• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.52-56
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• 2006

Some of factors affecting photo-conversion efficiency of dye sensitized solar cells (DSCs) are discussed in terms of $TiO_2$ electrodes. The first topic is on the surface modification of $TiO_2$ nano-particles, which is associated with electron traps on the surface of $TiO_2$ nano-particles. The surface is modified with dye molecules under pressurized $CO_2$ atmosphere to increase the surface coverage of $TiO_2$ nano-particles with dye molecules. This increases Jsc because of an increase in the amount of dye molecules and a decrease in the amount of trapping sites on $TiO_2$ nano-particles. In addition, the decrease in the amount of trap sites increases Voc because decreases in Voc are brought about by the recombination of $I_2$ molecules with electrons trapped on the $TiO_2$ surfaces. Selective staining for tandem cells is proposed. The second topic is on the contact between a $SnO_2$/F transparent conductive layer (TCL) and nano-particles. Polishing the TCL surfaces with silica nano-particles increases the contact, resulting in Jsc increases. The third topic is the fabrication of ion-paths in $TiO_2$ layers. Electro-spray coating of $TiO_2$ nano-particles onto TCL is shown to be effective for fabricating ion-paths in $TiO_2$ layers, which increases Jsc.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1712-1719
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• 2015

In recent days, there was a significant development on the electrical, thermal, mechanical, physical, chemical, magnetic and optical properties of the polyamide enamel, varnish and other insulating materials by the addition of nano fillers to it. Enamel was used in High Voltage Apparatuses used in Medical Electronics as insulation. Insulating materials determine the life time of the electrical apparatuses. The life time of the insulating materials was improved by the addition of nano fillers to it. Hence the life time of the electrical apparatuses was improved by the mixing of nano fillers to the enamel. In this research, the basic dielectric properties of the enamel and enamel mixed with nano composites of silica and alumina were analyzed and compared with each other. The addition of nano fillers has improved the quality factor and capacitance of the enamel. It was also observed that the addition of nano fillers has reduced the dissipation factor and dielectric losses of the enamel. Heat produced by the dielectric losses was also reduced by adding nano fillers to it.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2359-2362
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• 2007

MALDI-TOF-MS technique was applied to obtain structural and compositional information of synthetic polyamides, Nylon6 and Nylon66. Mass spectra of both the original and the hydrolyzed polyamide samples were analyzed using the self calibration method as well as the internal calibration method with the standard materials of known masses. The MALDI-TOF mass spectra of Nylon6 samples showed the presence of protonated, sodiated, and potassiated ions that were assigned to cyclic and NH2/COOH terminated linear oligomers. From the MALDI-TOF mass spectra of Nylon66 samples, the potassiated linear oligomers with three different end groups are identified as well as the cyclic oligomers, i.e., NH2/COOH terminated oligomers, NH2/NH2 terminated oligomers, and COOH/COOH terminated oligomers. Full characterization of the molecular species and end groups present in the polyamide samples has been achieved, and also the changes in mass spectral patterns after the hydrolysis of the samples are presented.

• 폴리머
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• 제36권6호
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• pp.727-732
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• 2012

양이온성 및 음이온성 계면활성제로 합성된 poly(butyl acrylate)(PBA), polystyrene(PS) 에멀젼을 다양한 농도로 혼합하여 높은 수율의 압력가소성 고분자 블렌드로 제조하였다. 이들 입자간의 heterocoagulation은 각 에멀젼의 농도에 크게 의존하였지만, 일정한 비율의 음이온과 양이온 사이에서만 진행되었고, 사용된 고분자의 양에 상관없이, 거의 균일한 조성의 블렌드가 얻어졌다. 비슷한 방법을 이용하여 음이온성 PBA와 양이온성 PS 나노입자에 음이온성 실리카 나노입자를 정전기적으로 첨가함으로써 정량적인 PBA/PS/Si 블렌드를 제조하였다. PBA/PS/Si 블렌드는 $25^{\circ}C$, 13.8MPa, 10분의 조건에서 압축성형으로 가공되었으며, 2 혹은 5 wt%의 실리카가 첨가된 시편의 경우, 반투명의 필름형상으로 성형되어 3.0 MPa의 인장강도와 25MPa의 탄성계수를 얻을 수 있었다.

