• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.235-240
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• 2010

The evolution of microstructure and phases of Mg-10Al-Mn alloy by cooling plate method during homogenization treatment have been investigated with metallographic analysis, scanning electron microscopy and energy dispersive spectroscopy. The ingots used for this experiment were prepared by cooling plate and homogenization heat treatment was performed at 300 and $400^{\circ}C$ for various holding times (0, 1, 4, 8 and 12h). The casting ingots were consisted of the fine grains and eutectic phases. And, these eutectic phases were dissolved into the matrix during homogenization treatment at $400^{\circ}C$ but the lower temperature (at $300^{\circ}C$) did not be.

• Journal of the Semiconductor & Display Technology
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• v.5 no.3 s.16
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• pp.23-27
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• 2006

Recently, Top emission organic light-emitting diode (TEOLED) has been attracted by their potential application for the development of flat panel display (FPD). We have fabricated the high luminance top emission organic-emitting diode (TEOLED) using dual cathode layer and three top emitting structure. These devices were characterized by electroluminescence (EL) and current density-voltage (J-V) measurements. After compared it with Au anode structure, luminance of the device using dual anode was better than using without Al device. Consequently, Al layers are very good candidates for a promising electron-injecting buffer layer for top emission light-emitting diode (TEOLED).

• Archives of Pharmacal Research
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• v.28 no.5
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• pp.557-560
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• 2005

Resveratrol, a phenolic antioxidant found in grapes, has been known to mediate various biological activities on the human body. In the present study, we tested the antifungal a ctivity of resveratrol against human pathogenic fungi before carrying out further studies to elucidate the antifungal mechanism(s) of resveratrol. Resveratrol displayed potent antifungal activity against human pathogenic fungi at concentration levels of 10-20 ${\mu}g$/mL. Furthermore, time-kill curve exhibited fungicidal effect of resveratrol on C. albicans, but the compound had no hemolytic activity against human erythrocytes. The destruction of C. albicans cells by resveratrol was confirmed by scanning electron microscopy. These results suggest that resveratrol could be employed as a therapeutic agent to treat fungal infections of humans.

• Journal of Microbiology and Biotechnology
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• v.6 no.1
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• pp.30-35
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• 1996

Distillery wastewater was used in a thermophilic laboratory-scale two stage anaerobic digester to test the effects of the redox potential of the first acidogenic reactor on the performance of the system. The digester consisted of first a acidogenic reactor and the an upflow anaerobic sludge blanket (UASB) reactor. The digestor was operated at a hydraulic retention time (HRT) of 48 h. Under these conditions, about 90% of the chemical oxygen demand as measured by the chromate method ($COD_{cr}$) was removed with a gas production yield of 0.4 l/g-COD removed. The redox potential of the acidogenic reactor was increased when the reactor was purged with nitrogen gas or agitation speed was increased. The increase in reduction potential was accompanied by an increase in acetate production and a decrease in butyrate formation. A similar trend was observed when a small amount of air was introduced into the acidogenic reactor. It is believed that the hydrogen partial pressure in the acidogenic reactor was decreased by the above mentioned treatments. The possible failure of anaerobic digestion processes due to over-loading could be avoided by the above mentioned treatments.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.373-377
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• 2009

A pathway for the formation of normal $CoAl_2O_4$ particles is suggested. The optimal amount of malonic acid was determined, and the characteristics of the obtained powders were investigated. Normal $CoAl_2O_4$ powders were prepared using solutions of malonic acid and metal nitrates. X-ray diffraction, Brunauer-Emmett-Teller (BET) and scanning electron microscope (SEM) measurements, as well as Fourier transform infrared (FTIR) and ultraviolet/visible (UV-Vis) spectroscopy were carried out. Normal $CoAl_2O_4$ crystallites were formed by a solid state reaction between $CoAl_2O_4$ and amorphous aluminum oxide. The optimal molar ratio of malonic acid to the nitrate anions present in the initial solution was found to be 0.30~0.35. The particles were composed of agglomerates of primary particles. The primary particles were 40 nm in size. This size was relatively constant regardless of the preparation temperature. However, the size of the agglomerated particles increased to 220 nm with increasing temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.227-227
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• 2008

