• Asian-Australasian Journal of Animal Sciences
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• v.22 no.6
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• pp.849-856
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• 2009

In this study, dietary supplementations of Korean Meju, fermented soybean meal (F-SBM) by Aspergillus oryzae, and A. oryzae itself were evaluated on growth performance, feed utilization, immune responses and phosphorus availability in juvenile parrot fish, a marine aquaculture fish species. Four isonitrogenous and isocaloric diets were formulated to contain 8% soybean meal (control diet), 4% Meju (50% soybean meal was replaced by Meju), 4% F-SBM (50% soybean meal was replaced by F-SBM), or 0.08% A. oryzae itself. One of the four experimental diets was fed to triplicate groups of fish for 8 weeks. At the end of the feeding trial, no significant differences were found in growth performances and feed utilization. Red blood cell counts in the fish fed the A. oryzae diet were significantly higher than that of fish fed the control diet. The antioxidant activity in Meju diet was significantly higher than that of the control and A. oryzae diets. Fish fed Meju and F-SBM diets showed numerically higher antioxidant activity of serum compared to that of fish fed the control diet, even though it was not significant. Liver superoxide dismutase activity of fish fed the test diets was significantly higher than that of fish fed the control diet. The apparent digestibility coefficients of protein of fish fed all the diets were not significantly different. Phosphorus absorption was numerically increased in fish fed F-SBM and A. oryzae diets compared to that of fish fed the control diet. This study indicates that the fermentation process of soybean meal does not impair growth performance and feed utilization in parrot fish. The fermentation process could enhance the availability of phosphorus in soybean meal and non-specific immune responses of parrot fish.

• Environmental Mutagens and Carcinogens
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• v.18 no.1
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• pp.26-31
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• 1998

Antimutagenic activity of Saururus chinesis (Lour.) Bail was investigated for food-borne mutagens using S. typhimurium TA98. Methanol extract from Saururus Chinesis (Lour.) Bail was fractionated into hexane, chloroform, ethylacetate and butanol fractions, followed by determination of antimutagenic activity for food-borne mutagenic heterogenic amines (HCA). The hexane fraction exhibited a strong antimutagenic activity for 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQ), 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 3-amino-1-methyl-5H-pyroid[4,3-b]indole acetate (Trp-2-A); however its fraction rather enhanced the bacterial mutagenicity of 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinozaline (4,8-diMeIQx) and 2-amino-3,7,8-trimethyl-3H-imidazo[4,5-f]quinoxline (7,8-diMeIQx). Active principle in the fraction was found to be two major compounds (${\gamma}$-crene B and epi-bicyclosesquiphellandrane) and 6 minor compounds (${\delta}$-caryophyllene, ${\gamma}$-elemene, ${\beta}$-cabebene, ${\delta}$-cadinene, ${\delta}$-selinene, and patchoulene). Modulation effect for the mutagenic activity of the food-borne mutagenic HCA by the fraction might be derived from a cumulative effect of each individual compounds. Hence, this hexane fraction might be use to reduce the production of mutagenic HCA during cooking process of protein-rich foods.

• Journal of the Korean Ceramic Society
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• v.32 no.6
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• pp.719-725
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• 1995

ZST powders were synthesized by coprecipitation of (Zr4+, Ti4+)-hydroxide in the presence of SnO2 particles. Zn(NO3)2 was used as a sintering additive, and according to the adding sequence, sintering and dielectric properties were investigated. Sintered densities of ZST prepared by adding Zn(NO3)2 before calcination were a little higher than those added after calcination, and dielectric properties of the specimen added by Zn(NO3)2 after calcination were better (sintered at 125$0^{\circ}C$/2 h ; Q$\times$f(GHz)=49, 000, $\varepsilon$r=41) than before calcination (Q$\times$f(GHz)=42, 000, $\varepsilon$r=39.5). Through the observation of TEM, it was identified that the cause was due to the difference of the degree of Zn2+ diffusion into grains. With increasing sintering time from 2 to 8 hrs, grain size was doubled and dielectric properties were somewhat deteriorated.

• Ceramist
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• v.22 no.4
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• pp.429-451
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• 2019

Quartz glass is a key material for making semiconductor process components because of its purity, low thermal expansion, high UV transmittance and relatively low cost. Domestic quartz glass has a market worth about 500 billion won in 2018, and the market power of Japanese materials is very high. Quartz glass for semiconductor process can be divided into general process and exposure. For general process, molten quartz glass is mainly used, but synthetic quartz glass with higher purity is preferred. Synthetic quartz glass is used as the photomask for the exposure process. Recently, as semiconductors started the sub-nm process, the transition from the transmission type using ArF ultraviolet (194 nm) to the reflection type using EUV ultraviolet (13.5 nm) began. Therefore, the characteristics required for the synthetic quartz glass substrates used so far are also rapidly changing. This article summarizes the current technical trends of quartz glass and recent technical issues. Lastly, the present situation and development possibility of quartz glass technology in Korea were diagnosed.

