Bacillus polymyxa KS - 1 이 생산하는 exopolysaccharide KS - 1 의 생산조건 및 특성

권기석 한국농화학회 1992 Applied Biological Chemistry (Appl Biol Chem) Vol.35 No.5

1942년 Leuconostoc mesenteroides에 의해 균체외로 생산하는 dextran을 blood plasma expander로 개발한 이래 bacteria, yeast, 그리고 mold 등의 다양한 미생물들에 의해 생산되는 다당류에 대한 많은 연구가 되여져 왔다. 자연계로부터 분리한 균주에 의해 생산되는 다당류가 시판중인 다당류와의 대체 또는 새로운 용도로 개발할 목적으로 연구되었다. Czapek medium (glucose 함유)에 0.5g/l의 yeast extract를 첨가하여 토양으로부터 다당류 생산 균주를 다당류의 구성성분을 조사하여 새로운 균주일 가능성이 높고 목적에 적합한 균주를 여러가지 생리학적, 화학적 동정법을 통해 본 결과 분리균주는 Bacillus polymyxa와 아주 근연한 균으로 최종적으로 B. polymyxa KS-1으로 명명하였다. 최적 배양조건은 배양온도 30℃, 초기 pH는 7.0에서 그리고 C/N ratio가 12일 때 균체증식 및 다당류 생산이 우수하였으며, 최적 배지조성에서의 glucose로부터 다당류 환원율은 약 33%이었다. 다당류 KS-1의 구성당의 비는 galactosamine mannose : glucose : galactose가 55 : 51 : 50 : 18의 비를 보인 새로운 다당류로 추정되며, 분자량은 Sepharose 4B를 이용시 peak molecular weight (Mp)는 약 80만에서 130만 dalton의 분자량을 갖는 복합다당류로서, 그 물성학적 성질은 NaCl 그리고 CaCl₂의 첨가 및 농도의 증가에 따라 shear rate에 대한 shear stress가 증가하는 현상을 보였으며, pH 안정성과 열안정성에서는 xanthan gum과는 다른 성질로 관찰되었다. 그 외 melting point, water activity(Aw) 등에서도 기존의 다당류와는 다른 특성을 보였다. 이러한 여러 물성학적 바탕으로 다당류 KS-1의 용도개발에 대한 결과로서 폐수처리 응집제 및 기존의 다당류 및 유화안정제와의 비교시 강한 활성을 갖는 유화 안정제(emulsfier)로 밝혀져 이에 관한 지속적인 연구가 수행되고 있다.

Evolution of Universities and Government Policy: The case of South Korea

권기석 아시아기술혁신학회 2015 Asian Journal of Innovation and Policy Vol.4 No.1

This paper investigates the two academic revolutions of the Korean higher education system. Since economic catch-up began in the 1960s, Korea has strongly encouraged the activities of its higher education system to serve industrial development as it has progressed through various developmental stages. At the ‘strong regulation’ stage, universities focused on the provision of technicians. As the need for higher education grew, the ‘massive expansion’ stage emerged. Finally, most recently, university research and its direct contribution to the economy have been invigorated by strong governmental support. Possibly, this is due to the fact that the Korean government has strongly controlled not only industry but also academia. As long as other East Asian universities have similar conditions to those of the development of Korean universities, we can generalise this model not only to universities in other East Asian countries, but also to universities in other rapid catch-up countries.

Analysis of National Basic Research System: The Case of South Korea

권기석,So-Yeon Park,장덕희 아시아기술혁신학회 2017 Asian Journal of Innovation and Policy Vol.6 No.2

In this paper, we analyze the basic research system in South Korea. We propose a national basic research system consisting of value, openness, input, transformation, and output. Based on this framework, we set up interview questionnaires, and 15 key informants have been interviewed. According to our results, first, in terms of value, basic research is recognized as an activity for creating knowledge in the understanding of nature. Second, as for openness, scientists and policy experts agree that active interaction with the global community is an important value for the national research system. Third, in terms of sustainable research resources, scientists are strongly required to effectively allocate research funding, maximizing the creativity of researchers and the efficient sharing of research equipment. Fourth, in transformation, basic researchers maintain that the Korean research system has is extremly dependent on the government’s external control, and its self-regulative system has been weak for over half century onw. Fifth, for global competitiveness, the interviewees agreed that the quality of basic research in Korea is approaching that of its global competitors. Finally, we put forward some policy implications on the basis of these findings.

