• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.319-320
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• 2008

본 연구에서는 대기압하에서 고품질의 산화막 증착을 목적으로 TEOS(Tetraethyl Orthosilicate)를 이용하여 APCVD법(Atmospheric Pressure CVD)으로 실리콘 산화막을 증착하고 하였으며, 특성 비교를 위하여 ICP-CVD를 이용하여 $SiH_4$ 와 $N_2O$ source gas를 이용하여 산화막을 증착하였다. 트랜지스터 제작후 Semiconductor measurement system을 이용하여 TFT의 전기적 특성을 측정 하였으며, 결과적으로 유기 사일렌을 사용한 경우 보다 우수한 전기적 특성을 확인할 수 있었다.

• Journal of the Korean institute of surface engineering
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• v.24 no.1
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• pp.25-30
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• 1991

The evaporation characteristics of Ag, Al, Au, Cr. Cu, In, Mg, Mn, Pb, Pd, Si, SiO, Sn, Ti and Zn with the various resistive heating sources have been studied. The employed sources are refractory metal (Mo, Ta and W) boats, W-wire, ceramic (usually Al2O3)-coated and -barriered refractory metal boats, and special boats such as baffled boats and intermetallic boats (nitride compound and graphite). We investigated the melting mode, evaporation rate at a specific power, and lifetime of the sources. A special boat holder is also discussed which is needed to cool the sources at a large heat capacity.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.179.2-179.2
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• 2011

바이오매스 가스화 프로세스 개발에 있어서 가장 기본적인 해결과제는 고발열량의 합성가스 제조, 냉가스 효율의 향상, 타르 발생량 저감 및 제거이다. 가스화 효율 향상에 대한 연구는 국내외 적으로 많이 이루어지고 있으나, 타르 발생량 저감에 대한 연구는 많이 이루어져 있지 않다. 타르는 분자량이 큰 방향적 탄화수소로 응축되면 점성이 높아 배관폐쇄, 정제설비의 압력손실 증가로 인해 운전정지 및 가스화율 저하의 원인이 된다. 가스화로에서 타르 발생량을 저감시키는 방법 중에는 Ni계 촉매를 이용하는 방법이 있으나, 카본 누적에 의한 활성저하, 알칼리금속에 의한 응집 등의 문제가 발생할 수 있다. 한편 철산화물은 합성가스 중의 C2-C3계의 타르를 분해하는데 효과가 알려져 있다. 따라서 본 연구에서는 적벽돌, 염색슬러지 회재 등에는 철산화물이 다량 함유되어 있는 것에 착안하여 폐기물중의 폐금속을 이용한 바이오매스 가스화에 대한 연구를 수행하였다. 점토광물계 폐기물인 적벽돌 파쇄물($SiO_2$ 67.2%, $Al_2O_3$ 19.7%, $Fe_2O_3$ 8.7%, $K_2O$ 2.0%, $TiO_2$ 1.2%, MgO 0.7%)을 전처리 한 후 유동매체로하여 우드펠렛을 가스화한 결과, 가스 생성량이 증가하고, 타르 및 탄화수소류가 감소하는 경향을 나타내었다. 특히 타르는 후단의 타르 트랩에서 타르가 거의 검출이 되지 않았다. 전처리를 하지 않은 적벽돌 파쇄물은 반응시간이 경과한 후에 가스화율이 증가함에 따라 철화합이 가스화로내에서 환원되어 타르를 분해하는데에는 어느 정도의 반응시간이 필요한 것을 확인하였다.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.30-35
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• 2004

PMW-PZT thick films of about $30{\mu}m$ thickness were fabricated on Pt/$TiO_2$/$SiN_x$Si substrate by the hybrid method of screen printing and PZT sol application. With the increase of the number of the sol application times, the sintered density and electrical properties of PMW-PZT thick films were evidently increased. For the PMW-PZT thick film with PZT sol application of 10-times, the dielectric constant ($\varepsilon_r$) was 745 at the frequency of 100 KHz and thepiezoelectric coefficient ($d_33$) was 155 pC/N at the applied pressure of 1 atm.

• New & Renewable Energy
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• v.6 no.1
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• pp.46-52
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• 2010

Membrane electrode assemblies (MEAs) for proton exchange membrane fuel cells (PEMFCs) have been extensively studied to improve their initial performance as well as their durability and to facilitate the commercialization of fuel cell technology. To improve the MEA performance, particularly at low Pt loadings, many approaches have been made. In the present study, MEA performance improvement was performed by adding $TiO_2$ particles into the catalyst layer of MEA. Most of previous studies have focused on the MEA performance enhancement under low humidity conditions by adding metal oxides into the catalyst layer mainly due to the water keeping ability of those metal oxides particles such as $Al_2O_3$, $SiO_2$ and zeolites. However, this study mainly focused on the improvement of MEA performance under fully humidified normal conditions. In this study, the MEA was prepared by decal method aiming for a continuous MEA fabrication process. The decal process can make very thin and uniform catalyst layer on the surface of electrolyte membrane resulting in very low interfacial resistance between catalyst layer and the membrane surface and uniform electrode structure in the MEA. It was found that the addition of $TiO_2$ particles into the catalyst layer made by decal method can minimize water flooding in the catalyst layer, resulting in the improvement of MEA performance.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.124.2-124.2
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• 2015

