• 멤브레인
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• 제22권1호
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• pp.1-7
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• 2012

니오븀 금속을 기반으로 하는 $Nb_{56}Ti_{23}Ni_{21}$ 합금 분리막의 수소 투과 특성 및 화학적 안정성에 관한 연구를 수행하였다. 이를 위하여 직경 10 mm, 두께 0.5 mm의 $Nb_{56}Ti_{23}Ni_{21}$ 합금 분리막을 제작하였으며, 2가지 조성($H_2$ 100%, $H_2$ 60% + $CO_2$ 40%)의 공급가스를 $450^{\circ}C$의 온도에서 투과시킬 때 압력에 따른 수소 투과 특성에 관한 실험을 진행하였다. 본 실험에서의 최대 수소 투과량은 순수한 수소를 투과시킬 경우 절대압력 3 bar에서 $5.58mL/min/cm^2$로 나타났다. 또한 공급가스 조성에 따른 각각의 경우 모두 Sievert's law에 잘 부합하였으며, 이산화탄소와의 혼합가스 사용시, 투과량은 수소 분압 감소에 비례하여 감소하였다. 투과 실험 후 XRD 분석을 통하여 $Nb_{56}Ti_{23}Ni_{21}$ 합금 분리막의 이산화탄소에 대한 화학적 안정성에 대한 실험을 수행하였다.

• Progress in Superconductivity
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• 제11권1호
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• pp.25-29
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• 2009

Polycrystalline samples of $(R_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ (R = Lu and Y) were synthesized by a solid-state reaction route, and the phase stabilities were examined by heating at temperatures between $800^{\circ}C$ and $900^{\circ}C$ in various atmospheres. A comparative analyses of the x-ray diffraction data of the $(Lu_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ and $(Y_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ compounds showed that the 123 phase of both compounds is stable under heating in air and $O_2$ of 1 atm. However, contrary to the $(Y_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ compound, the $(Lu_{0.8}Ca_{0.2})Ba_2Cu_3O_z$ compound was found to become unstable when heated in the low oxygen partial pressure below about 8 % $O_2\;in\;N_2$, Considering the instability of parent $LuBa_2Cu_3O_z$ compound, this result suggests that the phase stability of Lu-based 123 compounds is sensitive to both the composition and the oxygen partial pressure.

• 한국분무공학회지
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• 제14권1호
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• pp.34-38
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• 2009

This paper presents the pulsation of carburetor inlet and outlet pressure of a small SI gasoline engine. The engine used in this paper is a 23cc, single cylinder, diaphragm carburetor, two-stroke, air-cooled for brush cutter. The rpm and pressure wave pulsation at the inlet and the outlet of carburetor were measured and analysed for the understand of the internal air flow into the barrel on the diaphragm carburetor. These data should be used for the development of the duel fuel injection system for gasoline and LPG. The results showed that the carburetor inlet pressure variations were very steady, but the pressure variations at carburetor outlet were very sensitive to the pressure variation into the crank case and were to similar independently to the engine speed on partial opened throttle conditions. According to increasing engine speed, the pressure waves started to come out and be developed after closing the intake port of the engine at carburetor outlet. Reverse flow occurred on the WOT (wide open throttle) condition.

• 한국재료학회지
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• 제14권8호
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• pp.547-551
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• 2004

The sulfidation behaviour of Fe-XAl-0.3Y(X=5, 10, 14, 25 $wt.\%$) alloys was investigated at 1123 K in $H_2/H_{2}S$ gas atmosphere for $1\sim24$ hrs using SEM/EDX, XRD and EPMA. The weight changes of Fe-XAl-0.3Y alloys followed the parabolic rate law, Sulfidation rates of iron aluminide alloys with high Al content were one-twentieth lower than that of 5Al alloys. This is due to the formation of protective $Al_{2}O_3$ oxides on the surface of 10Al, 14Al and 25Al alloys. By calculating partial pressure of impurity oxygen contained $H_2/H_{2}S$ gas, the $Al_{2}O_3$ oxides formation could be explained using Fe-Al-S-O thermodynamic stability diagram. The sulfidation product scales of the 5Al alloy showed that thick iron sulfide scale(FeS) containing porosities formed during early stages of sulfidation. With continued sulfidation, aluminum sulfide was formed at the alloy/scale interface.

