• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.695-703
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• 2006

The dissolved oxygen level of any cell culture environment has a critical effect on cellular metabolism. Specifically, hypoxia condition decreases cell viability and recombinant protein productivity. In this work, to develop CHO cells producing recombinant protein with high productivity, mammalian expression vectors containing a human tissue-type plasminogen activator (t-PA) gene with hypoxia response element (HRE) were constructed and stably transfected into CHO cells. CHO/2HRE-t-PA cells produced 2-folds higher recombinant t-PA production than CHO/t-PA cells in a $Ba^{2+}-alginate$ immobilized culture, and 16.8-folds in a repeated batch culture. In a non-aerated batch culture of suspension-adapted cells, t-PA productivity of CHO/2HRE/t-PA cells was 4.2-folds higher than that of CHO/t-PA cells. Our results indicate that HRE is a useful tool for the enhancement of protein productivity in mammalian cell cultures.

• Microbiology and Biotechnology Letters
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• v.17 no.2
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• pp.165-169
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• 1989

To achieve higher ethanol productivity in the fermentation system, a continuous ethanol production has been investigated with the air-supplement in a packed-bed immobilized cell reactor system. Yeast cells were immobilized using sodium alginate gel. The results showed that, when the feed medium was saturated with oxygen through aeration into the medium reservoir, the maximum ethanol productivity of the reactor was enhanced from 35 g/$\ell$-gel-hr to 55 g/$\ell$-gel-hr at the residence time of 10-20 min. and the residence time for the 90% conversion of substrate to ethanol was reduced from 40 min. to 25 min. In case of 18% glucose medium, the maximum productivity was increased from 35 g/$\ell$-gel-hr to 45 g/$\ell$-gel-hr and time required for 90% conversion was from 90 min to 70 min. This behavior of air-supplemented reactor system might be due to the fact that both growth and viable fraction of yeast within the Eel were increased during reactor operation.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.210-216
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• 2021

This study aimed to enhance ethanol productivity of Saccharomyces cerevisiae through genome editing using CRISPR/CAS9. To increase ethanol productivity, ACC1, ELO1, and OLE1 were overexpressed in S. cerevisiae using the CRISPR/CAS9 system. The strains overexpressing ACC1, ELO1, and OLE1 survived up to 24 h in YPD medium supplemented with 18% ethanol. Moreover, the ethanol yields in strains overexpressing ACC1 (428.18 mg ethanol/g glucose), ELO1 (416.15 mg ethanol/g glucose), and OLE1 (430.55 mg ethanol/g glucose) were higher than those in the control strains (400.26 mg ethanol/g glucose). In conclusion, the overexpression of these genes increased the viability of S. cerevisiae at high ethanol concentrations and the ethanol productivity without suppressing glucose consumption.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.05a
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• pp.265-270
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• 1998

As the goal of enterprises is to pursuit benefits, the goal of safety management is not only preventing accidents but also promoting benefits and productivity. However, enterprises have failed to realize the necessity of safety management, partly because they didn't grasp any appropriate evidences advocating effectiveness of safety management. This study aimed to survey construction-site engineers' consciousness on safety management contributing to cost reduction, construction period and quality enhancement. The result of this study showed that constriction-site engineers recognized the ratio of direct cost to Indirect cost as 1:2. The proportion of repliers who thought that safety management is contributable to cost reduction was 35％, to construction period was 20％, and to quality enhancement was 48％. The construction sites with excellent safety accomplisments also had good work and selling amounts.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.917-921
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• 2000

One of the major limitations of productivity and quality in machining is machining accuracy of the machine tools. The machining accuracy is affected by geometric, volumetric errors of the machine tools. This paper suggests the enhancement method of machining accuracy for precision machining of high quality metal reflection mirror or optics lens, etc. In this paper, we study 1) the compensation of linear pitch error with NC controller compensation function using laser interferometer measurement, 2) the method for enhancing the accuracy of NC milling machining by modeling and compensation of volumetric error, 3) the generation of the parabolic face profile. And the method is verified by the parabolic face machining experiment with a vertical three axes NC milling machine. After this study, we will inspect using On-machine measurement and study the repetitive machining by a compensated path

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2116-2124
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• 2015

To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO₃ concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m²/s; temperature: 30℃ pH: 7-8; NaHCO₃ concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R² = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NO_X.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.63-65
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• 2001

• The Journal of Information Technology and Database
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• v.4 no.1
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• pp.117-128
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• 1997

본 논문에서는 소프트웨어 개발 프로제트의 수행시 당면하고 있는 문제들 - 납기지연, 개발예산 초과, 수정 및 변경시 관리상의 어려움 등 -을 해결하는데 상당한 도움을 줄 수 있는 한국적 프로젝트 개발방법론 관리방법론과 이와 연계된 마르미 지원도구를 소개하였다. 소개되어진 방법론과 지원도구는 국내 소프트웨어 개발 프로젝트의 생산성 및 품질향상에 중요한 기여를 할 것으로 기대되며, 궁극적으로 국내 소프트웨어 산업의 경쟁력 향상에 큰 역할을 할 것으로 기대된다.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.322-325
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• 2001

기업 내 관련 업무 및 조직의 유기적 연결을 통한 원활한 정보의 흐름은 생산성의 증대에 많은 영향을 주며 기업의 경쟁력과도 밀접한 관계가 있다. 이러한 이유로 연구개발에서부터 설계, 제조, 판매에 이르기까지 컴퓨터와 통신기술을 활용하여 기업의 업무 흐름을 통합적으로 관리할 수 있는 컴퓨터 시스템이 필요하다. 그러나 기업 내 업무의 성격 및 규모, 어플리케이션 튜닝 등의 충분한 검토가 수행되지 않은 컴퓨팅 시스템은 개발비용의 부담과 더불어 시스템의 성능을 오히려 저하시킬 수 있다 본 논문은 생산 제조 업체의 업무의 성격과 환경에 적합하고 업무의 흐름을 유기적으로 통합 관리할 수 있는 클라이언트/서버 기반 생산 관리 시스템을 설계 및 구현하였다.

• 한국IT서비스학회:학술대회논문집
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• 2006.05a
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• pp.430-438
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• 2006

대부분의 기업은 다양한 환경의 IT자원과 Application들을 운영해 왔으며, Point to Point 수준의 인터페이스를 개발 또는 운영해오다, 몇 년 전부터 전사적인 인터페이스 표준으로서 EAI(Enterprise Application Integration)을 도입해 왔다. 그러나 EAI를 도입한 대부분의 기업은 EAI도입 당시 기대한 ROI(Return of Investment)의 효과를 보지 못해왔으며, EAI개발 및 유지보수를 위한 비용이 적절한지 한번쯤 고민해 왔을 것이다. 본고는 SK텔레콤 EAI를 약 4년 이상 개발 및 운영경험과 사례를 기준으로 효과적인 EAI개발 및 운영 생산성을 향상 방안을 제안하고자 한다.