• Journal of Energy Engineering
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• v.11 no.2
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• pp.81-89
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• 2002

IGCC (Integrated Coal Gasification Combined Cycle) is a technology that generates electric power using coal gasification and gasified fuel. Carbon conversion value of IGCC is higher and the influence on the environment is lower than the pulverized coal power plant. Especially, in the nations where the weight of fossil fuel for power generation is remarkably high like in Korea, IGCC stands out as an alternative plan to cope with sudden limitation for the emissions. In this paper, system design study for the commercial IGCC system which the introduction is imminent to Korea was performed. Two cases of entrained gasification process are adapted, one is FHR(full heat recovery) type IGCC system for high efficiency and the other is Quench type IGCC system for low cost. System simulations using common codes like AspenPlus were performed for each system. In the case of Quench system, system option study and sensitivity analysis of the air extraction rate was performed. Thermal performance result for the FHR system is 42.6% (HHV, Net) and for the quench system is 40% (HHV, net) when 75% air is extracted.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.178-185
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• 2006

This paper investigates the steady-state combustion characteristics of the Homogeneous charge compression ignition(HCCI) engine with variable valve timing(VVT) and dimethyl ether(DME) direct injection, to find out its benefits in exhaust gas emissions. HCCI combustion is an attractive way to lower carbon dioxide($CO_2$), nitrogen oxides(NOx) emission and to allow higher fuel conversion efficiency. However, HCCI engine has inherent problem of narrow operating range at high load due to high in-cylinder peak pressure and consequent noise. To overcome this problem, the control of combustion start and heat release rate is required. It is difficult to control the start of combustion because HCCI combustion phase is closely linked to chemical reaction during a compression stroke. The combination of VVT and DME direct injection was chosen as the most promising strategy to control the HCCI combustion phase in this study. Regular gasoline was injected at intake port as main fuel, while small amount of DME was also injected directly into the cylinder as an ignition promoter for the control of ignition timing. Different intake valve timings were tested for combustion phase control. Regular gasoline was tested for HCCI operation and emission characteristics with various engine conditions. With HCCI operation, ignition delay and rapid burning angle were successfully controlled by the amount of internal EGR that was determined with VVT. For best IMEP and low HC emission, DME should be injected during early compression stroke. IMEP was mainly affected by the DME injection timing, and quantities of fuel DME and gasoline. HC emission was mainly affected by both the amount of gasoline and the DME injection timing. NOx emission was lower than conventional SI engine at gasoline lean region. However, NOx emission was similar to that in the conventional SI engine at gasoline rich region. CO emission was affected by the amount of gasoline and DME.

• Korean Journal of Environmental Agriculture
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• v.35 no.2
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• pp.128-136
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• 2016

BACKGROUND: Hydrothermal carbonization reaction is the thermo-chemical energy conversion technology for producing the solid fuel of high carbon density from organic wastes. The hydrothermal carbonization reaction is accompanied by the thermal hydrolysis reaction which converse particulate organic matters to soluble forms (hydro-thermal hydrolysate). Recently, hydrothermal carbonization is adopted as a pre-treatment technology to improve anaerobic digestion efficiency. This research was carried out to assess the effects of hydro-thermal reaction temperature on the methane potential and anaerobic biodegradability in the thermal hydrolysate of organic sludge generating from the wastewater treatment plant of poultry slaughterhouse .METHODS AND RESULTS: Wastewater treatment sludge cake of poultry slaughterhouse was treated in the different hydro-thermal reaction temperature of 170, 180, 190, 200, and 220℃. Theoretical and experimental methane potential for each hydro-thermal hydrolysate were measured. Then, the organic substance fractions of hydro-thermal hydrolysate were characterized by the optimization of the parallel first order kinetics model. The increase of hydro-thermal reaction temperature from 170℃ to 220℃ caused the enhancement of hydrolysis efficiency. And the methane potential showed the maximum value of 0.381 Nm³ kg^-1-VS_added in the hydro-thermal reaction temperature of 190℃. Biodegradable volatile solid(VSB) content have accounted for 66.41% in 170℃, 72.70% in 180℃, 79.78% in 190℃, 67.05% in 200℃, and 70.31% in 220℃, respectively. The persistent VS content increased with hydro-thermal reaction temperature, which occupied 0.18% for 170℃, 2.96% for 180℃, 6.32% for 190℃, 17.52% for 200℃, and 20.55% for 220℃.CONCLUSION: Biodegradable volatile solid showed the highest amount in the hydro-thermal reaction temperature of 190℃, and then, the optimum hydro-thermal reaction temperature for organic sludge was assessed as 190℃ in the aspect of the methane production. The rise of hydro-thermal reaction temperature caused increase of persistent organic matter content.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.4
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• pp.49-57
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• 2016

