• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.484.2-484.2
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• 2014

There are many efforts to improving the power conversion efficiencies (PCEs) of dye-sensitized solar cells (DSCs). Although DSCs have a low production cost, their low PCE and low thermal stability have limited commercial applications. This study describes the preparation of a novel multifunctional polymer gel electrolyte in which a cross-linking polymerization reaction is used to encapsulate $TiO_2$ nanoparticles toward improving the power conversion efficiency and long-term stability of a quasi-solid state DSC. A series of liquid junction dye-sensitized solar cells (DSCs) was fabricated based on polymer membrane encapsulated dye-sensitized $TiO_2$ nanoparticles, prepared using a surface-induced cross-linking polymerization reaction, to investigate the dependence of the solar cell performance on the encapsulating membrane layer thickness. The ion conductivity decreased as the membrane thickness increased; however, the long term-stability of the devices improved with increasing membrane thickness. Nanoparticles encapsulated in a thick membrane (ca. 37 nm), obtained using a 90 min polymerization time, exhibited excellent pore filling among $TiO_2$ particles. This nanoparticle layer was used to fabricate a thin-layered, quasi-solid state DSC. The thick membrane prevented short-circuit paths from forming between the counter and the $TiO_2$ electrode, thereby reducing the minimum necessary electrode separation distance. The quasi-solid state DSC yielded a high power conversion efficiency (7.6/8.1%) and excellent stability during heating at $65^{\circ}C$ over 30 days. These performance characteristics were superior to those obtained from a conventional DSC (7.5/3.5%) prepared using a $TiO_2$ active layer with the same thickness. The reduced electrode separation distance shortened the charge transport pathways, which compensated for the reduced ion conductivity in the polymer gel electrolyte. Excellent pore filling on the $TiO_2$ particles minimized the exposure of the dye to the liquid and reduced dye detachment.

• Ocean and Polar Research
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• v.26 no.3
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• pp.515-521
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• 2004

The processes of formation and dissociation of gas hydrates were investigated by monitoring pressure and temperature variations in a pressure cell in order to understand the kinetic behavior of gas hydrate and the controlling factors fur the phase transition of gas hydrate below freezing. Gas hydrates were made kom guest gases ($CH_4,\;CO_2$, and their mixed-gas) and fine ice powder. We found that formation and dissociation speeds of gas hydrates were not controlled by temperature and pressure conditions alone. The results of this study suggested that pressure levels at the formation of mixed-gas hydrate determine the transient equilibrium pressure itself.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.1
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• pp.11-17
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• 2009

Betamethasone propionate, an anti-inflammatory glucocorticosteroid, was detected in cosmetics with no indication on the label of this compound as an ingredient. The product was formulated as a topical spray or shampoo and labeled to contain zinc pyrithione as the active ingredient. A thin-layer chromatographic analysis was carried out on silica gel plates to provide a first indication about the presence of a compound with steroid structure and reactivity; then high-performance liquid chromatography (HPLC) separation allowed the identification of the corticosteroid agent and its quantification. To identify the corticosteroid agent from these commercial samples we collected the fractions suspected to have ketol steroids by prep HPLC and identified the compound as betamethasone propionate by NMR and MS spectrometry. Then we synthesized the standard for the betamethasone 17-propionate and 21-propionate and quantitate the corticosteroids from the sample by HPLC with that standards. By this method we identified the corticosteroid compounds from some commercial cosmetics such as zinc pyrithione sprays. The finding of betamethasone propionate in the products was shown by comparison to an authenticated standard of betamethasone propionate by retention time on reverse-phase HPLC. Two of the tested products contained betamethasone propionate at the levels of 0.005 ${\sim}$ 0.02% and the others were free of betamethasone propionate.

• Analytical Science and Technology
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• v.26 no.1
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• pp.99-105
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• 2013

To identify oxidative hair dyes in hair-coloring products, the thin-layer chromatography (TLC) screening method was used in accordance with Korean Quasi-drug Codex. However, the TLC method is not reliable when there are very small amount of materials to be tested or when $R_f$ values of several components are similar. In this study, Ultra Performance Liquid Chromatography (UPLC) with a rapid sample preparation method was developed for the reliable and sensitive identification of active components contained in oxidative hair-coloring products. Hexane-distilled water was used for the extraction of active components contained in the products prior to UPLC analysis. The limit of detection of active components was 6.7-77.9 ${\mu}g/L$, and the limit of quantitation was 22.3-259.7 ${\mu}g/L$. Except for ${\alpha}$-naphthol, the range of recovery ratio was 96.2-101.5%. From this study, we demonstrated that oxidative active hair-coloring components can easily be analyzed by rapid extraction method followed by UPLC analysis.