• Korean Chemical Engineering Research
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• 제48권5호
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• pp.598-602
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• 2010

본 논문에서는 다량의 수소를 포함한 다성분계 원료가스로부터 수소를 분리해 내는 분리막 시스템에 대하여 CFD 모델링과 모사를 수행하였다. 분리막 시스템은 환형 실린더 타입으로 원료가스의 유입을 위한 외부 lumen side와 sweeping gas가 유입되는 내부 permeation side로 구성된다. Lumen side의 운전온도와 압력은 $374^{\circ}C$, 7 기압 permeation side의 sweeping gas의 도입 온도와 압력은 $374^{\circ}C$, 3기압이며, 이러한 조건에서 운전이 가능한 Pd 분리막을 사용하였다. Sweeping gas의 흐름 방향에 따른 향류 및 병류 흐름에 대하여 각각 CFD 모사를 수행하였으며 수소 몰분율, 수소분압, 수소 플럭스 등에 대하여 결과를 비교하였다. 또한 lumen side의 원료가스 도입유속을 변화시켜 모사를 수행하고, 이에 따른 막분리 시스템의 효율을 비교하고 이에 대하여 고찰하였다.

• 한국광학회지
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• 제14권3호
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• pp.343-348
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• 2003

자체 제작한 고밀도(이론 밀도의 99%) ITO(I $n_2$ $O_3$:Sn $O_2$=90 wt%) 타깃과 직류 마그네트론 스퍼터링 방법을 이용하여 산소분압 $P_{o_{2}}$ (0 $P_{o_{2}}$ $\leq$$10^{-5}$ torr)와 성장 온도 Ts(10$0^{\circ}C$ $T_{s}$$\leq$35$0^{\circ}C$)를 변화시키면서 ITO 박막을 제작하고 전기적, 광학적 특성을 조사하였다. ITO박막의 비저항은 제작 온도가 증가함에 따라 감소하다가 $T_{s}$=30$0^{\circ}C$일 때 최저 비저항값 0.30 mΩ.cm를 나타내었고 $T_{s}$>30$0^{\circ}C$ 이상에서는 약간 증가하였다. $T_{s}$=30$0^{\circ}C$에서 제작한 ITO 박막의 최대 전하 농도는 6.6$\times$$10^{20}$ /㎤이었다. $T_{s}$를 고정하고 ITO 박막 제작 시 사용한 산소분압이 증가함에 따라 전하농도, 전하유동도는 급격하게 감소하여 비저항이 크게 증가하는 것으로 나타났다 ITO박막의 최저 비저항과 최대 전하 유동도는 각각 0.3 mΩ.cm와 39.3 $\textrm{cm}^2$/V.s였다. 또한 가시광 영역 (400~700 nm)에서 ITO박막의 광투과도는 80~90%로 높게 나타났다.나타났다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.497-497
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• 2013

Semiconducting amorphous InGaZnO (a-IGZO) has attracted significant research attention as improved deposition techniques have made it possible to make high-quality a-IGZO thin films. IGZO thin films have several advantages over thin film transistors (TFTs) based on other semiconducting channel layers.The electron mobility in IGZO devices is relatively high, exceeding amorphous Si (a-Si) by a factor of 10 and most organic devices by a factor of $10^2$. Moreover, in contrast to other amorphous semiconductors, highly conducting degenerate states can be obtained with IGZO through doping, yet such a state cannot be produced with a-Si. IGZO thin films are capable of mobilities greaterthan 10 $cm^2$/Vs (higher than a-Si:H), and are transparent at visible wavelengths. For oxide semiconductors, carrier concentrations can be controlled through oxygen vacancy concentration. Hence, adjusting the oxygen partial pressure during deposition and post-deposition processing provides an effective method of controlling oxygen concentration. In this study, we deposited IGZO thinfilms at optimized conditions and then analyzed the film's electrical properties, surface morphology, and crystal structure. Then, we explored how to generate IGZO thin films using DC magnetron sputtering. We also describe the construction and characteristics of a bottom-gate-type TFT, including the output and transfer curves and bias stress instability mechanism.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.906-909
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• 2006

