• YAKHAK HOEJI
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• v.31 no.2
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• pp.105-111
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• 1987

A high performance liquid chromatographic method was developed for the simultaneous determination of free and glycine conjugated bile acids. Free and glycine conjugated bile acids were extracted from bear gall bladder by methanol and from serum using a Sep-pak $C_{18}$ catridge. The extracted bile acids were labeled with 2-bromoacetyltriphenylene in acetonitrite using 18-crown-6-ether as a catalyst. Derivatized bile acids were separated from the individual bile acids on a reversedphase column (Chemcosorb 5-ODS-H) using acetonitrile-methanol-water(10:50:30) as a mobile phase and monitored by an UV-detector at 254nm. Linearities of calibration curve were obtained between 4 ng and 24 ng, and recoveries from bear gall bladder sample were higher than 94%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.968-971
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• 2003

Due to a low efficiency of phosphor with large Stoke shift in Vacuum Ultra Violet (VUV) excitation environment, new PDP phosphors which can be excited in UV excitation environment need to be developed. In this study, $Zn_2SiO_4:Tb$ phosphor was synthesized by solid-state reaction method at $1300^{\circ}C$ with varying Tb concentration, and its cross relaxation effect was observed by Photoluminescence (PL) measurement. In order to decrease $^5D_3{\to}7F_j$ transition with blue emission in $Zn_2SiO_4:Tb$ phosphor, Dy, co-activator element, was added to $Zn_2SiO_4:Tb$ phosphor. In 254nm excitation environment, broad-emission peak was observed around 524nm, green emission.

• Journal of Photoscience
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• v.8 no.1
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• pp.9-12
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• 2001

The photoisomerization behavior of benzylideneacetophenones, known as chalcones, was studied. We synthesized the chalcone derivatives that have ether groups at 4 and 4＇ positions. Due to the electron donating ability of the ether oxygen, the bond order of the single bond between two phenyl ring of the chalcone strengthened, which eventually increased the rotational barrier of the single bond. The rotational barrier of the single bond is about 20-22 kcal/mole. Thermal recovery of this process took about 1 min. The UV-visible spectra of these chromophores exhibit two characteristic absorption peaks at 276 nm and 340 nm. The relative intensity of the peaks varies depending on the alkyl chain length of the substituent. Photo-irradiation with the 365 nm light monotonously decreases the 340 nm peak. However, the photo-irradiation with 254 nm light induce two competing processes and produced rather complicated absorption profile.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.5
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• pp.659-668
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• 2012

In Korea, almost every water treatment plant suffers from seasonal problem of algae and turbidity which result from eutrophication and heavy rainfall. To relieve this problem, experimental investigation was performed to study the applicability of a floating-media and sand filter to preliminary water treatment in terms of algae and turbidity removal. Experimental results using pure-cultured algae influent showed that the shape of algae species as well as filtration velocity affects the removal efficiency. From the experiments using natural river water, it was concluded that algae removal is more sensitive to floating-media depth but turbidity more sensitive to sand depth. As the filtration velocity increased, the removal of turbidity decreased but that of algae was not affected. The floating-media and sand filter removed more than 30 % of TP, TN, turbidity, Chl-a and CODcr, and less than 20 % of DOC and $UV_{254}$.

• Natural Product Sciences
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• v.14 no.1
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• pp.68-72
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• 2008

A simple reversed phase HPLC method was developed for extracting pharmacologically active compounds coptisine, palmatine, berberine, and epiberberine from the roots of Coptis chinensis using a binary gradient of acetonitrile : 10 mM hexanesulfonic acid-Na monohydrate with UV detection at 254 nm. The coptisine (1), palmatine (2), berberine (3), and epiberberine (4) contents of the roots of C. chinensis collected from sixteen district markets in Korea and China were $6.79\;{\sim}\;24.63\;{\mu}g/g$, $5.40\;{\sim}\;20.75\;{\mu}g/g$, $21.40\;{\sim}\;81.21\;{\mu}g/g$, and $3.45\;{\sim}\;12.04\;{\mu}g/g$, respectively.

