• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.230-230
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• 2011

RF magnetron sputtering을 이용하여 Ar 및 $O_2$유량에 따라 GZO 박막을 유리기판 위에 제작하고 구조적, 광학적, 전기적 특성을 조사하였다. 박막 증착 조건의 초기 압력은 $1.0{\times}10^{-6}$ Torr, RF 파워는 25W, 증착온도는 상온으로 고정하였으며 기판은 Corning 1737 유리 기판을 사용하였다. 공정 변수로 Ar 유량을 40 sccm, 60 sccm, 80 sccm, 100 sccm으로 변화시켰으며, $O_2$ 가스비율을 5~20%으로 변화를 주어 실험을 진행하였다. GZO 타겟은 ZnO,Ga 분말을 각각 97:3 wt.%로 소결된 타겟을 사용하였다. 유리기판 위에 증착된 모든 GZO 박막에서 (002) 면의 우선 배향성이 관찰되었고 평균 85% 이상의 투과율을 나타내었다. 산소유량이 포함되지 않고 Ar 유량이 적은 GZO 박막의 결정성은 향상되었고, 광학적 밴드갭은 증가하였다. Hall 측정 결과 산소의 유량이 포함되어 있는 박막에서는 모두 완전한 산화물에 가까운 화학양론적 조성으로 면저항이 $10^6{\Omega}/{\Box}$ 이상인 부도체 특성을 보였으며, 산소가 포함되지 않은 샘플에서는 투명전도막 특성이 확인되었다. 산소가 포함되지 않은 Ar 유량이 60 sccm일 때 전기비저항 $3.25{\times}10^{-3}{\Omega}cm$, 전하의 농도 $9.41{\times}10^{20}\;cm^{-3}$, 이동도 2.04 $cm^2V^{-1}s^{-1}$로 투명전도막으로 적합한 전기적 특성을 얻었다. GZO 박막의 경우 산소가 포함될 경우 결정성이 저하되고, 절연특성을 갖는 것을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.325-325
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• 2013

본 연구에서는 선형 대향 타겟 스퍼터(Linear Facing Target Sputtering: LFTS) 시스템을 이용하여 성막한 Ti-doped In2O3 (TIO) 투명 전극의 전기적, 광학적 특성을 연구하였다. LFTS 시스템을 이용하여 유리기판 위에 TIO 박막을 증착시킬 때, 타겟과 기판 사이의 거리(Target-to-Substrate Distance)를 30 mm, 타겟과 타겟 사이의 거리(Target-to-Target Distance)를 65 mm, Ar/$O_2$ 가스의 비율 100：1로 각각 고정한 후, TIO 타겟에 인가되는 DC 파워와 공정압력을 변수로 TIO 박막을 하였다. LFTS 공정을 이용한 TIO 투명전극의 성막 공정 중 DC파워와 공정압력 변화에 따른 구조적, 표면적 특성 변화는 field-effect scanning electron microscopy (FE-SEM) 과 x-ray diffractometry (XRD) 분석을 통해 관찰되었다. 이렇게 증착된 200 nm 두께의 TIO 투명전극은 급속열처리 시스템으로 700도에서 후 열처리를 진행하였으며 상온에서 217.5 ohm/sq의 면저항을 나타내는 TIO박막이 열처리후 35 ohm/sq로 면저항이 급격히 감소됨을 확인하였다. 뿐만 아니라 열처리후 가시광선 영역 (400~800 nm)에서의 TIO 박막의 평균 투과율이 81.02%에서 83.4%로 향상됨을 UV/visible spectrometry 분석을 통해 확인하였다. 본 연구에서는 다양한 분석을 통해 TIO 박막의 특성과 ITO와 구별되는 다양한 장점을 소개한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.28-39
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• 2022

An experimental study was carried out to understand the characteristics of the long wave infrared signal emitted from the exhaust plume when water is sprayed around it. The micro-jet engine was used to generate the exhaust plume, and eight water spray nozzles were installed around the exhaust nozzle. Two water injection angles were applied, one is sparying parallel to the exhaust plume, and the other is spraying water into the exhaust plume. The measurement results are as follows. When spraying water parallel to the exhaust plume, the long wave infrared signal is decreased with water spray flow rate. When spraying water the exhaust plume, the long wave infrared signal shows a larger value than plume only.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.133-140
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• 2009

