• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1719-1723
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• 2014

In this study, the microwave dielectric properties of nano spheroidization glass powders added $Ba(Zn_{1/3}Ta_{2/3})O_3$ ceramics prepared by solid state reaction have been investigated. Adding $(Ba_{0.4}Ca_{0.6})SiO_3$ nano spheroidization glass powders could effectively promote the densification even in the case of decreasing the sintering temperature. When the glass frit is 0.3 wt% and sintering is carried out at a temperature of $1500^{\circ}C$ for 6 hr, a temperature stable microwave dielectric ceramic could be obtained, which has a dielectric constant (${\varepsilon}_r$) of 30.2, a quality factor ($Q{\times}f_0$) of 124,000 GHz and a temperature coefficient of resonance frequency (${\tau}_f$) of $2ppm/^{\circ}C$.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1255-1257
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• 1998

In this study,$ 5{\times}5$ dot-matrix display was implemented with powder electroluminescent device (PELD). Generally PELD which have a luminance from powder phosphor with electric field, inserted phosphor and dielectric layer between electrodes is basic structure. To make high brightness PELD compared to conventional device, new type of PELD was proposed as follows. New PELD had only one layer, which was mixed phosphor (ZnS:Cu) and dielectric (BaTiO3) material appropriately between electrodes. To compare and estimate the conventional and new type of PELD, the EL spectrum, transferred charge density, brightness and decay time was measured. As above result, we fabricated a hish brightness $ 5{\times}5$ dot-matrix display with new type of PELD. Its brightness was 6400 $cd/m^2$ at 200 V, 400Hz.

• Journal of Sericultural and Entomological Science
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• v.42 no.2
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• pp.93-98
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• 2000

This study was designed to investigate the effect of silkworm powder on oxygen radicals and their scavenger enzymes in brain membrances of SD rats. Hydroxyl radical (OH) levels resulted in a considerable decreases in brain mitochondria fraction. Superoxide radical (O$_2$) levels were a slightly decreased in brain cytosol fraction. Lipid peroxide (LPO) and Oxidized protein (OP) levels were significantly decreased in brain mitochondria and microsomes fraction. Mn-superoxide dismutase (SOD) activity was remarkably increased in the mitochondria fraction. Cu and Zn-SOD activities were effectively increased in brain cytosol fraction. GSHPx activity was considerably increased in brain cytosol fraction. These results suggest that anti-aging effect of silkworm plays an effective role in attenuating an oxidative stress and increasing a scravenger enzyme activity in brain membranes.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.676-677
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• 2006

Synthesis of zinc oxide nanorods, sheets and flower like structure were done by the sol-gel method using zinc acetate dihydrate and sodium hydroxide at $80^{\circ}C$ with 12 hours refluxing time nanorods, in case of as synthesized powder, with diameter of 20-60nm. Annealing at higher temperature (300 and $500^{\circ}C$,) in air ambient changes the morphology to sheet and flower like structure. The standard peak of zinc oxide was observed in IR at $523cm^{-1}$. The UV-VIS spectroscopy of zinc oxide shows a characteristic peak at 375nm.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.721-727
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• 2002

In order to overcome trade-off among compositions, process and properties of the glasses with high PbO-base composition for PDP Rib, we studied glass crystallization and crystallization kinetics by Differential Thermal Analysis(DTA). Glass powder was obtained through melting/cooling/grinding, with 3 wt%TiO2 addition for the crystal nucleation and growth in $62PbO-19B_2O_3-10SiO_2-9(Al_2O_3-K_2O-BaO-ZnO)$(in wt%) composition glass. This powder was heat-treated for 1 to 10 h at $445^{\circ}C$ for nucleation. DTA measurements were performed to obtain the crystallization peak with $5∼25^{\circ}C/min$ heating rates. DTA crystallization peak temperature increased with increasing the heating rate and decreased with increasing the heating time. Because the Avrami parameter (n) was approximately 1, the surface crystallization occurred. The maximum nucleation time was 2 h.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.272-277
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• 2019

