• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.414-419
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• 2005

This study was performed to compare the treatment efficiencies of two media, newly developed Bio-rock and conventional gravel, in soil clothing contact oxidation process. The composition of synthetic wastewater were $COD_{Cr}$ $150{\sim}370\;mg/L$, $BOD_5$ $150{\sim}270\;mg/L$, T-N $20{\sim}60\;mg/L$, T-P $5{\sim}25\;mg/L$, pH 7 and 2 mL/L of trace element solution. The experiment using two reactors was comparatively conducted for the flow rate of 40 L/d for 13 months, respectively. Initially Bio-rock reactor was increased to pH 12 due to $Ca(OH)_2$ with hydration of cement, but gravel reactor was dropped to pH 4 due to the degradation of organic material and nitrification. This significant pH variation deteriorated the growth and activity of microorganism. But the high pH of Bio-rock seems favorite to ammonia stripping and precipitation of phosphate. Such pH variation of Bio-rock and gravel reactors were finally stabilized to pH 8 and pH 6, respectively. The removal efficiencies of organic compounds from Bio-rock reactor were 96% of $COD_{Cr}$, 98% of $BOD_5$, 80% of T-N and 85% of T-P which stably coping against variation of influent concentration. But those of gravel reactor were 96% of $COD_{Cr}$, 96% of $BOD_5$, 42% of T-N and 40% of T-P, respectively. The Bio-rock was 2 times higher than T-N and T-P in treatment efficiency. And electron-microscopic examination showed that Bio-rock was more favorable to microbial adherence than gravel. The microbial populations were $5.2{\times}10^6\;CFU/mL$ of Bio-rock reactor compared to $2.6{\times}10^6\;CFU/mL$ in gravel reactor. In result Bio-rock was favor to microbial adherence and high treatment efficiency in spite of variation of influent concentration which had the advantages in saving running time and reducing site requirement.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.19-26
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• 2023

Hydrogen, a clean energy source free of COx emissions, is poised to replace fossil fuels, with its usage on the rise. Despite its high energy content per unit mass, hydrogen faces limitations in storage and transportation due to its low storage density and challenges in long-term storage. In contrast, ammonia offers a high storage capacity per unit volume and is relatively easy to liquefy, making it an attractive option for storing and transporting large volumes of hydrogen. While NH₃ decomposition is an endothermic reaction, achieving excellent low-temperature catalytic activity is essential for process efficiency and cost-effectiveness. The study examined the effects of different zeolite types (5A, NaY, ZSM5) on NH₃ decomposition activity, considering differences in pore structure, cations, and Si/Al-ratio. Notably, the 5A zeolite facilitated the high dispersion of Ni across the surface, inside pores, and within the structure. Its low Si/Al ratio contributed to abundant acidity, enhancing ammonia adsorption. Additionally, the presence of Na and Ca cations in the support created medium basic sites that improved N₂ desorption rates. As a result, among the prepared catalysts, the 15 wt%Ni/5A catalyst exhibited the highest NH₃ conversion and a high H₂ formation rate of 23.5 mmol/g_cat·min (30,000 mL/g_cat·h, 600 ℃). This performance was attributed to the strong metal-support interaction and the enhancement of N₂ desorption rates through the presence of medium basic sites.

• Microbiology and Biotechnology Letters
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• v.34 no.1
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• pp.7-14
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• 2006

Feather, generated in large quantities as a byproduct of commercial poultry processing, is almost pure keratin, which is not easily degradable by common professes. Four strains, SMMJ-2, FL-3, NO-4 and RM-12 were isolated from soil for production of extracellular keratinolytic protease. They were identified as Bacillus sp. based on their morphological and physiological characteristics. They shown high protease activity on 5.0% skim milk agar medium and produced a substrate like mucoid on keratin agar medium. Bacillus sp. SMMJ-2 had a faster production time for producing keratinolytic protease than other strains. This strain did not completely degrade whole chicken feather for five days in basal medium but completely degraded whole chicken feather when supplied with nitrogen source for 40hours in keratinolytic producing medium ($0.7%\;K_{2}HPO_{4},\;0.2%\;KH_{2}PO_{4},\;0.1%$ fructose, 1.2% whole chicken feather, $0.01%\;Na_{2}CO_3$, pH 7.0). When supplied with chicken feather as nitrogen source, keratinolytic protease activity was 89 units/ml/min. When soybean meal was used as nitrogen source, the keratinolytic protease production reached a maximum of 106 units/ml/min after 48 hours under $30^{\circ}C$, 180 agitation. To isolate the keratinolytic protease, the culture filtrate was precipitated with $(NH_4)_{2}SO_4$ and acetone. The recovery rate of keratinolytic protease was about 96% after treatment with 50% acetone. The enzyme was stable in the range of $30{\sim}50^{\circ}C$ and pH $6.0{\sim}12.0$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.5
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• pp.702-710
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• 2016

