• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.399-404
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• 2010

A hydrogen-producing bacterium (strain ES392) was isolated from pond water located in the Dong-Eui University, Busan, Korea. The cell was long-rod type ($1.4\;{\mu}m$) of about ($0.6\;{\mu}m$) in diameter, and not formed flagellum and spore. Phylogenetic analysis based on the 16S rRNA sequence and biochemical studies indicated that ES392 belonged to the genus Enterobacter sp. The optimum pH and temperature for hydrogen production was 7.5 and $35^{\circ}C$, respectively. The optimization of medium compositions which maximize hydrogen production from Enterobacter sp. ES392 was determined. As a result, the maximum hydrogen production was obtained under the conditions of 4% (w/v) sucrose, 0.5% (w/v) yeast extract and 50 mM potassium phosphate buffer (pH 7.5). Under batch culture conditions, the maximal hydrogen production and yield were obtained as 3481 mL/L and 1.33 mol/mol sucrose, respectively.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.400-406
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• 2012

To improve the hydrogen yield from biological fermentation of organic wastewater, a co-culture system of dark- and photo-fermentation bacteria was investigated. In a pure-culture system of the dark-fermentation bacterium Clostridium butyricum, a pH of 6.25 was found to be optimal, resulting in a hydrogen production rate of 18.7 ml-$H_2/l/h$. On the other hand, the photosynthetic bacterium Rhodobacter sphaeroides could produce the most hydrogen at 1.81mol-$H_2/mol$-glucose at pH 7.0. The maximum specific growth rate of R. sphaeroides was determined to be 2.93 $h^{-1}$ when acetic acid was used as the carbon source, a result that was significantly higher than that obtained using either glucose or a mixture of volatile fatty acids (VFAs). Acetic acid best supported R. sphaeroides cell growth but not hydrogen production. In the co-culture system with glucose, hydrogen could be steadily produced without any lag phase. There were distinguishable inflection points in a plot of accumulated hydrogen over time, resulting from the dynamic production or consumption of VFAs by the interaction between the dark- and photo-fermentation bacteria. Lastly, the hydrogen production rate of a repeated fed-batch run was 15.9 ml-$H_2/l/h$, which was achievable in a sustainable manner.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.983-989
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• 2008

Human insulin is a hormone well-known to regulate the blood glucose level. Recombinant preproinsulin, a precursor of authentic insulin, is typically produced in E. coli as an inactive inclusion body, the solubilization of which needs the addition of reducing agents such as $\beta$-mercaptoethanol. To make authentic insulin, recombinant preproinsulin is modified enzymatically by trypsin and carboxypeptidase B. The effects of $\beta$-mercaptoethanol on the formation of human insulin derivatives were investigated in the enzymatic modification by using commercially available human proinsulin as a substrate. Addition of 1 mM $\beta$-mercaptoethanol induced the formation of various insulin derivatives. Among them, the second major one, impurity 3, was found to be identical to the insulin B chain fragment from $Phe_1$ to $Glu_{21}$. Minimization of the formation of insulin derivatives and concomitant improvement of the production yield of human insulin were achieved by the addition of hydrogen peroxide. Hydrogen peroxide bound with $\beta$-mercaptoethanol and thereby reduced the negative effects of $\beta$-mercaptoethanol considerably. Elimination of the impurity 3 and other derivatives by the addition of over 10 mM hydrogen peroxide in the presence of $\beta$-mercaptoethanolled to a 1.3-fold increase in the recovery efficiency of insulin, compared with those for the case without hydrogen peroxide. The positive effects of hydrogen peroxide were also confirmed with recombinant human preproinsulin expressed in recombinant E. coli as an inclusion body.

• Journal of Energy Engineering
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• v.2 no.1
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• pp.75-82
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• 1993

A 50 ㎾ phosphoric acid fuel cell(PAFC) system using natural gas was simulated for steady state with the commercial software, ASPEN PLUS. The USER block and the FORTRAN block were prepared to simulate the cell. The changes of hydrogen yield according to the variation of several operating conditions were examined and the operating conditions to maximize hydrogen yield were obtained. The simulation results agree with the real data, which can be used to prepare the basic process data and the optimal conditions for the domestic commercial fuel cell system. H$_2$utilization rate over 50% should be maintained to achieve the efficiency of the conventional electricity generation. Energy consumption can be reduced by utilizing the heat released from the reformer and the cell which are operated at high temperatures.