This paper presents the experimental study to analyze the pressure and production behavior using depressurization and thermal methods in order to evaluate the hydrate productivity in the 2-D multi-well, plate-type apparatus which has 80 md permeability and 30% hydrate saturation. Injecting methane gas through multi-well allowed to set up the highly saturated hydrate system and combining two different sorts of sands made possible to build up the low permeability system. In this system, both depressurization and electric stimulation methods were applied. When operating pressure was low, according to the depressurization experiments results, the gas recovery was high, however strong pulses which appeared at initial stage of production would damage the operation system. Moreover, cases that hydrate reformed have occurred by endothermic reaction. We have conducted experiments four and six times for the depressurization magnitudes of 140 psi and 320 psi, respectively, to analyze production behavior for the method more in detail. For the cases that the depressurization magnitude was set as 140 psi, the unstable period appears in the results, but stabilized soon. In the experiment results for 320 psi the discontinuous and intermittent behavior has been observed. Thermal stimulation experiments was conducted with depressurizing 80 psi which is the case that shows stable behavior and low recovery. In the results, the gas recovery was high and the energy efficiency was low for long stimulating time. The energy efficiency and gas recovery increased for the soaking time of 1 minute after 2 minute-preheating. In the cases of which the soaking time exceeds 1 minute, energy loss by long soaking time caused low gas recovery and poor energy efficiency.

• Journal of the Korean Vacuum Society
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• v.14 no.4
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• pp.238-244
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• 2005

IZO thin films are prepared on a corning 7059 glass substrate in a mixed gases of Ar +$O_2$ by rf-magnetron sputtering, using a powder target with a composition ratio of $In_{2}O_{3}$ : ZnO=90 : 10 $wt.\%$. Their electrical sheet resistance are strongly dependent on the oxygen concentration introduced during the deposition, a minimum resistivity of $3.7\times10^{-4}\Omega\cdot$ cm and an average transmittance over $85\%$ in the visible range are obtained in a film deposited in pure Ar gas which is close to near the stoichiometry. During the heat treatment from room temperature up tp $600^{\circ}C$ in various environments, the electrical resistance changes are explained by cyrstallizations or oxidizations of In metal and InO contained in the IZO film. The electrical properties due to oxygen adsorption and phase transitions occurring at temperatures over $40000^{\circ}C$ during heat treatment in air are also investigated.

• Membrane Journal
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• v.6 no.3
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• pp.157-165
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• 1996

Polysulfone(PS) membranes were prepared from homogeneous PS solutions by the phase inversion technique. When propionic acid(PA) was added into a casting solution of n-methylpyrrolidone(NMP) and PS, precipitation rate of the solution film was accelerated. This kind of acceleration was consistent, even though a precipitating nonsolvent was changed from water to isopropanol. These phenomena were caused by decrease of nonsolvent tolerance in the casting solution due to addition of PA. PS powder was prepared by precipitation of a 3wt% solution in dimethylformamide(DMF) using ethanol as nonsolvent. Gas adsorption analysis of the powder showed that the capillary condensation sites were found in the powder structure. Membranes prepared from PS solution(15wt%) in NMP had the following characteristics of gas adsorption and water permeation. In gas adsorption analysis, the membrane precipitated using isopropanol showed low uptake of nitrogen gas and the capillary condensation sites were not found. On the contrary, a significant amount of the capillary condensation sites was found in the membrane coagulated by water, which was related to increase of nitrogen uptake. tn the membrane prepared froin the solution including PA, an increase of the Henry's law sites and the Langmuir sites was not found clearly. However, the capillary condensation sites were significantly increased, and the water transport also increased.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.15-20
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• 2010