• 접착 및 계면
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• 제15권2호
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• pp.69-76
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• 2014

연구에서는 aminopropyl trimethoxysilane (APTMS)과 aminopropyl triethoxysilane (APTES)를 비스페놀계 에폭시 수지와 각각 반응시켜서 2가지 종류의 epoxy-functionalized alkoxysilane (EAS)을 합성하였다. 합성된 EAS를 다양한 혼합비로 3-glycidyloxypropyl trimethoxysilane (GPTMS)과 tetraethyl orthosilicate (TEOS)와 혼합하고 hydrolysis-polycondensation 반응을 통해서 졸 상태의 실리카/에폭시 나노하이브리드 물질을 제조하였다. 제조된 나노 하이브리드 졸은 투명한 노란색이며 다양한 유기 용매와 상용성을 나타내었다. 경화제(TETA와 acrylic acid)와 나노 하이브리드 졸과 반응을 통해서 경화필름이 얻어졌으며, 나노 하이브리드 경화 필름은 순수 에폭시 수지 경화 필름에 비해서 높은 내열성과 기계적 물성을 나타내었다. TEM과 AFM 측정 결과, 나노 크기의 실리카 입자들이 경화된 하이브리드 필름 내에 생성, 분산되어있는 것을 확인할 수 있었다.

• 한국세라믹학회지
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• 제44권3호
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• pp.162-168
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• 2007

Silica wet gels were prepared ken water glass ($29\;wt%\;SiO_{2}$) by using Amberlite as a ion exchange resin. After washing in distilled water, the wet gels were further aged in a solution of TEOS/EtOH to strengthen of 3-dimensional network structure. As increase TEOS content in aging solution, BET surface area and porosity of the ambient dried silica aerogels were significantly decreased, and average pore diameter was also decreased 30 nm to -10 nm. Also, higher density and compressive strength were obtained in case of higher TEOS content. This is due to precipitation of $SiO_{2}$ nano particles by TEOS. Hence, TEOS addition plays an important role of both strengthening and stiffness of silica wet gel network. By adding over 30 vol% TEOS, a crack-free monolithic silica aerogel tiles were obtained and its density, compressive strength, and thermal conductivity were shown $0.232g/cm^{3}$, 7.3 MPa, and 0.029 W/mk, respectivly.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.78-83
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• 2009

In general, Light-hardening polymer was used UV nanoimprint technology. A light-hardening polymer was had the problem of poor hardness, durability. In order to overcome the problem of polymer, inter change optical glass. However glass is very manufacture and a lowering of standars transmittance. In order to glass recover was necessary polishing process. The process is magnetorheological fluids polishing. MR polishing has been developed as a new precision finishing technique to obtain a fine surface. Hence, Magnetorheological fluids has been used for micro polishing to get micro parts. This polishing process guarantees high polishing quality by controlling the fluid density electrically. The applied material in experiments is fused silica glass. Fused silica glass is widely used in the optical field because of high degree of purity. For MR polishing experiments, MR fluid was composed with DI-water, carbonyl iron and nano slurry ceria. The wheel speed and electric current were chosen as the variables for analyzing the characteristics of MR polishing process. Outstanding surface roughness of Ra=1.58nm was obtained on the fused silica glass specimen. And originally glass transmittance was recover on the fused silica glass.

• 세라미스트
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• 제22권3호
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• pp.256-268
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• 2019

Ceramic nano pigments have attracted much interest owing to recent demand for nontoxic, heavy metal-free pigments. In general, ceramic pigments must possess thermal stability at high temperature, however nanosized powder easily undergoes aggregation at high temperature, and its color turns. serveral groups have focused on to minimize agglomeration and oxidation, a core-shell structure with a silica coating is suggested. In this review, we introduce the reported the trend of nano-ceramic powders and we summarized method improve color and physical properties throuth morphology control and ceramic coating technology.

• Bulletin of the Korean Chemical Society
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• 제26권1호
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• pp.34-35
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• 2005

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.1033-1037
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• 2008

A copper cyclam-type complex was successfully immobilized onto mesoporous silica SBA-16. Characterization by NIR spectroscopy and TGA analysis confirmed that copper cyclam complex is immobilized onto mesoporous SBA-16. The Cu(II)-Cyclam-SBA-16 was proven to be a good catalyst for oxidation reaction of cyclohexene with conversion up to 77.8% after 13 h reaction and providing a high selectivity to cyclohexenol and 3-hydroperoxycyclohex-1-ene. The results suggest that the copper species play a major role as catalyst via reversible redox cycles as proven by cyclic voltammetry analysis.