• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.319-322
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• 2009

Gel polymer electrolytes were prepared by immersing a porous poly(vinylidene fluoride-co-hexafluoropropylene) membrane in an electrolyte solution containing small amounts of polymerizable additive (3,4-ethylenedioxythiophene, thiophene, biphenyl). The organic additives were electrochemically oxidized to form conductive polymer films on the electrode at high potential. With the gel polymer electrolytes containing different organic additive, lithium-ion polymer cells composed of carbon anode and LiCo$O_2$ cathode were assembled and their cycling performances were evaluated. Adding small amounts of thiophene or 3,4-ethylenedioxythiophene to the gel polymer electrolyte was found to reduce the charge transfer resistance in the cell and it thus exhibited less capacity fading and better high rate performance.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.676-680
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• 2004

Complexes M($C_7H_2NO_5)3H_2O{\cdot}H_2O{\cdot}0.25MeCN$ (M=Ni, Co) were crystallized from the reactions of $Ni(CH_3COO)_2{\cdot}4H_2O\;or\;Co(CH_3COO)_2{\cdot}2H_2O$ with KSCN and 2,6-dicarboxy-4-hydroxypyridine (chelidamic acid). The structures were characterized by X-ray crystallography. The crystal structures of 1 and 2 show a distorted octahedral coordination geometry around the M(II) ions, which are chelated by one nitrogen atom and two oxygen atoms of the chelidamic acid and three water molecules. Complexes 1 and 2 display the hydrogen-bonded 3D framework. The magnetic behavior of 2 exhibits antiferromagnetic interaction.

• Journal of Powder Materials
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• v.8 no.3
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• pp.163-167
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• 2001

A bulk porous $CaZrO_3/MgO$ composite with plantinum nano-dispersion was synthesized in air atmosphere through the combination of several in situ reactions, including the pyrolysis of $PtO_2$. A mixture of $CaMg(CO_3)_2$(dolomite), $ZrO_2$, $PtO_2$ and LiF (0.5 wt%, as an additive) was cold isostatically pressed at 200 MPa and sintered at $1100^{\circ}C$ for 2 h. The porous $CaZrO_3/MgO/Pt$ composite ($CaZrO_3/MgO$ : Pt=99 : 1 in volume) had a uniformly open-porous structure (porosity: 56%) with three-dimensional (3-D) network and a narrow pore-size distribution, similarly to the porous $CaZrO_3/MgO$ composites reported before. Catalytic Properties (viz., NO direct decomposition and NO reduction by $C_2H_4$) of the $CaZrO_3/MgO/Pt$ composite were investigated up to $900^{\circ}C$. In the absence of oxygen, the NO conversion rate reached ~52% for the direct decomposition and ~100% for the reduction by $C_2H_4$, respectively. The results suggest the possibility of the porous composite as a multifunctional filter, i.e., simultaneous hot gas-filtering and $de-NO_x$ in one component.

• Journal of Information Display
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• v.12 no.2
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• pp.93-96
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• 2011

Single-phased $CaZrO_3:Dy^{3+}$, $Tm^{3+}$ series have been successfully synthesized by solid-state reaction, and their luminescence properties were investigated. Under 355 nm excitation, $CaZrO_3:Dy^{3+}$ series showed characteristic emission of $Dy^{3+}$, which exhibited yellowish white color. By introducing $Tm^{3+}$ into the matrix, the emitted hue of the $Dy^{3+}$-doped sample could be easily tailored to white, and simultaneously, energy transfer from $Tm^{3+}$ to $Dy^{3+}$ was observed. The color coordinates of the optimum white-emitting sample were (0.321, 0.323), which were very close to the data of the National Television Standard Committee (0.33, 0.33). The co-activated phosphors presented good match to ultraviolet light-emitting diodes (LEDs), which revealed that they could be novel promising phosphors utilized in white LED application.

• Membrane Journal
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• v.20 no.3
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• pp.259-266
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• 2010

Porous poly(propylene) supported gel polymer electrolytes (GPE) were synthesized by thermal polymerization of DEGDMA [Di(ethylene glycol) dimethacrylate] in electrolyte solutions (1 M solution of $LiPF_6$ in EC/DEC 1 : 1 mixture) at $70^{\circ}C$. AC impedance spectroscopy and cyclic voltammetry were used to evaluate its ionic conductivity and electrochemical stability window of the GPE membranes. Lithium ion battery (LIB) cells were also fabricated with $LiNi_{0.8}Co_{0.2}O_2$/graphite and GPE membranes via thermal polymerization process. Through the thermal polymerization, self sustaining GPE membranes with sufficient ionic conductivities (over $10^{-3}\;S/cm$) and electrochemical stabilities. The LIB cell with 5% monomer showed the best rate-capability and cycleability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.253-253
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• 2007

