• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.467-471
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• 2001

DC accelerated aging characteristics of $Pr_{6}O_{11}$-based ZnO varistors, which are composed of $ZnO+Pr_{6}O_{11}+CoO+Cr_{2}O_{3}+Dy_{2}O_{3}$ ceramics were investigated with CoO content in the range of 0.5 - 5.0 mol%. The varistors doped with 1.0 mol% revealing maximum value(66.61) in the nonlinear exponent exhibited excellent stability, in which the variation rates of the varistor voltage, the nonlinear exponent and leakage current are -1.93%, -10.48%, and +288.79%, respectively, under DC accelerated aging stress, such as $(0.85V_{lmA}/115^{\circ}C/24h)+(0.90V_{lmA}120^{\circ}C/24h)+(0.95V_{lmA}/125^{\circ}C/24h)+(0.95V_{lmA}/150^{\circ}C/24h)$. Next the varistors doped with 2.0 mol% exhibiting the nonlinear exponent of 47.39 showed high stability.

• 한국세라믹학회지
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• 제25권2호
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• pp.136-142
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• 1988

β-Al2O3, which is used for solid electrolyte membrances in sodium-sulfur batteries, was prepared by sol-gel process. Sodium-n-propoxide NaOC3H7 and aluminum-isopropoxide Al(OC3H7)3 were hydrolyzated in the solution at pH 3, pH 7, pH 9 and pH 11, respectively. The sol-gel processed samples were calcined at several temperature steps, respectively and analysed by thermal analyser(DT-TGA), infrared spectrum analyser and X-ray diffraction analyser. The gelling rate of solution at pH 7 was much higher than that of the solution at pH 3. Thermal exchanging behavior of the gels at pH 3 were similar to Na2O·Al2O3·6H2O and, above pH 7, were similar to Na2O·Al2O3·3H2O. When samples' composition ratio was 9.13 : 90.87 [NaOC3H7:Al(OC3H7)3] at pH 7, β-Al2O3 was formed at 1100℃.

• 대한화학회지
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• 제24권2호
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• pp.175-177
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• 1980

• 한국결정성장학회지
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• 제4권3호
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• pp.294-305
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• 1994

초음파 분무법에 의한 $SnO_2(:F)$박막의 제막시 DBDA와 $SnCl_4.5H_2O$를 출발물질로 사용하은 경우 제막조건이 전기적, 광학적 그리고 표면형상 드의 특성에 미치는 영향에 대해 조사하였다. 박막의 비저항은 출발물질에 관계없이 용액내의 F/Sn의 비가 0.6일 때까지는 급격히 증가하였으며, $SnO_2.5H_2O$를 출발물질로 사용한 경우 DBDA의 경우보다 낮았다. 용액내의 F/Sn의 비가 1일 때 출발물질로서, $SnO_2.5H_2O$과 DBDA를 사용한 경우 광투과율은 각각 83%와 85%로서 DBDA 사용한 경우가 다소 높았다.

• 한국세라믹학회지
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• 제33권3호
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• pp.307-312
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• 1996

In following addition of 0.3, -0.6, 0.8, 1.0 and 5 weight percent MgSiF66H2O studies have been made of the setting and hardening characteristics of ordinary portland cement. MgSiF66H2O retarded the setting time of ordinary portland cement and extended the induction pariod of the hydration. In ordinary portland cement the setting characteristics were drastically altered especially at high MgSiF66H2O contents. Evidence was also obtained by the formation of a KSiF6 which was very fine particle. The results wee as follows. 1. Slump was slightly decreased when MgSiF66H2O added. 2. Setting time was retarded depending on the amount of retarding agent 2 to 8 hours 3. Compressive strength was almost same or some increased in comparision with opc. 4. When MgSiF66H2O was added to cement paste K2SiF6 were formed It was fine-sized distributed uniformly in cement grain and caused retardation of cement setting.

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.830-834
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• 2006

Lipid peroxidation induced by the reaction of cytochrome c with $H_2O_2$ was investigated. When linoleic acid micelles or phosphatidyl choline liposomes were incubated with cytochrome c and $H_2O_2$, lipid peroxidation was increased in cytochrome c and $H_2O_2$ concentrations-dependent manner. Radical scavengers, azide, formate and ethanol prevented lipid peroxidation induced by the cytochrome c/$H_2O_2$ system. Iron specific chelator, desferoxamine also prevented the cytochrome c/$H_2O_2$ system-mediated lipid peroxidation. These results suggest that lipid peroxidation may be induced by the cytochrome c/$H_2O_2$ system via the generation of free radicals. Carnosine, homocarnosine and anserine are present in the muscle and brain of many animals and human. Previous studies show that these compounds have an antioxidant function. In the present study, carnosine, homocarnosine and anserine significantly prevented the cytochrome c/$H_2O_2$ system-mediated lipid peroxidation. Carnosine and related compounds also inhibited the free radical-generating activity of cytochrome c. The results suggest that carnosine, homocarnosine and anserine may prevent lipid peroxidation induced by the cytochrome c/$H_2O_2$ system through a free radical scavenging.

