• Resources Recycling
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• v.18 no.6
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• pp.38-45
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• 2009

Dissolution characteristics of magnesite ore in hydrochloric acid solution and removal of impurity were investigated. The dissolution yield increased with increasing temperature and with decreasing particle size. The optimum conditions for dissolution were found to be reaction period of 120 min, reaction temperature of $80^{\circ}C$ and mean particle size of 100. Under optimal dissolution condition the extraction of Mg was 98%. It was found that most of Si and Al exist in the residue, and they can be removed by filtering. Dissolved impurity ions were precipitated as metal hydroxides by pH adjustment. Polymers were used as coagulants for metal hydroxides and the suitable coagulant dosage was 1mg/100ml of non-ionic polymer.

• Microbiology and Biotechnology Letters
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• v.3 no.3
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• pp.147-156
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• 1975

The possibility of using tapioca pellets as a raw material in glutanmic acid fermentation by Microcuccus glutamicus is shown. The ground pellets were diluted with water to 20％ solid level and treated with $\alpha$-anylase prepared from a thermophilic Actinomycetes strain culture for 90 min at 85$^{\circ}C$ under pH 6.0. The liquefied solution was further saccharified with commercial glucoamylase for 36 hours under the reaction conditions of 55$^{\circ}C$ and pH 5.0. The inhibitory effect of excess biotin content, 16 $\mu\textrm{g}$ Per liter of the hydrolzate, could be reduced effectively by adding 10 IU of penicillin per ml of the medium after five hours of the fermentation. The maximum glutamic acid yield of 38.5 g/l was obtained after 60 hours of shaking culture at 28-3$0^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.13 no.4
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• pp.321-327
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• 1985

Cultivation conditions for the production of extracellular alkaline protease by a nonpiamentation Serratia sp. and purification of the enzyme were studied. The maximum enzyme level was obtained at the beginning of stationary phase when the organism was cultured on brain heart infusion medium at $25^{\circ}C$ under aeration (gyratory shaking, 180 cycles/min). The enzyme was purified about 100 fold with 16.5％ yield by ammonium sulfate precipitation, ammonium sulfate fractionation followed by DEAE-cellulose chromatography (1st and 2nd). The purified enzyme moved as a single symmetrical peak in the analytical ultracentrifuge. The enzyme demonstrated its maximum activity at pH 8.5-9.0 and 4$0^{\circ}C$ when vitamin-free casein was used as a substrate.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1151-1158
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• 2011

In this study, a galactooligosaccharide (GOS) was synthesized using active ${\beta}$-galactosidase (${\beta}$-gal) inclusion bodies (IBs)-containing Escherichia coli (E. coli) cells. Analysis by MALDI-TOF (matrix-assisted laser desorption/ionization-time of flight) mass spectrometry revealed that a trisaccharide was the major constituent of the synthesized GOS mixture. Additionally, the optimal pH, lactose concentration, amounts of E. coli ${\beta}$-gal IBs, and temperature for GOS synthesis were 7.5, 500 g/l, 3.2 U/ml, and $37^{\circ}C$, respectively. The total GOS yield from 500 g/l of lactose under these optimal conditions was about 32%, which corresponded to 160.4 g/l of GOS. Western blot analyses revealed that ${\beta}$-gal IBs were gradually destroyed during the reaction. In addition, when both the reaction mixture and E. coli ${\beta}$-gal hydrolysate were analyzed by high-performance thin-layer chromatography (HP-TLC), the trisaccharide was determined to be galactosyl lactose, indicating that a galactose moiety was most likely transferred to a lactose molecule during GOS synthesis. This GOS synthesis system might be useful for the synthesis of galactosylated drugs, which have recently received significant attention owing to the ability of the galactose molecules to improve the drugs solubility while decreasing their toxicity. ${\beta}$-Gal IB utilization is potentially a more convenient and economic approach to enzymatic GOS synthesis, since no enzyme purification steps after the transgalactosylation reaction would be required.

