• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.313-313
• /
• 2011

일반적으로 초친수 박막들은 물의 퍼짐 현상이 발생하여 빠른 건조와 함께 표면에 붙은 이물질 제거와 공기 중의 미세먼지를 흡착을 하지 않음으로써 표면에 워터스폿(water spot, 물자국)이 생기지 않고 다시 깨끗해지는 자가세정 능력을 가져 유리 및 건축자재의 표면처리 용도로써 많이 사용하고 있다. 이러한 초친수 박막을 제조하는 방법으로는 sol-gel법, 진공 증착법, 화학 기상 증착법, 스퍼터링법 등을 이용한다. 이중 스퍼터링법은 높은 증착속도를 얻을 수 있으며, 비교적 낮은 진공도에서 박막제작을 할 수 있다는 장점을 가진다. 본 실험은 RF-magnetron sputtering법을 이용하여 화학적으로 매우 안정하고 높은 투과율을 가지며 기계적 표면 경도가 우수하여 코팅용 박막으로 널리 이용되고 있는 $TiO_2$와 $SiO_2$를 Single Layer와 Double Layer인 $TiO_2/SiO_2$/Glass박막을 제작하여 초친수 특성을 분석하였다. 광학적 특성을 알아보기 위해 UV-vis spectrophotometer장비를 사용하여 측정한 결과 가시광 영역에서 80% 이상의 높은 투과율을 나타내었다. 이는 모든 박막들의 광학적 특성이 우수하여 높은 광학적 특성을 요구하는 분야에 널리 사용 될 수 있다 것이라는 것을 확인 할 수 있었다. 또한 박막의 표면을 확인하기 위해 AFM을 측정한 결과 모든 박막들은 고른 거칠기를 나타내고 있다는 것을 볼 수 있었다. 이것으로 볼때 초친수 역시 초발수 박막의 표면과 마찬가지로 일정한 패턴을 가져야 하는 것을 확인 할 수 있었다. 박막이 초친수성을 띄기 위해 가장 중요시되는 조건인 접촉각이 5도 이하인 조건을 확인을 위해 Contact Angle을 이용하여 접촉각을 측정해 본 결과 박막들은 초친수성의 조건인 5도 보다 더욱 낮은 접촉각의 측정결과를 나타내었다. 위 실험결과를 볼 때 $TiO_2$와 $SiO_2$를 기반으로 단층 혹은 다층으로 박막을 제작하면 더욱 좋은 초친수 특성을 가져 사회적으로 여러 분야에 사용 가능 할 것이라 사료된다.

• Journal of the Mineralogical Society of Korea
• /
• v.28 no.3
• /
• pp.245-253
• /
• 2015

The performance of $TiO_2$ photo-catalytic oxidation process is significantly dependent on the amount of hydroxyl radicals produced during the process, and it is an essential prerequisite to quantify its production. However, precise and accurate methods for quantification of hydroxyl radicals have not been developed so far. For this reason, this study was initiated to compare existing methods for analysis of hydroxyl radicals produced by $TiO_2$ photo-catalytic oxidation and to propose a new method to overcome the limitation of established methods. To simulate $TiO_2$ photo-catalytic oxidation process, Degussa P25 which has been widely used as a standard $TiO_2$ photo-catalyst was used with the dose of 0.05 g/L. The light source of process was UVC mercury low-pressure lamp (11 W, $2,975mW/cm^2$). The results indicate that both potassium iodide (KI)/UV-vis spectrometer and terephthalic acid (TPA)/fluorescence spectrometer methods could be applied to qualitatively measure hydroxyl radicals via detection of triiodide ion ($I_3{^-}$) and 2-hydroxyterephthalic acid which are produced by reactions of iodine ion ($I^-$) and TPA with hydroxyl radicals, respectively. However, it was possible to quantitatively measure hydroxyl radicals using TPA method coupled with high-performance liquid chromatograph (HPLC). The analytical results using TPA/HPLC method show that hydroxyl radical of 0.013 M was produced after 8 hours operation of photo-catalytic oxidation under specific experimental conditions of this study. The proposed method is expected to contribute to precise the evaluation of the performance of photo-catalytic oxidation process.

