• The Korean Journal of Ceramics
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• v.4 no.3
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• pp.176-182
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• 1998

The effects of temperature, cooling surface tension on the fining were studied in alkali-alkaline earth-silica TV screen glassmelts containing ZnO. Sodium antimonate $(Na_2OSb_2O_5)$ was used as a fining agent. Viscosity and surface tension of the melts were determined. On the basis of these properties, fining tests for several batches were performed by "MF" (Melting and Fining) and "PMF" (Profiled melting and Fining) methods. The results of these tests showed an opposite behavior each other with increase in ZnO content. This hehavior has been discussed in terms of two fining processes-growth of bubbles and shrinkage of seeds. shrinkage of seeds.

• Korean Journal of Materials Research
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• v.14 no.5
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• pp.343-347
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• 2004

We investigated the growth feasibility of polycrystalline Si film on mica substrate for the transfer of the layer to a plastic substrate. The annealing temperature was limited up to $600^{\circ}C$ because of crack development in the mica substrate. Amorphous Si film was deposited on mica substrate by PECVD and was crystallized by furnace annealing. During the annealing, bubbles were formed at the Si/mica interface. The bubble formation was avoided by the Ar-plasma treatment before amorphous Si deposition. A uniform and clean polycrystalline Si film was obtained by coating $NiCl_2$ on the amorphous Si film and annealing at $500^{\circ}C$ for 10 h. The conventional Si lithography was possible on the mica substrate and the devices fabricated on the substrate could be transferred to a plastic substrate.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.2
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• pp.77-82
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• 1992

When a crystal is grown by FZ process, the melt zone is located at between the solid of upper and lower side and is kept by the solid-liquid interface tension. On the surface of the melt zone, a surface tension gradient is occured by the difference of temperature and solute concentration, it is the driving force of marangoni flow. The crystal even in the steady state growth can become imperfect for the dislocation distribution and the solute concentration in the peripheral region of the crystal are higher than those in the inner part and the probability of the formation of the defects such as voids, bubble penetration, secondary phase creation and crack is high near the solid-liquid interface. This is because the solid -liquid interface becomes irregular because of the local variation of temperature in that region due to marangoni convection.

• Journal of Environmental Science International
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• v.21 no.7
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• pp.779-785
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• 2012

Several tests and experimental work have been done for identifying the best growth conditions and accumulated amount of lipid moiety in B. braunii, a microalga(UTEX 572) in terms of media composition. The specific growth rate was found to be the highest at 0.15 g/L-day when the phosphorus concentration was doubled with the other ingredients at the normal level. Experiments for varied media compositions revealed that the accumulation of lipid was the highest at 48% (dry cell weight based) in the nitrogen deficient medium and its corresponding specific growth rate was comparative to that in the normal BG 11 medium. In the bubble column experiments, carbon dioxide containing air produced four times more cell mass than air only. Light and glucose addition also enhanced cell mass with maximum, 1.8 g/L and accordingly 42% of lipid composition, which turned out to be a better strategy for higher lipid-producing microalgal culture.

• Journal of Marine Bioscience and Biotechnology
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• v.8 no.1
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• pp.24-29
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• 2016

Microalgae are considered as superior biodiesel producers, because they could effectively produce high amount of lipid with fast growth rate. In this study, Chlorella vulgaris was exposed to various light wavelengths (${\lambda}_{max}$ 470 nm, ${\lambda}_{max}$ 525 nm, and ${\lambda}_{max}$ 660 nm) using light emitting diodes (LEDs) to examine effect of light quality on their growth and fatty acid production in 0.4-L bubble column photobioreactors. Fluorescent lamps were also used as polychromatic light sources (control). From the results, biomass productivity was varied by light wavelength from 0.05 g/L/day to 0.30 g/L/day. Maximum biomass productivity was obtained from red LED among tested ones. We also observed that contents of oleic acid and linolenic acid, which affect biodiesel properties, were significantly changed depending on supplied wavelength. These results indicated that production of algal biomass, and fatty acid content and productivity could be improved or controlled by supplying specific light wavelength.

• The Korean Journal of Mycology
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• v.34 no.1
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• pp.1-6
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• 2006

In order to select a suitable bioreactor type for the submerged cultivation of Ganoderma applanatum, both growth characteristics and polysaccharides production were compared among four different types of bioreactor. These include an external-loop type air-lift bioreactor (ETAB), a balloon type air bubble bioreactor (BTBB), a column type air bubble bioreactor (CTBB) and a stirrer type bioreactor (STB). The mycelial biomass produced from the reactors were in decreasing order: ETAB ($7\;g/{\ell}$) > BTBB ($6.2\;g/{\ell}$) > STB ($6\;g/{\ell}$) > CTBB ($5\;g/{\ell}$). Maximal soluble exopolysaccharides ($1\;g/{\ell}$) and endopolysaccharides (2.7%) were also obtained from ETAB. Thus, the ETAB was most suitable for submerged culture of G applanatum mycelium. Based on the results, ETAB was chosen for further detailed study. The most effective aeration rate for the mycelial growth in ETAB ranged from 0.05 to 0.1 vvm. For the maximal production, the mycelium at the initial growth stage needed low aeration rate to reduce cell damages by fluid flow. However, as the mycelia grew, the culture became viscous and thus needed higher aeration. The molecular weight of exopolysaccharides obtained from the culture grown in ETAB was higher than that from the culture grown in other bioreactors.