The secondary electron emission coefficient $({\gamma})$ of the cathode is an important factor for improving the discharge characteristics of AC-PDPs because of its close relationship to discharge voltage. In AC-PDPs, MgO is most widely used as a surface protective layer. In this experimental, we have investigated the electronic structure of the energy band structure of the MgO layer responsible for the high ${\gamma}$. The MgO layers have been deposited by electron beam evaporation method, where the $O_2$ partial pressures have been varied as 0, $5.2{\times}10^{-5}$ torr, $1.0{\times}10^{-4}$ torr, and $4.1{\times}10^{-4}$ torr, in this experiment. It is noted that work function that is energy gap between surface and first defect level of MgO layer has the lowest value for the highest O2 partial pressure of $4.1^{\ast}10^{-4}$ Torr.

• 한국광물학회지
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• 제16권1호
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• pp.49-63
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• 2003

흔히 발견되지 않는 광물상들이 후기 열수변질광물로서 거도광산에서 관찰된다. 열수광물들은 스카른 광물들을 열수변질시키거나 공간충진 정출작용으로 산출된다. 즉, 투휘석, 석류석 및 장석들을 교대하여 녹니석과 포도석, 일라이트 및 펌펠리아이트 등을 산출하거나 열극이나 정동에서 정출한 것으로 포도석, 펌펠리아이트, 클리노조이사이트, 일라이트 및 Ca-불석(스틸바이트와 스텔러라이트) 등이 있다. 이들 열수광물들에 대해 X-선 회절분석, 주사전자현미경 관찰 및 전자현미분석을 통해 광물상과 산출상태 등이 상세히 규명되었다. 후기 공간충진 열수광물들을 대상으로 슈라이네마크 작도법에 의한 상평형 관계를 규명하였으며, 등온-등압 $\mu$$H_2O$-$\mu$$CO_2$상평형도를 작도하였다. 그 결과 초기에 정출된 포도석, 펌펠리아이트, 클리노조이사이트, 일라이트 및 녹니석은 비교적높은 $CO_2$분압과 낮은 $H_2$O 분압 하에서 먼저 정출되었으며, 그 후 $H_2$O 분압이 증가하면서 일라이트와 수반되어 스틸바이트와 방해석이 정출되었다.

• 한국표면공학회지
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• 제31권1호
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• pp.54-62
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• 1998

In this study, the behaviorof ion nitriding of AISI 304 stainless steel was investigated using plasma ion nitriding system. The characteristics of ion nitriding, and their micsoctrucyures, and physical properties were investigated as a function of process parmeteds. important conclusions can be summarzied as follows. Firstly, it was found that growth of nitride layer in ion nitriding are mainly affected by N2 partial pressures and nitriding temperatures for AISI 304 stainless steel. The $N_2$<\TEX> partial pressure plays on important role in ion nitriding since it determiness the incoming flux of nitrogen species onto specimen surface. Nitriding thmprrature is also important besauseit determines the diffusion rates of nitrogen through nitride layers. While both parameters affects the characteristics rateding are controlled by nitridingen diffusion nitration profiles of N and alloying elements such as Cr and Ni are observed through niride layers. Secondly, nitride layer consists of the upper white laywe having various nitride phases and the underneath diffusion layers. The thickness of white layer increases with $N_2$<\TEX> partial pressures and nitriding temperatures. The thinkness of diffusion layer is increasting nitriding temperatures. Finally, nitriding of stainless steels steel show slighly low their corrsionce prorerties. However, passivation properties, which is normally observed in stainless steels, were still observed aftre ion nitriding.