압전 액츄에이터 및 초음파진동자의 응용범위가 넒어짐에 따라 변위량, 응력 등을 개선시키기 위해 전기기계결합계수 kp 및 압전 d상수가 종전보다 큰 재료가 요구되고 있으며, 초음파진동자나 압전 모터와 같이 마찰에 의한 열손실이 많이 발생하는 액츄에이터에 적용할 큰 기계적품질계수롤 가지는 저손실 압전 액츄에이터 및 초음파진동자용 재료가 필요한 실정이다. PZT계 세라믹스는 높은 유전상수와 압전특성으로 전자세라믹스분야에서 가장 널리 사용되어지고 있지만, $1200^{\circ}C$이상의 높은 소결온도 때문에 $1000^{\circ}C$ 부근에서 급격히 휘발되는 PbO로 인한 환경오염과 기본조성의 변화로 인한 압전특성의 저하가 문제시 되고 있다. $Pb(Ni_{1/3}Nb_{2/3})O_3$는 약 $-120^{\circ}C$정도의 큐리온도룰 가지는 강유전체로 Pb(Zr, Ti)$O_3$계 세라믹스에 치환 시 유전상수와 전기기계결합계수를 개선시키는 대표적인 성분이다. 따라서 본 연구에서는 저온소결 저손실의 적층형 압전 액츄에이터를 개발하기 위해 PMS-PMN-PZT계 세라믹스에 $Pb(Ni_{1/3}Nb_{2/3})O_3$ 세라믹스를 치환하고 $Li_2CO_3$와 $Na_2CO_3$ ZnO를 소결조재로 사용하여 저온소결 하였으며 PNN 치환량에 따른 결과를 관찰 하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.126-130
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• 2008

In this study, in order to develop low loss multilayer piezoelectric actuator, PZN-PZT ceramics were fabricated using $Li_2CO_3,\;Bi_2O_3$, CuO and ZnO as sintering aids, their structural, piezoelectric and dielectric characteristics were investigated according to the amount of ZnO addition, At the sintering temperature of $870^{\circ}C$, the density, electromechanical coupling factor(kp), mechanical quality factor(Qm), dielectric constant(${\epsilon}_r$) and piezoelectric constant($d_{33}$) of 0.4 wt% ZnO added specimen (sintered at $870^{\circ}C$) showed the optimum value of $7.812g/cm^3$, 0.535, 916, 1399, 335 pC/N respectively. Taking into consideration above piezoelectric properties of the specimen sintered at low temperature, it was concluded that PZN-PZT ceramics using 0.4 wt% ZnO as additive showed the optimum characteristics as the composition ceramics for low loss multilayer piezoelectric actuator application.

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2726-2732
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• 2014

The promoting effect of rhodium on the structure and activity of the supported Cu-Co based catalysts for CO hydrogenation was investigated in detail. The samples were characterized by DRIFTS, $N_2$-adsorption, XRD, $H_2$-TPR, $H_2$-TPD and XPS. The results indicated that the introduction of rhodium to Cu-Co catalysts resulted in modification of metal dispersion, reducibility and crystal structure. DRIFTS results of CO hydrogenation at reaction condition (P=2 MPa, $T=260^{\circ}C$) indicated the addition of 1 wt % rhodium improved hydrogenation ability of Cu-Co catalysts. The ethanol selectivity and CO conversion were both improved by 1 wt % Rh promoted Cu-Co based catalysts. The alcohol distribution over un-promoted and rhodium promoted Cu-Co based catalysts obeys A-S-F rule and higher chain growth probability was got on rhodium promoted catalyst.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.253-254
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• 2007

In this study, in order to develop low temperature sintering multilayer piezoelectric actuator, PMN-PNN-PZT system ceramics were fabricated using $Li_2CO_3-Bi_2O_3$-CuO as sintering aids and their piezoelectric and dielectric characteristics were investigated as a function of heating rate. At sintering temperature of $900^{\circ}C$, with increasing heating rate, electromechanical coupling factor(kp), mechanical quality factor(Qm) and dielectric constant $({\varepsilon}_r)$ were increased.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.207-207
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• 2010

휴대용 기기의 사용이 증가하면서 전지의 고용량화와 소형화가 요구되고 있다. 특히 의료용 센서 기기에서는 소형화가 매우 중요하며 인체에 해로운 물질로 구성되지 않는 것이 바람직하다. 최근 고체전해질을 사용하는 마이크로 배터리가 개발되고 있으나, 에너지 저장용량이 작아 응용분야가 제한적이다. Silicon wafer 위에 형성된 고단차의 3차원 박막 배터리를 형성한다면 표면적 증가에 의해 에너지 저장용량 역시 크게 증가할 것이다. 따라서 고단차의 3차원 구조위에 confomal한 박막을 형성하기 위해서는 기존 물리증착방법과는 달리 새로운 step coverage가 우수한 박막증착법이 필요하다. 본 연구에서는 atomic layer deposition(ALD)으로 박막 배터리의 cathode 물질인 $LiCoO_2$를 증착하기 위한 기초연구로서 cobalt oxide 박막의 ALD 공정을 연구하였다. Cobalt +2가 전구체와 $O_3$를 교대로 공급하여 박막을 증착하고 그 박막의 물리적, 화학적, 전기적 특성을 조사하였다. 이를 통해 exposure와 기판온도가 박막의 특성에 미치는 영향을 고찰하였다. 또한 pattern wafer위에 박막을 증착하여 step coverage를 조사하였다.