• Journal of Korean Society on Water Environment
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• v.21 no.2
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• pp.176-183
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• 2005

Chlorination of wastewater is recently practiced in Korea. While many researchers have studied the kinetics of aqueous chlorine(HOCl) with nitrogeneous compounds and other organic/inorganic contaminants in drinking water, the researches of wastewater chlorination are relatively few. The purpose of this study was to investigate the chlorine decay kinetics and parameters on wastewater chlorination. Chlorine decay rate increased with increasing initial chlorine concentration. The parameters affecting chlorine decay rate were different in each wastewater treatment plant. One of the most important parameters affecting chlorine decay was initial chlorine concentration, and other parameters such as $NH_3-N$, total coliform, $UV_{254}$ and Fe were also affected. The decay ratio of chlorine was decreased with increasing initial chlorine concentration, and the disinfection efficiency showed good correlation with the decay ratio.

• Analytical Science and Technology
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• v.8 no.4
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• pp.859-864
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• 1995

Mono- and oligosaccharides are derivatized with p-aminobenzoic ethyl ester (ABEE), strongly absorbs UV light at 254 nm, in the presence of sodium cyanoborohydride. C18-bonded silica column is used for the separation of sugar-ABEE derivatives in an isocratic mode. RP-HPLC conditions are optimized by using ternary mixture as mobile phase and $45^{\circ}C$ as a column temperature. Sugar-ABEE derivatives are separated well within a short run time (ca. 25 min) by reverse-phase partition chromatographic mode. The ($1{\rightarrow}6$) linkage type of dihexose-ABEE derivatives has shorter retention time than ($1{\rightarrow}4$)-linkage type. After acid hydrolysis of glycoproteins with 2M trifluoroacetic acid, monosaccharide composition and contents are determined. This procedure is very useful for the simultaneous analysis of neutral and amino sugars in a single chromatographic step using RP-HPLC without reacetylation of deacetylated amino sugars, which are produced by acid hydrolysis.

• Analytical Science and Technology
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• v.8 no.4
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• pp.835-841
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• 1995

The quantitation of inorganic anions in various drinking waters were investigated using capillary electrophoresis(CE) and the results were compared with ion chromatography(IC). With CE, in contrast to IC, was demonstrated rapid analysis, good efficiency, a low detection limit and the low comsumption of a solvent and samples. CE analysis was used 5 mM sodium chromate(pH 8.0) containing 20 mM tetraalkylammoniumbromide at -25kV applied voltage with indirect UV detection at 254 nm. This results in exceedingly short analysis time within 3 min. with efficiencies approaching 200,000 theoretical plates. The coefficients of variants of migration time are less than 0.8% and those of peak area are less than 2.3%. Detection limits for quantitative determination were 300 ppb-50 ppm level. These optimum conditions are applicable to various samples without pretreatment.

• Food Science and Biotechnology
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• v.14 no.1
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• pp.89-93
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• 2005

Squalene synthase (SQS) inhibitors were screened from various plants and food extracts. Effective SQS inhibitor was purified from fermented soybean paste using ethanol extraction, HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, and crystallization. Through UV spectrometry, $^1H$ NMR, $^{13}C$ NMR, and mass spectrometry, SQS inhibitor was identified as daidzein with molecular mass of 254 and molecular formula of $C_{15}H_{10}O_4$. Daidzein showed $IC_{50}$ value of 50 nmol/L against SQS, confirming its potential as therapeutic agent for hypercholesterolemia.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1485-1488
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• 2010

Novel photoluminescent graphene, graphene/europium/picolinate, was made from the reaction of the graphene carboxylate, europium(III) and $\alpha$-pyridoin anion in methanol solution. There was evidence on IR spectroscopic data that europium metal was coordinated by graphene carboxylate. The graphene/europium/picolinate materials emitted the red luminescence with main peaks at 609 and 695 nm, when solid sample was excited by an UV light at the wavelength of 254 nm. The surface morphology and physical properties of the graphene/europium/picolinate product have been investigated by IR, PL, SEM, TEM and TGA measurements.