• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.343-348
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• 1994

Enterobacter sp. producing -$\beta$-galactosidase with high transgalactosylation activity was isolated from dairy wastewater. The isolate had common biochemical features to E. aerogenes and E. cloacae. Enzyme production increased as the cell mass increased with optimum enzyme activity of 0.21 Unit/mg-protein (o-nitro-phenyl-$\beta$ -D-galactoside (ONPG) as substrate) until 8 hr of culture. Whole cells permeabilized by toluene were used to produce galacto-oligosaccharide. Optimum toluene concentration, temperature and pH for -$\beta$-galactosidase activity of permeabilized whole cells were 10% (v/v), $50^{\circ}C$ and 6.0, respectively. A maximum of 38% (w/w) of galacto-oligosaccharide was obtained with lactose concentration of 20% (w/w) at $40^\{\circ}C$ and pH 6.0.

• Journal of Microbiology and Biotechnology
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• v.1 no.3
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• pp.202-206
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• 1991

To produce acetoin as a precursor of the tetramethylpyrazine flavor compound from citrate by Lactococcus lactis ssp. lactis biovar. diacetilactis FC1, fermentation factors such as inital pH of culture media, temperature, concentration of Na-citrate, thiamin-HC1 and sugars were examined. The best acetoin production was achieved with initial pH in the culture media of 5.5, fermentation temperature of $34^{\circ}C$, Na-citrate concentration of 3%, addition of thiamin-HC1 at 2 mg/l and galactose as a carbon source. When fermentation was carried out under the optimum conditions, the exhaustion of Na-citrate and the production of acetoin took simultaneously and acetoin reached the maximum content, 80 mmole/l after 20 hours.

• YAKHAK HOEJI
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• v.44 no.6
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• pp.545-551
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• 2000

Magnesium trisilicate was prepared by reacting Magnesium sulfate solution with Sodium silicate solution in this study. The optimum synthesis conditions base on the yield of the product were established by applying Box-Wilson experimental design. It was found that the optimum synthesis conditions of Magnesium trisilicate were as follows; Reacting temperature : $57{\sim}90^{\circ}C$, Concentration of reactant solution : $19.1{\sim}20.0%$, Molar concentration ratio of two reactants : [Sod.silicate]/[Mg.sulfate] : $1.47{\sim}1.80$, Temperature of washing water : $45{\sim}48^{\circ}C$, Drying temperature : $65{\sim}82^{\circ}C$. The antacidic capacity of the five Magnesium trisilicate samples which shows the maximum antacidic efficacy was tested by pharmacopeia acid consuming capacity test. The five Magnesium trisilicate samples were identified by chemical analysis.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.124-132
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• 1998

The Korean-made passive samplers were evaluated at the working environment for field testing. Tested materials were n-hexane, toluene and trichloroethylene. The performance of passive samplers depended on types and concentrations of organic vapors. Sampling rates were not steady until certain concentrations. The optimum concentration for determination of airborne toluene by passive samplers was equal to or over 10 ppm which is 1/10 of the Korean occupational exposure limit. Optimum concentration of n-hexane was equal to and over 1 ppm which is 1/50 of Korean occupational exposure limit. But for trichloroehtylene, coefficient of variation was 53.5 %. Passive samplers may be used for determination of n-hexane. For other materials, further study on the performance of Korean-made passive samplers is required.

• Journal of the Korean institute of surface engineering
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• v.21 no.4
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• pp.149-159
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• 1988

Electrodeposition of chromium from low concentration chromjum (III) sulfate complexess in aqueous using sodium formate-glycine mixtures as a complexing agent was studied. In the bath formation, it is found that the optimum again temperature and time for equilibration of the electrolytes are nrcessary for 24 hrs at 45$^{\circ}C$and the optimum elecrical charge for low current electrolysis which might be produced Cr(II) ions in the electrolytes is necessary for minum 2Ah/$\ell$. The optmun concentration off standard electrolyte for main composition is 0.05M chromium(III) sulfate, 0.2M sodium formate-0.2M glycine, and I mMNaSCN as a catalysea, respectivwly. The standard electrolyte is shows good covering, good throwing power, and 6% of current efficiency (Cr(III)basis). The oppearance of electrodeposits shows att active bright chromium. The SEM morphology of the chromjum coating is observed as smooth surfaces and dispersed micro prcro pores. X-ray diffraction analysis shows a bcc structure which the perferred orintation of the chromium electrodeposits is strongin(200)plane.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.531-537
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• 1994