• KSBB Journal
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• v.8 no.5
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• pp.495-503
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• 1993

To investigate the characteristics of growth and oil production of peppermint cells during a batch culture, cells derived from peppermint callus was cultivated in an air bubble reactor. During the batch culture, effects of inoculum size, abiotic stress, yeast elicitor, and two stage culture on the cell growth, the productivity of oleolesin, and the formation of flavor components were determined and also the sugar concentrations and kinetics of cell growth were analyzed. Among the various sizes of inoculum, the culture with 2.0% packed cell volume inoculum showed the optimum condition for cell growth in the proposed bioreactor, and the cell yield and essential oil production reached to 5.7g/1 and 0.109g/1, respectively. When the abiotic stress of daily 8hr dark and $10^{\circ}C$ cold treatments were given to the culture cell growth decreased but essential oil production increased to 0.546g/l. In a modified Lin-Staba medium in which 100mg/l yeast extract as an elicitor was added to the culture, the cell growth and oil production increased, and menthol content was 22.5% of oil. In the two stage culture, in which the basic culture conditions of 27$^{\circ}C$, light, and without elicitor were employed during the first six days followed by the second stage with daily 8hr treatment of cold and dark condition, and also with yeast extract as an elicitor, cell growth decreased after eight days, essential oil production was not increased, and menthol was not detected. Dry cell yield was 0.38g dry cell/g sugar and specific growth rate was 0.25 day-1. The major terpenoid in the oil was not the menthol but pulegone and piperitone, precursors of menthol were accumulated. However, when yeast elicitor was added, menthol was produced to the level of 22.5% which was the highest value in the peppermint cell culture reported so far.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1890-1896
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• 2006

Lumostatic operation for cultivation of Haematococcus pluvialis was assessed to test the scale-up strategy of photobioreactors. Lumostatic operation is a method of maintaining a proper light condition based on the specific light uptake rate ($q_e$), by cells. Lumostatic operations were performed in 0.4-, 2-, 10-, and 30-1 scale bubble column photobioreactors and the results were compared with cultures illuminated with constant light intensity. Significant differences were observed in the maximal cell concentrations obtained from 0.4-, 2-, 10-, and 30-1 scale photobioreactors under constant light intensity, yielding the maximal cell concentrations of $2.8{\times}10^5$, $2.2\times10^5$, $1.5\times10^5$, and $1.1\times10^5$ cells/ml, respectively. The maximal cell concentration in a 0.4-1 photobioreactor under lumostatic operation was $4.3\times10^5$ cells/ml. Furthermore, those in 2-, 10-, and 30-1 scale photobioreactors were about the same as that in the 0.4-1 photobioreactor. The results suggest that lumostatic operation with proper $q_e$ is a good strategy for increasing the cell growth of Haematococcus pluvialis compared with a constant supply of light energy. Therefore, lumostatic operation is not only an efficient way to achieve high cell density cultures with minimal power consumption in microalgal cultures but it is also a perfect parameter for the scale-up of photobioreactors.

• The Korean Journal of Mycology
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• v.35 no.1
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• pp.37-42
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• 2007

The mushroom Lentinus lepideus was used to produce mycelial as well as soluble polysaccharides in bioreactor cultures. To determine optimal submerged culture conditions, both growth characteristics and water soluble polysaccharides production were compared among four different types of bioreactor and culture conditions. For the production of mycelial biomass, the following bioreactors were proven to be effective in decreasing order: an external-loop type air-lift bioreactor (ETAB; 7g/l), a balloon type air bubble bioreactor (BTBB; 6.2g/l), a stirrer type bioreactor (STB; 6g/l), and a column type air bubble bioreactor (CTBB; 5g/l). Maxiaml production of water soluble exopolysaccharides (EPS; 0.62g/l) and endopolysaccharides (PPS; 7.7%) could also be obtained from BTBB. The mycelial biomass increased with increase in glucose concentration from 15g/l to 75g/l in the media. In contrast, PPS contents in the cells decreased with increase in glucose concentration in the media, showing the highest PPS content (7%) at 15g/l. Among different medium feeding types, fed-batch culture based on concentration control in media (10g/l) produced higher mycelia than fed-batch culture based on volume control of media (5.8g/l) or batch culture (3.4g/l). EPS production was also higher in fed-batch culture based on medium concentration control than that in other feeding types.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.112-115
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• 2002

The green colonial algae Botryococcus braunii is characterized by unusual high hydrocarbon contents, ranging from 15 to 75% of dry weight, as long-chain unsaturated hydrocarbons. In two-phase bubble column using various organic solvents, poor recovery 08 - 32%) of hydrocarbon seems to be caused by insufficient mixing between two phases, which was operated using only aeration on the narrow interface between hydrophobic solvent and cell suspension. In addition, hydrocarbon was entrapped tightly in cell-matrix (formed by exopolysaccharide) of algal colony, which make difficult to extract using two-phase system. To improve recovery efficiency, mixed-solvent of extractive solvent (octane) and biocompatible solvent (octane) was tested in two-phase column for in situ extraction. In two-phase extraction culture using mixed-solvent, the algal growth was intensely inhibited even at low concentration of polar octanol solvent. the hydrocarbon recovery in two-stage cell-recycle extraction showed a 2.9 fold increase (57%) over that in two-phase extraction. Up to 60 % of hydrocarbon could be recovered without serious cell-damage in the case of downstream separation for 6 h at the high recycle flow rate using this process after batch culture.