• 한국미생물·생명공학회지
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• 제29권2호
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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.

• Journal of Microbiology and Biotechnology
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• 제2권2호
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• pp.129-134
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• 1992

Segregational instability of a recombinant plasmid, pDML6, encoding extracellular $\beta$-lactamase in Streptomyces lividans PD6 was characterized by growth kinetic analysis. The quantitative determination of the plasmid harbored in the mycelia was evaluated with mycelia fragmented mechanically, and also with colonies regenerated from protoplasts. Conditions for the formation of protoplasts and regeneration of protoplasts were established. The maximal specific growth rates of the host strain and the plasmid-harboring strain in a chemically defined medium without selection pressure were the same. The probability of plasmid loss from the harbouring cells was higher at higher growth rates. Mathematical models for the prediction of cell growth, substrate uptake, and accumulation of the cloned gene product were developed.

• 소성∙가공
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• 제13권2호
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• pp.129-136
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• 2004

Recently, instead of a matched die forming method requiring a high cost and long delivery term, a multi-point dieless forming method using a pair of matrix type punch array as flexible dies has been developed. Since the conventional multi-point dieless forming method has some disadvantages of difficulty in precise punch control and high-cost of equipment, a new concept of multi-point dieless forming method combined with an elasto-forming method has been suggested in this study. For optimal selection of elastomers, compression tests of rubbers, polyethylene and foams were carried out together with FEM analysis of the deformation behavior during sheet forming process using a rigid punch and elastomers. Compressive strain was concentrated on the upper central area of the elastomer under the punch, and the rubber exhibited higher concentration of the compressive strain than foams. Two-dimensional curved surface was formed successfully by the multi-point elasto-dieless forming method using an optimal combination of rubber and foam materials.

• 한국유기농업학회지
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• 제6권1호
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• pp.35-43
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• 1997

For the purpose of acquiring microbial agents that can be utilized to billogically control the major airborne disease to apple trees, such as canker(Valsa ceratosperma), the effective microorgaisms were isolated, tested for antagonistic activity to the pathogen causing major disease to apple trees and identifed. Screening of more than 3, 000 species of microorganisms collected in nature for them antagonistic action to the pathogen, Valsa ceratosperma causing disease to apple tree resulted in selection of effective species. Out of the 11 species, one species designated as CAP141 demonstrated outstanding activity. The bacterial strain, CAP141 exerted antagonistic efficiency of 65% on Valsa ceratosperma. The CAP141 was identified as a bacterial strain to Bacillus subtilis based on morphology, culture conditions, and physio-biochemical characteristics.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 제4회 박판성형 심포지엄
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• pp.21-28
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• 2003

Recently, instead of a matched die forming method requiring a high cost and long deliverly ten a multi-point dieless forming method using a pair of matrix type punch array as flexible dies has been developed. As this multi-point dieless forming method has some disadvantage of difficulty in precise punch control and high-cost of equipment, a new concept of multi-point dieless forming method combined with elastomer forming was suggested in this study. For optimal selection of elastomers, compression tests of rubbers, polyethylene and foams were carried out together with FEM analysis of the deformation behavior during sheet forming process using a rigid punch and elastomers. Compressive strain was concentrated on the upper central area of the elastomer under the punch, and the rubber exhibited higher concentration of the compressive strain than foams. Two-dimensional curved surface was formed successfully by the multi-point elasto-dieless forming method using an optimal combination of a rubber and foam.

• 한국정밀공학회지
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• 제15권9호
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• pp.15-24
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• 1998

In this research. we have proposed a new technique to determine .the combination of design parameters for the process design of a hot forged product using artificial neural network(ANN) and statistical design of experiments(DOE). The investigated problem involves the adequate selection of the aspect ratio of billet, the ram velocity and the friction factor as design parameters. An optimal billet satisfying the forming limitation, die filling, load and energy as well as more uniform distribution of effective strain, is determined by applying the ability of artificial neural network and considering the analysis of mean and variation on the functional requirement. This methodology will be helpful in designing and controlling parameters on the shop floor which would yield the best design solution.