최근 에너지 효율을 향상시키고 감성과 기능성을 동시에 만족시킬 수 있는 스마트 윈도우 (Smart Window) 기술이 큰 주목을 받고 있다. 신개념의 하이브리드형 열선차단 코팅기술로 고투명, 고단열 등 복합기능을 가지고 있음. 4계절 변화가 뚜렷한 대한민국 실정에 가장 적합하여 건축물의 냉 난방 에너지를 최소화하는데 크게 기여할 것으로 기대된다. 단열필름 제조 방식에는 보급형 필름으로 염료 방식, 금속 방식 등이 있고 고성능 필름에는 나노 세라믹 방식과 스퍼터 방식+세라믹 방식을 융합한 필름(스퍼터 IR 필름)이 있다. 본 연구에서는 DC pulse sputter를 이용하여 고굴절율 물질인 TiO2와 저굴절률 물질인 SiO2를 적층으로 성장시켜 단열 스마트필름을 제작해 보았다. 높은 가시광 투과율과 IR 차페 성능을 확인하였고, 제작한 스마트필름을 또다른 윈도우 기술에 적용하는 연구를 진행하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.169-169
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• 2010

650nm 적외선 차단 필터를 Macleod 프로그램을 이용하여 설계하고, 이온보조증착(IAD) 장비를 이용하여 코팅한 후 투과도, 파장, 두께특성을 조사하였다. 차단필터의 증착물질은 $TiO_2$ (n=2.30) /$SiO_2$ (n=1.46) 을 사용하여 45층의 다층 박막으로 증착하였다. 코팅된 차단필터는 차단파장이 651 nm로써 평균 ${\pm}5$ nm 이내의 편차를 보였다. 420~630 nm 파장영역에서 평균 투과도는 89%이었으며, 투과도의 균일도는 약 2.12로써 매우 균일하였다. 투과도기 단파장 영역에서 감소된 것은 다층박막 증착 시 산소가 결핍된 것으로 판단된다.

• Advances in nano research
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• v.13 no.1
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• pp.13-28
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• 2022

The pumpability of the grouts is significant issue in concept of the rheological and workability properties during penetrating to voids and cracks. To improve the fluidity features of the grout mixes, the usage of Colloidal Nano Particular Powders (CNPPs) with mineral additives such as fly ash (FA) can contribute. Therefore, the main purpose of this study can be explained as investigating the usage effects of four types of Colloidal Nano Particular Powders (n-TiO₂, n-ZnO, n-Al₂O₃ and n-SiO₂) as nano additives on the rheological, workability and bleeding properties of cement-based grout incorporated with fly as. Test results showed that the usage of FA in the grout samples positively contribute to increase on the fluidity of the grout samples as expected. The dilatant behavior was observed from the results for all mixes. Observing the effect of nano-sized additives in such cement-based grout mixtures with high fluidity has presented remarkable effects in this study.

• Korean Journal of Materials Research
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• v.19 no.11
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• pp.601-606
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• 2009

$BiFeO_3$ (BFO) thin films were prepared on $Pt/TiO_2/Si$ substrate by r.f. magnetron sputtering. The effects of deposition pressure on electrical properties were investigated using measurement of dielectric properties, leakage current and polarization. When BFO targets were prepared, Fe atoms were substituted with Mn 0.05% to increase electrical resistivity of films. (Fe+Mn)/Bi ratio of BFO thin films increases with increasing partial pressure of $O_2$ gas. The deposited films showed the only BFO phase at 10 mTorr, the coexistence of BFO and $Bi_2O_3$ phase at 30-50 mTorr, and the only $Bi_2O_3$ phase at 70 mTorr. The crystallinity of BFO films was reduced due to the higher Bi contents and the decrease of surface mobility of atoms at high temperature. The porosity and surface roughness of films increased with the increase of the deposition pressure. The films deposited at high pressure showed low dielectric constant and high leakage current. The dielectric constant of films deposited at various deposition pressures was 84${\sim}$153 at 1 kHz. The leakage current density of the films deposited at 10${\sim}$70 mTorr was about $7{\times}10.6{\sim}1.5{\times}10.2A/cm^2$ at 100 kV/cm. The leakage current was found to be closely related to the morphology and composition of the BFO films. BFO films showed poor P-E hysteresis loops due to high leakage current.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.371.2-371.2
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• 2016

Graphene electronics is one of the promising technologies for the next generation electronic devices due to the outstanding properties such as conductivity, high carrier mobility, mechanical, and optical properties along with extended applications using 2 dimensional heterostructures. However, large contact resistance between metal and graphene is one of the major obstacles for commercial application of graphene electronics. In order to achieve low contact resistance, numerous researches have been conducted such as gentle plasma treatment, ultraviolet ozone (UVO) treatment, annealing treatment, and one-dimensional graphene edge contact. In this report, we suggest a fabrication method of one-dimensional graphene metal edge contact without using graphene exfoliation. Graphene is grown on Cu foil by low pressure chemical vapor deposition. Then, the graphene is transferred on $SiO_2/Si$ wafer. The patterning of graphene channel and metal electrode is done by photolithography. $O_2$ plasma is applied to etch out the exposed graphene and then Ti/Au is deposited. As a result, the one-dimensional edge contact geometry is built between metal and graphene. The contact resistance of the fabricated one-dimensional metal-graphene edge contact is compared with the contact resistance of vertically stacked conventional metal-graphene contact.