• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.722-728
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• 2002

Eight strains producing bacterial cellulose (BC) were isolated from rotten fruits and traditionally fermented vinegars. One of the isolated strains from the rotten grape in Gwangju, Korea, maintained a relatively stable BC production in shaking cultures. This isolated strain proved to be Acetobacter xylinum, based on several biochemical and morphological tests. It was shown that the slant-baffled flask was more efficient than the conventional flask for the BC production in shaking cultures. To determine the most suitable carbon and nitrogen sources for the production of BC, various compounds were examined. Fructose was found to be the most effective carbon source with an optimal concentration of 2%. Mixed carbon source (glucose:fructose=1:3) was also better than glucose or fructose alone. Optimal nitrogen source, when basal medium was used, was 10% (v/v) com steep liquor (CSL). When com steep liquor was used with a mixed carbon source (glucose:fructose=1 :3),4% CSL exhibited the best BC production. Based on these results, a defined medium was developed for the BC production by Acetobacter xylinum KJ-1. When this medium was used under optimal culture conditions, the BC production was 7.2 g/1, which was approximately 3 times higher than that with the traditional HS medium.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.61-61
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• 2003

We have cloned the CGR1 gene encoding glutathione reductase (GR) which catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) from Candida albicans. The cgr1/cgr1 mutants were not viable when CaMAL2 promoter repressed the CGR1 expression. The growth of the mutants could be partially overcome by thiol compounds such as GSH, dithiothreitol, cysteine, N-acetylcysteine and GSSG. Interestingly, C. albicans with CGR1 overexpressed showed defective hyphal growth on solid medium and attenuated virulence. We have also cloned the GCS1 gene encoding ${\gamma}$-glutamylcysteine synthetase which catalyzes the first step of glutathione biosynthesis. The gcs1/gcs1 mutants were nonviable in minimal defined medium. The growth of the mutants could be resumed by supplementing with GSH, GSSG and ${\gamma}$-glutamylcysteine in the medium. The mutants had increased intracellular D-erythroascorbic acid level up to 2.25-fold when transferred to GSH-free medium. When the mutants were depleted of GSH, they showed typical markers of apoptosis. In conclusion, these results suggest that glutathione is an essential metabolite, and involved in hyphal growth, virulence and apoptosis in C. albicans.

• 대한기계학회논문집A
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• 제20권4호
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• pp.1275-1289
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• 1996

The plane elasticity problem of collinear cracks in a layered medium is investigated. The medium is modeled as bonded structure constituted from a surface layer and a semi-infinite substrate. Along the bond line between the two dissimilar homegeneous constituents, it is assumed that as interfacial zone having the functionally graded, nonhomogeneous elastic modulus exists. The layered medium contains three collinear cracks, one in each constituent material oriented perpendicular to the nominal interfaces. The stiffness matrix formulation is utilized and a set of homogeneous conditions relevant to the given problem is readily satisfied. The proposed mixed boundary value problem is then represented in the form of a system of integral equations with Cauchy-type singular kernels. The stress intensity factors are defined from the crack-tip stress fields possessing the standard square-root singular behavior. The resulting values of stress intensity factors mainly address the interactions among the cracks for various crack sizes and material combinations.

• 한국가축번식학회지
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• 제19권4호
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• pp.259-264
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• 1996

This study was carried out to investigate on the survival rates and in vitro developmental rates of bisected bovine embryos were by manipulator and micropipette. Bisected embryos were co-cultured in 20% FCS(v/v)＋TCM-199 media containing hormones, oviductal epithelial cells and cumulus cells 0 to 72 hrs after bisection. Survival rate and in vitro fertilization rate were defined as development rate on in vitro culture or FDA-test. The results are summarized as follows ; 1. The in vitro developmental rate of biseciton embryos co-cultured in 20% FCS＋TCM-199 medium containing PMSG, hCG, PMSG＋hCG, hCG＋$\beta$-estradiol 0 to 20 hrs and 20 to 40 hrs were 36.7, 26.7, 33.3, 40.0, and 30.0, and 30.0, 33.3, 30.0, 26.7, and 26.7%, respectively. The survival rate of bisection embryos co-cultured in TCM-199 medium containing hormones was significantly higher than that of non co-culture(25.0%). 2. The in vitro developmental rates of bisection embryos co-cultured in 20% FCS＋TCM-199 medium containing oviductal epithelial cells 4 to 5 hrs and 20 to 24 hrs were 40.0 and 33.3%, respectively. The survival rate of bisection embryos co-cultured in TCM-199 medium containing oviductal epithelial cells was significantly higher than that of non co-culture(25.0%). 3. The in vitro developmental rates of bisection embryos co-cultured in 20% FCS＋TCM-199 medium containing cumulus cells 4 to 5 hrs and 20 to 24 hrs were 43.3 and 36.7%, respectively. The survival rate of bisection embryos co-cultured in TCM-199 medium containing cumulus cells was significantly higher than that of non co-culture (25.0%).

