• Journal of Microbiology and Biotechnology
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• v.7 no.4
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• pp.262-266
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• 1997

To increase the high production of 1-deoxynojirimycin (DNJ) from Streptomyces sp. SID9135, the effect of various carbon sources, nitrogen sources, cationic metal ions, the initial pH of the medium, and agitation speed were investigated. The most effective carbon and nitrogen sources were found to be lactose 2.5% (w/v) and soybean meal 2.0% (w/v), respectively. None of the cationic metal ions examined had any detectable stimulating effect on DNJ production except $Fe^{+2}$ ion. The initial optimum pH for DNJ production ranged from 6-8 and agitation speed was most effective at 400 rpm. In the jar fermentor experiments under optimal culture conditions, the accumulation of DNJ reached about $640{\mu}g$/ml after 5 days of cultivation and the level remained the same for a further two days.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.3
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• pp.460-465
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• 2001

To prepare vinegar using concentration apple juice, response surface methodology (RSM) was applied to optimize and monitor the vinegar fermentation properties by two stage fermentation. In the first stage, the optimum conditions for maximum alcohol contents were 18.56。Brix of initial sugar concentration, 61.96 rpm of agitation rate and 67.32 hr of fermentation time. The optimum condition for maximum acidity in the second stage (vinegar fermentation) were 201.53 rpm of agitation rate and 179.42 hr of fermentation time. Malic acid content was the highest and its content little changed during acetic acid fermentation. Lactic acid content increased a little during alcohol fermentation. Acetic acid content apparently increased during acetic acid fermentation.

• KSBB Journal
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• v.17 no.4
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• pp.396-402
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• 2002

Biodiesel has attracted considerable attention during the past decade as a biodegradable, nontoxic, and renewable fuel, Several processes for the production of biodiesel have been developed, among which transesterification under alkali-catalysis gives high level yield of methyl esters in short reaction times. In this research, response surface method was applied to optimize the transesterification reaction under alkali-catalysis. It was found that reaction temperature, reaction time, and agitation rate of reactor had profound effects among the seven variables affecting on biodiesel conversion. The optimal temperature, reaction time, and agitation speed were 67$^{\circ}C$, 68 minutes, and 94 rpm, respectively. Under the optimal conditions, the experimental value of biodiesel conversion was 99.7%.

• Macromolecular Research
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• v.12 no.5
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• pp.519-527
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• 2004

Stable poly(methyl methacrylate-co-divinylbenzene) (poly(MMA-co-DVB)) microspheres were prepared by precipitation polymerization using acetonitrile as the main medium under various polymerization conditions, including modifications of the agitation speed, monomer and initiator concentrations, DVB content in the monomer mixture, and the use of various cosolvents. Gentle agitation was required to obtain smooth spherical particles. The individually stable microspheres were obtained at monomer concentrations of up to 15 vol% in an acetonitrile medium. The number-average diameter increased linearly with respect to increases in the monomer and initiator concentrations. We found, however, that the uniformity of the microspheres was independent of the variation of the polymerization ingredients because nuclei formation was solely influenced by the crosslinking reaction of the monomers. We obtained higher yields for the polymerization at higher concentrations of monomer and initiator. The concentration of DVB in the monomer mixture composition played an important role in determining not only the size of the microspheres but also the yield of the polymerization. In addition, although we employed various cosolvents as the polymerization medium, we found that acetonitrile/2-methoxyethanol was the only system that provided spherical particles without coagulation. This finding indicates that the precipitation polymerization is strongly dependent on the solvent used as the medium.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.4
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• pp.281-289
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• 2016

Agitation is a secondary process used to increase the PR stripping force on an ITO-glass surface; it is an efficient approach to stripping during production. It activates the stripper to chemically penetrate the PR layer and assists by breaking down the physical bonding forces at the surface. In this study, different stripping tests were conducted by varying the dipping time, the composition, the strip temperature, and the stripper concentration. Optimal PR strip conditions were estimated by using comparative visual inspection of stripped sample surfaces. The stripping process was affected by changes in the moving speeds and the sample positions. It was confirmed that the stripping capability improved at a dilute stripper ratio of 20-40% and a strip temperature of $30-40^{\circ}C$ and within 60 s of strip time.

