• Clean Technology
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• v.25 no.3
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• pp.245-255
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• 2019

Pressurized oxy-fuel combustion is a promising technology for $CO_2$ capture with a benefit of improving power plant efficiency compared with atmospheric oxy-fuel combustion. Prior to $CO_2$ compression in this process, a flue gas condenser (FGC) is used to remove $H_2O$ while recovering the latent heat. At the same time, the FGC has a potential for high-efficiency removal of $SO_x$ and $NO_x$ by exploiting their good solubility in water. In this study, experiments were carried out in a lab-scale, direct contact FGC under different pressures varying between 1 and 20 bar to evaluate the removal efficiency of $SO_2$ and $NO_x$ for individual gases and their mixture. In the tests for individual gases, 20% and 76% of $NO_x$ was removed at 1 bar and 10 bar, respectively. Even higher removal efficiencies were achieved for $SO_2$, and also these were maintained for longer as the pressure increased. In the tests for $SO_2$ and $NO_x$ mixture, the removal efficiency of $NO_x$ increased from 13% at 1 bar to 56% at 20 bar because of higher solubility at elevated pressures. $SO_2$ in the mixture was initially dissolved almost completely and then increased by 1,219 ppm at 1 bar and by 165 ppm at 20 bar. Overall, the removal efficiency of $SO_2$ and $NO_x$ was increased at elevated pressures, but it was lower in the mixture compared with individual gases at identical conditions because of a lower pH and associated chemical reactions in water.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.255-262
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• 2020

Blended cement with fly ash and bottom ash from Circulating Fluidized Bed Combustor boiler(CFBC) burned at a low temperature, can be high heat of hydration and abnormal setting caused by higher volumn contents of Fe₂O₃, free-CaO, SO₃. In this study, the ground CFBC bottom ash powder mixed with blast furnace slag was used as substitute activator of gypsum and recycled iron slag was produced from mix and pulverized by ball mill to increase the recycling rate. The effect on compressive strength of cements with the mixture of original and hydrated bottom ash mixtures with BFS with small water, respectively, was analyzed, and it was found that the hydrated bottom ash activator was more effective in initial strength development. To improve the initial strength of blended cement, an activator mixed with a blast furnace slag and bottom ash mixing ratio of 5:95 and 10:90, respectively, the slag cement by about 6%, and it was analyzed to develop an initial strength similar to gypsum as a conventional activator.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.376-382
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• 1990

An extracellular cellulase producing bacterium YE-5 was isolated from soil, and identified as a Cellulomonas sp. by its taxonomical characteristics. The maximal activities of avicelase (0.35 units/ml), CMCase (3.18 units/ml), FPase (0.315 units/ml) and $\beta$-glucosidase (0.882 units/ml) were obtained when this strain was cultured for 48 hrs at $30^{\circ}C$ in a medium containing 0.8% (w/v) Solka floc, 0.06010 (wlv) urea, 0.1% (w/v) $K_2HP0_4$, 0.1% (w/v) $MgS0_4.7H2_0$, 0.2% (w/v) bacto peptone, 0.2% (w/v) yeast extract and pH 6.5. The cellulase was purified by ammonium sulfate fractionation, DEAE-Sepharose column chromatography and Sephadex 6-100 column chromatography from culture filtrate of Cellulomonus sp. YE-5. The molecular weights of purified avieelase, CMCase I, and CMCase II were estimated to be about 95,000 ~ 105,000, 46,000 ~ 47,000 and 120,000 ~ 125,000, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.349-349
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• 2012

