• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.347.1-347.1
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• 2014

최근, 박막 트랜지스터는 빠른 동작 속도, 낮은 공정비용 그리고 저온공정 등의 특성을 필요로 하고 있다. 그 중 indium-zinc oxide (InZnO)는 높은 전기적 특성, 높은 광 투과도 그리고 우수한 안정성 때문에 기존의 반도체를 대체할 수 있을 것으로 기대된다. InZnO의 경우 indium과 zinc의 조성비에 따라 특성 변화의 차이가 크기 때문에 다양한 조성비에 대한 연구가 보고되고 있는데, 기존의 InZnO 박막을 증착하는 방법의 경우에 조성비의 변화 과정에 많은 공정상의 어려움이 있다. 이 같은 문제점 때문에 조성비의 변화를 용이하게 할 수 있는 용액공정을 이용한 연구가 진행되고 있다. 또한 용액공정은 높은 균일성, 공정 시간 및 비용 감소 그리고 대면적화가 가능한 장점을 가지고 있다. 한편, 용액공정을 기반으로 한 InZnO의 경우에 용액 상태에서 고체 상태의 순수한 금속 산화물 상태로 바꾸기 위해 post-treatment 가 필요하다. 일반적으로 furnace 열처리 방법을 사용하는데, 이 경우 낮은 열효율 및 고비용 등의 문제점을 가지고 있다. 특히 glass 또는 flexible 기판의 경우 열처리 온도에 대한 제약이 있다. 이러한 문제를 해결하기 위한 방법으로 최근에 microwave irradiation를 이용한 저온 post-treatment 방법이 보고되고 있다. Microwave irradiation는 짧은 공정시간 및 열 균일성 등의 장점이 있다. 따라서 본 연구에서는 다양한 indium과 zinc의 조성비를 갖는 용액을 제작한 후 spin coating을 이용하여 증착한 InZnO 기반의 박막 트랜지스터를 제작하였다. Furnace와 microwave 방식으로 post-treatment 하여 비교 평가한 결과 microwave irradiation 한 경우 furnace 열처리 한 경우 보다 더 안정된 동작 전압을 가지는 것으로 나타났다. 따라서 저온공정이 가능한 microwave irradiation 방법으로 post-treatment 한다면 차세대 산화물 반도체로서의 적용이 가능할 것으로 기대된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.17-18
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• 2006

고상 확산 방법을 이용하여 얕은 소스/드레인 접합을 가지는 SOI (Silicon-On-Insulator) MOSFET 소자를 제작하였다. 확산원으로는 PSG(Phosphorus silicate glass) 박막과 PBF(Poly Boron Film) 박막이 각각 n, p-type 소자 형성을 위해 사용되었다. 얕은 접합 형성을 위하여 급속 열처리 방법(RTA: Rapid Thermal Annealing)을 이용하여 PSG와 PBF로부터 인과 붕소를 SOI MOSFET 소자의 소스/드레인으로 확산시켰다. 또한, 소자 특성 개선을 위한 후 속 열처리 공정으로 희석된 수소 분위기 중에서 FA(Furnace Annealing)를 실시하였다. SPD 기술을 적용하여 10 nm 이하의 매우 얕은 p-n 접합을 형성할 수 있었고, 양호한 다이오드 특성을 얻을 수 있었다. 또한, SPD 방법으로 결함이 없는 접합 형성이 가능하며, 소자 제작 공정의 최적화를 통해 차세대 CMOS 소자로 기대되는 SOI MOSFET를 성공적으로 제작할 수 있었다.