In this study, AZO (Al: 3 wt%) thin films have been prepared on PES Plastic substrates at various working pressure (5~20 mTorr), $O_2$ gas flow rate(0~3%) and the fixed substrate temperature of 200 f by using the RF magnetron sputtering and their optical and electrical properties have been studied. The XRD measurement shows that AZO thin films exhibit c-axis preferred orientation. From the results of AFM measurements, it is known that the lowest surface roughness (3.49 nm) is obtained for the AZO thin film fabricated at 5 mTorr of working pressure and 3% of $O_2$ gas flow rate. The optical transmittance of AZO thin films is measured as 80% in the visible region. We observe that the energy band gap of AZO thin films increases with decreasing the working pressure and the $O_2$ gas flow rate. This phenomenon is due to the Burstein-Moss effect. Hall measurement shows that the maximum carrier concentration ($2.63\;{\times}\;10^{20}\;cm^{-3}$) and the minimum resistivity ($4.35\;{\times}\;10^{-3}\;{\Omega}cm$) are obtained for the AZO thin film fabricated at 5mTorr of working pressure and 0% of $O_2$ gas flow rate.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.660-667
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• 2010

In this research polyimide, Matrimid 5218, hollow fiber membrane was used to recover sulfur hexafluoride($SF_6$) which is one of the six greenhouse gases from $N_2/SF_6$ mixture gas. Fibers were spun from using dry-wet phase inversion method. The module was manufactured by fabricating fibers after surface coating with silicone elastomer. The scanning electron microscopy(SEM) studies showed that the produced fibers typically had an asymmetric structure; a dense top layer supported by a sponge-like substructure. The developed module had a permeance of 0.78-1.36 GPU for $N_2$ with $N_2/SF_6$ selectivity of 2.44-5.08 at various pressure and temperature. For recovery of $SF_6$, a membrane module and 10 vol.% $SF_6$ from $N_2/SF_6$ mixture gas was used. The effects of various operating condition such as pressure, temperature, and retentate side flow rate were tested. When pressure and temperature were increased and retentate flow rate was decreased, the $SF_6$ purity in recovered gas was increased up to 37.5 vol.% with decreasing recovery ratio. When retentate flow rate was increased pressure and temperature was decreased, the $SF_6$ recovery ratio in retentate side was increased up to 89% with decreasing the $SF_6$ purity in retentate side.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.47-53
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• 2011

$SF_6$ (Sulfur hexafluoride) possesses high GWP (Global Warming Potential) as sepcified by the IPCC (Intergonvernmental Panel of Climate Change). Recently, the recovery-separtion of $SF_6$ research area, including permeation properties studies using various membrane's materials and the practical operation of recovery-separtion using membrane of waste $SF_6$ gas is in the initial state. The separation efficiency of a single $SF_6$ and waste $SF_6$ mixture was evaluated using a PSF (polysulfone), PC (tetra-bromo polycarbonate) and PI (polyimide) hollow fiber membranes. According to the results of single gases permeation properties, PI membrane has the highest permselectivity of $N_2$ gas in $N_2/SF_6$ gas. Under the condition of P=0.5 MPa, the highest concentration of recovered $SF_6$ is 95.6 vol % in the separation experiment of $SF_6/N_2$ mixture gas by PC membrane. Under the operation pressure of P=0.3 MPa at a fixed retentate flow rate fixed of 150 cc/min, the maximum recovery efficiency of $SF_6$ is up to 97.8% by PSF membrane. From the results above, it is thought that the separation and recovery technique of $SF_6$ gas using membrane will be used as the representative eco-technology in the $SF_6$ gas treatment in the future.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.461-467
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• 1998

Two hundred grams of fresh jujubes at whitish green maturity was packaged in the film bags of different gas permeabilities and stored at 0 and $5^{\circ}C$. Through the storage package atmosphere and jujube quality were monitored. Package of $30\;{\mu}m\;CPP$ film resulted in anaerobic conditions of $O_2$ content below 1% and $CO_2$ content above 15%, and caused off-flavor at both temperatures within 4 weeks. Package of $60\;{\mu}m\;LDPE$ film also showed potential risk of anaerobic condition development within 5 weeks, because of high $CO_2$ and/or low $O_2$ concentration at 0 and $5^{\circ}C$. Microperforated film packages could preserve quality of jujubes for 10 and 7 weeks at 0 and $5^{\circ}C$, respectively, which were significantly longer than shelf lives for perforated air pack and hermetically sealed packages.