• 한국수소및신에너지학회논문집
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• 제25권6호
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• pp.570-576
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• 2014

LFG (Land-Fill Gas) includes components of $CH_4$, $CO_2$, $O_2$, $N_2$, and water. The preparation of synthesis gas from LFG as a DME (Dimethyl Ether) feedstock was studied by methane reforming of $CO_2$, $O_2$ and steam over NiO-MgO-$CeO_2$/$Al_2O_3$ catalyst. Our experiments were performed to investigate the effects of methane conversion and syngas ratio on the amount of LFG components over NiO-MgO-$CeO_2$/$Al_2O_3$ catalyst. Results were obtained through the activity reaction experiments at the temperature of $900^{\circ}C$ and GHSV of 4,000. The results were as following; it has generally shown that methane conversion rate increased with the increase of oxygen and carbon dioxide amounts. Highly methane conversion of 92~93% and syngas ratio of approximately 1.0 were obtained in the feed of gas composition flow-rate of 243ml/min of $CH_4$, 241ml/min of $CO_2$, 195ml/min of $O_2$, 48ml/min of $N_2$, and 360ml/min of water, respectively, under reactor pressure of 15 bar for 50 hrs of reaction time. Also, it was shown that catalyst deactivation by coke formation was reduced by excessively adding oxygen and steam as an oxidizer of the methane reforming.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.407-410
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• 2012

The properties of Al-doped ZnO (AZO) films were investigated as a function of H2/(Ar + H2) gas ratio using an AZO (2 wt% Al2O3) ceramic target in a radio frequency (RF) magnetron sputtering system. The deposition process was done at 200 ℃ and in 2 × 10-2Torr working pressure and with various ratios of H2/(Ar + H2) gas. During the AZO film deposition process, partial H2 gas affected the AZO film characteristics. The electron resistivity (~ 9.21 × 10-4 Ωcm) was lowest and mobility (~17.8 ㎠/Vs) was highest in AZO films when the H2/(Ar + H2) gas ratio was 2.5%. When the H2/(Ar + H2) gas ratio was increased above 2.5%, the electron resistivity increased and mobility decreased with increasing H2/(Ar + H2) gas ratio in AZO films. The carrier concentration increased with increasing H2/(Ar + H2) gas ratio from 0% to 7.5%. This phenomenon was explained by reaction of hydrogen and oxygen and additional formation of oxygen vacancy. The average optical transmission in the visible light wavelength region over 90% and an orientation of the deposition was [002] orientation for AZO films grown with all H2/(Ar + H2) gas ratios.

• 한국추진공학회지
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• 제20권3호
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• pp.17-24
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• 2016

본 연구에서 리세스가 있는 기체수소/액체산소 2차원 동축 전단 분사기에 대해 연소해석을 수행하였다. 이상기체와 실제기체 상태방정식을 이용한 정상상태 난류연소에 대해 표준 ${\kappa}-e$ 모델과 층류 화염편 모델이 선택되었다. 리세스 길이가 증가할수록 연소실 내 재순환의 크기가 커지고 와도가 강해졌다. 또한, 온도, 연소생성물, 압력의 변화가 리세스 길이에 큰 영향을 받았다. 해석된 결과들은 리세스가 있는 분사기에 의해서 효과적인 연소기를 얻을 수 있음을 보여주었다.

• 반도체디스플레이기술학회지
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• 제8권1호
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• pp.33-38
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• 2009

We have investigated the effect of the ambient gases on the characteristics of AZO thin films for the OLED (organic light emitting diodes) devices. These AZO thin films are deposited by rf-magnetron sputtering under different ambient gases (Ar, Ar+$O_2$, and Ar+$H_2$) at 300. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon mixing gas has been changed from 0.2sccm to 1sccm and from 0.5sccm to 5sccm, respectively. The AZO thin films were preferred oriented to (002) direction regardless of ambient gases. The electrical resistivity of AZO film increased with increasing flow rate of $O_2$ under Ar+$O_2$ while under Ar+$H_2$ atmosphere the electrical resistivity showed minimum value near 1sccm of $H_2$. All the films showed the average transmittance over 80% in the visible range. The OLED device was fabricated with different AZO substrates made by configuration of AZO/$\acute{a}$-NPD/DPVB/$Alq_3$/LiF/Al to elucidate the performance of AZO substrate.

• 반도체디스플레이기술학회지
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• 제9권1호
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• pp.35-40
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• 2010

We have investigated the effects of hydrogen injection via in-situ gas addition ($O_2$, $H_2$, or $O_2$ + $H_2$ gas) and plasma post-treatment (Ar or Ar + H plasma) on material properties of ZnO that is considered to be as a channel layer in transparent thin film transistors. The variations in the electrical resistivity, optical transmittance and bandgap energy, and crystal quality of ZnO thin films were characterized in terms of the methods and conditions used in hydrogen injection. The resistivity was significantly decreased by injection of hydrogen; approximately $10^6\;{\Omega}cm$ for as-grown, $1.2\;{\times}\;10^2\;{\Omega}cm$ for in-situ with $O_2/H_2\;=\;2/3$ addition, and $0.1\;{\Omega}cm$ after Ar + H plasma treatment of 90 min. The average transmittance of ZnO films measured at a wavelength of 400-700 nm was gradually increased by increasing the post-treatment time in Ar + H plasma. The optical bandgap energy of ZnO films was almost monotonically increased by decreasing the $O_2/H_2$ ratio in in-situ gas addition or by increasing the post-treatment time in Ar + H plasma, while the post-treatment using Ar plasma hardly affected the bandgap energy. The role of hydrogen in ZnO was discussed by considering the creation and annihilation of oxygen vacancies as well as the formation of shallow donors by hydrogen.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.91.1-91.1
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• 2010