• Korean Journal of Materials Research
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• v.21 no.11
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• pp.604-610
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• 2011

The effect of $BaF_2$ flux in $Y_3Al_5O_{12}:Ce^{3+}$(YAG:Ce) formation was investigated. Phase transformation of $Y_3Al_5O_{12}$(YAG) was characterized by using XRD, SEM, and TEM-EDS, and it was revealed that the sequential formation of the $Y_4Al_2O_9$(YAM), $YAlO_3$(YAP) and $Y_3Al_5O_{12}$(YAG) in the temperature range of 1000-1500$^{\circ}C$. Single phase of YAG was revealed from 1300$^{\circ}C$. In order to find out the effect of $BaF_2$ flux, three modeling experiments between starting materials (1.5$Al_2O_3$-2.5$Y_2O_3$, $Y_2O_3$-$BaF_2$, and $Al_2O_3$-$BaF_2$) were done. These modeling experiments showed that the nucleation process occurs via the dissolution-precipitation mechanism, whereas the grain growth process is controlled via the liquid-phase diffusion route. YAG:Ce phosphor particles prepared using a proposed technique exhibit a spherical shape, high crystallinity, and an emission intensity. According to the experimental results conducted in this investigation, 5% of $BaF_2$ was the best concentration for physical, chemical and optical properties of $Y_3Al_5O_{12}:Ce^{3+}$(YAG:Ce) that is approximately 10-15% greater than that of commercial phosphor powder.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.825-831
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• 2012

The retrofitting of a thickening unit process is widely considered in municipal wastewater treatment plants in Korea to enhance the anaerobic digestion efficiency. The authors examined the effect of feed concentration (2-34.1 g VS/L) and feed to microorganism (F/M) ratio (0.50-1.35 g VS/g VS) on anaerobic batch digestion of sewage sludge. Methane yield over 90 mL $CH_4/g$ $VS_{feed}$ was found at a feed concentration in the range of 12-26 g VS/L and a F/M ratio below 0.6 g VS/g VS. A high F/M ratio decreased methane yield and rate with oragnic acid accumulation. As sudden increase of sewage sludge concentration prior to anaerobic digestion would jeopardize the digester performance due to the rasied F/M ratio, gradual increase of the sludge feed concentration or an additional biomass retention in the digester is recommended.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.371-379
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• 2005

Adsorption equilibria of the gases $H_2$, $CH_4$, and $C_2H_4$ and their binary mixtures on activated carbon (Calgon co.) have been measured by static volumetric method in the pressure range of 0 to 18 atm at temperatures of 293.15, 303.15, and 313.15 K. From the parameters obtained from single component adsorption isotherm, multi-component adsorption equilibria could be predicted and compared with experimental data. The binary experimental data were applied to four models : extended Langmuir, extended Langmuir-Freundlich, Ideal Adsorbed Solution theory (IAST), and Vacancy Solution Model (VSM). The models were found to describe the experimental data with a reasonable accuracy. Extended L-F model predicts equilibria of mixture better than any other model.

• Membrane Journal
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• v.22 no.3
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• pp.171-177
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• 2012

Effect of humic acid (HA), photo-oxidation and adsorption with periodic $N_2$ back-flushing was investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. It was compared and investigated with the previous result at water back-flushing in viewpoints of membrane fouling resistance ($R_f$), permeate flux (J), and total permeate volume ($V_T$). As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_T$ was the highest at HA 2 mg/L. As HA concentration increased from 2 to 10 mg/L, the membrane fouling resistance after 180 mins' operation ($R_{f,180}$) improved 0.8 times more than that of water back-flushing. Therefore, HA concentration should affect on the membrane fouling at $N_2$ back-flushing than water back-flushing. Turbidity treatment efficiencies were almost constant independent of HA concentration, but HA treatment efficiency was the maximum at HA 2 mg/L. This means that adsorption and photo-oxidation of photocatalyst beads could removed HA at HA 2 mg/L, but it was not enough at 4 mg/L. Beyond HA 6 mg/L, UF could effectively treat HA by thick cake layer on membrane surface and severe inner membrane fouling.

• ETRI Journal
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• v.24 no.3
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• pp.211-220
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• 2002

This study characterizes an oxide etching process in a magnetically enhanced reactive ion etching (MERIE) reactor with a $CHF_3/CF_4$ gas chemistry. We use a statistical $2^{4-1}$ experimental design plus one center point to characterize the relationships between the process factors and etch responses. The factors that we varied in the design include RF power, pressure, and gas composition, and the modeled etch responses were the etch rate, etch selectivity to TiN, and uniformity. The developed models produced 3D response plots. Etching of $SiO_2$ mainly depends on F density and ion bombardment. $SiO_2$ etch selectivity to TiN sensitively depends on the F density in the plasma and the effects of ion bombardment. The process conditions for a high etch selectivity are a 0.3 to 0.5 $CF_4$ flow ratio and a -600 V to -650 V DC bias voltage according to the process pressure in our experiment. Etching uniformity was improved with an increase in the $CF_4$ flow ratio in the gas mixture, an increase in the source power, and a higher pressure. Our characterization of via etching in a $CHF_3/CF_4$ MERIE using neural networks was successful, economical, and effective. The results provide highly valuable information about etching mechanisms and optimum etching conditions.

• Journal of Microbiology and Biotechnology
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• v.32 no.5
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• pp.672-679
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• 2022

Microbial lipases are used widely in the synthesis of various compounds due to their substrate specificity and position specificity. 4-Ethyl malate (4-EM) made from diethyl malate (DEM) is an important starting material used to make argon fluoride (ArF) photoresist. We tested several microbial lipases and found that Photobacterium lipolyticum M37 lipase position-specifically hydrolyzed DEM to produce 4-EM. We purified the reaction product through silica gel chromatography and confirmed that it was 4-EM through nuclear magnetic resonance analysis. To mass-produce 4-EM, DEM hydrolysis reaction was performed using an enzyme reactor system that could automatically control the temperature and pH. Effects of temperature and pH on the reaction process were investigated. As a result, 50℃ and pH 4.0 were confirmed as optimal reaction conditions, meaning that M37 was specifically an acid lipase. When the substrate concentration was increased to 6% corresponding to 0.32 M, the reaction yield reached almost 100%. When the substrate concentration was further increased to 12%, the reaction yield was 81%. This enzyme reactor system and position-specific M37 lipase can be used to mass-produce 4-EM, which is required to synthesize ArF photoresist.