\;M$). $Zn^{2+}$ itself binds to AlaDH with positive cooperativity and the cooperativity is independent of substrate concentration. The Hill coefficients of substrate biding in the presence of $Zn^{2+}$ are not affected by the enzyme concentration indicating that $Zn^{2+}$ binding does not change the polymerization-depolymerization equilibria of the enzyme. Among other metal ions, $Zn^{2+}$ appears to be a specific reversible inhibitor inducing conformational change through the intersubunit interaction. These results indicate that $Zn^{2+}$ is an allosteric competitive inhibitor and substrate being a non-cooperative per se, excludes the $Zn^{2+}$ from its binding site and thus exhibits positive cooperativity. The allosteric mechanism of AlaDh from Bacillus subtilis is consistent with both MWC and Koshland's allosteric model.

• 한국식품영양학회지
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• 제10권1호
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• pp.53-59
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• 1997

Aspergillus fumigatus IFO 5840이 생산하는 cytosine deaminase에 미치는 cytosine analogue의 영향을 조사하여 다음의 결과를 얻었다. 1. Cytosine deaminase의 강한 저해를 나타내는 cytosine analogue는 2-thiouracil, 2-thiocytosine, 2-mercaptopyrimidine, 및 6-azacytosine이었다. 2. 본 효소에 대한 2-thiocytosine 및 6-azacytosine의 50% 효소활성 저해농도(HIC)는 각각 0.80mM과 1.15mM이었다. 3. 2-thiocytosine은 일정한 수준에서 본 효소의 반응을 정지시키는 반면, 6-azacytosine은 반응시간에 비례하여 일정한 비율로 저해하였다. 4. 2-thiocytosine과 6-azacytosine은 cytosine이나 5-fluorocytosine의 기질 종류에 관계없이 본 효소의 저해제로 작용하였으며 2-thiocytosine이 6-azacytosine보다 약 2배 정도의 높은 저해를 나타내었다. 5. cytosine을 기질로 하였을 경우, 2-thiocytosine과 6-azacytosine에 의해 경쟁적 저해를 나타내며 이들에 대한 Ki값은 각각 4.5$\times$10-4M과 1.756$\times$10-3M이었으며 cytosine, 2-thiocytosine 및 6-azacytosine에 대한 Hill 계수(Hn)는 각각 1.80, 1.81, 2.45로 나타났다.

• The Plant Pathology Journal
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• 제26권2호
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• pp.198-202
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• 2010

A study was conducted to find out the relationship of physico-chemical properties (viz. organic carbon(OC), pH, electrical conductivity, nitrogen, phosphorus and potassium content) of ginger growing soil with incidence percentage of rhizome rot and wilt disease complex of ginger. Organic carbon content and pH of the ginger soil contributed significantly (93%) in the prediction of ginger rhizome rot and wilt disease complex incidence with negative correlation. Soil having weak acidic reaction with OC percent greater than 2.25 was observed to have the lower average incidence of the disease.

• 생약학회지
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• 제20권2호
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• pp.83-87
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• 1989

The alkaloids of thirty five Korean plants which belong to Rhamnaceae, Sterculiaceae, Celastracea, Urticaceae and Rubiaceae were screened. Plant was extracted and solvent fractionated to yield ether soluble alkaloidal fraction and butanol soluble fraction. Each fraction was subjected to alkaloidal test by Dragendorff's reaction. The result showed eighteen plants strong positive, fourteen weak and six negative to alkaloidal test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.65-84
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• 2002

The Observational Method proposed by Terzaghi can be applied for the safe and economic construction projects where the exact prediction of the behavior of the structures is difficult as in the underground excavation. The method consists of measuring lateral displacement, ground settlement and axial force of supports in the earlier stage of the construction and back analysis technique to find the best fit design parameters such as earth pressure coefficient, subgrade reaction etc, which will minimize the gap between calculated displacement and measured displacement. With the results, more reliable prediction of the later stage can be obtained. In this study, back analysis programs using the Direct Method, based on the Hill Climbing Method were made and evaluated, and to overcome the limits of the method, Genetic Algorithm(GA) was applied and tested for the actual construction cases.

