• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.4
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• pp.309-316
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• 2001

Helianthus tuberosus has been known to inhibit the growth of weeds and other plants sharing its habitat. This study was conducted to identify the allelochemicals of Helianthus tuberosus which were extracted with water and solvents. Aqueous extracts of leaf, stem, root, tuber and tuber peel of Helianthus tuberosus except tuber did not show significant differences in phytotoxicity to alfalfa seedlings. It was considered that Helianthus tuberosus contained fewer or less potential water-soluble substances that were toxic to alfalfa. Methanol extract of leaves of Helianthus tuberosus was sequentially partitioned in increasing polarity with n-hexane, ethylacetate and n-butanol. Each extract had a yield of 148, 12, 15.7 and 9.5g, respectively. Inhibitory effects on germination of alfalfa seeds treated with four fractions were not significantly different. But the significant reductions on hypocotyl length were observed for all the solvent extracts. Among the four fractions, the ethylacetate fraction showed the most significant inhibition effect on bioassay with alfalfa. Further separation of the active ethylacetate fraction by open column chromatography led to the 25 subfractions. In bioassay of each sub-fraction with alfalfa seeds, sub-fraction No. 13 showed the most inhibitory effect on seedling growth. $^1$H NMR and gas chromatography-mass spectrometry analysis revealed that sub-fraction No. 13 was the mixture of straight-chain saturated fatty acids.

• Korean Journal of Materials Research
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• v.17 no.8
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• pp.433-436
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• 2007

Nano-structured polyaniline have been synthesized by interfacial polymerization method at room temperature. An aqueous solution of aniline in chloroform and another solution of ammonium peroxydisulfate in doping acid were prepared at different times terminated with methanol at room temperature. SEM, UV-vis were used to characterize the polyaniline with regard to their morphology and structure. The diameter and length of polyaniline can be controlled by the reaction time. Nano-structured polyaniline were found to have superior sensitivity for volatile organic compounds(VOCs). As the reaction time to increase from 30minute to 2hours the sensitivity were decreased to VOCs vapors. The sensitivity of Nano-structured polyaniline sensor appeared to VOCs better than the sensitivity of chemical synthesis sensors. The sensitivity of Nano-structured polyaniline sensor improved benzene vapors.

• Corrosion Science and Technology
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• v.3 no.6
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• pp.227-232
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• 2004

The carboxylates as a corrosion inhibitor has been studied by many researchers because of its environmental safety and low depletion rate. However, conventional test methods of inhibitor such as weight loss measurements, linear polarization resistance and corrosion potential monitoring etc., evaluate uniform corrosion of metals. These methods are unable to evaluate crevice-related corrosions, which are encountered in most of heat exchanging facilities. In order to choose the optimum corrosion inhibitor, the appropriate test methods are required to evaluate their performances in service environment. From this point of view, polarization technique was used to evaluate the characteristics of sodium heptanoate on corrosion behavior for carbon steel. Especially a thin film crevice sensor technique were applied to simulate the crevice corrosion in this study. From these experiments, we found that oxygen as an oxidizing agent was required to obtain stable passive film on the metal. Presence of oxygen, however, accelerated crevice corrosion. Potential shift by oxygen depletion and weakened inhibitive film inside the crevice were responsible for such accelerated feature. It is shown that film for corrosion inhibition is a mixture of sodium heptanoate and iron (II) heptanoate as reaction product of iron surface and sodium heptanoate. The iron (II) heptanoate which has been synthesized by reaction of heptanoic acid and ferrous chloride in methanol solution forms bidentate complex.

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.48-52
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• 2001

The needles of Pinus densiflora, grown in the campus of Kangwon National University were collected, extracted with acetone-$H_2O$ (7:3, v/v) and freeze dried to give 10.4 g of ethylacetate soluble powder. A portion of the freeze dried powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol, and ethanol-hexane mixture as eluents. The extractives contained a large amount of flavan compounds in addition to a small amount of flavonoid derivatives such as kaempferol-3-O-glucopyranoside, and quercetin-(6"-O-acetyl)-glucopyranoside which has not been isolated from this species yet. Some spectrometric analyses such as NMR and FAB-MS were performed to identify the structures of the isolated flavonoid derivatives.

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.53-59
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• 2001

The needles of torreya(Torreya nucifera S. et Z) were collected, extracted with acetone-$H_2O$(7:3, v/v), fractionated with hexane, chloroform and ethylacetate, and freeze dried to give some dark brown powder. The ethylacetate soluble mixture was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. Most of the needle extractives were flavan and its methyl ether compounds such as (+)-catechin, (-)-epicatechin, (+)-gallocatechin, (-)-epigallocatechin, 3'-O-methyl-(+)-catechin and 3'-O-methyl-(-)-epicatechin including protocatechuic acid, one of benzoic acids. $^1H$- and $^{13}C$-NMR, NOE and CI-MS analyses were performed to elucidate the structures of the isolated compounds.

