• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.31-35
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• 2005

본 연구는 토양에 휘발유 첨가제인 MTBE와 휘발유의 주성분인 BTEX를 headspace 법에 의해 동시 분석하는 방법이다. 인산으로 pH를 2로 조절한 후 NaCl로 포화시킨 용액 5ml를 헤드스페이스 바이알에 보존제로 넣은 후 토양시료 약 2g을 이 용액에 침지시켜 시료 채취한 다음 헤드스페이스 장치에 넣고 $80^{\circ}C$에서 40분 가온하여 상부 기상의 일정량을 취해 GC-MS (SIM)으로 분석하였다. 본 분석법에 의한 검출한계는 methyl-tert-butyl ether(MTBE)와 benzene, toluene, ethylbenzene, o,m,p-xylene(BTEX)이 각각 0.1, 0.1, 0.1, 0.2, 0.1, 0.2 ng/g이었고, 직선성은 0.995이상이었으며, 재현성도 10%내외의 정밀한 값을 보였다. 실제 시료를 분석한 결과, MTBE가 3-6,993 ng/g의 농도분포를 보였고 total BTEX는 1 ng/g으로 검출되었다. 이 방법은 빠르고 정밀 정확한 분석법으로 공정시험법으로 활용가치가 높다.

• Journal of Food Hygiene and Safety
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• v.14 no.2
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• pp.140-145
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• 1999

Analytical method for preservatives in food was developed using gas chromatography/mass spectrometry (GC/MS). Propionic acid, sorbic acid, benzoic acid, ethyl salicylate, ethyl p-hydroxy benzoate, iso-propyl p-hydroxy benzoate, n-propyl p-hydroxy benzoate, iso-butyl p-hydroxy benzoate, n-butyl p-hydroxy benzoate, p-hydroxy benzoic acid and dehydro acetic acid were extracted from cooling beverage with diethyl ether. The polar hydroxyl and carboxyl groups of food preservatives were derivatized with N-methyl-N-tert-butyldimethylisilyl-trifluoroscetamide (MTBSTFA) to form the corresponding tert-bytyldimethyl-silylated derivatives, and submitted to GC/MS analysis. The mass spectra of the derivatives were investigated for the selection of monitoring ions for multi-residue analysis of 11 preservatives by GC/MS. The macro program was also developed for the qualitative analysis of these preservatives in food.

• Proceedings of the Korean Environmental Health Society Conference
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• 2004.06a
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• pp.169-172
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• 2004

A gas chromatography/mass spectrometric assay method was developed for the determination of propylene oxide adduct, N-(3-hydroxypropyl)valine. Adduct was released from hemoglobin by alkaline hydrolysis and extract at pH 8 with ethyl ether. The dried extract was completely derivatized with N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA)/TMS-I (100:3). The detection limits of the assay were 0.08 ng/g for N-(3-hydroxypropyl)valine based upon assayed hemoglobin of 0.1 g. The method was applied to the determination of propylene oxide adduct formed in young female Sprague-Dawley rats after treatment for 1, 2 and 3 weeks with 0.008 % propylene oxide via the drinking water. An adduct was detected by proposed procedure. The structure of the adduct could be assigned to N-(3-hydroxypropyl)valine.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.10 no.1
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• pp.49-74
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• 1984

Rheology of gels prepared with stearyl dimethyl benzyl ammonium hectorite (SDBAH) and various polar additives in n-butyl acetate was investigated by measuring the viscosity and rheogram. Including generally recognized polar additives, additional studies on the rheogram and viscosity were made with ether-type methyl cellosolve and carbitol, with dimethyl sulfoxide (DMSO) having sulfonyl group, and furthermore with above-mentioned polar additives containing small quantity of water, It was observed that molecular size, dipole moments and dielectric constants of polar additives had a great influence on viscosity increase and rheology of SDBAH gel, and the increase of SDBAH interlayer spacing was important factor in gel formation and viscosity change. It was also shown that thixotropy effect was increased with the increase of polar additive concentration, finally changed to rheopexy from thixotropy as the concentration of polar additives was increased more than about 40% of SDBAH weight. In addition thixotropy changed to rheopexy as the increase of shear rate. It was further found that the aqueous solutions of polar additives (water content, 5-25%) had more effects on rheology than additives without water, and particularly 95clo DMSO solution was the most effective. And the optimum concentration of polar additives showing maximum viscosity in the same SDBAH concentration system was examined.

