• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.9
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• pp.577-580
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• 2015

In this paper, in order to develop the composition ceramics with the outstanding piezoelectric properties, $Pb(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_{0.09}(Zr_{0.5}Ti_{0.5})_{0.88}O_3$ ceramics substituted with $BiFeO_3$ were prepared by the conventional solid-state reaction method. The addition of small amount of $Li_2CO_3$ and $CaCO_3$ as sintering aids decreased the sintering temperature of the ceramics. The effects of $BiFeO_3$ substitution on their piezoelectric and dielectric properties were investigated. when 0.015 mol $BiFeO_3$ was substituted, the optimal physical properties of $d_{33}=590pC/N$, $E_c=8.78kV/mm$ were obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.277-278
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• 2007

In this study, in order to develop multilayer piezo-actuator, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3,\;Na_2CO_3$, ZnO as sintering aids and their piezoelectric and dielectric properties were investigated according to the Bi substitution. Bi substitution enhanced electromechanical coupling factor$(k_p)$ and dielectric constant$({\varepsilon}_r)$. However, mechanical quality factor was deteriorated. At the sintering temperature of $870^{\circ}C$ and Bi substitution of 1mol%, density, electromechanical coupling factor$(k_p)$, mechanical quality factor$(Q_m)$, Dielectric constant$({\varepsilon}_r)$ and piezoelectric constant$(d_{33})$ of specimen showed the optimum value of $7.878g/cm^3$, 0.608, 835, 1603 and 397pC/N, respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.2
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• pp.116-123
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• 2007

[ $La_{0.5}Ce_{0.5}Co_{1-x}Cu_xO_{3-{\alpha}}$ ](X=0, 0.1, 0.3, 0.5) perovskites were prepared by coprecipitation method at pH 7 or pH 11 and its catalytic activity of selective CO oxidation was investigated. The characteristics of these catalysts were analyzed by $N_2$ adsorption, X-ray diffraction(XRD), SEM, $O_2$-temperature programmed desorption(TPD). The pH value at a preparation step made effect on particle morphology. The smaller particle was obtained with a condition of pH 7. The better catalytic activity was observed using catalysts prepared at pH 7 than pH 11. The maximum CO conversion of 98% was observed over $La_{0.5}Ce_{0.5}Co_{0.7}Cu_{0.3}O_{3-{\alpha}}$ at $320^{\circ}C$. Below $200^{\circ}C$, the most active catalyst was $La_{0.5}Ce_{0.5}Co_{0.9}Cu_{0.1}O_{3-{\alpha}}$, of which conversion was 92% at $200^{\circ}C$. By the substitution of Cu, the evolution of ${\alpha}$-oxygen was remarkably enhanced regardless of pH value at preparation step according to $O_2$-TPD. Among the different ${\alpha}$-oxygen species, the oxygen species evolved between $400^{\circ}C$ and $500^{\circ}C$, gave the better catalytic performance for selective CO oxidation including $La_{0.5}Ce_{0.5}CoO_3$ in which Cu was absent.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.128-132
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• 2007

The thermal and magnetic properties of amorphous (FeCo)SiBNb ribbon alloys with high glass forming ability have been investigated. The glass forming ability was enhanced by Co substitution in amorphous ($Fe_{1-X}Co_X)_{72}Si_4B_{20}Nb_4$ alloys with the thickness of about $40{\mu}m$. With the increase in Co content, the temperature range of supercooled liquid phase increased indicating the high glass forming ability of the Co-added alloys. Further the ac permeability increased, and the core loss decreased considerably by Co substitution, while small change in $B_8$ (magnetic flux density at 800 A/m) was observed. The frequency characteristics of permeability deteriorated as compared to conventional amorphous ribbon alloys with the thickness of about $20\;{\mu}m$ due to the increased skin effect.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.405-411
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• 1992

The substitution reaction and structrue of products obtained from the reaction of Equatorial-Skew-[Co(TRDTRA)($OH_2$)] (TRDTRA = trimethylenediaminetriacetate) with $CN^-, NO^{-}_{2}$ and $NCS^-$ ions have been investigated by means of electronic absorption spectroscopy and theoretical calculation based on the Yamatera's theory. According to kinetic data, the substitution reaction order for the complexes such as $CN^-, NO^{-}_{2}$ and $NCS^-$ was the first order, respectively, and overall reaction order was second order. It has been determined that the structure of products having $CN^{-} and NO^{-}_{2}$ ions was Polar-Chair type complexes which were accompanying with isomerization and having $NCS^-$ ion was Equatorial-Skew type complex which was not accompanying with isomerization.