• Food Science and Preservation
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• v.9 no.1
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• pp.97-101
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• 2002

Antimicrobial and antioxidative activities of various solvent extracts from different parts of the loquat were investigated to process it as the functional food. The extraction yield showed higher in butanol fraction of 4.95% in peel and 4.42% in seed than others, but water fraction showed high extraction yield of 3.89% in leafs 23.6% in the seedless fruit and 21.1% in fresh, In the antimicrobial activity test, ethyl acetate fraction that leaf and fruit excluded seed inhibited higher 19, 15 mm and 16, 15 m in clear zone far Staphylococcus aureus and Escherichia coli in each. Ethyl acetate fraction that extracted from a series of polar and nonpolar solvent fractionation of methanol extracts showed better results in the hydrogen donating activity of 82% in leaf, 74% in seedless fruit, 68% in seed, 52% in peel and 30% in fresh.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.232-238
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• 2021

The development of a low cost catalyst with high performance and small amount of carbon deposition on catalyst from toluene steam reforming were investigated by using coal ash as a support material. Ni-loaded coal ash catalyst showed similar catalytic activity for toluene steam reforming compared with the Ni/Al2O3. At 800 ℃, the toluene conversion was 77% for Ni/TAL, 68% for Ni/KPU and 78% for Ni/Al2O3. Ni/TAL showed similar toluene conversion to Ni/Al2O3. However, Ni/KPU produced higher hydrogen yield at relatively lower toluene conversion. Ni/KPU catalyst showed a remarkable ability of suppressing the carbon deposition. The difference in coke deposition and hydrogen yield is due to the composition of KPU ash (Ca and Fe) which increase coke resistance and water gas shift reaction. This study suggests that coal ash catalysts have great potential for the application in the steam reforming of biomass tar.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.55-61
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• 2006

신규 $Nb_2Zr_6O_{17-x}N_x$ 광촉매를 고상합성법처리(solid state synthesis) 후 암모니아가스($NH_3$)에 의한 기상처리법(ammonolysis)으로 합성하였다. 합성된 신규 광촉매 및 이를 다시 Pt 및 $RuO_2$를 도핑 하여 $H_2S$를 광분해하여 수소를 발생 실험을 수행하였다. 이 신규 oxynitrid계 광촉매는 가시광하에서 $H_2S$를 광분해하여 수소를 발생하는(Quantum yield = 13.5 %) 우수한 광촉매 활성을 보여주었다.

• Journal of the Korean Society of Safety
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• v.23 no.1
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• pp.1-11
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• 2008

In this study, small punch test and tensile test were performed with specimens directly machined from an ASTM A53 grade B carbon steel pipe at which an explosion accident was occurred in the Heavy Oil Unit. Main damage mechanism of the pipe was known as a high temperature hydrogen attack(HTHA). Effects of HTHA on the mechanical strength change of the A53B steel were studied in detail. Small punch test results have showed that maximum reaction forces, SP energy and ductility were decreased at hydrogen attacked part of the pipe compared with sound part of the pipe. Yield strength and tensile ultimate strength were calculated with the obtained small punch test curve results using different methods and compared the estimation methods. Small punch test simulation has been also performed with the finite element method and then mechanical strength, equivalent strain and fracture toughness were calculated with the obtained numerical analysis results. It was shown that the fracture toughness data calculated from small punch equivalent energy obtained by the finite element analysis for SP test was very low at the hydrogen attacked part.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.238-243
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• 2012

The purpose of this study is to search the temperature-rise time conditions for adequate reforming temperature region of hydrogen generation system. And we measured theexhaust gas at the exit of that system in order to know the combustion state of hydrogen generation system's combustor. We found the optimum condition of heat supply and temperature-rise time at well burned state. And the results were nearly same when the reactants were entered to each reactors. We will further consider the effects of temperature change near the exothermic reactors and find out hydrogen yield through reforming experiment.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.158.2-158.2
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• 2011

DME is acronym of dimethyl ether, which is spotlighted as an ideal fuel to produce hydrogen due to its high hydrogen/carbon ratio, high energy density and easiness to carry. In this research, we calculated thermodynamic hydrogen (or syngas) yield from DME autothermal reforming and compared to other fuels. The reforming efficiency was about 80% above $700^{\circ}C$. Lower OCR has higher reforming efficiency but, it requires additional heat supply since the reactions are endothermic. SCR has no significant effect on the reforming efficiency. The optimized condition is $700^{\circ}C$, SCR 1.5, OCR 0.45 without additional heat supply. Comparing to other commercial gaseous fuels (methane and propane), DME has higher selectivity of $H_2O$ and $CO_2$ than the others due to the oxygen atom in the molecule. To apply DME autothermal reforming to real system, a proper catalyst is required. Therefore, it is performed the experiment comparing various novel metal catalysts based on CGO. Experiments were performed at calculated condition. The composition of product was measured and reforming efficiency was calculated. The catalysts have similar efficiency at high temperature(${\sim}800^{\circ}C$) but, CGO-Ru has the highest efficiency at low temperature ($600^{\circ}C$).