The Reforming system is an effective method to generate hydrogen which uses for fuel cell system. The purpose of this study is to present characteristics of an autothermal reformer at various operating conditions and to investigate ideal conditions for reforming efficiency. Dominant chemical reactions are Full Combustion, Steam Reforming reaction, Water-Gas Shift reaction and Direct Steam Reforming reaction. Operating parameters of the autothermal reformer are inlet temperature, Oxygen to Carbon Ratio, Steam to Carbon Ratio and Gas Hourly Space Velocity. Autothermal reformer is filled with catalysis of a packbed-bed type. Using numerical approach, we have investigated on various reaction conditions.

• Corrosion Science and Technology
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• 제5권3호
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• pp.94-98
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• 2006

The next generation nuclear power reactor will use Pb-Bi as the cooling material. The steel structure materials such as HT-9 used in the reactor suffer from corrosion when they are exposed to high temperature Pb-Bi. Therefore corrosion should be prevented to use Pb-Bi as the coolant material without any safety problem. One method is to control the oxygen content in Pb-Bi. An appropriate amount of oxygen in Pb-Bi can produce a thin oxide layer on steel, and this layer protects the steel from corrosion attack. Since the required oxygen content in Pb-Bi is in the range of $10^{-5}$ to $10^{-7}$ wt%, this small oxygen content can be controlled by flowing a mixture of hydrogen gas and water vapor. The stagnant corrosion test of HT-9 samples was performed by controlling the oxygen content up to 2,000 hours. The corrosion behavior of HT-9 was analyzed at the temperatures of $500^{\circ}C$ and $650^{\circ}C$ with a reduced condition and a oxygen content of $10^{-6}$ wt%.

• 공업화학
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• 제30권6호
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• pp.719-725
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• 2019

본 실험에서는 활성탄소섬유에 산소플라즈마 처리를 실시하여 산소작용기 도입 함량에 따른 유독성 화학작용제의 모사 가스인 dimethyl methylphosphonate (DMMP) 감응특성에 대하여 고찰하였다. 산소플라즈마 처리 유량이 증가할수록 활성탄소섬유 표면에 산소가 6.90%에서 최대 36.6%까지 도입되어 DMMP 가스 감응특성에 영향을 미치는 -OH가 증가하였다. 그러나 유량이 증가할수록 산소플라즈마 처리 시 발생한 산소 활성종으로 인하여 활성탄소섬유 표면에 식각이 발생하여 비표면적은 감소하는 경향을 보였다. DMMP 가스센서의 저항변화율은 산소플라즈마 처리 유량이 증가함에 따라 4.2%에서 최대 25.1%까지 증가하였다. 이는 산소플라즈마 처리로 인하여 활성탄소섬유에 발달된 -OH와 DMMP 가스의 수소결합으로 인한 것이라 여겨진다. 따라서 산소플라즈마 처리는 상온에서 유독성화학작용제 가스를 감지하기 위한 중요한 표면처리 방법 중 하나라고 판단된다.

• The Korean Journal of Ceramics
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• 제4권3호
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• pp.183-188
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• 1998

Gas sensitizations of tin oxide film were investigated by measuring the change of film resistance in various gas atmospheres such as $N_2,\; O_2,\; H_2O$. The main test sample, polycrystalline $SnO_2$ film containing small Sb as a dopant was prepared by a sputtering technique and showed a long term stability in base resistance and thus, in gas sensitivity. The adsorption of oxygen on the film surface as a type of $(O_{ads})$ at the temperature of around $300^{\circ}C$ played important roles in sensor operating mechanism. The roles were ⅰ) the increase of base resistance in ambient air, which consequently lead to high sensitivity and ⅱ) the promotion of fast recovery. The reaction of hydrogen gas with the already adsorbed $(O_{ads})$ ions was considered as a decisive sensitization mechanism of tin oxide film. However, the dissociation of hydrogen molecules on film surface, by direct donation of electron to film also took a major part in the sensitization. The effect of humidity on gas sensitization was found to be negligible at the sensor operating temperature of around $300^{\circ}C$.

• 한국항공우주학회지
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• 제36권5호
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• pp.491-496
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• 2008

본 연구에서는 RBCC (Rocket Based Combined Cycle)엔진이나 기존 램제트 추진기관의 초기 추력 제공에 과산화수소 가스발생기를 이용하는 새로운 추진시스템을 제안하였고, 기초 연구 수행으로서 촉매 분해된 과산화수소 제트에 케로신을 분사하여 자연발화 및 연소 특성을 연구하였다. 과산화수소는 촉매 베드를 통하여 분해된 후 축소노즐을 통해 연소실로 분사됐으며 이 제트에 인젝터를 통하여 수직으로 케로신을 액상으로 분무하였다. 연소실내에서의 온도와 압력을 측정하여 점화를 확인하고 자연발화 특성을 조사하였다. 400°C의 연소실 온도와 연료와 산화제 혼합비 0.6이상에서 자연발화와 안정적인 연소가 가능하였다. 이 결과를 통하여 램제트의 새로운 초기 가속장치의 가능성을 확인할 수 있었다.