박막형 GaAs 계 III-V 태양전지는 ELO (Epitaxy Lift-off) 기술에 의하여 기판으로부터 분리되어 얻어질 수 있다. 지금까지 이 기술에 대해 개발된 결과에 의하면 박막 III-V 태양전지의 효율이 기존 기판 기반의 태양전지 효율과 비슷한 수준을 얻고 있으며, 기판의 재활용, 플렉서블, 및 신축성 태양전지로의 적용분야 등의 보고들도 발표되고 있어 실리콘 태양전지가 접근하기 힘든 특정한 응용분야로의 가능성을 밝게 해주고 있다. 그러나, 이 ELO방식에 의한 박막형 III-V 태양전지가 실질적으로 상업화 되기 위해서는 생산 수율의 개선 및 기판 재활용 시의 저손실 등 해결해야 할 당면과제들이 놓여 있다. 기판재활용의 가능성을 위해 아직까지 발표된 셀의 크기는 $2{\times}2mm^2$ 이하이며, 보다 넓은 셀에 대하여 기판재활용 방식으로 재생된 효율을 갖는 III-V 박막 태양전지는 보고된 바 없다. 본 연구에서는, $1{\times}1mm^2$, $2{\times}2mm^2$, 그리고 $5{\times}5mm^2$에 대하여 ELO 에 의한 박막 태양전지를 제작해 보고, 보다 넓은 면의 박막 태양전지를 효율적으로 제작하기 위한 방법을 연구하고자 한다. 또한, 이 셀들을 유연한 PDMS transfer에 부착하여 플렉서블 태양전지로의 가능성에 대해서도 기술하고자 한다. 사용된 박막 태양전지 구조는 한국광기술원에서 제작한 22% GaAs 단일 접합 태양전지와 같은 구조로 되어 있으며, 희생층으로는 AlGaAs 층을 사용하였고, ELO을 위한 에칭용 홀 지름은 5, 10, 그리고 $20{\mu}m$에 대하여 조사하였다.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.142-150
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• 2002

Streptomyces polychromogenes IFO 13072 was used as a strain producing cholesterol oxidase(EC 1.1.3.6). The conditions of cholesterol oxidase production were investigated. The optimum composition of medium for production of the enzyme was 1% dextrin, 0.5% casamino acid, 0.1% $KH_2$PO$_4$, 0.5% $NaNO_3$ and 0.05% $MgSO_4$(pH 7.3). The enzyme was purified specifically by cholesterol affinity column chromatography with a yield of 23.2%. The purified enzyme showed a single polypeptide on SDS-PAGE and the molecular weight was estimated about 52,000 daltons. The optimum pH and temperature of the cholesterol oxidase were pH 7.0 and $37^{\circ}C$, respectively. The enzyme was stable in the range of pH 6.0~7.0 and $25^{\circ}C$. The cholesterol oxidase activity was strongly inhibited by metal ions such as $Hg^{2＋}$ and $Fe^{2＋}$ and inhibitors such as dithiothreitol, mercaptoethanol and isonicotinic acid. The Michaelis constant(Km) for the cholesterol was found to be 25 mM by Lineweaver-Burk plot analysis.

• Applied Biological Chemistry
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• v.41 no.6
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• pp.465-470
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• 1998

For the need of bio-degradable flocculant in stage of wastewater treatment, some cultural conditions of bioflocculant production were optimized with Aeromonas hydrophila KH-54. About 260 strains of type culture and bacteria isolated from marsh, pond, activated sludge, etc were examined for their ability to flocculate kaolin particles and swine wastewater. Among them, KH-54 showed the highest flocculating activity and was identified as Aeromonas hydrophila according to the cultural, morphological and physiological properties. The maximum production of the flocculant secreted by Aeromonas hydrophila KH-54 was observed in culture medium containing 2.0% mannitol, 0.05% ammonium chloride, 0.02% potassium phosphate dibasic, 0.01% $MgSO_4{\cdot}7H_2O$ and 0.05% yeast extract at initial pH 7.0 when cultured on rotary shaker controlled at $25^{\circ}C$ and 150 rpm. Under the optimized condition, the flocculating ability reached to 770 units/ml of kaolin flocculating activity and 81% of NTU removal efficiency against swine wastewater after 4 days cultivation. The bioflocculant was also effective on various organic wastewaters other than swine wastewater, showing NTU removal rate ranging from 92% to 34%.