• Journal of Ginseng Research
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• 제35권1호
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• pp.60-68
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• 2011

The chemical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity changes of ginsenoside $Rb_1$-glycine and ginsenoside $Rg_1$-glycine mixtures by Maillard reaction were investigated to identify the role of Maillard reaction in the increased antioxidant activity of ginseng by heat-processing. The DPPH radical scavenging activity of $Rg_1$-glycine mixture was more strongly increased by heat-processing than that of $Rb_1$-glycine mixture. From the analyses of ginsenosides, $Rb_1$ was gradually changed into 20(S)-$Rg_3$, 20(R)-$Rg_3$, $Rk_1$ and $Rg_5$ by heat-processing. $Rg_1$ was gradually changed into 20(S)-$Rh_1$, 20(R)-$Rh_1$, $Rk_3$ and $Rh_4$ by heat-processing. However, the generation of these less-polar ginsenosides was not related to the increased DPPH radical scavenging activity of $Rb_1$-glycine and $Rg_1$-glycine mixtures because their DPPH radical scavenging activities were already significantly increased when dried at $50^{\circ}C$, which temperature induce no structural changes of ginsenosides. In the comparison of browning compound levels of $Rg_1$-glycine and $Rb_1$-glycine mixtures, the extents of Maillard reaction were positively correlated with their increased free radical scavenging activities. Based on the chemical and DPPH radical scavenging activity changes of $Rg_1$-glycine and $Rb_1$-glycine mixtures by heat-processing, we clearly identified that the increased free radical scavenging activity of ginsenoside is mediated by the Maillard reaction between sugar moiety of ginsenoside and amino acid.

• 한국분말재료학회지
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• 제6권4호
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• pp.314-319
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• 1999

The solid state reaction by mechanical alloying(MA) generally proceeds by lowering the free energy as the result of a chemical reaction at the interface between the two adjacent layers. However, Lee et $al.^{1-5)}$ reported that a mixture of Cu and Ta, the combination of which is characterized by a positive heat of mixing of +2kJ/mol, could be amorphized by mechanical alloying. This implies that there exists an up-hill process to raise the free energy of a mixture of pure Cu and la to that of an amorphous phase. It is our aim to investigate to what extent the MA is capable of producing a non-equilibrium phase with increasing the heat of mixing. The system chosen was the ternary $Cu_{30}Ta_{ 70-x}Mo_ x$ (x=35, 10). The mechanical alloying was carried out using a Fritsch P-5 planetary mill under Ar gas atmosphere. The MA powders were characterized by the X-ray diffraction with Cu-K $\alpha$ radiation, thermal analysis, electron diffraction and TEM micrographs. In the case of x=35, where pure Cu powders were mixed with equal amount of pure Ta and Mo powders, we revealed the formation of bcc solid solution after 150 h milling but its gradual decomposition by releasing fcc-Cu when milling time exceeded 200 h. However, an amorphous phase was clearly formed when the Mo content was lowered to x=10. It is believed that the amorphization of ternary $Cu_{30}Ta_{60}Mo_{10}$ powders is essentially identical to the solid state amorphization process in binary $Cu_{30}Ta_{70}$ powders.

• Journal of Ginseng Research
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• 제39권3호
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• pp.274-278
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• 2015

Background: Steaming of ginseng is known to change its chemical composition and biological activity. This study was carried out to investigate the effect of different steaming time-scales on chemical constituents and antiproliferative activity of Vietnamese ginseng (VG). Methods: VG was steamed at $105^{\circ}C$ for 2-20 h. Its saponin constituents and antiproliferative activity were studied. The similarity of chemical compositions between steamed samples at $105^{\circ}C$ and $120^{\circ}C$ were compared. Results: Most protopanaxadiol and protopanaxatriol ginsenosides lost the sugar moiety at the C-20 position with 10-14 h steaming at $105^{\circ}C$ and changed to their less polar analogues. However, ocotillol (OCT) ginsenosides were reasonably stable to steaming process. Antiproliferative activity against A549 lung cancer cells was increased on steaming and reached its plateau after 12 h steaming. Conclusion: Steaming VG at $105^{\circ}C$ showed a similar tendency of chemical degradation to the steaming VG at $120^{\circ}C$ except the slower rate of reaction. Its rate was about one-third of the steaming at $120^{\circ}C$.

• 한국대기환경학회지
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• 제20권1호
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• pp.87-97
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• 2004

NMHC (non-methane hydrocarbons) and fine particles such as P $M_{10}$ and P $M_{2.5}$ were measured at KIST (Korea Institute of Science and Technology) in Seoul for a month from the end of May. At the beginning of June, peak ozones exceeded 100ppb both near KIST and in Seoul while ozone and fine particles decreased from the middle of June due to frequent precipitation. Because the measurement site was close to trees on a hill, isoprene concentration went up to 4.1ppb with an average of 0.76ppb. Toluene was the highest all day long, but particularly high concentration in the afternoon implied a contribution of emission from solvent use as well as vehicle exhaust. Eighty-five percent of P $M_{10}$ was P $M_{2.5}$ on an average since major ions except sea salt, including nitrate, were present within P $M_{2.5}$. Daily variations of pollutants were generally similar except for NMHC. One of major differences in NMHC variation was maintenance of a relative high concentration in rainy day, showing that NMHC were not effectively scavenged by precipitation.ion.ion.