CdS is II-VI semiconductor with a wide band gap of approximately 2.42 eV. CdS is the most popularly employed heterojunction partner to p-CdTe due to its similar chemical properties. The as-deposited films are annealed in Rapid Thermal Annealing (RTA) system in various atmosphere(Air, Vacuum and $N_2$) at $500^{\circ}C$. In this work, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of chemical bath deposited (CBD) CdS films on glass is carried out. In case of the annealed CdS films in $N_2$, grain size was larger than as-annealed films.

• Journal of the Semiconductor & Display Technology
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• v.7 no.1
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• pp.47-51
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• 2008

The Al:Au double-layer metal electrode for use in transparent, dual emission of organic light-emitting diode (OLED) was fabricated. The electrode of Al:Au metals with various thicknesses was deposited by the vacuum thermal evaporation technique. For Al thickness of 1 nm, a bottom luminance of $4880\;cd/m^2$ was observed at 8 V. Otherwise, top luminance of $2020\;cd/m^2$ were observed at 8 V. In addition, the threshold voltages of the electrodes were 2.2 V. It was forward that the inserting 1 nm Al between LiF and Au enhanced electron injection with tunneling effect.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.667-670
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• 2009

The understanding of behaviors of hydroperoxyl/superoxide anion radicals (${H_2O_2}^./{O_2}^{-.}$) generated from a photoirradiated $TiO_2$ surface is essential to improve the efficiency of $TiO_2$ photocatalytic reactions by decreasing the recombination of photoinduced electron-hole ($e^--h^+$) pairs. In contrast with previous studies, we found that ${H_2O_2}^./{O_2}^{-.}$ generated on the surface of illuminated $TiO_2$ particles are mobile. ${H_2O_2}^./{O_2}^{-.}$ formed by the photocatalysis of $TiO_2$ particles immobilized onto the inner surface of a coil-quartz tube were forced under a continuous flow through a knotted tubing reactor (KTR) and into the aqueous phase completely separated from the $TiO_2$ particles, and were measured by a chemiluminescence (CL) technique using 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[ 1,2-a]pyrazin-3-one (MCLA) as the reagent. The initial concentration of the ${H_2O_2}^./{O_2}^{-.}$ stream entering the KTR was determined by its half-life (98 s) at pH 5.8. We suggests that the efficiency of $TiO_2$ photocatalytic reactions may be further improved by utilizing the mobility of ${H_2O_2}^./{O_2}^{-.}$.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.4
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• pp.502-506
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• 2012

In order to find the structural characteristics of the thin films of group II-VI semiconductor compounds compared with those of powder materials, films were made of 4 powders of ZnS, CdS, CdSe, and CdTe(Aldrich), each with 99.99 % purity. For the ZnS/CdS multi-layers, the ZnS layer was coated over the CdS layer on an $AlO_x$ membrane, which served as a protective layer within a vacuum at the average speed of 1 ${\AA}$/sec. After studying the structures of the group II-VI semiconductor thin films by using X-ray spectroscopy, we found that the ZnS, ZnS/CdS, CdS, and CdSe films were hexagonal and exhibited some degree of preferred orientation. Also, the particles of the thin films of II-VI semiconductor compounds proved to be more homogeneous in size compared to those of the powder materials. These results were further verified through scanning electron microscopy(SEM), EDX analysis, and powder and thin film X-ray diffraction.

• Journal of Powder Materials
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• v.15 no.2
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• pp.136-141
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• 2008

The mechanochemical process were employed to prepare the red phosphors (Y,Gd)$BO_3:Eu^{3+}$. The main factors affecting particle size, particle distribution, and luminescent properties of the product were investigated in details. Particles sized around 200-600 nm are formed after intensive milling. The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectrum. Results revealed that phosphors with different morphology, small particle size and high luminescence intensity could be obtained by mechanochemical process.