The bioactivity of soy grits cheonggukjang was enhanced by fermentation using three ${\beta}$-glucosidase-producing Bacillus subtilis strains (HJ 18-9, HJ 25-8, and HJ 18-9+HJ 25-8) for 48 h at $37^{\circ}C$. The results indicate that protease, cellulase, and a-amylase activities significantly increased (P<0.05) with increasing fermentation time. In addition, the amino-type nitrogen content of B. subtilis-fermented soy grits cheonggukjang increased to 91.0~168.0 mg% after 48 h of fermentation. Among the isoflavones in soy grits cheonggukjang, contents of ${\beta}$-glucosides or acetyl-glucosides were reduced while aglycone content increased upon fermentation. In particular, soy grits cheonggukjang fermented with B. subtilis HJ18-9 and HJ25-8 showed the largest increases in aglycone content compared to complex treatment. These results provide useful information for development starter (single and complex) as well as for production of high quality fermented soybean food.

• Applied Biological Chemistry
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• v.18 no.3
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• pp.109-116
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• 1975

In order to utilize the agricultural waste products for animal feeds, two high xylanase producing mold strains were selected from various sources of samples. The optimum conditions of xylanase production and the characteristics of the mold enzyme were investigated,and summarized as follows. 1. Two Aspergillus niger strains (experimental No. 1701 and 430) showed the high xylanase activity. 2. The highest xylanase production was obtained at pH 5.0-6.0 in two days. 3. Xylanase production in strain 1701 was increase with the addition of carboxy methyl cellulose, $NH_4H_2PO_4$ and corn steep liquor as carbon sources and natural nutrients, as respectively, while the other carbon, nitrogen, phosphate sources, natural nutrients and minerals gave no remarkable effect. In the strain 430, the enzyme procuction was not effected with the above substrate sources. 4. Maximum xylan hydrolysis reaction with the crude enzyme extract (33.3% v/v) was obtained in the 2% substrate concentration at pH 5.0 and $60^{\circ}C$ in three hours in both strains. 5. Maximum xylan hydrolysis rate was 95% at the optimum conditions for xylanase activity.

• Journal of Wetlands Research
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• v.18 no.1
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• pp.68-75
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• 2016

A set of lab-scale polymer synthetic fiber packed column wetlands composing three columns (CW1, CW2 and CW3) with different hydraulic regimes, recirculation frequencies and pollutant loading rates, were operated in 2012. Synthetic fiber tested as an alternative wetland medium for soil mixture or gravel which has been widely used, has very high pore size and volume, so that clogging opportunity can be greatly avoided. The inflow to the wetland was artificial stormwater. All the wetlands achieved effective removal of TSS (94%~96%), TCOD (68%~73%), TN (35%~58%), TKN (62%~73%) and NH4-N (85%~ 99%). Particularly, it was observed that COD was released from the fiber during one distinct period in all wetlands. This was probably due to the degradation of polymer fiber, and the released organic matters were found to serve as carbon source for denitrification. In addition, with longer retention time and frequent recirculation, lower effluent concentration was observed. With higher pollutant loading rate, higher nitrification and denitrification rates were achieved. However, although organic matters were released from the fiber, the lack of carbon source was still the limiting factor for the system since the release persisted only for 40 days.

• Korean Journal of Food Science and Technology
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• v.15 no.4
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• pp.385-391
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• 1983

The change of free amino acid contents and nitrogen compounds in the course of the Chungkookjang fermentation that occurred by utilizing Bacillus natto and Bacillus subtilis are to the following effects. pH, during the growth period, that is 6.35 in pH at the first stage of fermentation, were turned into 8.2 after 72 hours. Crude protein content increased irregularly from 16.82%-18% and total sugar decreased. Increasing with the progress of fermentation time, protease activity showed the maximum value between 48-60 hours, but Bacillus natto activated a little than Bacillus subtilis. Amino nitrogen and water soluble nitrogen content increased but difference was found that is, Bacillus natto increased more than Bacillus subtilis. Glutamic acid content was the highest among the contents of free amino acid between both Bacillus sp. and the order of the next contents showed as leucine, phenylalanine, histidine alanine. arginine, but difference was found between Bacillus sp., that is, Bacillus natto was higher than Bacillus subtilis. In view of the results as above, Bacillus natto was excellent than Bacillus subtillus as Bacillus strains of Chungkookjang koji production.