• Journal of the Korean Ceramic Society
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• v.45 no.2
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• pp.90-93
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• 2008

The oxygen gas behavior in PDP (plasma Display Panel) glass melts doped with sulfate ($SO_4^{-2}$) or blast furnace slag (BFS, $S^{2-}$) or both by means of yttria-stabilized zirconia (YSZ) electrodes was observed after the first fining. The temperature dependence of oxygen equilibrium pressure ($P_{O2}$) in each melt showed typical behavior, namely $P_{O2}$ decreased as temperature decreased. This suggests that an oxidation of $S^{4+}$ to $S^{6+}$ took place. However, the $P_{O2}$-value at constant temperature increased in the following order: BFS$P_{O2}$ of the melt doped with sulfate+BFS was much lower than that of the melt with only sulfate, although only 10% of sulfur was added by the BFS. This behavior can be explained by the redox reaction between sulfide ions in the BFS and dissolved oxygen ions in the melt during the first fining.

• Journal of Korea Foundry Society
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• v.26 no.5
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• pp.227-231
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• 2006

Liquid formability of bulk amorphous alloys is known to be very poor due to their high viscosity comparing with conventional metallic materials. It is important to have the fabricating technology of bulk amorphous alloys in order to make the components with complicated shape. Liquid formability includes the mold cavity filling ability and the hot tear(crack) resistance during solidification. A mold made of a commercial tool steel for the formability test was designed. Melting was performed by the arc melting furnace with melting capacity of 200 g in an argon atmosphere. Liquid formability and glass forming ability of Cu base and Ni base bulk amorphous alloys were measured and evaluated. Mold filling ability of Ni-Zr-Ti-Si-Sn alloy was better than that of Cu-Ni-Zr-Ti alloy, however the reverse is the hot tear resistance. Bulk amorphous alloy is very susceptible to crack if partial crystallization occurs during solidification. Crack resistance was thought to be closely related with the glass forming ability.

• Journal of Power System Engineering
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• v.17 no.2
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• pp.108-113
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• 2013

In this study, lightweight aggregate was made from basalt stone powder sludge. Clay and glass powder were respectively added from 0 to 20 wt% and from 0 to 100 wt%. The glass powder helped to form glassy phase which trapped generating gas in the materials. $CaCO_3$ helping bloating process was added from 0 to 10 wt%. It was possible to produce lightweight aggregate at range from $1150^{\circ}C$ to $1200^{\circ}C$. The specimen was heated in furnace at 1100, 1150 and $1200^{\circ}C$ for 15 min, respectively, to sinter aggregates. Chemical composition of materials were determined, and characteristics were analyzed, including specific gravity, water absorption. Lightweight aggregate which was heated at $1200^{\circ}C$ had specific gravity of $0.53g/cm^3$, water absorption of 3.08%, and this value satisfied KS L 8551 standard.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.6
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• pp.299-304
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• 2012

Geopolymer was made using magnetic separation fly ash with NaOH(Sodium Hydroxide) and the water glass as alkali activators in this study. Compressive strength of geopolymers ceramics was measured and analyzed according to the type of materials. Under the conditions of fly ash without magnetic separation and 28 day curing after molding, the compressive strength of the geopolymer reached up to 28 MPa.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.222-224
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• 2006

A non-vacuum process for $Cu(In,Ga)Se_2$ (CIGS) thin film solar cells from nanoparticle precursors was described in this work CIGS nanoparticle precursors was prepared by a low temperature colloidal route by reacting the starting materials $(CuI,\;InI_3,\;GaI_3\;and\;Na_2Se)$ in organic solvents, by which fine CIGS nanoparticles of about 20nm in diameter were obtained. The nanoparticle precursors were mixed with organic binder material for the rheology of the mixture to be adjusted for the doctor blade method. After depositing the mixture of CIGS with binder on Mo/glass substrate, the samples were preheated on the hot plate in air to evaporate remaining solvents ud to burn the organic binder material. Subsequently, the resultant (porous) CIGS/Mo/glass simple was selenized in a two-zone Rapid Thermal Process (RTP) furnace in order to get a solar ceil applicable dense CIGS absorber layer. Complete solar cell structure was obtained by depositing. The other layers including CdS buffer layer, ZnO window layer and Al electrodes by conventional methods. The resultant solar cell showed a conversion efficiency of 0.5%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.5
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• pp.246-254
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• 2013

