• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.11a
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• pp.92-95
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• 1993

실험실 규모의 유동층 반응기(0.8 m H $\times$ 0.08 m I.D.) 에서 반응온도(700 -80$0^{\circ}C$), 유동화속도(1.5 - 3 Umf)의 영향에 따른 생성물의 수율, 생성가스의 조성, 생성가스의 발열량의 변화를 질소 분위기하에서 조사하였다. 반응온도를 700 에서 850 $^{\circ}C$로 증가시킬 때 촤의 수율은 36% 정도로 온도에 따라 큰 차이를 보이지 않은 반면 가스의 수율은 온도가 증가함에 따라 22 %에서 800 $^{\circ}C$까지 30%가량 증가하다 그 이상의 온도에서는 증가하지 않았다. 또한 수소와 메탄은 온도가 증가함에 따라 그 생성량이 증가하는 반면 에탄과 프로펜은 감소하였으며 단위 부피당 가스의 발열량은 감소하였다.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.1044-1050
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• 2007

In this study, Bio-hydrogen is produced from organic waste mixtures containing food waste and waste activated sludge (WAS). The effects of different operational factor on hydrogen production, including various solubilization methods for pretreatments of WAS, pH and different ratios of food waste and WAS, were investigated. The highest hydrogen production values are obtained as 4.3 mL $H_2/g$ $VS_{consumed}$ in the case of applying the mixed pre-treatments of alkali and ultrasonic. The pH value in bio-reactor increased from 4 to 8 after the ultrasonic treatment with alkali and the hydrogen yield touched its highest value in the pH range of 5.0 to 5.5. Similarly, the hydrogen production reached the level of 13.8 mL $H_2/g$ $VS_{consumed}$ using the same pre-treatment method from the mixture of food waste and WAS. The ratio of 2 : 1 produced a maximum amount of hydrogen of 5.0 L $H_2/L/d$. The amount of volatile fatty acids(VFAs) including acetate, propionate and butyrate, were also varied considerably. Propionate decreased consistently with rising of hydrogen while butyrate comparing to acetate relatively increased in the effluent.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.865-872
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• 2014

The study was conducted to evaluate the effect of addition of food waste in brown water for anaerobic hydrogen production. Batch experiment was carried out to determine appropriate food waste to brown water mixing ratio. Maximum hydrogen yield of $6.92mmol\;H_2/g\;COD_{removed}$ was obtained at 70% food waste and 30% brown water. Semi-pilot scale reactor was operated based on result of batch experiment. Semi-pilot reactor operated, mixing 70% food waste and 30% brown water showed significant increment in butyric acid concentration. B/P (Butyric to propionic acid ratio) which is considered as governing factor for hydrogen production was found high (52.64). Maximum hydrogen yield of $25.03mmol\;H_2/g\;COD_{removed}$ was obtained. Result of this study concluded that mixing of food waste to brown water at appropriate ratio assists in enhanced hydrogen fermentation.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.95-101
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• 2016

For a natural gas steam reforming, comparative studies of the performance in a conventional packed-bed reactor and a membrane reactor, a new conceptual reactor consisting of a reactor with series of hydrogen separation membranes, have been performed. Based on experimental kinetics reported by Xu and Froment, a process simulation model was developed with Aspen $HYSYS^{(R)}$, a commercial process simulator, and effects of various operating conditions like temperature, $H_2$ permeance, and Ar sweep gas flow rate on the performance in a membrane reactor were investigated in terms of reactant conversion and $H_2$ yield enhancement showing improved $H_2$ yield and methane conversion in a membrane reactor. In addition, a preliminary cost estimation focusing on natural gas consumption to supply heat required for the system was carried out and feasibility of possible cost savings in a membrane reactor was assessed with a cost saving of 10.94% in a membrane reactor.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.134-139
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• 2024

In the steam reforming of methane reactions, the effect of adding noble metals Ru and Pd to a Ni-based catalyst as promoters was analyzed in terms of catalytic activity and hydrogen production. The synthesized catalysts were coated on the surface of a honeycomb-structured metal monolith to perform steam methane reforming reactions. The catalysts were characterized by XRD, TPR, and SEM, and after the reforming reaction, the gas composition was analyzed by GC to measure methane conversion, hydrogen yield, and CO selectivity. The addition of 0.5 wt% Ru improved the reduction properties of the Ni catalyst and exhibited enhanced catalytic activity with a methane conversion of 99.91%. In addition, reaction characteristics were analyzed according to various process conditions. Methane conversion of over 90% and hydrogen yield of more than 3.3 were achieved at a reaction temperature of 800 ℃, a gas hourly space velocity (GHSV) of less than 10000 h^-1, and a ratio of H₂O to CH₄ (S/C) higher than 3.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.375-378
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• 2002

Hydrogen producing bacterium, strain Ye13-6 was isolated from the sludge of the factory areas in Gunpo through the acclimation in basal salt medium(BSM) supplemented with 10g/ ${\ell}$ of sucrose. Isolated strain Ye13-6 was a facultative anaerobe which could grow in both aerobic and anaerobic environments. Effects of the concentrations of glucose and sucrose on the hydrogen production rate and the hydrogen production yield were investigated. When glucose in the range of 1${\sim}$12g/ ${\ell}$ was supplemented to the BSM, strain Ye13-6 could grow without lag phase. An increased glucose concentration increased the specific hydrogen production rate linearly to 60mmol-$H_2$ ${\cdot}$ mg-$DCW^{-1}$ ${\cdot}$ $h^{-1}$. The hydrogen production yield was maintained over a range from 2.6 to 3.1mol-$H_2$ ${\cdot}$ mol-$glucose^{-1}$. When sucrose in the range of 1${\sim}$12g/ ${\ell}$ was supplemented to the BSM, strain Ye13-6 could grow after ten hours. An increased sucrose concentration increased the specific hydrogen production rate and the hydrogen production yield to 163mmol-$H_2$ ${\cdot}$ mg-$DCW^{-1}$ ${\cdot}$ $h^{-1}$ and to 4.5mol-$H_2$ ${\cdot}$ mol-$sucrose^{-1}$, respectively.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.758-762
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• 2019

