• Korean Journal of Materials Research
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• v.26 no.5
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• pp.258-265
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• 2016

Fluorine-doped tin oxide (FTO) nanoparticles have been successfully synthesized using ultrasonic spray pyrolysis. The morphologies, crystal structures, chemical bonding states, and electrochemical properties of the nanoparticles are investigated. The FTO nanoparticles show uniform morphology and size distribution in the range of 6-10 nm. The FTO nanoparticles exhibit excellent electrochemical performance with high discharge specific capacity and good cycling stability ($620mAhg^{-1}$ capacity retention up to 50 cycles), as well as excellent high-rate performance ($250mAhg^{-1}$ at $700mAg^{-1}$) compared to that of commercial $SnO_2$. The improved electrochemical performance can be explained by two main effects. First, the excellent cycling stability with high discharge capacity is attributed to the nano-sized FTO particles, which are related to the increased electrochemical active area between the electrode and electrolyte. Second, the superb high-rate performance and the excellent cycling stability are ascribed to the increased electrical conductivity, which results from the introduction of fluorine doping in $SnO_2$. This noble electrode structure can provide powerful potential anode materials for high-performance lithiumion batteries.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.611-616
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• 2010

A cobalt oxide - tin oxide nanocomposite based gas sensor on an $SiO_2$ substrate was fabricated. Granular thin film of tin oxide was formed by a rheotaxial growth and thermal oxidation method using dc magnetron sputtering of Sn. Nano particles of cobalt oxide were spin-coated on the tin oxide. The cobalt oxide nanoparticles were synthesized by polymer-assisted deposition method, which is a simple cost-effective versatile synthesis method for various metal oxides. The thickness of the film can be controlled over a wide range of thicknesses. The composite structures thus formed were characterized in terms of morphology and gas sensing properties for reduction gas of $H_2$. The composites showed a highest response of 240% at $250^{\circ}C$ upon exposure to 4% $H_2$. This response is higher than those observed in pure $SnO_2$ (90%) and $Co_3O_4$ (70%) thin films. The improved response with the composite structure may be related to the additional formation of electrically active defects at the interfaces. The composite sensor shows a very fast response and good reproducibility.

• Macromolecular Research
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• v.11 no.6
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• pp.410-417
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• 2003

Poly(methyl methacrylate-co-acrylonitrile) [P(MMA-co-AN)]/Na-MMT nanocomposites were synthesized through emulsion polymerization with pristine Na-MMT. The nanocomposites were exfoliated up to 20 wt% content of pristine Na-MMT relative to the amount of MMA and AN, and exhibited enhanced storage moduli, E', relative to the neat copolymer. The exfoliated morphology of the nanocomposite was confirmed by XRD and TEM. 2-Acryla-mido-2-methyl-1-propane sulfonic acid (AMPS) widened the galleries between the clay layers before polymerization and facilitated the comonomers, penetration into the clay to create the exfoliated nanocomposites. The onset of the thermal decomposition of the nanocomposites shifted to a higher temperature as the clay content increased. By calculating areas of tan$\delta$ of the nanocomposites, we observed that the nanocomposites show more solid-like behavior as the clay content increases. The dynamic storage modulus and complex viscosity increased with clay content. The complex viscosity showed shear-thinning behavior as the clay content increased. The Young's moduli of the nano-composites are higher than that of the neat copolymer and they increase steadily as the silicate content increases, as a result of the exfoliated structure at high clay content.

• Journal of Sensor Science and Technology
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• v.13 no.5
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• pp.323-328
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• 2004

N-type semi-conducting oxides such as $SnO_{2}$, ZnO, and $ZrO_{2}$ have been known for the detecting materials of inflammable or toxic gases. Of those materials, $SnO_{2}$-based sensors are well known as high sensitive materials to detect toxic gases. And the sensitivity is improved if catalysts are added. Detecting toxic gases, especially DMMP (di-methyl-methyl-phosphonate) and DPGME (Dipropylene glycol methyl ether), was performed by a mixture of Tin oxide ($SnO_{2}$) and Zirconia ($ZrO_{2}$). The films consist of each three different mass% of Zr (from 1 mass% to 5 mass%), and they were tested by XRD, SEM, TEM, BET. Nano-structure, pore and particle size was controlled to verify the sensor's sensing mechanism. The sensors was evaluated at five different degrees (from $200^{\circ}C$ to $400^{\circ}C$) and three different concentrations (from 500 ppb to 1500 ppb). The sensors had good sensitivity of both simulants, and high selectivity of DMMP.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2015-2020
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• 2011

A series of isoxazol-indolin-2-one was designed for GSK-3${\beta}$ inhibitors as novel anticancer agents based on their binding mode analysis in GSK-3${\beta}$ crystal structure. Total 21 compounds were synthesized and evaluated for their inhibitory activity against two tumor cell lines (DU145 and HT29). Most of the synthesized compounds were potent with above 80% inhibitory activity at 100 ${\mu}M$, and several compounds were examined for inhibitory activity against GSK-3${\beta}$. Among them, 15(Z) ($R_1$=H, $R_2$=3-Cl-phenyl) was most active with 78% inhibition of tumor cell line (HT29) at 20 ${\mu}M$ and 72% inhibition of GSK-3${\beta}$ at 20 ${\mu}M$.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1690-1691
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• 2011

