• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1379-1381
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• 1998

Powder electroluminescent device (PELD) structured conventionally dielectric and phosphor layer, between electrode and their layer fabricated by screen printing splaying or spin coating method. To promote performance of PELDs, we approached the experiments for different structure and thickness variation of PELD. Thickness variation($30{\mu}m{\sim}130{\mu}m$) was taken. To investigate electrical and optical properties of PELDs, EL spectrum, transferred charge density using Sawyer-Tower's circuit brightness was measured. Variation of structure in PELDs was as follows: WK-1 (ITO/BaTiO3/ZnS:Cu/Silver paste), WK-2 (ITO/BaTiO3/ZnS:Cu/BaTiO3/ZnS:Silver paste), WK-3 (ITO/BaTiO3/ZnS:Cu/BaTiO3/Silver paste), WK-4(ITO/BaTiO3+ZnS:Cu/Silver paste) As a result, structure of the highest brightness appeared WK-4 possessed 60 ${\mu}m$ thickness. The brightness was 2719 cd/$m^2$ at 100V, 400Hz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.282-286
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• 2003

We investigated the effects of calcination temperature and sintering additives on the sintering behaviors and microwave dielectric properties of $(Zn_{0.8}Mg_{0.2})TiO_3$. Highly densified samples were obtained at the sintering temperatures below $1000^{\circ}C$ with additions of 0.45 wt.% $Bi_2O_3$ and 0.55 wt.% $V_2O_5$. From the examination of the existing phases and microstructures before and after sintering of $(Zn_{0.8}Mg_{0.2})TiO_3$ system calcined at the various temperatures ranging from $800^{\circ}C$ to $1000^{\circ}C$, it was found that high $Q{\times}f_o$ values were obtained when unreacted or second phases in calcined body were reduced. When calcined at $1000^{\circ}C$ and sintered at $900^{\circ}C$, it consists of hexagonal as a main phase with uniform microstructure and exhibits $Q{\times}f_o$ value of 42,000 GHz and dielectric constant of 22.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1605-1610
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• 2017

The electrochemical luminescence (ECL) device was investigated, which has similar structure to the dye-sensitized solar cell. The structure of the ECL cell in this experiment reliably induces a large amount of the oxidation around electrodes. The band gap of the ECL electrode is of 3.0 - 3.2 eV. Titanium dioxide ($TiO_2$) nanoparticle has following properties: a band gap of 3.4 eV, a low-priced material, and 002 preferred orientation (Z-axis). Zinc Oxide (ZnO) nanorod is easy to grow in a vertical direction. In this paper, in order to determine material suitable for the ECL device, the properties of various materials for electrodes of ECL devices such as ZnO nanorod (ZnO-NR) and $TiO_2$ nanoparticle ($TiO_2-NP$) were compared. The threshold voltage of the light emission of the ZnO-NR was 2.0 V which is lower than 2.5 V of $TiO_2-NP$. In the other hand, the luminance of $TiO_2-NP$ was $44.66cd/m^2$ and was higher than that of $34cd/m^2$ of ZnO-NR at the same applied voltage of 4 V. Based on the experimental results, we could conclude that $TiO_2-NP$ is a more suitable electrode material in ECL device than the ZnO-NR.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.05a
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• pp.82-83
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• 1988

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.13-16
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• 1994

In this paper, xPb(Zn$_{1/3}Nb_{2/3}$)$O_3$-yPbTiO$_3$-zPbZrO$_3$-(0.5wt%)MnO$_2$ ceramics were fabricated by the mixed oxide method sintered at $1250^{\circ}C$ for 2[hr] and then the deielectric, electromechanical coupling factor($K_{p}$ and mechanical coupling factor(Qm) properties were investigated. In 0.1PZN-0.45PT-0.45PZsample, dielectric properties and electromechanical coupling factor were 829 and 29%. In the case of 0.5PZN-0.45PT-0.50PZ sample, that was 101 according to mechanical quality facotr. molphotropic phase boundary(MPB) certained area which $PbTiO_3$addition quatity 40∼50[㏖%].