• Environmental and Resource Economics Review
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• v.22 no.1
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• pp.77-98
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• 2013

China, the world's largest $CO_2$ producer, is likely to be obligated to reduce greenhouse gas emissions under the post-Kyoto protocol. This paper estimates a Shephard input distance function for the Chinese fossil-fueled power generation sector to measure the shadow price of $CO_2$ emissions, technical efficiency, and indirect Morishima elasticities of substitution between inputs. Empirical results show that, on average, it costs approximately 3.2 US dollars per year to reduce $CO_2$ emissions by one ton over the period 1981-2009. This finding indicates that Chinese power sector is expected to benefit from selling emission permits to other countries such as Korea and Japan, given that our estimate for China is lower than the ones previous literatures estimated for the power sector in these countries. The maximum attainable average $CO_2$ reduction potential amounts to approximately 25 million tons per year by improving technical efficiency. Capital is substitutable with both coal and oil and capital is relatively more readily substituted for these fuels.

• Proceedings of the Korean Magnestics Society Conference
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• 1999.04a
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• pp.24-25
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• 1999

• Proceedings of the Korean Magnestics Society Conference
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• 1998.10a
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• pp.66-67
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• 1998

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1525-1530
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• 2004

Mutagen X (MX) exists in our drinking water as the bi-products of chlorine disinfection. Being one of the most potent mutagen, it attracted much attention from many researchers. MX and its analogs are synthesized and modeled by quantitative structure activity relationship (QSAR) methods. As a result, factors affecting this class of compounds have been found to be steric and electrostatic effects. We tried to collect all the data available from the literature. With both CoMFA and CoMSIA various combinations of physiochemical parameters were systematically studied to produce reasonable 3-dimensional models. The best model for CoMFA gave $q^2$ = 0.90 and $r^2$ = 0.97, while for CoMSIA $q^2$ = 0.85 and $r^2$ = 0.94. So the models seem to be reasonable. Unlike previous result of CoMFA, in our case steric parameter alone gave the best statistics. Although the steric contribution was found to be the most important in both CoMFA and CoMSIA, steric parameter along with electrostatic parameter produced slightly better model in CoMSIA. Overall, steric contribution is clearly the most important single factor. However, when we compare chlorine and bromine substitution, chlorine substitution can be more mutagenic. This indicates that other factors such as electrostatic effect also influence the mutagenicity. From the contour maps, steric contribution seems to be focused on rather small area near C6 substituent of the furanone ring, rather than C3 substituent. Therefore the locality of steric contribution can play a significant role in mutagenicity.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.466-472
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• 2000

As cathode materials of LiMn2O4-based lithium-ion secondary batteries, Li(Mn1-$\delta$M$\delta$)2O4 (M=Ni and Co, $\delta$=0, 0.05, 0.1 and 0.2) materials which Co and Ni are substituted for Mn, were syntehsized by the solid state reaction at 80$0^{\circ}C$ for 48 hours. No second phases were formed in Li(Mn1-$\delta$M$\delta$)2O4 system with substitution of Co. However, substitution of Ni caued to form a second phase of NiO when its composition exceeded over 0.2 of $\delta$ in Li(Mn1-$\delta$M$\delta$)2O4. As the results of charging-discharging test, the maximum capacity of Li(Mn1-$\delta$M$\delta$)2O4 appeared in $\delta$=0.1 for both Co and Ni. Also, Li(Mn1-$\delta$M$\delta$)2O4 electrode showed higher capacity and better cycle performance than LiMn2O4.