• Archives of Pharmacal Research
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• 제20권4호
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• pp.297-305
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• 1997

A new serum-free defined medium was developed that supports the growth of normal rat mammary epithelial cells. Mammary organoids from the glands of female F344 rats were cultured in a serum-free medium. Monolayer culture colonies developed within a week and remained viable for months in culture. Upon subculture of one-week-old primary colonies, almost the same morphology of colonies was developed. The scrape loading/dye transfer technique showed that most of colonies that developed in a serum-free medium containing EGF, human transferrin, insulin, and hydrocortisone (basal serum-free medium, BSFM) failed to show cell-cell communication. However, colonies cultured in BSFM supplemented with prolactin, $E_2$, and progesterone (complete hormone serum-free medium, CHSFM) showed cell-cell communication at 14 days of primary culture or of subculture. By flow cytometry with FITCPNA and PE-anti-Thy-1.1 monoclonal antibody, we distinguished four RMEC subpopulations in cultures in both media: Thy-1.1+ cells, PNA+ cells, cells negative to both reagents and cells positive to both reagents. It is likely that combined prolactin, cortisol, and insulin in CHSFM stimulate terminal differentiation of clonogenic cells.

• 한국가축번식학회지
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• 제17권4호
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• pp.271-278
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• 1994

The aim of this study was to compare the two culture systems 1) co-culture with cumulus cells and 2) chemically defined medium supplemented with amino acids (CR1aa) and fetal calf serum (FCS) of in vitro produced bovine embryos from follicular oocytes in vitro. Bovine follicular oocytes were collected from ovaries of slaughtered cows and matured in TCM199 supplemented with 10% FCS and hormones (1$\mu\textrm{g}$/ml FSH-P and 1$\mu\textrm{g}$/ml oestradiol-17$\beta$)24 hours at 39$^{\circ}C$ under 5% CO2 in air. The capacitation of spermatozoa from ejaculated or frozen bull semen was induced by centrifugation through Percoll density gradient (45%, 90%). Then capacitated spermatozoa (1$\times$106/ml) were inseminated into 50${mu}ell$ droplet containing matured follicular oocytes and incubated for 40~42 hours. Cleaved embryos of 2~4cell stage were transferred to the co-culture with cumulus cells and/or CR1aa medium supplemented with FCS. In semen source, the developmental rates to the blastocyst and the hatched blastocyst stages were higher in ejaculated semen(27.6% and 14.9%) than those of frozen-thawed semen(18.3% and 11.8%), respectively. In two culture systems, the proportions of embryonic development upto the blastocysts and the hatched blastocysts were higher of CR1aa medium (22.1% and 12.1%) than those of cumulus cell co-culture (16.8% and 5.1%), respectively. The number of cells in exapnded blastocysts was slightly higher in cumulus cells co-culture (122.6$\pm$8.5) than that in CR1aa medium (117.9$\pm$5.9). The present results indicated that the early development of in vitro produced bovine embryos can be maintained efficiently in CR1aa medium as well as in co-culture with cumulus cells.

• 한국수정란이식학회지
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• 제13권3호
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• pp.235-243
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• 1998

