• 한국세라믹학회지
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• 제29권8호
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• pp.587-592
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• 1992

Sheets of SiC-SiC whisker maxed matrix were prepared from the mixed slurry of SiC whisker and SiC matrix by the rolling method. With the increase of SiC whisker, the pore size, the porosity and the phosphoric acid absorbency of the matrix were increased, while the bubble pressure was decreased. The activation energy for the transfer of H+ ion was decreased with the increase of mixing ratio of SiC whisker to the SiC matrix from the measurement of hydrogen ion conductivity. The activation energy was evaluated as 0.25 eV when the mixing ratio of SiC whisker to the SiC matrix was 1 : 2 and the activation energy was 0.16 eV for the 2 : 1 matrix. It means that SiC whisker matrix contributes to attain a better microstructure for the diffusion of hydrogen ion. From the measurement of single cell performance of matrix with various mixing ratio, it is concluded that if SiC-SiC whisker maxed matrix has a sufficient bubble pressure to prevent the crossover of H2 gas, the current density of a fuel cell is increased with the increase of acid absorbency of the matrix. Current density was improved from 140 mA/$\textrm{cm}^2$ for 0.25 mm thickness of matrix to 170 mA/$\textrm{cm}^2$ for the 0.20 mm one at 700 mV.

• 한국대기환경학회지
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• 제19권6호
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• pp.679-687
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• 2003

In this study, we investigated the analytical techniques to quantify the ambient concentration of hydrogen sulfide (H$_2$S) in air at ppt concentration level. For this purpose, an on-line GC analytical system equipped with both pulsed-flame photometric detector (PFPD) and thermal desorption unit (TDU) was investigated by collecting ambient air samples. The results of our study generally indicated that calibration conditions of GC system is highly sensitive to affect the accuracy of the analytical technique. Most importantly. we found that the use of different matrices in the the preparation stage of working standards was sensitive to control the overall performance of this technique. The calibration of our analytical system was tested by the two types of working standard (prepared by mixing either with high purity $N_2$ or with the ambient air). According to this test, the latter represented more efficiently the detecting conditions of actual air samples. The peak occurrence patterns of both air samples and standards (prepared by mixing with ambient air) were altered in a similar manner as the function of the loaded volume; however, it was not the case for the $N_2$-mixed standards. Results of our study suggest that detection of H$_2$S is highly different from other sulfides and that its quantification requires minimiaing interfering effects of non -pure substance (like water vapor) and (either sorptive or destructive) loss effects.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.95-98
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• 2010

본 연구에서는 고농도 과산화수소와 케로신을 산화제와 연료로 사용하는 다중 인젝터 액체로켓엔진을 설계, 제작하였고 수류시험을 수행하였다. 이 엔진에는 6개의 동축 선회형 인젝터를 사용하였으며, 유동해석 결과를 바탕으로 정체 구간과 재순환 영역을 최소화한 매니폴드 유로를 설계, 제작하였다. 최종적으로 수류실험을 통해 추진제의 공급 유량 및 분무 성능을 확인하였으며, 인젝터의 설계 타당성을 검증하였다.

• Bulletin of the Korean Chemical Society
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• 제17권10호
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• pp.939-943
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• 1996

Reactions that proceed within mixed acetylene-methanol and ethylene-methanol cluster ions were studied using an electron-impact time-of-flight mass spectrometer. When acetylene and methanol seeded in helium are expanded and ionized by electron impact, the ion abundance ratio, [CH3OH+]/[CH2OH+] shows a propensity to increase as the acetylene/methanol mixing ratio increases, indicating that the initially ionized acetylene ion transfers its charge to adjacent methanol molecules within the clusters. Investigations on the relative cluster ion intensity distributions of [CH3OH2+]/[CH3OH+] and [(CH3OH)2H+]/[CH3OH·CH2OH+] under various experimental conditions suggest that hydrogen-atom abstraction reaction of acetylene molecule with CH3OH ion is responsible for the effective formation of CH2OH ion. In ethylene/methanol clusters, the intensity ratio of [CH3OH2]/[CH3OH] increases linearly as the relative concentration of methanol decreases. The prominent ion intensities of (CH3OH)mH over (CH3OH)m-1CH2OH ions (m=1, 2, and 3) at all mixing ratios are also interpreted as a consequence of hydrogen atom transfer reaction between C2H4 and CH3OH to produce the protonated methanol cluster ions.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2771-2778
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• 2009

본 연구는 주유소 부지와 같이 소규모 오염지역에 가장 많이 적용되는 굴착된 오염토양에 펜톤산화반응이 적용될 때 투입되어야 할 과산화수소와 철 촉매의 적정량을 산정하고 혼합방식 및 투입방식을 개선하여 과산화수소와 철 촉매의 과량 투입으로 인한 2차오염과 과다한 처리비용 문제를 해결하고자하였다. 경유 10,000mg/kg의 농도로 오염시킨 인공오염토양을 사용하여 실험을 진행하였고 회분식 실험결과 과산화수소의 농도가 증가할수록 경유제거효율이 높아지는 경향을 보였다. 또한 철 촉매를 주입했을 경우 과산화수소만 주입했을 시보다 훨씬 높은 경유제거효율을 보였으며 Fe(II)에 비해 Fe(III)을 주입하였을 때 제거효율이 더 높게 나타났다. 칼럼실험은 회분식 실험결과를 바탕으로 진행되었고 펜톤산화반응에 의한 현장복원이 이루어질 때 문제시되고 있는 혼합문제의 해결방법을 모색하고자 칼럼을 사용하여 시약 주입방법을 달리하며 실험하였으며 분리 분할 주입의 경우 가장 높은 효율을 얻을 수 있었다. 칼럼실험을 비교해 본 결과 단을 분리시켜 Fe(III)철 촉매를 주입하고 과산화수소를 분할 주입한 경우 92.8%의 높은 제거효율로 현장주입 조건을 모사한 과산화수소만 주입한 첫 번째 방법의 경유제거효율 10.5%보다 9배가량 높은 것으로 나타났다. 따라서 본 연구결과를 경유오염토양의 펜톤산화 복원 시 현장에 적용하면 과산화수소와 철 촉매의 과량 투입으로 인한 2차 오염과 과다한 처리비용 문제를 해결 할 수 있을 것으로 사료된다.

