• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2005.11a
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• pp.183-184
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• 2005

Four different coatings deposited using cold spray process were studied with two different powder agglomerating techniques (spray d교 and evaporated powder) and using $TiO_2$ nano-sized powders with and without a 10wt% addition of ZnO. Characterization was performed by SEM, XRD and roughness test. Also the photocatalytic effect of the coatings was evaluated. Although the change of powder preparation techniques and the addition of ZnO into $TiO_2$ did not show appreciable variations in the surface morphology and Anatase phase transformation, it did show influence on the surface roughness of the coating, the highest roughness being found in the coatings made by spray powder prepared method. Regarding the photocatalytic effect it was observed that the using the spray dry coating and the addition of ZnO are promoter of purification at higher rates.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.292-292
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• 2010

Among the semiconducting materials, ZnO has considerably attracted attention over the past few years due to the high activities in removing organic contaminants created from industry. In this work, ZnO nanoparticles were synthesized by spray pyrolysis method using the zinc acetate dihydrate as starting material at various synthesis temperatures. The structures of the synthesized ZnO were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer, Emmett & Teller (BET), Fourier Transformation Infrared (FT-IR), and UV-vis spectroscopy. The Miller indices of XRD patterns indicate that the synthesized ZnO nanoparticles showed a hexagonal wurtzite structure. With increasing synthesis temperature, the mean diameter of ZnO nanoparticles increased, and their crystallinity was improved. Also, the photocatalytic activity of ZnO was studied by the photocatalytic degradation of methyleneblue (MB) under UV irradiation (365 nm) at room temperature. The results show that the photocatalytic efficiency of ZnO nanoparticles was enhanced by increasing synthesis temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.188-188
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• 2012

ZnO particles with a size range of 50-150 nm were coated with polydimethylsiloxane (PDMS) with a thin film thickness of 3-4 nm using a simple ambient-pressure chemical vapor deposition methods. Surfaces consisting of the PDMS-coated ZnO nanoparticles were found to be superhydrophobic with a water contact angle higher than $160^{\circ}$. The superhydrophobicity was sustained in the presence of UV light. Photocatalytic activity and photocorrosion of ZnO were nearly completely quenched in the presence of PDMS coating. It is suggested that our PDMS-coating can be of potential interest for the application of ZnO in UV protection agents and energy and electronic devices.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.40-47
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• 2002

Because UV wavelength lights can activate photocatalysts, plasma is used as a light source of a photocatalytic reactor. Even though plasma has good intensity for photo reaction, substrate of catalyst coating was limited by the geometry of plasma generator. Usually bead type substrate was used for a pack bed type reactor. Honeycomb monolith type substrate was used with UV lamps instead plasma, due to the light penetration the honeycomb monolith length was too short to show good activity In this study a photocatalytic reactor, which is using a honeycomb monolith substrate, was investigated with plasma as an activation light source. As a parametric study the effects of 1311owing factors on plasma generation and power consumption are examined; supply voltage, substrate length, environment condition, catalyst loading and ratio. Using the test results, the practicability test was done with simulated synthetic gases representing bad smells and automotive exhaust gases.

• Analytical Science and Technology
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• v.12 no.3
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• pp.209-217
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• 1999

To elucidate the decay of the rose bengal (RB) sensitized and thiourea (TU) supersensitized photocurrent, spectroscopic analyses of the dye solution were performed. Absorption and fluorescence spectroscopic analyses of sensitizing solution before and after irradiation enabled to conform the new mechanism of the photocatalytic dimerization between RB and TU. And it was also found that the geometrical arrangement of the transition dipole moment is oblique and the angle between the dipoles is $124^{\circ}$ in the dimer of dye molecules.

