• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.72-78
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• 2003

In the process of producing chitosan from crustacean shell, the use of excessive acid and alkli is causing the problems of environmental pollution and of production cost. In this study, one way to solve these problems is to cultivate fungi, then, to extract chitosan from the cell wall. By means of flask incubation and batch cultivation, the optimum cultivation conditions for mass production of continuous cultivation was found. Four strains used for the production of fungal chitosan were Gongronella butleri IF08080, Absidia coerulea IF05301, Rhizopus delemar IF04775, Mucor tuberculisporus IF09256. In flask incubation to select strain of producing much chitosan by means of experiment of the effect of initial pH, Absidia coerulea IFO 5301 had highest yield in FCs, 258.1 $\pm$ 47.3 mg/200 $m\ell$l at pH 6.5. In flask incubation under the optimum cultivation condition, temperature 27$^{\circ}C$, culture time 6days, glucose 2%, peptone 1%, (NH$_4$)$_2$ SO$_4$ 0.5%, $K_2$HPO$_4$ 0.1 %, Nacl 0.1 %, MgSO$_4$ㆍ7$H_2O$ 0.05%, CaCl$_2$ㆍ2$H_2O$ 0.01 %, the yield of DCW brought the highest yields. In batch bioreactor, the optimum cultivation condition was that cell suspended solution was 70 $m\ell$, aeration rate 0.5 l/min, agitation rate 800 rpm, culture time 36 hr. In continuous bioreactor, the optimum substrate flow rate was 4 ι/day.

• Journal of Plant Biology
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• v.34 no.4
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• pp.289-296
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• 1991

Cultures of hairy root induced from ginseng(Panax C.A. Meyer) transformed with Agrobacterium rhizogenes (strain A4, ATCC 15834) were established and morphologically two different hairy root strains (HB1, HB2) were obtained. To determine the optimum growth rate, the hairy root (HB2) was cultured in various liquid medium supplemented with or without plant growth hormone. The growth rate of hairy root cultured on MS medium was 1.3-3.1 times higher than those cultured on other media, and the optimum sucrose concentration and pH were 3-6%, 5.5-6.5, respectively. Also, the growth rate of hairy root was increased when 0.02 M ammonium nitrate, 1.2 mM potassium phosphate (monobasic) and 0.5 mg/l IBA were supplied to liquid medium. The saponin patterns and contents of hairy root (HB2) were determined by TLC and HPLC. The crude saponin contents were 4.67% and the total saponin contents were 1.0%, on dry weight basis.

• The Korean Journal of Mycology
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• v.25 no.1 s.80
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• pp.30-34
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• 1997

Glomerella cingulata (conidial state: Colletotrichum gloeosporioides) was identified as the causal organism of anthracnose of citrus on the basis of morphological characteristics of the conidial state of the fungus isolated from infected leaves of Satsuma mandarin and its ascigerous state isolated from diseased twigs. The pathogen infected the leaves of Satsuma mandarin, citron and Natsu daidai only by wound inoculation. The optimum temperature range for mycelial growth and sporulation of conidia of the strain was $25{\sim}30^{\circ}C$, respectively. The characteristics of anthracnose strain of Satsuma mandarin such as growth rate and color of colony, shape and size of conidia, and appressoria were similar to those of FGG strain. However, the strain isolated from infected leaves and twigs of Satsuma mandarin was different from FGG strain to cause postharvest anthracnose of citrus, because some of morphological and pathological characteristics of the strain isolated did not correspond to those of FGG strain.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.73-85
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• 1997

The rolling force and roll deformation behavior in the twin roll type strip continuous casting process has been computed to estimate the thermal charcteristics of a caster roll. To calculation of rolling force, the relationship between flow stress and strain for a roll material and casting alloy are assumed as a function of strain-rate and temperature because mechanical properties of a casting materials depends on tempera- ture. The three dimensional thermal dlastic-plastic analysis of a cooling roll has also been carried out to obtain a roll stress and plastic strain distributions with the commercial finite element analysis package of ANSYS. Temperature fields data of caster roll which are provided by authors were used to estimated of roll deformation. Roll life considering thermal cycle is calculated by using thermal elastic-plastic analysis results. Roll life is proposed as a terms of a roll revolution in the caster roll with and without fine failure model on the roll surface. To obtain of plastic strain distributions of caster roll, thermomechan- ical properties of roll sleeve with a copper alloy is obtained by uniaxial tensile test for variation of temperature.

