• Korean Journal of Pharmacognosy
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• v.25 no.1
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• pp.70-72
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• 1994

From the herb of Artemisia princeps var. orientalis o-coumaric acid and 4,5-O-dicaffeoylquinic acid were isolated and identified by chemical and spectral analysis.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1465-1466
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• 2011

We have studied structural and electrical properties of $(Na_{0.5}K_{0.5})NbO_3$ ceramics addition with $BiTiO_3$. The $(Na_{0.5}K_{0.5})NbO_3-BiTiO_3$ ceramics were fabricated by the conventional mixed oxide method, their dielectric and piezoelectric properties were investigated with the variations of additvie amount $BiTiO_3$. At the sintering temperature of $1130^{\circ}C$, the density, dielectric constant, grain size of 0.05mol% $BiTiO_3$ specimen showed the values of 4.69 g/$cm^3$, 898 and $24.8{\mu}m$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.291-291
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• 2013

The wettability of TiO2 layers is controlled by forming highly ordered arrays of nanocones using nanopatterning, based on self-assembly and dry etching. Nanopatterning of TiO2 layers is achieved via formation of self-assembled monolayers of SiO2 spheres fabricated using the Langmuir-Blodgett technique, followed by dry etching. Compared to a thin film TiO2 layer, the nanopatterned TiO2 samples show a smaller static water contact angle, where the water contact angle decreases as the etching time increases, which is attributed to the Wenzel equation. When TiO2 layers are coated by 1H,1H,2H,2H-perfluorooctyltrichlorosilane, we observed the opposite behavior, exhibiting superhydrophobicity (up to contact angle of $155^{\circ}$) on the nanopatterned TiO2 layers. Self-assembled nanopatterning of the TiO2 layer may provide an advanced method for producing multifunctional transparent layers with self-cleaning properties.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.37-41
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• 2012

A lithium ion conducting borosilicate glass was fabricated by a conventional melt quenching technique from a mixture of Li2CO3, B2O3 and SiO2 powders. The Li ion conductivity of the lithium borosilicate glasses was evaluated in terms of the SiO2/B2O3 ratio. In the Li2O-B2O3-SiO2 ternary glass, the glass forming region decreases with an increasing Li2O content. At the same Li2O, the crystallization tendency of the glass samples increases with the SiO2/B2O3 ratio, resulting in a reduced glass forming region in the Li2O-B2O3-SiO2 ternary glass. The electrical conductivity moderately depends on the SiO2/B2O3 ratio in the Li2O-B2O3-SiO2 ternary glass. The conductivity of the glasses slightly increases with the SiO2/B2O3 ratio. The observed phenomenon can be explained by the modification of the glass structure as a function of the SiO2 content.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.638-644
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• 2008

The effects of $Nb_2O_5$ and $MnO_2$ on the positive temperature coefficient of resistivity (PTCR) behavior of lead-free $Ba_{0.99}(Bi_{1/2}Na_{1/2})_{0.01}TiO_3$ (BaBiNT) ceramics were investigated in order to fabricate a PTC thermistor available at high temperature of > $120^{\circ}C$. In particular, 0.05 mol% $Nb_2O_5$ added BaBiNT ceramic, which has significantly increased Curie temperature (Tc) of $160^{\circ}C$, showed good PTCR behavior; low resistivity at room temperature $(\rho_r)$ of $80.1{\Omega}{\cdot}cm$, a high $\rho_{max}/\rho_{min}$ ratio of $5.65{\times}10^3$ and a large resistivity temperature factor (a) of 18.5%/$^{\circ}C$. Furthermore, the improved $\rho_{max}/\rho_{min}$ of $6.48{\times}10^4$ and a of 25.4%/$^{\circ}C$ along with higher $T_c$ of $167^{\circ}C$ despite slightly increased $\rho_r$ of $569{\Omega}{\cdot}cm$, could be obtained for the BaBiNT + 0.05 mol% $Nb_2O_5$ + 0.02 wt% $MnO_2$ ceramic cooled down at a rate of $200^{\circ}C/h$.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.721-723
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• 2005

We applied the Atmospheric Pressure Plasma (AP-plasma) to the MgO film to try to control the Aging-time on the PDP production-line. The MgO film surface and the discharge characteristics of AC-PDPs were investigated, using the plasma-treated MgO film. The Aging-time change can be achieved by treating the MgO film with plasma. This method can be adapted to the mass production-line.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.91-92
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• 2007

An anomalous positive temperature coefficient of electrical resistivity (PTCR) was investigated in a ferroelectric lead-free perovskite-type compound $(Bi_{0.5}Na_{0.5})TiO_3$ within $BaTiO_3$-based solid solution ceramics. The effect of $Nb_2O_5$ content on the electrical properties and the microstructure of (1 - x) $BaTiO_3-x\;(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) ceramics made using a conventional mixed oxide process also has been studied. The Curie temperature was obviously increased with the increasing of $(Bi_{0.5}Na_{0.5})TIO_3$ content. The Nb - doped BNT ceramics (x=0.01) display low resistivity values of $10^{1{\circ}}C-10^{2{\circ}}C$ ohm.cm at room temperature and the Curie Temperature of $T_c=160^{\circ}C$.

• Archives of Metallurgy and Materials
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• v.67 no.4
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• pp.1507-1510
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• 2022

An optimum route to synthesis the W-based composite powders with homogeneous dispersion of oxide nanoparticles was investigated. The La₂O₃ dispersed W powder was synthesized by ultrasonic spray pyrolysis using ammonium metatungstate hydrate and lanthanum nitrate. The dispersion of Y₂O₃ nanoparticles in W- La₂O₃ powder was carried out by a polymer addition solution method using yttrium nitrate. XPS and TEM analyses for the composite powder showed that the nano-sized La₂O₃ and Y₂O₃ particles were well distributed in W powder. This study suggests that the combination processing of ultrasonic spray pyrolysis and polymeric additive solution is a promising way to synthesis W-based composite powders.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.194-196
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• 2004

$BaTiO_3/SrTiO_3$ heterolayered thick films on the $Al_2O_3$ substrate by screen printing method with stacking periodicity. The stacking periodicity of $BaTiO_3/SrTiO_3$ heterolayer structure was varied from $(BaTi_O_3)_1/(SrTiO_3)_1$ to $(BaTi_O_3)_3/(SrTiO_3)_3$. The total thickness of the $BaTiO_3/SrTiO_3$ films was about $120{\mu}m$. There was an interdiffusion at the interface of the $BaTiO_3$ and $SrTiO_3$ layers. The dielectric constant of $BaTiO_3/SrTiO_3$ heterolayered thick films was increased with decreasing stacking periodicity of the $BaTiO_3/SrTiO_3$. The dielectric constant of the ($(BaTi_O_3)_1/(SrTiO_3)_1$ herterolayered thick films was about 1780.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1566-1571
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• 2009

The discharge electrodes in ac PDP are coated with dielectric layer, and transparent MgO thin films are deposited on the dielectric layer. The main role of the MgO thin films in ac PDP is to protect the dielectric layer from sputtering by ion bombardment in the glow-discharge plasma. An additional important role of the MgO thin film is the high secondary electron emission coefficient which leads the low firing voltage and low cost of the PDP. In this paper, we investigated the relations of the crystal orientation about deposition thickness, deposition rate, temperature of substrate, and distance between the MgO tablet and the substrate. Additionally, we investigated the discharge characteristics of the AC PDP using nano-powder MgO tablet