In this study, a thermal hydrolysis technology was used to treat the poultry carcasses that were killed due to Avian Influenza (AI) occurrence, as well as to determine the possibility of fueling for the resultant products. Experimental results showed that the poultry carcasses were liquefied except for sand, and showed the optimum efficiency at $190^{\circ}C$ and operating time of 60 minutes. It has been shown that liquid products obtained after thermal hydrolysis has good conditions for fuel conversion since it had high carbon contents and calorific value, as well as low ash content. In addition, it was possible to operate the thermal hydrolysis facility by using only the waste heat generated in the combustion without injecting the auxiliary fuel, and the exhaust gas generated in the combustion has a small influence on the atmosphere.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.101-109
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• 2010

Efficient L-lactic acid production from Jerusalem artichoke tubers, by Lactobacillus casei G-02, using simultaneous saccharification and fermentation (SSF) in a fed-batch culture, is demonstrated. A kinetic analysis of the SSF revealed that the inulinase activity was subjected to product inhibition, whereas the fermentation activity of G-02 was subjected to substrate inhibition. It was also found that the intracellular NADH oxidase (NOX) activity was enhanced by the citrate metabolism, which dramatically increased the carbon flux of the Embden-Meyerhof-Parnas (EMP) pathway, along with the production of ATP. As a result, when the SSF was carried out at $40^{\circ}C$ after an initial hydrolysis of 1 h and included a sodium citrate supplement of 10 g/l, an L-lactic acid concentration of 141.5 g/l was obtained after 30 h, with a volumetric productivity of 4.7 g/l/h. The conversion efficiency and product yield were 93.6% of the theoretical lactic acid yield and 52.4 g lactic acid/l00 g Jerusalem artichoke flour, respectively. Such a high concentration of lactic acid with a high productivity from Jerusalem artichokes has not been reported previously, making G-02 a potential candidate for the economic production of L-lactic acid from Jerusalem artichokes on a commercial scale.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.117-126
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• 2010

A chitinase (CHT) and a protease (PRO) were purified from the culture supernatant of Serratia sp. TKU017, with shrimp shell as the sole carbon/nitrogen source. The molecular masses of CHT and PRO determined by SDS-PAGE were approximately 65 kDa and 53 kDa, respectively. CHT was inhibited by $Mn^{2+}$ and $Cu^{2+}$, and PRO was inhibited by most tested divalent metals and EDTA. The optimum pH, optimum temperature, pH stability, and thermal stability of CHT and PRO were pH 5, $50^{\circ}C$, pH 5-7, and <$50^{\circ}C$, and pH 9, $40^{\circ}C$, pH 5-11, and <$40^{\circ}C$, respectively. PRO retained 95% of its protease activity in the presence of 0.5 mM SDS. The result demonstrates that PRO is an SDS-resistant protease and probably has a rigid structure. The $4^{th}$-day supernatant showed the strongest antioxidant activity (70%, DPPH scavenging ability) and the highest total phenolic content ($196{\pm}6.2\;{\mu}g$ of gallic acid equiv./ml). Significant associations between the antioxidant potency and the total phenolic content, as well as between the antioxidant potency and free amino groups, were found for the supernatant. With this method, we have shown that shrimp shell wastes can be utilized and it is effective in the production of enzymes and antioxidants, facilitating its potential use in industrial applications and functional foods.

• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.1-7
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• 2000

Bioconversion of fumarate to succinate was anaerobically conduced in a synthetic medium containing glycerol as a hydrogen donor and fumarate as a hydrogen acceptor. We investigated the effects of pH, carbon and nitrogen sources, conversion substrate, and other culture conditions on the production of succinate using a nwely isoloated Enterococcus facalis PKY1. Addition of a variety of carbonates to the medium significantly increasd the rates of production of succinate. The production of succinate and cell growth were relatively satisfactory in the pH range of 7.0-7.6. By using glycerol as a hydrogen donor, high purity succinate was produced with few byproducts. Yeast extract as a sole nitrogen source was the most effective for producing succinalte. As a result, the optimum condition of biconversion was obtained at a medium containing 20g/I glycerol, 50 g/l fumarate, 15 g/l yeast extract, 10 g/l $K_2HPO_4$, 1 g/I NaCl, 50ppm $MgCl_2{\cdot}6H_2O$, 10ppm $FeSo_4{\cdot}7H_2O$, and 5 g/I $Na_2CO_3$ at pH 7.0-7.6. Under the optimum condition, a succinate concentration of 153 g/I was produced in 36 h. The total volumetric production rate and the molar yield of succinate were 4.3 g/l/h and 85%, respectively.

• Korean Journal of Human Ecology
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• v.4 no.1
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• pp.79-92
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• 2001

E. coli transformants EC3, EC4. and EC6. harboring citron oil degrading pathway genes, were co-cultured in M9 media with citron oil as a sole carbon source at 28$^{\circ}C$. Each co-culture(EC3+EC4, EC3+EC6, EC4+EC6 and EC3+EC4+EC6) showed three to four times higher cell growth than each transformant single culture. Microbial conversion products from the co-cultures were determined by GC-MS. Linalool. 4-terpineol and ${\alpha}$-terpineol were the major common products from co-cultures. Various minor products also were detected and important in flavor characteristics of cultures.

• Journal of Korean Society on Water Environment
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• v.32 no.1
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• pp.46-51
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• 2016

In this study, we synthesized a combination of graphene oxide (GO) and titanium dioxide (TiO₂) and confirm that GO can be used for CO₂ photoreduction. TiO₂ exhibited highly efficient combination with other conventional electric charges generated by these paration phenomenon for suppression of hole-electron recombination. This improved the efficiency of CO₂ photoreduction. The synthetic form of GO-TiO₂ used in this study was agraphene sheet surrounded by TiO₂ powder. Efficiency and stability were enhanced by combination of GO and TiO₂. In a CO₂ photoreduction experiment, the highest CO conversion rate was 0.652 μmol/g·h in GO10-TiO₂ (2.3-fold that of pure TiO₂) and the highest CH₄ production rate was 0.037 μmol/g·h in GO0.1-TiO₂ (2.4-fold that of pure TiO₂). GO enhances photocatalytic efficiency by functioning as a support and absorbent, and enabling charge separation. With increasing GO concentration, the CH₄ level decreases to~45% due to decreased transfer of electrons. In this study, TiO₂ together with GO yielded a different result than the normal doping effect and selective CO₂ photoreduction.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.561-566
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• 2008

Gasification plant using petroleum coke for refinery and power generation process is increased from considering petroleum coke as a valuable fuel. In this study, gasification of petroleum coke was performed to utilize petroleum coke and to develop essential technology using 1T/D coal gasification system. In case of petroleum coke gasification, because of lower reactivity, consumption of oxygen is higher than coal gasification. The calorific value of syngas from petroleum coke mixed with coal at a mass ratio of 1:1 shows about $6.7{\sim}7.2MJ/Nm^3$. Although carbon conversion could reach more than 92% according to oxygen amount, cold gas efficiency shows lower value than the case of coal. Therefore, it was shown that complemental study in burner design to atomize slurry droplet is required to elevate gasification performance of petroleum coke which has lower reactivity than coal.