• The Plant Pathology Journal
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• v.24 no.3
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• pp.309-316
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• 2008

Mycelium of Ophiostoma quercus albino strain cultured in liquid culture media was harvested, lyophilized, and stored for examining biocontrol efficacy against wood discoloration by staining fungi in the laboratory and field conditions. Dry weight of mycelium grown in brown sugar yeast extract broth(BYB) showed 3.8 times higher than that grown in potato dextrose broth(PDB). The optimum culture period in BYB was 4 weeks. In vitality test of the albino strain, the lyophilized mycelium stored in liquid nitrogen($-196^{\circ}C$) or in a refrigerator($4^{\circ}C$) kept the vitality until 13 months after storage; however, the mycelium stored at room temperature lost the vitality completely after 13 months. The mycelium stored in liquid nitrogen or in a refrigerator protected wood chips from the discoloration by pretreating mycelial suspension on pine wood chips. The mycelium stored at room temperature for 7 months also showed complete protection. These results suggest that the lyophilized mycelium have a biocontrol efficacy only if it keeps the least vitality. In the field conditions, both albino strain and $Woodguard^{(R)}$(commercial chemical protectant) showed significant differences(p=0.05) in discoloration rate as compared to the non-treated control when these were treated on the wood logs of Pinus rigida. The albino strain showed better protection than $Woodguard^{(R)}$. Isolation frequency of blue stain fungi from the chips of wood logs treated with the albino strain was 0% at three months after treatment, while that treated with $Woodguard^{(R)}$ was 76.7%. In another experiment, pre-treatment of mycelial suspension on the cut surface of wood logs also showed significant protection from wood discoloration. Spraying of both albino strain on the cut surface and insecticides on the bark also showed relatively good control effects as compared to insecticide alone on the bark or nontreated control.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.87-90
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• 2008

Since fastener bolt for airplane require high specific strength and corrosion resistance, Ti-6Al-4V alloy is widely used. However, the Ti-6Al-4V bolt is generally manufactured by cutting and rolling because of their poor workability. The aim of present work is to develop hot forming technology for high strength Ti-6Al-4V. Various heat-treatments were applied to specimen in order to increase hot-workability and prevent galling with die Multiple forging were simulated with FE code to determine optimum process parameters including specimen temperature, strain rate, local strain, and thermal shrinkage. Forged samples were heat-treated again to increase their mechanical properties.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.328-331
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• 2009

Microstructural evolution of alpha and beta phases during dynamic globularization of near-beta Ti-13Nb-13Zr alloy was investigated to determine the optimum processing conditions. The submicrocrystalline alloy sheet with ${\sim}80%$ of high-angle grain boundaries was produced utilizing dynamic globularization at temperature of $600^{\circ}C$, equivalent strain rate of $10^{-1}\;s^{-1}$ and strain of 1.4. The refined structure with the gain size of ${\sim}0.4{\mu}m$ showed 25-60% enhanced mechanical compatibility as compared to those of the conventional mill-annealed or solution treated and aged microstructures.

• Microbiology and Biotechnology Letters
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• v.27 no.6
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• pp.452-457
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• 1999

Several bacterial strains utilizing crude oil as their sole carbon and energy sources were isolated from marine. One of the strains named KCL-1 showed the highest degradative activity for crude oil and the best growth rate. This strain was identified as a Klebsiella sp. based on the morphological, biochemical, and physiological characteristics. The optimum cultural conditions were as follows; $32^{\circ}C$~$37^{\circ}C$ for temperature and 7.0 for initial pH. Additionally, the optimal concentration of sodium chloride was 3.0%, indicating that this strain was derived from seawater. KCL-1 could use several kinds of n-alkane hydrocarbons from octadecane to hexacosane as a sole carbon source. The degradation of crude oil by KCL-1 was stimulated by addition of octadecane in the culture. The emulsifying activity by KCL-1 was highest after 3 days of cultivation under the condition of 3.0% sodium chloride, pH 7.0 and $37^{\circ}C$.

• Transactions of Materials Processing
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• v.18 no.3
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• pp.251-255
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• 2009

Since fastener bolt for airplane require high specific strength and corrosion resistance, Ti-6Al-4V alloy is widely used. However, the Ti-6Al-4V bolt is generally manufactured by cutting and rolling because of their poor workability. The aim of present work is to develop hot forming technology for high strength Ti-6Al-4V. Various heat-treatments were applied to specimen in order to increase hot-workability and prevent galling with die. Multiple forging were simulated with FE code to determine optimum process parameters including specimen temperature, strain rate, local strain, and thermal shrinkage. Forged samples were heat-treated again to increase their mechanical properties.

• Transactions of Materials Processing
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• v.11 no.6
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• pp.538-546
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• 2002

Hot deformation behavior of Udiment720Li was characterized by compression tests in the temperature range of 10$25^{\circ}C$ to 115$0^{\circ}C$ and the strain rate range of $0.0005 s^{-1};to;5 s^{-1}$. The combination of dynamic material model (DMM) and Ziegler's instability criterion was applied to predict an optimum condition and unstable regions for hot forming. A dynamic recrystallization model coupled with FEM results was used to interpret the evolution of microstructures. In order to verify the reliability of the present coupled model, isothermal forging was performed in the temperature range 1050~115$0^{\circ}C$ at strain rates of $0.05 s^{-1};and;0.005 s^{-1}$. The present model was successfully applied to the hot forming process of Udimet720Li.