적정 배양액의 선정, ITS의 첨가와 BSA의 농도조절 및 NaCl 농도의 조절을 통해 소 수정란의 무혈청, 체세포배제 배양체계를 확립하기 위하여 수행한 실험에서 다음과 같은 결론을 얻었다. 1. 배양액으로 CRlaa, TALP 및 SOF를 사용하여 발육률을 검토한 결과, 발육률의 유의적인 차이는 나타나지 않았다. 2. 배양액내의 고분자물질원으로 BSA, FBS 및 PVA를 첨가하여 사용한 결과 BSA 및 FBS 첨가군이 PVA 첨가군보다 유의적으로 높은 발육률을 나타내었다(p〈0.01). 3. 배양액내의 BSA 농도를 달리 하면서(1, 3, 8 mg/ml) 1% ITS를 첨가하여 실험한 결과 BSA의 농도가 증가할수록 후기배로의 발육률이 높았으며 모든 군에서 ITS 첨가군이 후기배로의 발육률이 높았으나 BSA가 1 mg/ml로 첨가된 군에서만 ITS 첨가에 따른 유의적인 차이가 인정되었다(p〈0.05). 4. 배양액내의 N3Cl 농도를 114 mM과 90 mM 로 나누어 소 수정란을 배양한 결과 90 mM 군의 후기배로의 발육률이 114 mM 군에 비해 유의적으로 높게 나타났다(p〈0.05).

• 생명과학회지
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• 제6권3호
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• pp.204-212
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• 1996

본 연구는 포유동물 수정란의 체외발생에 인, 아미노산과 BSA가 미치는 영향을 조사하기 위하여 체외성숙 및 수정된 소의 수정란을 한정 무단백 배양액에서 배양하였다. 배양액에 포함된 인의 농도를 0.00, 0.10. 0.35, 1.05와 2.10mM로 조정하였을 때 0.00부터 1.05mM 농도에서는 수정후 48시간 까지 수정란 발생에 영향을 미치지 않았고, 수정후 96시간과 114에서의 8세포기와 상실배 발생이 0.35mM에서 유의적(P<0.05)으로 붕가하였다. 19종 아미노산의 첨가는 수정후 96, 144, 192시간에 각각8세포기(49-50%), 상실배(38-40%), 배반포(29-32%)발생을 유의적(P<0.05)으로 증가하였으나, glutamine단독 첨가는 영향이 없었다. BSA첨가는 첨가시간에 관계없이 수정후 48, 96, 144, 192시간에서 각각 2세포기, 8세포기, 상실배와 배반포의 발생을 증가시켰다.

• 벤처창업연구
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• 제7권2호
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• pp.19-24
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• 2012

본 연구는 중소기업 융합개념과 융합유형을 명확히 정립하고 중소기업 융합 사례를 유형별로 파악하여 융합을 통한 중소기업 경쟁력 증대에 도움이 되고자 하였다. 중소기업 융합유형은 Deloitte(2009)에서 제시한 기술과 산업, 가치개선과 창출 2가지 차원을 수용하여 기술은 투입, 산업은 산출의 차원에서 정의하여 중소기업 융합을 기술개선-시장확대형, 기술개선-시장창출형, 기술창출-시장확대형, 기술창출-시장창출형 4가지로 나누고 중소기업 융복합기술개발사업 우수사례집('11년 8월)에 소개된 기업들을 중심으로 융합유형을 분류하였다. 그 결과, 전체 13개의 사례 중 기술개선-시장확대형 5개, 기술개선-시장창출형 4개, 기술창출-시장확대형 3개, 기술창출-시장창출형 1개 순으로 나타나 중소기업의 경우 기술창출 보다는 기술개선에, 시장창출보다는 시장확대에 초점을 두고 융합이 이루어지고 있었다. 이러한 중소기업 융합 유형별 사례분석을 통해 파악할 수 있는 것은 중소기업이 융합을 통한 신기술이나 신시장을 창출하는 것이 매우 어렵다는 것이다. 따라서 중소기업은 기술개선을 통한 시장확대를 융합의 목표와 결과로 생각하고 있는 것으로 추정된다. 국가의 신성장동력을 육성하기 위해서 신기술이나 신산업 창출도 중요하지만 중소기업의 현실을 고려한 정책지원도 함께 고려해야 한다.

• 한국식품영양과학회지
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• 제24권4호
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• pp.582-586
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• 1995

The effects of cultural temperature and nutritional components on the production of ethanol using juice of Pyrus serotina as the substrate for Saccharomyces cerevisiae ATCC 4124 were studied. After anaerobic cultivation in 5L flask of a defined pear juice at 2$0^{\circ}C$, ethanol concentration of 11.5%(v/v) could be obtained. The addition of a small amount of K2S2O5 was essential for the successful production of ethanol. Ethanol concentration could be further enhanced by supplementing a small of various complex nitrogen sources. When 0.05% of yeast extract and 0.05% of (NH4)2HPO4 were added to a defined medium, ethanol concentration obtained after 7 day cultivation at 2$0^{\circ}C$ was 12.3%.