• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.915-921
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• 2007

As a preliminary measurement of siloxanes in landfill gas(LFG), this study was conducted to determine the best suitable solvent applicable to the extraction of siloxanes in the domestic landfill using liquid-absorption method. Three solvents of n-hexane, acetone, and methanol were tested and the results obtained from GC analysis for each solvent were compared to their properties. Results showed that the resolution in the GC spectrum was the best from methanol due to the lack of overlapping of the peaks between silane and solvent. The detected siloxanes concentration were varied at maximum 2.6 times depending on the types of solvent as well as extraction velocity and impinger steps. In total, the highest concentration of siloxanes was obtained from methanol, which showed ideal pattern in the absorption of each impinger step and the least relative standard deviation. Accordingly, it is concluded that methanol is the most suitable solvent for the extraction of siloxanes in the domestic landfill. However, it is considered that solvent suitability can vary depending on the waste components and landfill record in landfills.

• Journal of the Korean Chemical Society
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• v.24 no.5
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• pp.371-379
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• 1980

The spectral properties of the solvated electrons in tetrahydrofuran(THF)-water binary system have been investigated. In this study, the solvated electrons have been produced by applying nsec Q-switch Nd(YAG) laser photolysis technique. The experimental method photolysis were schematically described. The solvent and the temperature effects on the absorption spectrum of solvated electrons have also been studied. The observation of the spectrum with increasing THF content and temperatue showed a trend that the former shifted to longer wavelength and the other showed broadening effect. The half-life of solvated electrons were also increased with THF content. The absorption maxima of the mixtures were always observed in the middle of that of pure water and THF. The correlation between the volume and the absorption energy of solvated electrons were discussed from the results.

• Proceedings of the Korean Printing Society Conference
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• 1995.11a
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• pp.13-17
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• 1995

헤테로원자(X=O, S, Se)의 변환에 따라 용액상에서 Merocyanine색소 및 Cyanine색소의 헤테로원자X는 p궤도의 원자보다 d궤도의 원자가 공명에 관여하여 공역계확장에 기여하였고, 유전률이 큰 용매 일수륵 Merocyanine색소는 장파장으로 흡수극대치가 이동하였다. 또 Cyanine색소의 기저상태는 $I^-$이온과 정전하 발색단을 가진 이온성 화합물로 되어 있으므로 극성용매에서 $I^-$ 이온의 전하가 색소본체로 전하 이동전이가 발생하여 단파장화 하였다. 고상에서 색소의 농도가 높을 수록 색소분자간의 거리가 가까워져 색소 상호작용이 변화하여 흡수스펙트럼에서는 전체적으로 폭이 넓은 형태로 나타났으며 이것은 농도가 높을 수록 색소분자간의 거리가 가까워져 색소 상호작용이 변화한 때문이라고 생각된다. 또한 3차원 형광의 저농도에서 보이지 않는 새로운 스펙트럼이 Cyanine색소에서 나타났으며 이 스펙트럼은 색소고유의 흡수에 기인한 것으로 Eximer형광으로 생각된다. 광전특성에 있어서는 Merocyanine색소가 Cyanine색소보다 활성화에너지가 낮아 전하이동도가 커짐에 따라 높은 광전특성을 나타내었다. 그리고 Merocyanine색소 헤테로원자(X)의 비교에서 광전특성은 O

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.401-406
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• 1999

Trace amount of cadmium was quantitatively extracted with 1% Aliquat 336-MIBK from 0.2M KSCN and 0.01M-HCl. Test tubes with a screw cap stopper were used for extraction in place of conventional separating funnels and organic solvents used were less dense than water. In this analysis, 22 times concentration effect was achieved with higher selectivity without interference. The detection limit of cadmium was 0.7ppb, therefore trace cadmium was easily analyzed by this method. The proposed method was applied to the determination of cadmium in blood serum and extraction mechanism was elucidated.

• 월간산업보건
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• s.90
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• pp.2-8
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• 1995

원자 흡수 분광법과 용매 추출을 이용한 크롬의 정량분석 조건을 연구하였다. tertiary amine류 중 octy기를 갖는 trioctylamine(TOA)과 quaternary ammonium salt류 중 octy1 기를 갖는 trioctylmethylammonium chloride(TOMAC)가 음이온 교환기로 사용되었다. 또한 첨가되는 산의 종류와 산의 농도 변화에 따라서 원자흡수분광기를 이용하여 흡광도를 측정하였다. TOA사용시 염산의 농도가 0.1M-0.3M사이, TOMAC사용시 염산의 농도가 0.03M-0.1M사이에서 최대 흡광도를 나타내었다. 산이 첨가된 MIRK에 용해된 TOA나 TOMAC와 Cr과의 mole농도 비율이 1:1이상이 된 것이 최대 추출효율을 보았다. 추출과정을 검토한 결과, 본 실험에서 사용된 방법은 비슷한 다른 방법들과 비교하여 보면 크롬의 추출효율이 좋은 것으로 판명되었다.