Translucent opal glass was fabricated in order to substitute polycarbonate diffuser of LED lighting for the purpose of improving the durability problem. Calcium phosphate was used for the opacifier of opal glass and melted at $1550^{\circ}C$ for 2 hrs in electric furnace. Because opal glass was made by phase separation and growth of opacifier grains during cooling procedure after forming of melted glass, we identified the effect of opaque properties by the change of forming and cooling temperature, as R.T. (room temperature), $850^{\circ}C$, $1100^{\circ}C$ and $1200^{\circ}C$. As the results, it had excellent optical properties for the diffuser of LED lighting in the fabricated sample of forming and cooling at $1200^{\circ}C$, with no dazzling from direct light by high haze value over 82 % and low parallel transmittance value under 10 %. For the thermal properties, it had expressed thermal expansion coefficient of $6.352{\times}10^{-6}/^{\circ}C$ and softening point of $839^{\circ}C$.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.94-99
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• 2017

Dinickel-silicide $(Ni_2Si)/glass$ was employed as a counter electrode for a dye-sensitized solar cell (DSSC) device. $Ni_2Si$ was formed by rapid thermal annealing (RTA) at $700^{\circ}C$ for 15 seconds of a 50 nm-Ni/50 nm-Si/glass structure. For comparison, $Ni_2Si$ on quartz was also prepared through conventional electric furnace annealing (CEA) at $800^{\circ}C$ for 30 minutes. XRD, XPS, and EDS line scanning of TEM were used to confirm the formation of $Ni_2Si$. TEM and CV were employed to confirm the microstructure and catalytic activity. Photovoltaic properties were examined using a solar simulator and potentiostat. XRD, XPS, and EDS line scanning results showed that both CEA and RTA successfully led to tne formation of nano $thick-Ni_2Si$ phase. The catalytic activity of $CEA-Ni_2Si$ and $RTA-Ni_2Si$ with respect to Pt were 68 % and 56 %. Energy conversion efficiencies (ECEs) of DSSCs with $CEA-Ni_2Si$ and $RTA-Ni_2Si$catalysts were 3.66 % and 3.16 %, respectively. Our results imply that nano-thick $Ni_2Si$ may be used to replace Pt as a reduction catalytic layer for a DSSCs. Moreover, we show that nano-thick $Ni_2Si$ can be made available on a low-cost glass substrate via the RTA process.

• Korean Journal of Materials Research
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• v.27 no.5
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• pp.281-288
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• 2017

In this study, Fe-Ni slag, converter slag and dephosphorization slag generated from the steel industry, and fly ash or bottom ash from a power plant, were mixed at an appropriate mixing ratio and melted in a melting furnace in a mass-production process for glass ceramics. Then, glass-ceramic products, having a basalt composition with $SiO_2$, $Al_2O_3$, CaO, MgO, and $Fe_2O_3$ components, were fabricated through casting and heat treatment process. Comparison was made of the samples before and after the modification of the process conditions. Glass-ceramic samples before and after the process modification were similar in chemical composition, but $Al_2O_3$ and $Na_2O$ contents were slightly higher in the samples before the modification. Before and after the process modification, it was confirmed that the sample had a melting temperature below $1250^{\circ}C$, and that pyroxene and diopside are the primary phases of the product. The crystallization temperature in the sample after modification was found to be higher than that in the sample before modification. The activation energy for crystallization was evaluated and found to be 467 kJ/mol for the sample before the process modification, and 337 kJ/mol for the sample after the process modification. The degree of crystallinity was evaluated and found to be 82 % before the process change and 87 % after the process change. Mechanical properties such as compressive strength and bending strength were evaluated and found to be excellent for the sample after process modification. In conclusion, the samples after the process modification were evaluated and found to have superior characteristics compared to those before the modification.