In this paper, a manufacturing method of an anti-glare cover glass on LCD for outdoor use is proposed. The main specification of cover glass is hardness and anti-glare. Hardness is achieved by using the tempered glass, and anti-glare(AG) film is laminated to meet anti-glare specification no the tempered glass. However, the AG film is difficult to maintain the AG performance continuously because the abrasion resistance of the PET film itself is as weak as about 3H. Therefore, a novel production procedure using screen printing method is proposed. The proposed coating is implemented by applying $ZnO-B_2O_3-SiO_2$ powder on glass surface and the glass is made with enhanced hardness through tempering process. In order to apply the ZBS powder uniformly on the glass surface, a screen printing process is used. The main parameters to be considered in screen printing are the oil concentration and mesh opening size. Because the amount of ZBS powder applied to the printing process is controlled by these two parameters, the correlativity is confirmed through the experiments. In order to evaluate the performance of the proposed method, the haze, surface roughness and transmittance are selected as the performance index and are compared with the AG film. As a result of comparison, it is verified that the transmittance of the proposed tempered glass is 83.1%, which is slightly lower than 89.5% of AG film, but the hardness is more than double to 7H.

• Journal of the Korean Ceramic Society
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• v.12 no.1
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• pp.5-11
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• 1975

Thick film resistor paste was made utilizing oxide materials such as SnO, SnO＋Sb2O3, and SnO＋Zn. The oxide materials were mixed respectively with Q-12 glass powder and finally suspended in ethyl cellulose dissolved in ethyl cellosolve. Thick film resistor was made by screen printing the paste on the alumina substrate and firing it at a suitable temperature. Among thick films made from the resistor paste, the thick film containing 85% SnO and fired at $600^{\circ}C$ demonstrated the finest electrical properties showing 10 K ohm in sheet resistance, 110 ppm/$^{\circ}C$ in TCR. In general, TCR of the thick films made from the oxide-mixture paste is good in linearity, therefore it is suggested the oxide-mixture paste is utilized as the negative thermistor.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.213-219
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• 1996

Pellet type $Pt/MoO_{3}$ gas sensor which is operating at much lower temperature than conventional ceramic sensors such as $SnO_{2}$ or ZnO was fabricated. Morphology and crystal structure of $Pt/MoO_{3}$ according to calcination temperature have been characterized with Transmission Electron microscopy and X-Ray powder diffraction. The characterization indicates that as calcination temperature is increased, overlayers of $MoO_{3}$ on Pt are produced, but additionally, the Cl content associated with the Pt phase diminishes. The gas dasorption test showed that the change in surface morphology is closely related to hydrogen storage capacity of the sample. The gas sensitivities at $50^{\circ}C$ and $150^{\circ}C$ are very high.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.486-491
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• 2004

Dimensionally stable anode(DSA) can be used for the hydro-metallurgy of non-ferrous metals like as Zn, and the electrolysis of sea water. MnO$_2$ electrode satisfies the requirements of DSA, and has a good cycle life and a low overpotential for oxygen evolution. MnO$_2$ electrodes based on Ti matrix were prepared by using thermal decomposition method and also MnO$_2$ was coated on Ti and Pb matrix with DMF and PVDF compositions. The MnO$_2$ electrodes prepared by thermal decomposition method had very weak adhesive strength onto Ti matrix and MnO$_2$ layer was removed out so that electrochemical properties for MnO$_2$ were not investigated. The viscosity of solvent used as a binder of MnO$_2$ Powder increased with the increasing PVDF contents. The thickness of the MnO$_2$ layer on Pb matrix in DSA, which was prepared with 5 times dipping at the solution mixed with PVDF : DMF = 1 : 9, was 150${\mu}{\textrm}{m}$. When the ratio of PVDF to MnO$_2$ was lower than 1 : 6, the Pb electrode didn't show any reaction irrespective of the concentrations of DMF. However, When the ratio of PVDF to MnO$_2$ was higher than 1: 6, the Pb electrode showed constant current reactions and homogeneous cyclic voltammetry even though at a high cycle. The reason for the high current and homogeneous cyclic voltammetry is the good catalytic reactions of MnO$_2$ powder in electrode.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.406-409
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• 2004

A blue phosphor(ZnS:Cu) is manufactured by solid state reaction for ACPEL(AC powder EL). The effect of artificial defect on phosphor surface on the ZnO phase conversion and resulting luminescence have been studied. It was found that ZnS:Cu could converse to cubic phase more easily due to the formation of artificial defect on 1st fired phosphor by ball-milling process, resulting in improvement of luminescence of phosphor phosphors under the driven EL condition. We found out an optimized ball-mill condition through considering effect of each ball-mill conditions such as milling time and milling rpm on defect. Also we determined relationship between emission luminescence and phase of phosphor based on analyses of crystal structures of phosphors. A significant improvement above 30% was observed in electroluminescence by the artificial defect on ZnS:Cu phosphors compared to non-treated phosphors.