• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.484-490
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• 2008

Electrospun of PVP (polyvinylpyrrolidone) ultra fine fibers were fabricated using various solvents including methanol, ethanol, 2-propanol, butanol, acetone, methylene chloride, and DMF, which possess different properties such as boiling point, dielectric constant, and dipole moment. Electrospun PVP fiber was influenced by viscosity, conductivity, and surface tension of spinning solution. Therefore, the electrospun PVP fiber was successfully prepared under critical conditions of viscosity > $0.114kg/m{\cdot}s$, conductivity > 1.02 mS/m, surface tension < 30.0 mN/m. In case of an ethanol solvent system, average diameter of PVP fiber increased from 1701 nm to 5454 nm as increased the applied voltage from 10 kV to 20 kV.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.528-534
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• 2006

The purpose of this paper is to investigate the optimal operating condition for the hydrogen production by biogas reforming using the plasmatron induced thermal plasma. The component ratio of biogas($CH_4/CO_2$) produced by anaerobic digestion reactor were 1.03, 1.28, 2.12, respectively. And the reforming experiment was performed. To improve hydrogen production and methane conversion rates, parametric screening studies were conducted, in which there are the variations of biogas flow ratio(biogas/TFR: total flow rate), vapor flow ratio($H_2O/TFR$: total flow rate) and input power. When the variations of biogas flow ratio, vapor flow ratio and input power were 0.32~0.37, 0.36~0.42, and 8 kW, respectively, the methance conversion reached its optimal operating condition, or 81.3~89.6%. Under the condition mentioned above, the wet basis concentrations of the synthetic gas were H2 27.11~40.23%, CO 14.31~18.61%. The hydrogen yield and the conversion rate of energy were 40.6~61%, 30.5~54.4%, respectively, the ratio of hydrogen to carbon monoxide($H_2/CO$) was 1.89~2.16.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1384-1389
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• 2023

This work aimed to evaluate the feasibility of biohydrogen production from Barley Straw and Miscanthus. The primary obstacle in plant biomass decomposition is the recalcitrance of the biomass itself. Plant cell walls consist of cellulose, hemicellulose, and lignin, which make the plant robust to decomposition. However, the hyperthermophilic bacterium, Caldicellulosiruptor bescii, can efficiently utilize lignocellulosic feedstocks (Barley Straw and Miscanthus) for energy production, and C. bescii can now be metabolically engineered or isolated to produce more hydrogen and other biochemicals. In the present study, two strains, C. bescii JWCB001 (wild-type) and JWCB018 (ΔpyrFA Δldh ΔcbeI), were tested for their ability to increase hydrogen production from Barley Straw and Miscanthus. The JWCB018 resulted in a redirection of carbon and electron (carried by NADH) flow from lactate production to acetate and hydrogen production. JWCB018 produced ~54% and 63% more acetate and hydrogen from Barley Straw, respectively than its wild-type counterpart, JWCB001. Also, 25% more hydrogen from Miscanthus was obtained by the JWCB018 strain with 33% more acetate relative to JWCB001. It was supported that the engineered C. bescii, such as the JWCB018, can be a parental strain to get more hydrogen and other biochemicals from various biomass.

• 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.22 no.5
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• pp.668-673
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• 2012

Biohydrogen production from organic wastewater by anaerobically activated sludge fermentation has already been extensively investigated, and it is known that hydrogen can be produced by glucose fermentation through three metabolic pathways, including the oxidative decarboxylation of pyruvic acid to acetyl-CoA, oxidation of NADH to $NAD^+$, and acetogenesis by hydrogen-producing acetogens. However, the exact or dominant pathways of hydrogen production in the anaerobically activated sludge fermentation process have not yet been identified. Thus, a continuous stirred-tank reactor (CSTR) was introduced and a specifically acclimated acidogenic fermentative microflora obtained under certain operation conditions. The hydrogen production activity and potential hydrogen-producing pathways in the acidogenic fermentative microflora were then investigated using batch cultures in Erlenmeyer flasks with a working volume of 500 ml. Based on an initial glucose concentration of 10 g/l, pH 6.0, and a biomass of 1.01 g/l of a mixed liquid volatile suspended solid (MLVSS), 247.7 ml of hydrogen was obtained after a 68 h cultivation period at $35{\pm}1^{\circ}C$. Further tests indicated that 69% of the hydrogen was produced from the oxidative decarboxylation of pyruvic acid, whereas the remaining 31% was from the oxidation of NADH to $NAD^+$. There were no hydrogen-producing acetogens or they were unable to work effectively in the anaerobically activated sludge with a hydraulic retention time (HRT) of less than 8 h.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.949-954
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• 2006