• Membrane Journal
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• v.10 no.3
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• pp.139-147
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• 2000

Non-Fickian (or anomalous) diffusion was observed in transient sorption of aromatic solvents(such as benzene, toluene, and chlorobenzene) in fluoropolymers (such as ETFE, ECTFE and PVDF). In this study, five other transient sorption models (Crank, Long ＆ Richman, Berens ＆ Hopfenberg, Neogi, Li) based on Fick's law were employed to fit the anomalous sorption data for aromatic solvents. The adjustable parameters were determined by least square analysis of the measured and predicted fractional uptake. For ETFE sorption data slightly deviating from Fickian behavior, all the models exhibited satisfactory results in fitting the anomalous sorption data. In particular, Neogj model predicted intrinsic diffusivity (0.4～0.8$\times$10$^{-5}$ $\textrm{cm}^2$/day) and equilibrium diffusivity (0.13～0.31$\times$10$^{-4}$ $\textrm{cm}^2$/day) as well as relaxation kinetics related to non-Fickain diffusion. For a typical sigmoidal sorption behavior in PVDF, only Crank's model could give the reasonable evaluation on transport properties. The ratio of intial diffusivity (D$_{i}$) to final equilibrium diffusivity (D$_{\infty}$) was ranged from 80 to 200. For the final stage of uptake In ECTFE with drastic acceleration, all the models exhibited significant deviations from the sorption data. New diffusion models based on thermodynamics and continuum mechanics should be employed to get valuable information on transport properties as well as relaxation kinetics coupled with non-Fickian diffusion.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.368-368
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• 2011

I-III-VI족 화합물반도체인 CuInSe2(CIS)는 1.02 eV 직접천이형 bandgap을 가지고 있으며 높은 광흡수 계수($1{\times}10^5\;cm^{-1}$)를 가지고 있어 박막형태양전지의 광흡수층으로 많이 사용되고 있다. 특히 저비용, 대면적화, 고효율의 태양전지 구현을 위해 CIS 나노입자를 합성하고 용매에 분산시켜 Ink화하는 연구가 진행되고 있다. 하지만 기존의 CIS 나노입자합성에 사용되는 수열합성법은 독성이 강하고 고비용의 용매를 사용하는 단점을 갖고 있다. 따라서 본 연구에서는 이러한 문제를 해결하고자 수용액기반의 수열합성법과 열처리과정을 통하여 CIS 나노입자를 합성하였다. 합성된 나노입자를 XRD, EDAX, SEM, TEM 분석을 통하여 CIS가 합성된 것을 확인하였다.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1061-1068
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• 1996

The conducting polymer composites were prepared by imbibing the porous particle wish the $FeCl_3$ oxidant solution, drying the imbibed porous particle, and imbibing again with pyrrole solution for polymerization to take place in the pore of porous particles. The effect of synthesis conditions on the conductivity of composite polymers were investigated. It was found that the conductivity of composite polymers was dependant on the concentration of pyrrole monomer, nature of the oxidants and solvents used for the oxidant and pyrrole, which influence the degree of penetration/distribution of polyprrole in the composite and reaction of dopant with pyrrole.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.665-665
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• 2013

박막형 태양전지에서 광흡수층으로 널리 쓰이는 metal chalcogenide 화합물 중, CuInS2(CIS)은 전기적, 광학적 특성이 우수하여 널리 연구되고 있다. CIS계 태양전지 최근 동시 증발법을 이용하여 20.3%의 고효율을 기록한 바 있으나 기존 진공, 고온 기반 공정 기술은 초기 투자 비용이 높고, 고가의 희귀원소인 In 등의 원료 활용도가 떨어져 원가 절감에 있어 한계가 있다. 이에 따라 제조 비용 절감과 원료 사용 효율을 향상시키기 위해 비진공 방식을 이용한 광흡수 층 증착 공정에 관한 연구가 활발히 진행되고 있다. 본 연구에서는 상온, 상압, 저온에서 합성이 가능한 CIS계 광흡수층을 전자 전달 및 빛 포집에 유리한 ZnO 나노구조와 응용함으로써 superstrate 구조의 박막형 태양전지를 구현하고 그 특성을 평가하였다. CIS 박막 태양전지에서 투명창층으로 쓰이는 ZnO 박막을 수열합성법으로 합성된 ZnO 나노로드 어레이로 대체하여 빛 산란 효과를 줄이고, 전하 수집 및 이동 효과를 극대화하였다. 또한 CIS 광흡수층은amine계 용매와 금속염 및 thiourea를 조합하여 저온에서 코팅 후 건조시켜 박막을 제조하였다. 각 요소 박막들의 물성을SEM, XRD, UV-transmittance 분석을 통해 살펴보았으며, 소면적 태양전지 제작을 통해 박막 구조 대비 30배 이상의 광변환효율(최고효율 3.30%)을 기록하였다.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.2
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• pp.127-135
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• 2007

This study was to evaluate the efficiency of different solvent systems to extract active ingredients from different parts of medicinal plants used as oriental medicinal herb in the cosmetic industry. We tested efficacies related to the antioxidative effects and UV absorption of herbal extracts as complex of active ingredients, not each single ingredient. When extracting medicinal plant which is used effective medicine, we should consider the collecting conditions like collecting time, place, part and extracting conditions like solvent, temperature, time, and etc. Among them, extraction solvent and collecting part are very important factors for the efficacy. As increased interest in medicinal plants, more intensive studies on collecting conditions and extracting processes were needed for the developments in the herbal ingredient industry. We evaluated the efficiency of different solvent systems to extract active ingredients from different parts of plants (Terminalia chebula, Syzygium aromaticum, Paeonia lactiflora, Morus alba, Scutellaria baicalensis) widely used as medicine and food. As results, we found that proper condition can make better data and decrease the required quantity.