• Microbiology and Biotechnology Letters
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• v.8 no.2
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• pp.119-123
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• 1980

Culture conditions of yellow pigment in Monascus sp. were studied. According to the studies of culture conditions optimum condition was found to be pH 4.5, 3 days of incubation with 3% of sucrose as carbon source, 0.2 ％ of yeast extract as nitrogen source and 75m1 of medium in the 500m1 erlenmyer flask by rotary shaking (rpm 180) at 180 r.p.m. Effective levels of inorganic compounds were found to be 0.25 % of potassium phosphate monobasic and 0.1 ％ of Magnesium sulfate.

• Applied Biological Chemistry
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• v.31 no.4
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• pp.356-360
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• 1988

The alkaline protease producing bacteria isolated from soil and identified as Bacillus subtilis. The optimum medium for alkaline protease production from the microorganism was as follows; soluble starch, 1.5% ; proteose peptone, 0.5% ; $K_2HPO_4$, 0.1% ; $MgSO_4{\cdot}7H_2O$, 0.02% and sodium carbonate, 1.0%. The optimum temperature for alkaline protease production was $35^{\circ}C$, and the initial pH of medium was pH 10.5. The alkaline protease activity was about 2,300 U per ml of culture broth by Casein-Folin Method. A 9.2 fold purification of alkaline protease was obtained from culture broth. The recovery was 14% and purified enzyme was identified as single band, and its molecular weight was about 19,000. The optimum temperature for enzyme reaction was $70^{\circ}C$, and optimum pH was 12. The activity of purified enzyme was inhibited by metal ion ($Fe^{++}$), and Phenylmethylsulfonyl Fluoride, a serine protease inhibitor.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.458-463
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• 2005

Considering the characteristics of a filtration bio-reactor equipped with a mesh filter module which can effectively maintain high concentration of biomass and enhanced solid-liquid separation performance, the hybrid process of filtration bio-reactor combined with coagulation was investigated to get improved filtration characteristics as well as water quality in this work. Two bio-reactors (Run-1 & Run-2) were operated under the following conditions: working volume of 25 L, continuous loading of a synthetic wastewater (BOD: 200 mg/L, T-N: 50 mg/L, T-P: 5 mg/L), where an appropriate amount of alum ($Al_2(SO_4)_3{\cdot}18H_2O$) was added once a day into the reactor (Run-2). In the system without using a alum (Run-1), the clogging of mesh filter module was observed two times through 85 days of whole operation. Meanwhile, the filter module did not clog even at higher MLSS concentration (6,000~12,000 mg/L) and the stable filtration (0.7 mid) was continued in the case of using a alum. Due to the stable formation of cake layers, BOD and SS were shown below 6 and 3 mg/L, respectively. T-P and pH of the effluent were changed because of the intermittent addition of the alum. In the case of Al/P=2.5, the average T-P removal efficiency per day was 85.2% and the average T-P concentration of the effluent was 0.3 mg/L. However, the removal efficiency of phosphate was influenced by pH in the reactor.

• KSBB Journal
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• v.13 no.1
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• pp.58-64
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• 1998

An extracellular lipid-producing strain, Rhodotorula glutinis K-501, was isolated from soil. The extracellular lipid produced by the cell was found to have good and stable emulsifying activity. Factors affecting the extracellular lipid production were studied to optimize culture conditions for maximum production. Sucrose and ammonium sulfate were selected as best carbon and nitrogen sources, respectively because they gave the highest concentration of product. The optimum C/N ratio was 50. Optimum concentrations of $KH_2PO_4,\; Na_2HPO_4, \;and\; CaCl_2 $were 3.5, 1.0, 0.75, and 0.1g/L, respectively. The optimum temperature and initial pH were determined as $22^{\circ}C$ and 7.0, respectively. When the batch culture was conducted with a sucrose concentration of 60g/L under the optimized conditions, extracellular lipid was produced to a concentration of 8.1g/L with a high production yield of 51.9% based on dry cell weight.