• Korean Chemical Engineering Research
• /
• v.52 no.5
• /
• pp.667-671
• /
• 2014

In this study, we suggest a facile method to control conditions of single component independently when preparing consisting two-component metal oxides nanofiber by simply dispersing nanoparticles in precursor solution. The well dispersed $SiO_2$ nanoparticles in $TiO_2$ nanofibers were successfully synthesized through a simple electrospinning process. The as-synthesized nanodfibers were investigated via FE-SEM, XRD and EDS for structural studies, furthermore, the analysis of UV-VIS and photocatalytic activity were carried out for demonstrate the effect of $SiO_2$ nanoparticles dispersed in $TiO_2$ nanofibers. As a result, $TiO_2$ nanofibres dispersed with $SiO_2$ nanoparticles have enhanced photocatalytic activity than that of $TiO_2$ nanofibres only. In this strategy, the introduction of $SiO_2$ nanoparticles in $TiO_2$ nanofibers were attribute to enlarge absorption in the visible region (380~440 nm). Additionally, $Br{\o}nsted$ acid sites generated in each metal oxide of Ti and Si increase OH radicals efficiently as well as it limit recombination loss by holding photogenerated electrons for high efficient photocatalytic activity.

• Analytical Science and Technology
• /
• v.18 no.2
• /
• pp.139-146
• /
• 2005

Removal of NO contained in automobile exhaust gas was accomplished by the non-selective catalyst reduction method. The catalysts were prepared through loading of a specific amount of Ag into ${\gamma}-Al_2O_3$. The conversion of $NO_x$ was studied by varying the temperatures, $O_2$ concentrations and $SO_2$ concentrations for the prepared catalysts. The influence of the structure of catalyst to $NO_x$ conversion was followed through the analysis of the physical properties of the prepared catalysts. Experiments were conducted on each of the catalysts by varying the reaction conditions to find an optimum condition. The catalyst $Ag/{\gamma}-Al_2O_3$ shows a highest $NO_x$ conversion when the Ag content was 2 wt% and a reaction temperature of about $450^{\circ}C$. and after conducting the experiments, samples of before and after experiments analyzed using XRD, XPS, TPR, and UV-Vis DRS experiments. The result indicated that when Ag oxide content could not be maintained well at high temperatures $NO_x$ conversion decreased.

• Journal of the Korean Chemical Society
• /
• v.34 no.5
• /
• pp.452-459
• /
• 1990

A series of oxo-and sulfido-bridged molybdenum (V) complexes, Mo$_2$O$_4$L$_2$, Mo$_2$O$_3$L$_4$, Mo$_2$O$_2$S$_2$L$_2$, and Mo$_2$OS$_3$L$_2$ [L = bis(hydroxyethyl)dithiocarbamate] have been prepared. The complexes with bridging and terminal oxo groups have been synthesized by the reactions of (PyH)$_2$MoOCl$_5$ or MoCl$_5$ and ligand in water. One of the rest two complexes, in which bridging and terminal oxo groups have been replaced by sulfido in Mo$_2$O$_4^{2+}$ core, Mo$_2$O$_2$S$_2$L$_2$ have been prepared by addition of triphenylphosphine to a chloroform solution of Mo$_2$OS$_3$L$_2$. While, Mo$_2$OS$_3$L$_2$ is obtained from aqueous solution of (NH$_4$)$_2$MoS$_4$ and ligand in the presence of sodium dithionite. The complexes are identified by elemental analysis, and spectral data of IR, UV-vis, nmr, and mass. Also, the electrochemical behaviour for the complexes in dimethylsulfoxide has been investigated by the cyclic voltammograms.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.24 no.4
• /
• pp.169-175
• /
• 2014

Digital ink-jet printing system has many advantages such as fast and fine printing of various images, high efficiency and low cost process. Generally digital ink-jet printing requires ceramic pigments of cyan, magenta, yellow and black with thermal and glaze stability above $1000^{\circ}C$ for the application of porcelain product design. In this study, pink-red colored $CaO-SnO_2-Cr_2O_3-SiO_2$ pigment was synthesized using solid state reaction. The synthesis conditions of $Ca(Cr,Sn)SiO_5$ pigment such as annealing temperature, amount of mineralizer and non-stoichiometric composition were optimized. Crystal structure and morphology of the obtained $Ca(Cr,Sn)SiO_5$ pigment were analyzed using XRD, SEM, PSA, FT-IR and effect of Cr substitution on the pigment color was analyzed using Uv-vis. spectrophotometer and CIE $L^*a^*b^*$ measurement.