Sodium borohydride,$NaBH_4$, has many advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFC). When PEMFC is used for marine use, $NaBH_4$ hydrolysis using seawater is economical. Therefore, in this study, hydrogen was generated by using seawater instead of distilled water in the process of hydrolysis of $NaBH_4$. Properties of $NaBH_4$ hydrolysis reaction using activated carbon supported Co-B/C catalyst were studied. The yield of hydrogen decreased as $NaBH_4$ concentration and NaOH concentration were increased during $NaBH_4$ hydrolysis using sea water. At higher concentrations of $NaBH_4$ and NaOH, byproducts adhered to the surface of the catalyst after hydrolysis reaction using sea water, reduced hydrogen yield compared to distilled water. The activation energy of $NaBH_4$ hydrolysis is 59.3, 74.4 kJ/mol for distilled water and sea water, respectively. In order to increase the hydrogen generation rate in seawater as high as distilled water, the reaction temperature has to be increased by $80^{\circ}C$ or more.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.926-931
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• 2011

Among various techniques for hydrogen production from organic wastewater, a dark fermentation is considered to be the most feasible process due to the rapid hydrogen production rate. However, the main drawback of it is the low hydrogen production yield due to intermediate products such as organic acids. To improve the hydrogen production yield, a co-culture system of dark and photo fermentation bacteria was applied to this research. The maximum specific growth rate of R. sphaeroides was determined to be $2.93h^{-1}$ when acetic acid was used as a carbon source. It was quite high compared to that of using a mixture of volatile fatty acids (VFAs). Acetic acid was the most attractive to the cell growth of R. sphaeroides, however, not less efficient in the hydrogen production. In the co-culture system with glucose, hydrogen could be steadily produced without any lag-phase. There were distinguishable inflection points in the accumulation of hydrogen production graph that resulted from the dynamic production of VFAs or consumption of it by the interaction between the dark and photo fermentation bacteria. Lastly, the hydrogen production rate of a repeated fed-batch run was $15.9mL-H_2/L/h$, which was achievable in the sustainable hydrogen production.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.443-450
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• 2014

Selective catalytic reduction of nitrogen monoxide by hydrogen ($H_2$-SCR of NO) over platinum catalysts impregnated on zirconia-incorporated silica ($ZrO_2-SiO_2$) and manganese oxide ($MnO_x$) was investigated. $Pt-MnO_x$ catalyst showed low conversions and low yields of $N_2O$ and $NO_2$ at $100{\sim}350^{\circ}C$. On the other hand, NO conversions over $Pt/ZrO_2-SiO_2$ were very high, but $N_2O$ was predominantly produced at $100-150^{\circ}C$ and the yield of $NO_2$ increased with temperature at $200-300^{\circ}C$, resulting in poor $N_2$ yields. $Pt-MnO_x/ZrO_2-SiO_2$ exhibited a small enhancement in $N_2$ yield at $100-150^{\circ}C$ due to the synergy of $MnO_x$ and $ZrO_2-SiO_2$. The surface composition and oxidation state of the catalyst components and the acidity of the catalysts were examined. IR spectra of the adsorption of NO and their subsequent reactions with hydrogen on these catalysts were also recorded. The variations of conversion and product yield according to the catalyst components in the $H_2$-SCR of NO were discussed in relation to their catalytic roles.

• Korean Journal of Food Science and Technology
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• v.4 no.3
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• pp.200-205
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• 1972

Effects of several different petroleum fractions (LGO, HGO, VGO, Diesel oil, SP(E), HGO-wax, L/M-wax), stepwise addition of calculated amounts of HGO at defined intervals, recycling of spent media on cell growth of Candida tropicalis KIST 351 were studied using $2.5{\ell}$ fermenter by batch process. In addition, continuous cultivation of the yeast was also performed in the light of biomass production using $28{\ell}$ fermenter with LGO. 1) Cell concentration, yield on the basis of gas oil and n-paraffin with the petroleum fractions were in the range of $11{\sim}15g/{\ell}$, $10{\sim}12%$ and $77{\sim}82%$, respectively. 2) By stepwise addition of the gas oil, cell concentration and yield on the oil were increased up to 18.9 g/land 13%, respectively. 3) Spent medium slowed emulsifying ability of hydrocarbon and stimulating effect on the cell growth. Without additional supplementation of $Mg^{++}$ up to 20% of spent medium could be reused, while by adding of the $Mg^{++}$, 50% of medium could be recycled. 4) Optimum condition of continuous cultivation for biomass production was attained at the dilution rate of $D=0.1{\sim}0.125\;hr^{-1}$. Maximum yield coefficient on consumed n-paraffin was 0.94 at $D=0.1\;hr^{-1}$, however, 24% of supplied n-paraffin in the media was not utilized at this dilution rate.