This study was undertaken with objective of optimizing the conditions of fermentation in an aqueous two-phase system which is composed of polyethylene glycol (PEG) 20000 and crude dextran (Dx). The data were obtained and analyzed using the Box-Wilson's experimental design protocol and the response surface methodology. To reach this end a multilinear polynomial regres- sion model was developed, which can be utilized for the purpose of optimizing the extractive fermentation. Optimum conditions for batch fermentation with aqueous two phase system were found to be at 4.2~5.4% PEG/3.2~4.2% Dx range. The composition of the center was 4.8% PEG/ 3.6% Dx. Optimum operating conditions for initial sugar concentration and fermentation time were approximately 160 g/l, and 21~22 hr, respectively. Fermentation in the aqueous two phase system composed of 5% PEG/4% Dx showed increase of 23% in ethanol concentration, of 9.5% in ethanol yield, and of 19% in ethanol productivity as compared to the case of fermentation of neat Jerusalem artichoke juice.

• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.332-336
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• 2007

Pseudomonas stutzeri strain KCCM 34719 was used in this experiment to determine the effects of increasing Pb(II) concentrations on its growth rate. To obtain optimum growth conditions, strain KCCM 34719 was cultivated in nutrient broth under various conditions, such as temperature, pH, and NaCl concentration. Optimal conditions for cell growth were $30^{\circ}C$ of temperature, 8.0 of pH, and 3% of NaCl concentration, respectively. Growth response of bacterial cell to Pb(II) showed tolerance to concentrations ranging from 10 to 100 mg ${\ell}^{-1}$ in liquid culture, following a growth pattern similar to the control. Growth rate was greatly inhibited at 200 mg ${\ell}^{-1}$ of Pb(II).

• YAKHAK HOEJI
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• v.45 no.1
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• pp.23-28
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• 2001

Hydrotalcite was prepared by reacting with sodium carbonate, magnesium hydroxide and aluminum chloride solutions in this study. The optimum synthesis conditions based on the yield of the product were established by applying Box-Wilson experimental design. It was found that the optimum synthesis conditions of hydrotalcite were as follows ; reacting temperature : 63~9$0^{\circ}C$, concentration of reactant solution : 18.20~19.82%, molar concentration ratio of two reactants [Mg(OH)$_2$] / (AICl$_3$.6$H_2O$) : 6.0, temperature of washing water : 29.0-34.4$^{\circ}C$, drying temperature : 56-77.6$^{\circ}C$. The physicochemical properties of hydrotalcite as medicine were studied by use of chemical analysis, bulk volume test and acid consuming capacity measurements.

• Microbiology and Biotechnology Letters
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• v.24 no.4
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• pp.452-458
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• 1996

A yeast strain TH65 producing a high level of proteinase under alkaline condition was isolated, and identified as Yarrowia lipolytica by morphological, physiological, and biochemical characteristics. In proteinase productivity, glycerol and glucose among tested carbon sources were very effective, and optimum concentration of glucose was 0.5%. Skim milk was found to be most effective nitrogen source in productivity, and its optimum concentration was 0.6%. But, cysteine, cystine and tryptophane decreased the proteinase productivity. Yeast extract was relatively effective at the range of 0.1-0.5%. The yeast showed maximum production of proteinase at 18$\circ$C, pH 9-11, and cultivation time of 36 hours.

• Journal of the Korean institute of surface engineering
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• v.24 no.4
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• pp.206-214
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• 1991

In the basic study of selective electroless Ni plating of Si wafers, plating rate and physical properties are investigated to obtain optimum conditions of contact hole filling. Si wafers are excellently activated in the concentration of 0.5M IF, 1mM PdCl2, 2mM EDTA at $70^{\circ}C$, 90sec. The optimum condition of Ni-B deposition on p-type Si wafers is 0.1M NiSO4, 0.11M Citrate, $70^{\circ}C$, pH6.8, 8mM DMAB. The main factor in the sheet resistences variation of films is amorphous and on heat treating matrix was transformed into a stable phase (Ni+Ni3B) at $300-400^{\circ}C$. But pH or DMAB concentration in the plating solution doesn't play role of heat-affected phase change.