• Transactions on Electrical and Electronic Materials
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• 제1권1호
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• pp.6-11
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• 2000

The hydrogen plasma treatment of silicon wafers in the reactive ion-etching mode was studied for the application to silicon-on-insulator wafers which were prepared using the wafer bonding technique. The chemical reactions of hydrogen plasma with surface were used for both surface activation and removal of surface contaminants. As a result of exposure of silicon wafers to the plasma, an active oxide layer was found on the surface. This layer was rendered hydrophilic. The surface roughness and morphology were examined as functions of the plasma exposing time and power. In addition, the surface became smoother with the shorter plasma exposing time and power. The value of initial surface energy estimated by the crack propagation method was 506 mJ/㎡, which was up to about three times higher as compared to the case of conventional direct using the wet RCA cleaning method.

• 한국수소및신에너지학회논문집
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• 제7권2호
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• pp.121-128
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• 1996

수소액화를 위한 직접냉각장치를 개발하고, 이의 성능특성을 시험하였다. 직접냉각장치는 액화용기, 복사쉴드, 저온조와 GM냉동기 등으로 구성하였다. 개발된 액화장치의 cool-down 및 warm-up특성이 상세하게 규명되었다. 본 냉각장치에서 냉각이 시작된지 약 45분 후, 액화용기내의 수소가 액화되기 시작함을 확인하였다. 또한 동일한 실험을 기체헬륨에 대하여 수행하였으며, 기체헬륨은 주어진 작동조건에서 액화되지 않으므로 수소의 경우와는 다른 cool-down 및 warm-up 특성을 보였다. 충전된 기체의 자연대류현상의 영향을 고찰하기 위하여 액화용기내에 진공상태를 유지하면서 시험하였다. 이때 진공상태에서의 액화용기의 냉각시간은 현저히 증가함을 보였다.

• Advances in Energy Research
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• 제1권1호
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• pp.13-33
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• 2013

The present work is an attempt to provide an overview, about the status of R&D and current trends in Hydrogen Production using High Temperature Reactors. Bibliographic references from the INIS database, the Science Direct database and the NTIS database were downloaded and analyzed. Ten year data on the subject, published between 2001 and 2010, was selected for the study. Appropriate qued ry formulations on these databases, resulted in the retrieval of 621 unique bibliographic records. Using the content analysis method, all the records were analyzed. Part One of the analysis details Scientometric R&D indicators, Part Two is a subject-based analysis, grouped under: A. International Initiatives and Programmes for Hydrogen Production; B. European R&D initiatives for Hydrogen production; C. National Initiatives and Programmes for Nuclear Hydrogen Production; D. Reactor Technologies for Nuclear Hydrogen production; E. Fuel Developments; F. Hydrogen Production Processes using HTRs and G. Materials Consideration for Nuclear Hydrogen Production. The results of this analysis are summarized in the study.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.524-534
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• 2013

Gasoline direct injection(GDI) engine has a high thermal efficiency, but it has a problem to increase carbon emissions such as soot and $CO_x$. In this study, the objective is to analyze numerically a problem for adding the hydrogen during the intake stroke so as to reduce the injected amount of gasoline in GDI engines. For selection of the base model, the cylinder pressure of simulation is matched to experimental data. The numerical analysis are carried out by a CFD model with the hydrogen addition of 2%, 3% and 4% on the volume basis. In the case of 3% hydrogen addition, the injected gasoline amount is only changed to match the maximum pressure of simulation to that of the base model for additional study. It is found that the combustion temperature and pressure increase with the hydrogen addition. And NO emission also increases because of the higher combustion temperature. $CO_x$ emissions, however, are reduced due to the decrease of injected gasoline amount. Also, as the injected gasoline amount is reduced for the same hydrogen addition ratio, the gross indicated work is no significant, But NO and $CO_x$ emissions are considerably decreased. On the order hand, $CO_x$ emissions of two cases are more decreased and their gross indicated works are higher obtained than those of the base model.

• 설비공학논문집
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• 제11권3호
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• pp.349-358
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• 1999

Thermodynamic cycle analysis has been performed to maximize the liquid amount for various hydrogen liquefaction systems using GM(Gifford-McMahon) refrigerator. Since the present authors' previous experiments showed that the liquefaction rate was approximately 5.1mg/s in a direct contact with a commercial GM refrigerator, the purpose of this study is to predict how much the liquefaction rate can be increased in different configurations and with improved heat exchanger performance. The optimal operating conditions have been analytically sought with real properties of normal hydrogen for the single-stage GM precooled L-H(Linde-Hampson) system, the two-stage GM direct contact system, the two-stage GM precooled L-H system and the two-stage helium GM-JT (Joule-Thomson) system. The maximum liquefaction rate has been predicted to be only about 7 times greater than the previous experiment, when the two-stage precooling is employed and the effectiveness of heat exchangers approaches to 99.0%. It is concluded that the liquefaction rate is limited mainly by the cooling capacity of the current GM refrigerators and a larger scale of hydrogen liquefaction is possible with a greater capacity of cryocooler at 60-70 K range.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3279-3281
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• 1999

This paper describes a method of direct wafer bonding using surfaces activated by a radio-frequency hydrogen plasma. The hydrogen plasma cleaning of silicon in the RIE mode was investigated as a pretreatment for silicon direct bonding. The cleaned silicon surface was successfully terminated by hydrogen, The hydrogen-terminated surfaces were rendered hydrophilic, which could be wetted by Dl water rinse. Two wafers of silicon and silicon dioxide were contacted to each other at room temperature and postannealed at $300{\sim}1100^{\circ}C$ in an $N_2$ atmosphere for 2 h. From the AFM results, it was revealed that the surface became rougher with the increased plasma exposure time and power. The effect of the plasma treatment on the surface chemistry was investigated by the AES analysis. It was shown that the carbon contamination at the surface could be reduced below 5 at %. The interfacial energy measured by the crack propagation method was 122 $mJ/m^2$ and 384 $mJ/m^2$ for RCA cleaning and hydrogen plasm, respectively.

• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.514-523
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• 2021

This study investigated the effect of anode fuel composition on the performance of direct borohydride/hydrogen peroxide fuel cells (DBHPFCs). The effect of sodium borohydride (NaBH₄) and sodium hydroxide (NaOH) concentrations on fuel cell performance was determined through fuel cell tests. Fuel cell performance increased with an increase in the NaBH₄ concentration, whereas it decreased with an increase in the NaOH concentration. The anode fuel composition was selected as 10 wt% NaBH₄+10 wt% NaOH+80 wt% H₂O based on the fuel viscosity, electrochemical reaction rate, and decomposition reaction rate. DBHPFCs were also tested to analyze the effect of operating temperature and operation time on fuel cell performance. The present results can be used as a reference basis to determine operating conditions of DBHPFCs.

• Korean Chemical Engineering Research
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• 제61권2호
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• pp.175-188
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• 2023

화석연료를 대체할 수 있는 친환경 미래 에너지로 수소에너지에 대한 전세계적 관심이 높아지고 있다. 이에 따라 미생물, 원자력 등을 이용한 차세대 수소 생산 기술이 개발되고 있으나, 화석연료 기반의 수소 생산 비용을 뛰어 넘기에는 아직 많은 시간과 노력이 필요한 상황이다. 화석연료 기반의 수소 생산 과정에서 온실가스의 배출량을 최소화 할 수 있는 방안으로 메탄 직접분해 반응 기술이 최근 관심을 모으고 있다. 공정의 경제성 향상을 위해서 수소 생산과 동시에 생산된 탄소물질의 고부가화 대한 연구가 필수적이며, 고부가 탄소 물질 중 하나인 탄소나노튜브(Carbon nanotube, CNT)의 품질 및 수율 등과 관련한 촉매반응 연구가 지속되어 왔다. 또한 공정기술 측면에서, 연속적인 생산이 가능하며 기체-고체 접촉 효율이 좋은 유동층 공정을 적용시켜 생산성과 경제성을 확보하고자 하는 연구가 시도되었다. 최근 유동층을 이용한 메탄 직접분해 반응기술은 수소 270 kg/day, 탄소 1000 kg/day의 생산이 가능한 정도의 기술 개발이 진행되었으며, 향후 촉매 재활성화, 분리 및 재순환 기술 등이 개발되면 공정의 효율이 크게 제고될 것이다. 이에 본 총설에서는 메탄 직접 분해에 활용되는 촉매 및 유동층 메탄 열분해 기술의 최근 연구들을 고찰하였다.

• 한국수소및신에너지학회논문집
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• 제11권1호
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• pp.1-9
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• 2000

The goals of this research are to understand the $NO_x$ emission in direct injected diesel engine with premixed hydrogen fuel. Hydrogen fuel was supplied into the test engine through the intake pipe. Amount of hydrogen-supplemented fuel was 70 percent basis heating value of the total fuel. The effects of exhaust gas recirculation(EGR) on $NO_x$ emission were studied. The exhaust gas was recirculated to the intake manifold and the amount of exhaust gas was controlled by the valve. The major conclusions of this work include: (i) the tested engine was run without backfire under 70 percent hydrogen fuel supplemented; (ii) the peak cylinder pressure was decreased with increase of EGR ratio due to the decrease of oxygen concentration in an intake pipe; and (iii) $NO_x$ emission was decreased by 77% with 30% EGR ratio. Therefore, it may be concluded that EGR is effective method to lower $NO_x$ emission in hydrogen fueled diesel engine.

• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.292-298
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• 2011

This study examines the effects of the ambient temperature (AT), methanol feeding temperature (MFT), methanol concentration (MC) and methanol flow rate (MFR) on the performance and cell temperature (CT) of a 5-stacked direct methanol fuel cell (DMFC). The AT, MFT, MC, and MFR are varied from $-10^{\circ}C$ to $+40^{\circ}C$, $50^{\circ}C$ to $90^{\circ}C$, 0.5M to 3.0M and 11.7 mL $min^{-1}$ to 46.8 mL $min^{-1}$, respectively. The performance of the DMFC under various operating conditions is analyzed from the I-V polarization curve, and the methanol crossover is estimated by gas chromatography (GC). The performance of the DMFC improves significantly with increasing AT. The open circuit voltage (OCV) decreases with increasing MC due to the enhanced likelihood of methanol crossover. The cell performance is improved significantly when the MFR is increased from 11.7 mL $min^{-1}$ to 28.08 mL $min^{-1}$. The change in cell performance is marginal with further increases in MFR. The CT increases significantly with increasing AT. The effect of the MFT and MFR is moderate, and the effect of MC is marginal on the CT of the DMFC.