• Applied Chemistry for Engineering
• /
• v.26 no.3
• /
• pp.341-346
• /
• 2015

In this study, poly ${\varepsilon}$-caprolactone(PCL) microcapsules containing lemongrass oil was prepared by the solvent evaporation method. Effects of concentrations of PCL and poly vinyl alcohol (PVA) as well as stirring speeds when preparing microcapsules were investigated. Specific peaks of lemongrass oil in PCL microcapsules at 1600 and $2900cm^{-1}$ were observed by FT-IR. The particle size and shape of microcapsules were also measured by polarizing microscope and optical microscopy. The average particle size of microcapsules decreased with increasing the stirring rate. At the stirring speed of 1500 rpm, and 1 wt% of each PCL and PVA concentrations, the smallest particles were formed. Collection efficiencies of lemongrass oil of 77.5% and 69.5% were obtained when 1.5 wt% of PCL and 2 wt% of PVA were used, respectively. In addition, the release behavior and antioxidant activity of lemongrass oil from PCL microcapsules were examined using UV-Vis spectrophotometry. When 0.5 wt% PCL and 2.0 wt% PVA were used with the slow stirring rate, microcapsules showed a fast release rate. The characteristics of antioxidant activity exhibited similar to that of the release behavior.

• Journal of the Korean Vacuum Society
• /
• v.16 no.6
• /
• pp.453-457
• /
• 2007

Zinc oxide (ZnO) and Ga doped zinc oxide (GZO) with different thickness in range of 10nm to 100nm are prepared on glass substrate by RF magnetron sputtering at room temperature. The structural and optical properties of the thin films is evaluated. The structural properties of ZnO and GZO are investigated by Tunneling Electron Microscopy (TEM) and scanning electron microscopy (SEM). Optical properties are also investigated by UV-VIS-NIR spectrophotometer (200$\sim$1400nm). The much larger grain size of ZnO compared to GZO decreased the light scattering at the grain boundary and improved the transmittance. The transmittance of ZnO is higher than that of GZO through all of the ranges of wavelengths. In case of over 50nm, we found that the transmittance of ZnO is 20% higher than that of GZO.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.40 no.2
• /
• pp.141-153
• /
• 2014

This study is about the development of cholesteric liquid crystals (CLCs), which are highly applicable to cosmetics formulation. The CLCs made from non-animal origin were chosen not only because they are free of animal viruses but also because they give a sense of security to the cosmetic consumers. Three kinds of new cholesteric derivatives (CI, CC, CN) were synthesized using non-animal cholesterol [NAB cholesterol (ARCH LONZA)], which was originally made by fermentation process. To develop high applicability to cosmetics formulation, we attempted to find out the optimum compositions in which CLCs can maintain their color over a wide range of temperature. The CLCs in 41 different compositions were prepared by the combinations of three cholesteric derivatives and a visual evaluation method was employed to determine the range of temperature at which the CLCs display their color. The 205 UV-VIS spectral data obtained from 41 CLCs at various temperatures were simultaneously analyzed to investigate the critical factors affecting the characteristics of the CLCs. Results showed that A4, A5, A6 and A7 were the best compositions to cosmetics formulation. A6 composition had a great moisturizing effect by the artificial skin test ($AmoReSkin^{TM}$).

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.41 no.10
• /
• pp.1356-1362
• /
• 2012

UV-VIS spectrophotometric and high-performance liquid chromatographic (HPLC-DAD) methods were applied in order to identify and quantify the composition of polyphenols in commercial cocoa-containing products. Total polyphenolic contents of cocoa mix, choco-syrup, milk chocolate, and dark chocolate were evaluated using Folin-Ciocalteu's phenol reagent according to a UV-VIS spectrometric method. Antioxidant capacities of cocoa extracts by methanol were evaluated by 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) (ABTS) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The obtained results show that the polyphenolic contents and antioxidant capacities of cocoa products and chocolates depend on solid cocoa content. Among the tested cocoa products and chocolates, the most abundant phenolic compound was epicatechin.