• Environmental Engineering Research
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• v.19 no.2
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• pp.123-130
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• 2014

Percolation is the important process of extracting the soluble constituents of a fine mesh, porous substance by passage of a liquid through it. In this study, bio-wastes were percolated under various conditions through continuous percolation processes, and the energy potential of percolate was evaluated. The representative bio-wastes from the K composting plant in Darmstadt, Germany were used as the sample for percolation. The central objective of this study was to determine the optimal amount of process water and the optimum duration of percolation through the bio-wastes. For economic reasons, the retention time of the percolation medium should be as long as necessary and as short as possible. For the percolation of the bio-wastes, the optimal percolation time was 2 hr and maximum percolation time was 4 hr. After 2 hr, more than two-thirds of the organic substances from the input material were percolated. In the first percolation process, the highest yields of organic substance were achieved. The best percolation of the bio-wastes was achieved when the process water of 2 L for the first percolation procedure and then the process water of 1.5 L for each further percolation procedure for a total 8 L for all five procedures were used on 1,000 g fresh bio-waste. The gas formation potentials of 0.83 and $0.96Nm^3/ton$ fresh matter (FM) were obtained based on the percolate from 1 hr percolation of 1,000 g bio-waste with the process water of 2 L according to the measurement of the gas formation in 21 days (GB21). This method can potentially contribute to reducing fossil fuel consumption and thus combating climate change.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.596-604
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• 2016

In this study, we used a stochastic approach for guaranteeing the reliability and robustness of the performance with regard to the design of polymer components, while taking into consideration the degradation properties and operating conditions in automobiles. Creep and tensile tests were performed for obtaining degradation properties. The Prony series, which described the viscoelastic models, were calculated to use the creep data by the Maxwell fluid model. We obtained the stress data from the frequency response analysis of the polymer components while considering the degradation properties. Limit state functions are generated by using these data. Reliability assessments are conducted under the variation of the degradation properties and area of frequency at peak response. For this study, the input parameters are assumed to be a normal distribution, and the reliability under the yield stress criteria is evaluated by using the Monte Carlo Simulation. As a result, the reliabilities, according to the three types of polymer materials in automotive components, are compared to each other and suggested the applicable possibility of polymeric materials in automobiles.

• Journal of Bio-Environment Control
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• v.9 no.2
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• pp.73-78
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• 2000

This study was carried out to investigate appropriate processing conditions for expanded rice hulls to be used as a medium material in nutrient cultures. The water holding capacity of expanded rice hulls produced by using a domestic grinder with 8 mm gap and 3 mm cutter height was 271.0, and the bulk density and CEC were 0.19g·m-3 and 37.0 cmol·kg-1, respectively. These values are higher than those of perilte. However, geometric mean diameter (GMD) of expanded rice hulls was 1.01mm which was smaller than that of perlite, indicating unfavorable porosity. After supplying nutrient solution, the faster water percolation in expanded rice than perlite required more frequent water supply. There was no significant difference in tomato fruit yield between expanded rice hull and perlite. The pH increase and the lack of nitrogen in early stage of culture are to be solved in the future.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.47-55
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• 2006

Recovery of acids from the waste etching solution of containing nitric, hydrofluoric and acetic acid discharged from silicon wafer manufacturing process has been attempted by using solvent extraction method. With EHA (2-Ethylhexlalcohol) for acetic acid and TBP(Tri-butly Phosphate) for nitic and hydrofluoric acid as extraction agent was carried on experiment to obtain the process design data in separation procedure. From the McCabe-Thiele diagram analysis, we obtained the optimum conditions of phase ratio(O/A) and stages to separate the each acid sequently from the mixture acids. The recovery yield was obtained 90% above for acetic acid from the acid mixtures, 90% above for nitric acid from acetic acid extraction raffinate and then 67% above for hydrofluoric acid from final extraction raffinate.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.4
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• pp.293-303
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• 2017

The purpose of this study is to measure the effects of droughts and public investments in irrigation facilities on rice production. We estimated the effects of droughts and the fraction of irrigated paddy fields with irrigation facilities on rice yields through a panel regression model. The results showed that the effect of drought on rice yield was negative but modest. Also, we found that increases in the ratio of irrigated paddy fields to total paddy fields by 1% enhance rice yields by 0.025-0.035%. However, the ratio of irrigated paddy fields to total paddy fields has insignificant effects on reducing harmful droughts effects regardless of the conditions of irrigated paddy fields.

• Resources Recycling
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• v.19 no.6
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• pp.70-76
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• 2010

It was to investigate the optimum leaching conditions for the NaOH hot digestion and hydrochloric acid leaching of Monazite. The optimum condition for NaOH hot digestion was that the concentration of NaOH/TREO mole ratio was 15, the temperature of decomposition $140^{\circ}C$, and reaction time 2 hrs. And the optimum condition for the hydrochloric acid leaching of NaOH hot digestion product was that the concentration of hydrochloric acid was 6N, leaching time 2 hrs and pulp density about 15%. The yield of rare earth oxide was above 90% on the above experimental condition.