The purpose of this paper is to develop water jet plasma reactor and investigate the optimal condition of the syngas production by reforming of hydrocarbon fuel. Fuel used was propane and plasma was generated by arc discharge on water jet surface. Discharge slipping over the water surface has a number of advantages such as a source of short-wave and UV radiation, and it can be used for biological and chemical purification of water. Parametric screening studies were conducted, in which there were the variations of power ($0.18{\sim}0.74$ kW), water jet flow rate($38.4{\sim}65.6$ mL/min), electrode gap($5{\sim}15$ mm) and treatment time($2{\sim}20$ min). When the variations were 0.4 kW, 53.9 mL/min, 10 mm and 20 min respectively, result of maximum $H_2$ concentration was 61.6%, intermediates concentration were 6.1% and propane conversion rate was 99.8%.

• KSBB Journal
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• v.23 no.1
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• pp.83-89
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• 2008

Food wastewater derived from the three-stage methane fermentation system developed in this lab contained high concentration organic substances. The organic wastewater should be treated through advanced wastewater treatment system to satisfy the "Permissible Pollutant Discharge Standard of Korea". In order to treat the organic wastewater efficiently, several optimum operation conditions of a modified $UV/TiO_{2}$ photocatalytic system have been investigated. In the first process, wastewater was pre-treated with $FeCl_{3}$. The optimum pH and coagulant concentration were 4.0 and 2000mg/L, respectively. Through this process, 52.6% of CODcr was removed. The second process was $UV-TiO_{2}$ photocatalytic reaction. The optimum operation conditions for the system were as follows: UV lamp wavelength, 254 nm; wastewater temperature, $40^{\circ}C$; pH 8.0; and air flow rate, 40L/min, respectively. Through the above two combined processes, 69.7% of T-N and 70.9% of CODcr contained in the wastewater were removed.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.239-244
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• 2007

For the simultaneous methane recovery and $CO_2$-stripping, we have been developed dual vent auto circulation bubble lift column reactor, and evaluate optimum conditions for monoethanolamine (MEA) solutions as a $CO_2$ absorbent. At the 5 wt% MEA solution, we investigated the pH change during $CO_2$-stripping and absorption reaction, $CO_2$-stripping rate with reaction time, methane recovery efficiency for various inflow rates of air, $CO_2$-stripping rate for flow liquid over flow height, and $CO_2$-stripping dependency on the temperature of absolvent solutions. The suggested optimum conditions for $CO_2$ recovery with MEA in the dual vent auto circulation bubble lift column reactor were 40 mm over flow liquid height, 1.5 L/min of air inflow rate, and $25^{\circ}C$ of absorbent solution temperature.

• KSBB Journal
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• v.22 no.1
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• pp.58-61
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• 2007

A Insecticidal effect of Ginkgo biloba leaves extract was conducted for Dermatophagoides pteronyssinus as a predominant species in korea. D. pteronyssinus has been cultured in constant temperature and humidity chamber at the 25$^{\circ}C$ and 75% of relative humidity. The mortality of mites was determined by counting the dead bodies for every hour within 48 hours with pin hall microscope after treated by Ginkgo biloba leaves extract spreaded on 0.1 g of mass cultured media. The sequence of mortality for D. pteronyssinus are as follows, bilobalide was 91.6%, 80$^{\circ}C$ water extract was 82.8%, second water fraction was 75%, ethyl acetate fraction from 80$^{\circ}C$ water fraction was 73%, first ethyl acetate fraction from 80$^{\circ}C$ water extract was 69.4%, putaltrin was 65%, distilled water was 58%, methanol extract was 57.8%, Ginkgolide-A was 57.1 %, ethyl acetate fraction of 80$^{\circ}C$ water extract was 55%, respectively. From the these results we conclude that the bilobalide is the most effective component in the Ginkgo biloba leaves extract having insecticidal effect on house dust mite.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.1
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• pp.57-63
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• 2011

Development of alternative energy is needed as the fossil is started to be exhausted. This alternative energy should be environmental friendly and renewable. Currently, the alternative energy which gets the most attraction is hydrogen. Hydrogen can be produced by a number of different processes. Among those methods, hydrogen production in biological way is considered as the most environmental friendly method. However, productivity of biological hydrogen production is not good enough to be commercialized yet. Thus, many researchers are trying to improve productivity and yield of biohydrogen production. Here, progress in the diverse developmental approaches on biological hydrogen production, is reviewed.