본 논문에서는 H1N1 인플루엔자 A 바이러스(influenza A H1N1 virus) 검출을 위한 산화아연 나노구조(zinc oxide nano structure) 기반의 전기화학적 면역센서를 제작하고 그 특성을 분석하였다. H1N1 인플루엔자 A 바이러스는 빠른 전파 속도 때문에 정확하고 빠른 검출이 필요하다. 먼저, 2 $mm^2$의 표면적을 갖는 패턴된 금 전극 위에 열수방식(hydrothermal method)으로 성장시킨 산화아연 나노구조가 선택적으로 형성되도록 리프트-오프(lift-off) 방법을 사용하였다. 0.01 M phosphate buffered saline(pH 7.4)에서 2 ${\mu}g$/mL 농도의 1차 항체를 정전기력에 의해 산화아연 나노구조에 고정화한 후, 10 pg/mL ~ 5ng/mL 농도의 H1N1 항원을 적용하여 포획 항체에 결합시키고 HRP(horseradish peroxidase) 효소가 결합된 검출 항체를 항원에 결합시키는 샌드위치 ELISA법을 이용하였다. HRP와 반응하는 TMB(3,3', 5,5'-tetramethylbenzidine)와 과산화수소가 포함된 acetate buffered 용액(pH 5)을 전해질로 사용하고 순환전압전류 측정법(cyclic voltammetry)으로 센서의 특성을 분석하였다. 측정된 순환전압전류그래프(cyclic voltammogram)에서 H1N1 항원 농도 10 pg/mL ~ 5 ng/mL의 응답 전류는 276.47 ${\pm}$ 21.72 nA (평균 ${\pm}$ 표준편차, n=4) ~ 478.89 ${\pm}$ 6.21 nA로 측정되었고, logarithmic하게 증가하는 응답 전류 특성을 보였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.226-231
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• 2014

Thin thermistor films of solutions with nickel and manganese oxides were prepared by metal-organic decomposition (MOD). The structural properties of the thin films were investigated as a function of annealing temperature. Field emission scanning electron microscope (FE-SEM) results indicated that the thin films had a thin thickness, smooth and dense surface. The crystallization temperature of $414.9^{\circ}C$ was confirmed from thermogavimetric-differential thermal analysis (TG-DTA) curve. A single phase of cubic spinel structure was obtained for the thin film annealed from $700^{\circ}C$ to $800^{\circ}C$, which was confirmed from the X-ray diffraction (XRD). From the selected area electron diffraction (SAED) in high resolution transmission electron microscope (HRTEM), the nano grains (2~3 nm) of spinel phase with (311) and (222) planes were detected for the thin film annealed at $500^{\circ}C$, which could be applicable to read-out integrated circuit (ROIC) substrate of the uncooled microbolometer with low processing temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.5
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• pp.373-379
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• 2020

In this study, TiN-coated cBN (cubic-structure boron nitride) powders were successfully synthesized by a sol-gel method using titanium (IV) isopropoxide (TTIP) and by controlling the heat treatment conditions. After the sol-gel process, amorphous nano-sized TiO_x was uniformly coated on the surface of cBN powder particles. The obtained TiO_x-coated cBN powders were heated at 1,000~1,300℃ for 1 or 6 h in a flow of 95%N₂-5%H₂ mixed gas. With increasing temperature, the chemical composition of the TiO_x coating layer changed in the order of TiO₂→Ti₆O₁₁→Ti₄O₇→TiN due to reduction of the Ti ions. The TiN coating layer was observable in the samples heated at 1,200℃ and appeared as the main phase in the sample heated at 1,300℃. The resulting thickness of the TiN coating layer of the sample heated at 1,300℃ was approximately 45~50 nm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.176-181
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• 2009

In this work, a new type of DSCs based on nanoporous FTO structure is being developed for research aimed at low-cost high-efficiency solar cell application. The nanoporous FTO materials have been prepared through the sol-gel combustion method followed by thermal treatment at $450{\sim}850[^{\circ}C]$. The properties of the nanoporous FTO materials were investigated by IR spectra, BET and TEM analyses, and the photovoltaic performance of the prepared DSCs were examined. It can be seen from the result that the nanoporous FTO exhibited good transparent conductive properties, well suited for DSCs application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.2
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• pp.100-104
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• 2012

Fin-type SONOS (silicon-oxide-nitride-oxide-silicon) flash memory has emerged as novel devices having superior controls over short channel effects(SCE) than the conventional SONOS flash memory devices. However despite these advantages, these also exhibit undesirable characteristics such as corner effect. Usually, the corner effect deteriorates the performance by increasing the leakage current. In this paper, the corner effect of fin-type SONOS flash memory devices is investigate by 3D Process and device simulation and their electrical characteristics are compared to conventional SONOS devices. The corner effect has been observed in fin-type SONOS device. The reason why the memory characteristic in fin-type SONOS flash memory device is not improved, might be due to existing undesirable effect such as corner effect as well as the mutual interference of electric field in the fin-type structure as reported previously.