• KIEAE Journal
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• v.4 no.2
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• pp.37-40
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• 2004

New visible photocatalyst(Nanovis$^{(R)}$) has been synthesized to overcome the barrier of limitation of UV light utilization of current $TiO_2$ photocatalyst. It was found that red shift of absorption spectrum to 550nm was achieved. Its physical properties were characterized by XRD, BET and TEM. It is also observed that Nanovis$^{(R)}$ has a photocatalytic activity for photodegradation of Trichloroethylene under visible light irradiation. V,VII group doped into substitutional sites of $TiO_2$ has proven to be indispensable for band-gap narrowing and photocatalytic activity. These test results lead us to conclude that Nanovis$^{(R)}$ can be used for IAQ improvemen and for photocatalytic water splitting to hydrogen.

• Advances in nano research
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• v.4 no.3
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• pp.157-165
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• 2016

The photocatalytic (PC) activity of anatase titania nanoparticles can be improved through codoping with transition metals and nitrogen. In addition, the PC activity can also be improved by creating monodisperse, mesoporous nanoparticles of titania. The question naturally arose as to whether combining these two characteristics would result in further improvement in the PC activity or not. Herein, we describe the synthesis and photocatalytic characteristics of codoped, monodisperse anatase titania. The transition metals tested in the polydisperse and the monodisperse forms were Mn, Co, Ni, and Cu. In each case, it was found that the monodisperse version had a higher PC activity compared to the corresponding polydisperse version.

• Elastomers and Composites
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• v.51 no.1
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• pp.10-16
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• 2016

Nanosized palladium particles were synthesized using palladium(II) chloride, trisodium citrate dihydrate, and sodium borohydride under stirring condition. Nanosized palladium-graphene composites were prepared from palladium nanoparticles, and graphene was enclosed with polyallylamine under stirring condition for 1 h followed by ultrasonication for 3 h. Nanosized palladium-graphene composites were heated in an electric furnace at $700^{\circ}C$ for 2 h and characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. UV-vis spectrophotometry was used to evaluate the nanosized palladium-graphene composites as a catalyst in the photocatalytic degradation of various organic dyes such as methylene blue, methyl orange, rhodamine B, and brilliant green under ultraviolet light at 254 nm.

• Elastomers and Composites
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• v.53 no.2
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• pp.75-79
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• 2018

ZnS:Mn-glycine (ZnS:Mn-Gly) nanocomposites were synthesized by capping ZnS:Mn nanocomposites with glycine. Zinc sulfate heptahydrate ($ZnSO_4{\cdot}7H_2O$), glycine ($C_2H_5NO_2$), manganese sulfate monohydrate ($MnSO_4{\cdot}H_2O$), and sodium sulfide ($Na_2S$) were used as the source reagents. $ZnS:Mn-Gly-C_{60}$ nanocomposites were obtained by heating the ZnS:Mn-Gly nanocomposites and fullerene ($C_{60}$) at a 2:1 mass ratio in an electric furnace at $700^{\circ}C$ for 2 h. X-ray diffraction (XRD) was used to characterize the crystal structure of the synthesized nanocomposites. The photocatalytic activity of the $ZnS:Mn-Gly-C_{60}$ nanocomposites was evaluated, via the degradation of brilliant green (BG) dye under 254 nm irradiation, with a UV-vis spectrophotometer.

• Journal of Powder Materials
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• v.19 no.3
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• pp.196-203
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• 2012

$TiO_2$ was successfully formed on a Ti specimen by MAO (Micro-Arc-Oxidation) method treated in $Na_3PO_4$ electrolyte. This study deals with the influence of voltage and working time on the change of surface microstructure and phase composition. Voltage affected the forming rate of the oxidized layer and surface microstructure where, a low voltage led to a high surface roughness, more holes and a thin oxidized layer. On the other hand, a high voltage led to more dense surface structure, wider surface holes, a thick layer and fewer holes. Higher voltage increases photocatalytic activity because of better crystallization of the oxidized layer and good phase composition with anatase and rutile $TiO_2$, which is able to effectively separate excited electrons and holes at the surface.