• KSBB Journal
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• v.26 no.2
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• pp.143-150
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• 2011

The aim of the study was to optimize harvesting method for concentrating microalgae from microalgae mass culture. It is well known that the mass density of microalgae is usually very low and these are small size (5-20 ${\mu}m$) in the culture medium. It is essential that microalgae is harvested and concentrated economically for economical biodiesel production from microalgae. In this study, to determine optimized conditions for microalgae harvesting by chemical flocculation. Flocculation of three algae, Chlorella ellipsoidea, Dunaliella bardawil, and Dunaliella tertiolecta, was performed using various chemical flocculants, such as inorganic flocculants (aluminium sulfate, aluminium potassium sulfate, ferrous sulfate, ferric sulfate, ferric chloride, calcium hydroxide, sodium carbonate, sodium nitrite, and sodium aluminate), organic flocculant (polyacrylamide), and biopolymer flocculants (chitosan and starch). The results indicated that aluminium based inorganic flocculants is suitable for microalgae harvesting such as Chlorella ellipsoidea, Dunaliella bardawil, and Dunaliella tertiolecta. The results also recommended that flocculant doses, agitation speed, agitation time, sedimentation time for economical microalgae harvesting method using chemical flocculants.

• Resources Recycling
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• v.7 no.3
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• pp.42-51
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• 1998

Hydrogen in atmosphere can easily dissolve in melt of light metal alloys. Increasing demand for recycling of light metal a alloys has, therefore, focused attention on the removal of hydrogen gas, and alloy addition in melt has become an imporLant r refining process. For this purpose behaviors of mixing and hydrogen degassing in impeller agitated refming vessel with/without barnes were investigated. Flow patterns, mixing time behavior and kinetics of degassing in various agitating conditions were analysed in watet model experiments. And, numerical analysis on turbulent flow pattern in impeller agitated vessels was performed.

• KSBB Journal
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• v.13 no.3
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• pp.303-307
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• 1998

The fermentation conditions for the maximal production of the useful polysaccharides(water soluble polysaccharide and cell bound polysaccharide) from marine bacterium Zoogloea sp.(KCCM 10036) were investigated with a 5 L jar fermentor. The maximal production of these polysaccharides was obtained under the conditions of initial pH 7.8, 30$^{\circ}C$, 400 rpm of agitation speed, 2 Wm of aeration rate, 10%(w/v) of inoculum size and 2.5%(w/v) of glucose substrate and 10.38 g/L of total polysaccharide was produced. Apparent viscosity of the culture broth was increased with the production of these polysaccharides and the maximum value was reached to 22,500 cp.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.188-196
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• 2014

Extracellular production of recombinant human bone morphogenetic protein-7 (rhBMP-7) was carried out through the fermentation of Bacillus subtilis. Three significant fermentation conditions and medium components were selected and optimized to enhance the rhBMP-7 production by using the response surface methodology (RSM). The optimum values of the three variables for the maximum extracellular production of rhBMP-7 were found to be 2.93 g/l starch, 5.18 g/l lactose, and a fermentation time of 34.57 h. The statistical optimization model was validated with a few fermentations of B. subtilis in shake flasks under optimized and unoptimized conditions. A 3-L jar fermenter using the shake-flask optimized conditions resulted in a higher production (413 pg/ml of culture medium) of rhBMP-7 than in a shake flask (289.1 pg/ml), which could be attributed to the pH being controlled at 6.0 and constant agitation of 400 rpm with aeration of 1 vvm.

• Microbiology and Biotechnology Letters
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• v.29 no.2
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• pp.96-103
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• 2001

Phaffia rhodozyma is the most promising microbial source of astaxanthin production, though wild-type strains are needed to increase the astaxanthin content for commercial production. To increase astaxanthin content for commercial production, a mutant strain of P. rhodozyma was selected and culture conditions of the mutant selected were optimized. P. rhodozyma was treated with mutagenic agent such as NTG, acriflavine, and UV in serial order and carotenoids hyper-producing mutant strain was selected based on the capabilities of cell growth on the agar plate containing chemical inhibitors and carotenoids production. Among the mutants tested, a mutant WS-2 was finally selected. Mutant WS-2 produced 1.26mg carotenoids/g-dry cell weight and this value was about- 4-folds higher than that of wild-type. The optimum culture conditions were $24^{\circ}C$ of temperature, 1.5vvm of aeration and 300rpm of agitation. In the optimized condition, cell and carotenoids concentrations were 7.62g/l and 14.9mg/l, respectively.