• Journal of Korea Foresty Energy
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• v.21 no.1
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• pp.41-48
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• 2002

The barks of oak trees (Quercus acutissima and Quercus variabilis) were collected, extracted with acetone-$H_2O$ (7:3, v/v), fractionated with hexane, $CH^2C1^2$ EtOAc and -$H_2O$, then freeze dried to give dark brown powder. The EtOAc soluble mixtures of the trees were chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. The structures of isolated compounds were characterized by $^1H$, $^13C$ and 2D-NMR spectroscopy and molecular weights were determined by FAB-MS spectra. The isolated compounds from Quercus acutissima were (+)-catechin, (+)-gallocatechin, gallic acid and taxifolin-3-O-$\beta$-D-glucopyranoside and the compounds from Quercus variahilis (+)-catechin, caffeic acid and taxifolin-3-O-$\beta$-D-glucopyranoside.

• KSBB Journal
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• v.8 no.4
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• pp.320-327
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• 1993

Latex microspheres of styrene/acryl copolymer with acrylamide functional group were used for the stable covalent immobilization of an enzyme applicable for enzymatic synthesis of glycoside. The latex microspheres were coated with polyethyleneimine to establish structural and functional properties relevant to the covalent Immobilization with a high retention of activity. Polythyleneimine-coated microspheres satisfactorily immobilized the invertase for methyl fructoside synthesis, and model reaction were formed into alginate-enclosed microspheres biocatalyst. Using the alginate-enclosed microspheres biocatalyst, the yield of model glycoside was obtained as high as 52.2% at concentration of aqueous 30%(v/v) methanol and 0.291mo1/1 sucrose solution with 2U/ml of activity. The present study showed that the latex microspheres were successfully applied to enzymatic synthesis of glycoside.

• Journal of Korea Foresty Energy
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• v.22 no.1
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• pp.30-36
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• 2003

2kg of pollen extracted with EtOH(98%), concentrated, and fractionated with a series of hexane, CH$_2$Cl$_2$ EtOAc and $H_2O$ on a separately funnel. Each fraction was freeze dried to give dark-brown powder and EtOAc soluble portion of the powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol as eluents. Spectrometric analysis such as NMR and FAB-MS including TLC were performed to characterize the structures of isolated compounds. Pollen contained a small amount of flavonol derivatives such as quercetin-3-O-$\beta$-D-glucopyranoside and kaempferol-3-O-$\beta$-D-rutinoside in addition to a small amount of flavanonol compound such as aromadendrin-5-methyl ether and acid compound such as.

• Archives of Pharmacal Research
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• v.20 no.3
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• pp.291-296
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• 1997

The studies were carried out to evaluate the constituents in the aerial part of Isodon excisus var. coreanus (Labiatae). From the aqueous fraction of methanol extract, compound I (${\alpha}$-[[3-(3, 4-dihydroxyphenyl)-1-oxo-2-propenyl]oxy]-3,4-dihydroxy-benzenepropanoic acid), compound II (9-methyl-dihydroferulic acid-4-O-.betha.-D-glucopyranosyl $(1{\rightarrow}2)$-${\alpha}$-L- rhamnopyranosyl (1.rarw.4)-.betha.-D-glucopyranoside), compound III (ent-7.alpha., 11${\alpha}$,15.betha.-trihydroxy-kaur-16-en-1-O-.betha.-D-glucopyranoside) and compound IV ($2{\alpha}$,3${\beta}$,$7{\alpha}$,23-tetrahydroxy-olean-12 -en-28-oic acid 28-O-${\beta}$-D-glucopyranoside) were isolated and identified on the basis of their physicochemical and spectroscopic evidences[IR, FAB(-)MS,$^{1}H-NMR,$$^{13}C-NMR,$$ HMQC$$^{1}H-^{1}H $COSY and HMBC (Heteronuclear Multiple Bond Connectivity)]. Especially, New compounds II and III were named Isodonin A and Isodonin B respectively.

• Journal of Forest and Environmental Science
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• v.21 no.1
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• pp.16-23
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• 2005

The leaves of Paulownia Coreana Uyeki were collected, extracted with acetone-$H_2O$(7:3, v/v), fractionated with n-hexane, methylene chloride and ethylacetate, and freeze dried to give some dark brown powder. The ethylacetate soluble mixture was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. Spectrometric analysis such as NMR and MS including TLC were performed to characterize the structures of the isolated compounds. From the ethylacetate fraction, five flavonoides and three phenolic acids were isolated and determined.