• Bulletin of the Korean Chemical Society
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• 제25권6호
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• pp.852-858
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• 2004

Crystal structures of lanthanide complexes with NTA (NTA = nitrilotriacetate) are reported. The complexes of $[Ln(NTA)_2{\cdot}H_2O]^{3-}$ (Ln = Sm, Eu, Gd, Tb and Ho) crystallize in the orthorhombic space group Pccn. In the structures, the trivalent lanthanide ions are completely encapsulated via coordination to the two nitrogen atoms and the six carboxylate oxygen atoms of the two NTA ligands, and one water oxygen atoms. The complexes form a slightly distorted capped-square-antiprism polyhedron. Of the complexes, $[Eu(NTA)_2{\codt}H_2O]^{3-}$,\;[Tb(NTA)_2{\cdot}H_2O]^{3-}\;and\;[Dy(NTA)_2{\cdot}H_2O]^{3-}$ excited at the 325 He-Cd line produce very characteristic luminescence features, arising mostly from the f ${\to}$ f transitions. The absolute quantum yields of these complexes are determined at room temperature. Surprisingly, the $[Dy(NTA)_2{\cdot}H_2O]^{3-}$ complex is more luminescent than the $[Eu(NTA)_2{\cdot}H_2O]^{3-}\;and\;[Tb(NTA)_2{\cdot}H_2O]^{3-}$ complexes.

• 소성∙가공
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• 제27권1호
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• pp.48-53
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• 2018

Aluminum nitride (AlN) is used by the semiconductor industry that has requirements for high thermal conductivity. The theoretical thermal conductivity of single crystal AlN is 320W/mK. Whereas, the values measured for polycrystalline AlN ceramics range from 20 W/mK to 280 W/mK. The variability is strongly dependent upon the purity of the starting materials and non-uniform dispersibility of the sintering additive. The conventional AlN sintering additive used yttria ($Y_2O_3$), but the dispersibility of the powder in the mixing process was important. In this study, we investigated the mechanical and thermal conductivity of yttrium nitrate ($Y(NO_3)_3{\cdot}6H_2O$), as a sintering additive in order to improve the dispersibility of $Y_2O_3$. The sintering additives content was in the range of 2 to 4.5wt.%. The density of AlN gradually increased with increasing contents of sintering additive and the flexural strength gradually increased as well. The flexural strength of the sintered body containing 4 wt% of $Y_2O_3$ and $Y(NO_3)_3{\cdot}6H_2O$ was 334.1 MPa and 378.2 MPa, respectively. The thermal conductivities were 189.7W/mK and 209.4W/mK, respectively. In the case of hardness, there was only a slight difference and the average value was about 10 GPa. Therefore, densification, density and strength values were found to be proportional to its content. It was confirmed that AlN using $Y(NO_3)_3{\cdot}6H_2O$ displayed relatively higher thermal conductivity and mechanical properties than the $Y_2O_3$.

• 한국전기전자재료학회논문지
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• 제11권4호
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• pp.288-292
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• 1998

In this paper, we fabricated $SnO_2$ composite ceramics doped with 0~20mol% $SnO_2$ of bulk type to investigate the CO and $H_2$ gas sensitivity in various composition, temperature, and concentration of CO and $H_2$ gas. At the temperature range from $100^{\circ}C\sim425^{\circ}C$, the measured 1000ppm and 250ppm CO gas sensitivities of $SiO_2-SnO_2$composite ceramics were about 1.0~7.6 and 1.0~5.6, respectively. These values were about 1.0~1.5 times larger than pure $SnO_2$. The maximum 1000ppm CO gas sensitivity of $SiO_2-SnO_2$composites were measured around $325^{\circ}C$. At the temperature range from $270^{\circ}C\sim380^{\circ}C$, the 1000ppm and 500ppm $H_2$gas sensitivities of $SiO_2-SnO_2$ composites were about 2.9~21.2 and 2.1~11.3, respectively. Also the maximum 1000, 500 ppm $H_2$ gas sensitivities of samples were measured around.

• 대한화학회지
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• 제17권3호
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• pp.169-173
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• 1973

세자리 schiff base리간드로서 salicylidene amino-o-hydroxy benzene 은 salicylaldehyde와 o-amino phenol로서 합성하였으며 이 세자리 schiff base 리간드와 Mo(VI), Mo(V), Mo(IV) 및 Mo(III) 의 과산화상태의 몰리브덴 착물들의 반응으로 새로운 착물[Mo O$_2(H_2O)\;(C_{13}H_9O_2N)]$, [MoO Cl(H$_2O)(C_13H_9O_2N)]$, $[Mo(SCN)_2(H_2O)(C_{13}H_9O2_N)]$ 및 $[Mo(H_2O)_2 (C_{13}H_9O_2N)]_2O$들을 얻었다. 이들 착물에서 Mo(VI), Mo(V) 및 Mo(IV)착물들은 리간드와 몰리브덴의 mole비가 1:1인 착물로서 몰리브덴 이온은 6배위 팔면체로서 주어지나 Mo(III) 착물은 Mo-O-Mo의 산소 bridge bond를 갖는 poly nuclear 착물로서 mole비 1:1인 착물로 주어짐을 원소분석치와 자외선흡광도 및 적외선 spectra의 고찰로서 알아보았다.