• YAKHAK HOEJI
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• v.26 no.4
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• pp.257-260
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• 1982

Measurement of water is a subject of continued interest. High resolution proton magnetic resonance has not been very effective in the determination of water. Especially spectral overlap with other proton signals from the sample is undesirable result. However, trifluoroacetic anhydride reacts with water and forms trifluoroacetic acid and the proton signal of trifluoroacetic acid did not overlap with that of samples. By use of this fact, water in acetone, ethyl ether, dioxane, dichloroethane and methyl isobutyl ketone is analyzed by high resolution proton magnetic resonance (PMR). This method is capable of detecting as little as 200ppm of $H_{2}O$. And it is very rapid, simple and accurate.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.6
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• pp.895-904
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• 2011

Stratified charge has been thought as one of the ways to avoid a sharp pressure rise on HCCI combustion. The purpose of this study is to evaluate the potential of stratified charge for reducing PRR on HCCI combustion. The pre-mixture with thermal, mixing and EGR stratifications is charged in Rapid Compression Machine. After that, the pre-mixture is compressed and in that process, in-cylinder gas pressure and temperature are analyzed. Additionally numerical calculation with multi-zones modeling is run to know the potential of stratified charge for reducing PRR.

• Elastomers and Composites
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• v.55 no.3
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• pp.205-214
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• 2020

A series of wholly aromatic polyhyroxyamide (PHA) copolymers were prepared by direct polycondensation reaction of isophthalic acid and diacids containing bulky units with 3,3'-dihydroxybenzidine. The inherent viscosities of the PHAs measured at 35℃ in DMAc solution were in the range of 0.31-0.56 dL/g. The solubility study revealed that the PHAs were readily soluble in aprotic solvents such as, dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP) at room temperature and in less polar solvent such as pyridine. However, the polybenzoxazole (PBO) copoymers were quite insoluble in all organic solvents except partially soluble in concentrated sulfuric acid and partially soluble in NMP containing LiCl. The PBO copolymers showed maximum weight loss temperature in the range of 593-632℃ and high char yields in the range of 65.0-71.2% at 900℃ in a nitrogen atmosphere.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.116-119
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• 1997

In this paper A double-layer organic electroluminescent(EL) device was fabricated using a TPD(N,N'-dipheny] -N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4.4'-diamine: aromatic diamine), as a hole-transport material and tris (8-hydroxy quinolinate) aluminum(Alq$_3$) as a an emiting material and its performance characteristics were investigated. structure of devices is ITO/TPD/Alq$_3$/Al. we have fabricated hole transport layer of two types. Doping material of Hole Transport material is Poly(methyl methacrylate)(PMMA) and PEI(Poly-Ether-Imide). Carrier injection from the electrodes to the doped PMMA and PEI layer through the dopants and concomitant electroluminescence from Alq$_3$were observed. Green emission with luminance of 40cd/m$^2$was achieved at a drive voltage of 30V

• Journal of Applied Biological Chemistry
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• v.49 no.1
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• pp.21-23
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• 2006

As part of a program to discover bioactive natural products from marine organisms, two new enantiomers, ent-3,6-Epidioxy-4,6,8,10-tetraethyltetradeca-7,11-dienoic acid and ent-[3,5-Diethyl-5-(2-ethyl-hex-3-enyl)-5H-furan-2-ylidene]-acetic acid methyl ether, were isolated from a sponge Plakortis sp. These compounds showed strong in vitro antiproliferative effects on promastigotes of Leishmania mexicania, flagellate protozoan that causes leishmaniasis. Structures were assumed by interpretation of NMR spectroscopic data and optical rotation. Both compounds exhibited significant antileishmanial activities in vitro with $IC_{50}$ of 1.0-23.0 ${\mu}g/ml$.

• Natural Product Sciences
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• v.14 no.4
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• pp.227-232
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• 2008

Phytochemical further investigation of the chloroform extract of the aerial parts of Crucianella maritima L. (Rubiaceae) growing in Egypt resulted in the isolation of a new anthraquinone; 3-formyl-1-hydroxy-2-methoxy anthraquinone (3) along with the four known compounds isolated for the first time from the genus Crucianella; alizarin-1-methyl ether (2), 1,4-dihydroxy-2-methoxy anthraquinone (5), 1, 3, 6-trihydroxy-2-methoxy anthraquinone (7) and the flavonol kaempferol (8), beside four known compounds previously isolated from the same plant. The structures of the isolated compounds were established based on different spectroscopic data including UV, IR, EIMS, 1D and 2D-NMR. Moreover, the antioxidant and antimicrobial activities of the isolated compounds were evaluated.