• 한국수소및신에너지학회논문집
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• 제17권1호
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• pp.8-20
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• 2006

For large scale separation hydrogen from different mixing ratio(60/40 and 80/20 vol.%) of hydrogen and methane $1Nm^3/hr$ and $4Nm^3/hr$ 2bed-6step pressure swing adsorption(PSA) process was used, respectively. The effects of the feed gas pressure, adsorption time, the feed flow rate and the P/F(purge to feed) ratio on the process performance were evaluated. In the $1Nm^3/hr$ PSA results, 11 atm adsorption pressure and 0.10 P/F ratio might be optimal values to obtain more than 75 % recovery and 99 % purity hydrogen in these processing. The optimum feed flowrate was 22 LPM and 17 LPM in the ratio 60/40 and 80/20, respectively. In the $4Nm^3/hr$ PSA results, 10 atm adsorption pressure might be simulated values to obtain more than 80 % recovery and 99 % purity hydrogen in these processing.

• KSBB Journal
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• 제23권3호
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• pp.199-204
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• 2008

Culture conditions for biological hydrogen production were investigated in wastewater of Takju manufacturing factory. Rhodobacter spaeroides KCTC1425, photosynthesis bacteria, and Enterobacter cloacae YJ-1, anaerobic bacteria were used. The hydrogen production were $195.3m{\ell}{\cdot}H_2/{\ell}$ broth for Rhodobacter spaeroides KCTC1425 and $271.8m{\ell}{\cdot}H_2/{\ell}$ broth for Enterobacter cloacae YJ-1 during 36 h. The hydrogen production increased with light intensity, and were highest over 12000Lux. In mixed culture of Rhodobacter spaeroides KCTC1425 and Enterobacter cloacae Y J-1, the optimum mixing ratio of hydrogen production was 20 and 80. Adding volume of yeast extract for maximum hydrogen production was 15 $g/{\ell}$, but there was no effect over that. $Na_2MoO_4$ was most effective among the inorganic salts, and the optimum volume was 0.4 $g/{\ell}$. In semi-continuous culture, total hydrogen production was $13086m{\ell}{\cdot}H_2/{\ell}$ broth for 144 h with operating period of 24 h.

• 대한기계학회논문집B
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• 제27권11호
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• pp.1579-1586
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• 2003

A gun-type burne. fur a LPG(Liquified Petroleum Gas) boiler was utilized for hydrogen combustion. The study was performed to obtain fundamental data prior to the design of a very low NO$\_$x/, hydrogen-fueled burner. First, numerical simulations were performed to predict mixing characteristics between air and fuel flows, and temperature distributions, etc. Experimental study was then performed to find out flame lengths, temperature distributions, and NO$\_$x/ concentrations. The results showed that a gun-type burner for a LPG boiler can be successfully used for hydrogen combustion without any major retrofitting. The hydrogen flame was very stable and 75 ppm of NO$\_$x/ in average was observed for the conditions considered in this study. Hydrogen combustion could be therefore a solution to avoid the problem of green-house gas(CO$_2$) if hydrogen becomes cost-effective.

• 한국분말재료학회지
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• 제22권4호
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• pp.266-270
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• 2015

The synthesis of NiTi alloy powders by hydrogen reduction and dehydrogenation process of NiO and $TiH_2$ powder mixtures is investigated. Mixtures of NiO and $TiH_2$ powders are prepared by simple mixing for 1 h or ball milling for 24 h. Simple-mixed mixture shows that fine NiO particles are homogeneously coated on the surface of $TiH_2$ powders, whereas ball milled one exhibits the morphology with mixing of fine NiO and $TiH_2$ particles. Thermogravimetric analysis in hydrogen atmosphere reveals that the NiO and $TiH_2$ phase are changed to metallic Ni and Ti in the temperature range of 260 to $290^{\circ}C$ and 553 to $639^{\circ}C$, respectively. In the simple-mixed powders by heat-up to $700^{\circ}C$, agglomerates with solid particles and solidified liquid phase are observed, and the size of agglomerates is increased at $1000^{\circ}C$. From the XRD analysis, the presence of liquid phase is explained by the formation and melting of $NiTi_2$ inter-metallic compound due to an exothermic reaction between Ni and Ti. The simple-mixed powders, heated to $1000^{\circ}C$, lead to the formation of NiTi phase but additional Ni-, Ti-rich and Ti-oxide phases. In contrast, the microstructure of ball-milled powders is characterized by the neck-grown particles, forming $Ni_3Ti$, Ti-oxide and unreacted Ni phase.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.594-597
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• 2009

The mixing characteristics of pylon injection in a Scramjet combustor and effects of film cooling to protect pylon from air-heating. Three-dimensional Navier-Stokes equations with $k-{\omega}$ SST turbulence model were used. Fuel hydrogen and air were considered as coolants. There were remarkable improvements of penetration and mixing rate with the pylon injection. There also over-heating on the front surface of pylon without film cooling. The coolant injected parallel to the front surface of the pylon protect the pylon from over-heating.