• Proceedings of the Korean Nutrition Society Conference
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• 2003.10a
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• pp.86-86
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• 2003

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1053-1054
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• 2002

• Bulletin of the Korean Chemical Society
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• v.23 no.12
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• pp.1695-1696
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• 2002

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.661-662
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• 2001

• Polymer(Korea)
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• v.29 no.3
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• pp.308-313
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• 2005

The effects of molecular environments on photoisomerization of an azobenzene group were investigated using In-situ UV/Vis spectroscopy and optical anisotropy measurement technique. The reversible and repeatable photoisomeritation reactions of azobenzene were observed by irradiating the film containing 4-hydroxyazobenzene and by measuring absorption intensities of the characteristic bands of trans and cis isomers simultaneously. When the self-assembled monolayer with azobenzene groups was used as an alignment layer for a liquid crystal cell, the homeotropic alignment was induced due to their compact packing structures of azobenfene groups along the vertical direction of the substrate. By irradiating UV light on this cell, the trans-azobenzene groups change to cis-isomers through the photoisonlerieation and then resulting in the planar alignment of liquid crystal molecules.

• Journal of Ginseng Research
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• v.44 no.6
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• pp.784-789
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• 2020

Background: The separation of isomeric compounds from a mixture is a recurring problem in chemistry and phytochemistry research. The purification of pharmacologically active ginsenoside Rb₃ from ginseng extracts is limited by the co-existence of its isomer Rb₂. The aim of the present study was to develop an enzymatic elimination-combined purification method to obtain pure Rb₃ from a mixture of isomers. Methods: To isolate Rb₃ from the isomeric mixture, a simple enzymatic selective elimination method was used. A ginsenoside-transforming glycoside hydrolase (Bgp2) was employed to selectively hydrolyze Rb₂ into ginsenoside Rd. Ginsenoside Rb₃ was then efficiently separated from the mixture using a traditional chromatographic method. Results: Chromatographic purification of Rb₃ was achieved using this novel enzymatic elimination-combined method, with 58.6-times higher yield and 13.1% less time than those of the traditional chromatographic method, with a lower minimum column length for purification. The novelty of this study was the use of a recombinant glycosidase for the selective elimination of the isomer. The isolated ginsenoside Rb₃ can be used in further pharmaceutical studies. Conclusions: Herein, we demonstrated a novel enzymatic elimination-combined purification method for the chromatographic purification of ginsenoside Rb₃. This method can also be applied to purify other isomeric glycoconjugates in mixtures.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1463-1468
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• 2007

Emission of methyl bromide(MeBr) of soil fumigant was implicated in stratospheric ozone depletion. To determine the environmental fate for 1,3-dichloropene(1,3-D) of alternatives fumigants for MeBr, this paper researched the transformation for 1,3-D in water and soil. Half lives of cis-1,3-D in water with first-order kinetics are 9.9day and 1.7day at $25^{\circ}C\;and\;40^{\circ}C$, half lives of trans-1,3-D are 8.6day and 1.5day at $25^{\circ}C\;and\;40^{\circ}C$, respectively. Transformation for 1,3-D in water at high temperature faster then at low temperature. Hydrolysis for 1,3-D in water are unaffected at $pH\;2.5{\sim}pH\;10.0$, but hydrolysis for 1,3-D at pH 11.5 higher then at $pH\;2.5{\sim}pH\;10.0$. Half lives of cis-1,3-D in soil are 11.5day and 7.7day at 3% and 10% of soil moisture, half lives of trans-1,3-D are 9.9day and 6.9day at 3% and 10% of soil moisture, respectively. Transformation for 1,3-D in water increased with increasing soil moisture. Transformation for trans-1,3-D isomer are more rapid then cis-1,3-D isomer in water and soil. This research has identified that transformation for 1,3-dichloropropene are affected by temperature, pH, soil moisture, and isomer of cis and trans in water and soil.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.607-611
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• 1991

The stereochemical ratio cis and trans isomer of the hydration reaction of trans-$[Co(en)(tmd)Cl_2]^+$ complex ion were studied with varing temperature by the spectrophotometric method. It was observed that the ratio of cis-isomer was about 30%, and the intermediate was rearranged. And in order to investigate this mechanism more clearly, stability energy profile, interaction diagram and orbital correlation diagram were calculated by the EHT method. By the calculation, the mechanism of cis-isomer was in good agreement with the experimental results, and it was estimated that the hydration reaction was carried through some distorted square pyramid (sp).

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.854-857
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• 1999

The properties of Fe-Se-Te system(FeSe(sub)1-xTe(sub)x, x=0.2, 0.5, 0.8) have been studied by means of the X-ray diffraction method and Mossbauer spectroscopy. The results of X-ray diffraction patterns show that three samples have the ixed structure of tetragonal PbO and a small amount of hexagonal NiAs structure respectively. For x=0.5 the lattice parameters of tetragonal PbO structure are a=3.795$\AA$, c=5.896$\AA$ and c/a=1.55. The Mossbauer spectra were obtained with the various temperature variation and than they do not exhibit magnetic hyperfine structure but show a strong doublet. The values of observed isomer shift and quadrupole splitting suggest that the irons of all samples exist in the +2 oxidation state with a major covalent contribution. The temperature dependence of isomer shift values for x=0.8 seems to be originated from the second order Doppler effect.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.470-475
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• 2013

Zr-benzendicarboxylate structure, UiO-66 was prepared in 1-L batch scale by using a unique sonochemical-solvothermal combined synthesis method. The produced UiO-66 showed uniform particles of ca. $0.2{\mu}m$ in size with the BET surface area of $1,375m^2/g$ in high product yield (>95%). The UiO-66 showed 198 and 84 mg/g $CO_2$ adsorption capacity at 273 K and 298 K, respectively, with excellent $CO_2$ selectivity ($CO_2:N_2=32:1$) at ambient conditions. The isosteric heat of $CO_2$ adsorption varied from 33 to 25 kJ/mol as the adsorption progressed. The UiO-66 tested for xylene isomer separation in a liquid-phase batch mode confirmed preferential adsorption of the adsorbent for o-xylene over m-, and p-xylene.