• International Journal of Industrial Entomology and Biomaterials
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• 제46권2호
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• pp.55-59
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• 2023

One of the necessary conditions for the mass production of the edible insect, the white-spotted flower chafer Protaetia brevitarsis seulensis (Kolbe), is to breed a strain with excellent egg-laying ability. To identify external morphological traits related to egg-laying ability, we investigated the effects of the weight, length, and width of female adults on egg production. Correlation and multiple regression analyses revealed a positive correlation between the weight of female adults and egg production. This study suggests that selection of heavier females is a good strategy for breeding strains with superior egg-laying characteristics. The results of this study will serve as important foundational data for future breeding of superior strains.

• Archives of Pharmacal Research
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• 제12권4호
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• pp.249-253
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• 1989

High producers or blocked mutants of aminoglycoside antibiotic-producing Streptomyces spp. were selected by application of an agar plug method and by culturing individual colonies in broth. The productivities of aminoglycoside antibiotic producing organisms were increased by selection of a high producer from colonies obtained by spreading spores of wild strain, or survived from treatment of a mutagen or from the colonies regenerated from protoplast-formation and cell-wall regenerations. Some mutagen treated colonies lost the ability to produce antibiotics (5-8%). Some A-factor negative and deostreptamine or streptidine negative mutants were obtained by N-methyl-N'-nitro-N-nitrosomethylguanidine (MNNG) treatment. Many of the survivors from the MNNG treatment lost the ability to produce antibiotics. Major colonies produced less amount of antibiotics ; only few survived colonies produced more antibiotics than the parent. Resistance of Streptomyces spp. against the antibiotics produced by itself was also markedly affected by mutagen treatment.

• Journal of Microbiology and Biotechnology
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• 제18권3호
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• pp.483-489
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• 2008

Nine newly isolated mushroom strains were tested to assess both their zinc tolerance and potential for zinc removal from an aqueous solution. Four strains of ectomycorrhizal fungi, namely Clavariadelphus truncatus (T 192), Rhizopogon roseolus (T 21), Lepista nuda (T 373), and Tricholoma equestre (T 174), along with five strains of white rot fungi, Lenzites betulina (S 2), Trametes hirsuta (T 587), Ganoderma spp. (T 99), Polyporus arcularius (T 438), and Ganoderma carnosum (M 88), were investigated using zinc-amended solid and liquid media. Their biosorption properties were also determined. The colony diameter and dry weight were used as tolerance indices for fungal growth. C. truncatus and T. equestre were not strongly inhibited at the highest concentrations of (225 mg/l) zinc in solid media. The most tolerant four strains with solid media, C. truncatus, G carnosum, T. hirsuta, and T. equestre, were then chosen for tolerance tests in liquid media. An ectomycorrhizal strain, C. truncatus, was also detected as the most tolerant strain in liquid media. However, the metal-tolerant strains demonstrated weak activity in the biosorption studies. In contrast, the highest biosorption activity was presented by a more sensitive strain, G. carnosum. In addition, seven different biosorbent types from G. carnosum (M 88) were compared for their Zn (II) biosorption in batch experiments.

• Journal of Microbiology and Biotechnology
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• 제5권2호
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• pp.61-67
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• 1995

To investigate the role of induction on CGTase production for alkalophilic Bacillus firm us var. alkalophilus H609, the constitutive mutants that form a halo around its colonies at non-inducible AG agar media containing amylose and glucose were selected. The selected constitutive mutants could produce CGTase in the range of 18.9 to 28.8 units/ml $\cdot A_{600}$ in the alkaline basal medium, and finally a constitutive mutant Bacillus firmus var. alkalophilus CM46 was selected. The constitutive nature of CM46 was also confirmed in protein level using SDS-PAGE. The effects of induction and catabolite repression for both parent strain Bacillus firmus var. alkalophilus H609 and constitutive mutant CM46 were also compared by adding soluble starch and glucose during cultivation. The selected mutant CM46 was a non-inducible but a catabolite regulated type mutant. Even though inductive regulation was released, the specific CGTase activity defined as CGTase activity per cell concentration was not increased compared with that of parent strain. The cell growth and CGTase production patterns of constitutive mutant Bacillus firmus var. alkalophilus CM46 were compared with the parent strain to identify CGTase production characteristics.