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.7-11
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• 2015

In this study, $Si_3N_4$/SnZnO/AZO/Ag/Ti/ITO multi-layer film were prepared on glass substrate by DC/RF magnetron sputtering method. To prevent interfacial reaction between Ag and ITO layer, Ti buffer layer was inserted. Optical properties and sheet resistance were studied depending on laminating times of each multi-layered film especially in visible ray. The simulation program, EMP (essential macleod program), was adopted and compared with experimental data to expect the experimental result. It was found out that the transmittance of the first stacked $Si_3N_4$/SnZnO/AZO/Ag/Ti/ITO multi-layer film was more than 90%. However, with increasing stacking times, the optical properties of $Si_3N_4$/SnZnO/AZO/Ag/Ti/ITO multi-layer film get worse. Consequently, Ti layer is good for oxidation barrier, but too many uses of this layer may have an adverse effect to optical properties of TCO film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.1017-1024
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• 2000

Effect of the microwave dielectric properties and the microstructure on a mole fraction(x=0.1~0.9) of (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$ ceramics was investigated. When (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$(x=0.1~0.9) ceramics were sintered at 130$0^{\circ}C$, 135$0^{\circ}C$ and 140$0^{\circ}C$ for 2hr, the microwave dielectric properties were obtained $\varepsilon$r=6.8~8.3, Q.f$_{0}$=36000~77600. On the other hand, the temperature coefficients of resonant frequency($\tau$$_{f}$) were obtained in the properties of -62ppm/$^{\circ}C$ to -49ppm/$^{\circ}C$. In order to adjust the temperature coefficient of resonant frequency($\tau$$_{f}$), CaTiO$_3$was added in (1-x)Mg$_2$SiO$_4$-xZnAl$_2$O$_4$ceramics. 0.7Mg$_2$SiO$_4$-0.2ZnAl$_2$O$_4$-0.1CaTiO$_3$ceramics sintered at 135$0^{\circ}C$ for 2hr showed the excellent microwave dielectric properties of $\varepsilon$r=7.7, Q.f$_{0}$=32000, and $\tau$$_{f}$=-7.9 ppm/$^{\circ}C$.EX>.>.EX>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.297-297
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• 2007

The $(B_{0.5},Sr_{0.5})TiO_3$ ceramics, which added with low sintering materials $Li_2CO_3$ and ZnBO, was investigated for LTCC(low temperature co-fired ceramic) applications. To compare sintering temperature of $(B_{0.5},Sr_{0.5})TiO_3$ respectively, we added 1, 2, 3, 4, and 5wt% of $Li_2CO_3$ and ZnBO to $(B_{0.5},Sr_{0.5})TiO_3$. For confirming the sintering temperature, the respective specimens were sintered from $750^{\circ}C$ to $1200^{\circ}C$ by $50^{\circ}C$. The case of $Li_2CO_3$ greatly lowered the sintering temperature of $(B_{0.5},Sr_{0.5})TiO_3$ ($1350^{\circ}C$) below $900^{\circ}C$. The addition of ZnBO improved the loss tangent of $(B_{0.5},Sr_{0.5})TiO_3$. The crystalline structure of $LiCO_3$ doped $(B_{0.5},Sr_{0.5})TiO_3$ and ZnBO doped $(B_{0.5},Sr_{0.5})TiO_3$ was analyzed with the X-ray diffraction (XRD) analysis. The dielectric permittivity and loss tangent of $Li_2CO_3$ doped BST and ZnBO doped BST were measured with the HP 4284A precision. From the electrical characterization, we respectively obtained the dielectric permittivity 1361, loss tangent $6.94{\times}10^{-3}$ at $Li_2CO_3$ doped $(B_{0.5},Sr_{0.5})TiO_3$ (3wt%) and the dielectric constant 1180, loss tangent $3.70{\times}10^{-3}$ at ZnBO doped $(B_{0.5},Sr_{0.5})TiO_3$(5wt%).

• Journal of Korean Society of Environmental Engineers
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• v.38 no.4
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• pp.177-183
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• 2016

Sewage treatment using microorganisms is affected by multiple factors such as microbial properties, characteristics of sewage and operating conditions, and nanoparticles inflow may cause negative effects on sewage treatment system especially on the system stability and efficiency. It was studied to assess the toxic effects of nanoparticles on microorganism growth. The activated sludge in the sewage treatment plant of university was cultured in the optimized medium for each strain. Bacillus (gram-positive), Pseudomonas and E.coli (gram-negative) in the activated sludge were selected as target microorganisms, and ZnO and $TiO_2$ were chosen as nanoparticles. For same concentration of nanoparticles, average growth inhibition rate of Bacillus was 60% or more, while that of Pseudomonas was less than 10%. The toxicity of nanoparticles was shown to be higher for gram-positive bacteria than gram-negative bacteria because of their differences on structure of cell wall, components of cell wall protein, physiology of cells and metabolism. ZnO affected 3 times more negative on the growth of microorganisms as compared to $TiO_2$. It was assumed that, therefore, toxicity of ZnO was found to be greater than $TiO_2$.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.186.2-186
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• 2003