• Microbiology and Biotechnology Letters
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• v.2 no.2
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• pp.79-82
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• 1974

Present experiments were designed to estimate the effects of pretreatments by various kinds of alkalis to the agricultural wastes such as cereal straws as the substrate on the production of cellulosic single-cell protein. Among the various kinds of alkalis NaOH was proved to be the most effective on improving the digestibility of cellulose by the bacteria isolated. NH$_4$OH which is inferior to NaOH in the effectiveness of treatment might have more economic advantage in the price, and the ammonium salt resulted from the neutralization can be used as the nitrogen source by bacteria. The treatment with higher concentration than 1 normality of NH$_4$OH didn't increase the productivility of cell mass. About five per cent of (NH$_4$)$_2$SO$_4$ in medium resulted from the neutralization didn't have any influence in the cell mass productivility. Futhermore, the cell mass productibility was higher in the case of neutralization than alkali free washing. The digestibility of straws was increased from 7.9％ to 46.0％ by NH$_4$OH treatment, and 6.3∼6.45g of dry cell were obtained from 40g of NH$_4$OH treated straws. In the case of NaOH treatment, 8.6g of cell mass was obtained from 40g of substrate.

• Resources Recycling
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• v.29 no.5
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• pp.64-72
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• 2020

When the multi-stage combustion process is applied to the cement kiln to reduce nitrogen oxide emissions in the cement industry, oxidation/reduction section that can increase combustion efficiency by reducing NO_x to NO and completely burning unburned materials is essential In this study, when applied the oxidation/reduction system of the cement kiln preheater and calciner, the optimal oxidation/reduction calcination crisis that can secure the quality stability of the final product, cement clinker, was to be observed macroscopically, and the mass change of raw materials according to the burning conditions, decarbonation rate, and calcination rate were investigated. The results showed that the thermal decomposition of raw materials tends to be promoted in the oxidation condition rather than in the reduction condition, and that the thermal decomposition of limestone, which has a relatively high CaO content, is carried out later than that of cement raw meal, which is thought to be caused by the CO₂ fractionation in the kiln. The thermal decomposition properties of raw materials according to oxidation/reducing burning condition showed a relatively large difference in temperature range lower than normal limestone themal decomposition temperature, which is thought to be expected to improve the thermal efficiency of raw materials according to the formation of oxidation condition in the section 750℃ of burning temperature. However, for this study, lab scale. Because there is a difference from the field process as a scale study, it is deemed necessary to verify the actual test results of the pilot scale.

• Journal of Animal Science and Technology
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• v.49 no.5
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• pp.667-676
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• 2007

This study was conducted to determine effects of cellulolytic microbes inoculation to sawdust-based spent mushroom substrate(SMS) during deepstacking on fermentation parameters, total microbial counts and cellulolytic enzyme activity and to on SMS nutrients utilization by sheep. For sheep metabolism trials, six sheep(ram, average 54.8kg) were fed a Control diet(70% concentrates, 15% rice straw and 15% SMS with no microbial treatment on a dry basis) and a Treatment diet(the same diet including SMS with a microbial treatment) for 2 trials. Spent mushroom substrates with or without a microbial(4 strains including 1 strain of Enterobacter ludwigii, 1 strain of Bacillus cereus and 2 strains of Bacillus subtillis) treatment (1% of SMS on wet basis) were deepstacked for 7 days. The internal temperatures in 1.2 M/T of SMS deepstacks reached to 50±5℃ within 7 days of storage. Total microbial counts remarkably decreased (P<0.05) with a deepstacking process and were not affected(P>0.05) by the microbial treatment. For fibrolytic enzyme activity, CMCase and xylanase activities were decreased(P<0.05) by a deepstacking process. After deepstacking, the microbial treatment showed about 2.5-times higher(P<0.05) for CMCase activity and about 4-times higher(P<0.05) for xylanase activity than those of the Control. Activities of ligninolytic enzymes such as laccase and MnP were not affected by the microbial treatment. The sheep fed the microbially treated SMS diet had a tendency of greater total tract digestibilities of ash(P=0.051), NFE (P=0.071), hemicellulose(P=0.087) and NDF(P=0.096) than those fed the untreated SMS diet. Nitrogen balance of sheep was not affected(P>0.05) by feeding of microbially treated SMS. Accordingly, these results indicate that cellulolytic microbes inoculation during deepstacking of SMS may improve the bio- utilization of SMS by sheep.