Collaborative Research Network and Scientific Productivity: The Case of Korean Statisticians and Computer Scientists

권기석,김진국 아시아기술혁신학회 2017 Asian Journal of Innovation and Policy Vol.6 No.1

This paper focuses on the relationship between the characteristics of network and the productivity of scientists, which is rarely examined in previous studies. Utilizing a unique dataset from the Korean Citation Index (KCI), we examine the overall characteristics of the research network (e.g. distribution of nodes, density and mean distance), and analyze whether the network centrality is related to the scientific productivity. According to the results, firstly we have found that the collaborative research network of the Korean academics in the field of statistics and computer science is a scale-free network. Secondly, these research networks show a disciplinary difference. The network of statisticians is denser than that of computer scientists. In addition, computer scientists are located in a fragmented network compared to statisticians. Thirdly, with regard to the relationship between the researchers’ network position and scientific productivity, a significant relation and their disciplinary difference have been observed. In particular, the degree centrality is the strongest predictor for the scientists’ productivity. Based on these findings, some policy implications are put forward.

Mobility and productivity: brain circulation and sustainability of the Korean academic system

권기석,박정민,김소민 아시아기술혁신학회 2023 Asian Journal of Innovation and Policy Vol.12 No.1

The purpose of this study is to examine the unique characteristics of the Korean academic system with regard to brain circulation, with a specific emphasis on the influence of overseas-trained academics on research activities within the Korean academic system. We have analyzed the statistical data on individual characteristics and performances of 48,499 Korean academics in science and engineering. We have examined the results at both the system and individual levels within the broader context of the macro characteristics of the Korean academic system. Our analysis reveals that the total number of domestically-trained academics exceeds the number of overseas-trained academics. However, in terms of research funding, overseas-trained academics tend to receive more funding than domestically-trained academics. Furthermore, after controlling other factors such as funding, personal attributes, and environmental factors, our analysis demonstrates that overseas training has a significant and favorable impact on the publication of internationally renowned journals. As such, the presence of overseas returnees has been essential for the effective functioning of the Korean academic system in the global research network and for conducting high-quality academic research. Therefore, the advantages of dependence on scientific core countries such as the US for overseas training have persisted. Nevertheless, upon scrutinizing the group of recently appointed 5,806 academics exclusively, we have discovered that junior academics who received their education domestically exhibit sufficient academic proficiency compared to their colleagues educated overseas. This observation highlights the potential for the Korean academic system to evolve into a self-sustaining system.

Network, Channel, and Geographical Proximity of Knowledge Transfer: The Case of University-Industry Collaboration in South Korea

권기석,장덕희,박한우 아시아기술혁신학회 2015 Asian Journal of Innovation and Policy Vol.4 No.2

The relationship between geographical proximity and academics’ formal and informal knowledge-transfer activities in the network is analyzed with a mixed research method. With social network analysis as a basis, we have explored the networks between academics and firms in the 16 regions of South Korea. The result shows Seoul and Gyunggi are identified as central nodes, meaning that the academics in other regions tend to collaborate with firms in these regions. An econometric analysis is performed to confirm the localization of knowledge-transfer activities. The intensity of formal channels measured by the number of academic papers is negatively, but significantly associated with the geographical proximity. However, we have not found any significant relationship between the formality of the channels and geographical proximity. Possibly, the regional innovation systems in South Korea are neither big enough nor strong enough to show a localization effect.

Isolation of Acinetobacter calcoaceticus BP-2 Capable of Degradation of Bisphenol A

권기석,김동걸,이중복,신기선,금은주,손호용,Kwon, Gi-Seok,Kim, Dong-Geol,Lee, Jung-Bok,Shin, Kee-Sun,Kum, Eun-Joo,Sohn, Ho-Yong Korean Society of Life Science 2006 생명과학회지 Vol.16 No.7

Bisphenol A (BPA), 2,2-bis(4-hydroxyphenyl) propane, has been widely used as a monomer for production of epoxy resins and polycarbonate plastics, and final products of BPA include adhesives, protective coatings, paints, optical lens, building materials, compact disks and other electrical parts. Since BPA is a toxic chemical to elicit acute cell cytotoxicity and chronic endocrine disrupting activity, the degradation of BPA has been focused during last decades. To overcome the problem of photo-, and chemical-degradation of BPA, in this study, a bacterium that is able to biodegrade BPA, was isolated. The bacterium, isolated froln the soil of plastic factory, was identified as Acinetobacter calcoaceticus (strain BP-2) based on physiological and 16S rDNA sequencing analysis. A. calcoaceticus BP-2 was able to grow in the presence of $1140{\mu}g\;ml^{-1}$ BPA. Biodegradation experiments showed that BP-2 mineralized BPA via 4-hydroxybenzoic acid and 4-hydroxyacetophenone, and average degradation rate was $53.3{\mu}g\;ml^{-1}\;day^{-1}$ under optimal conditions (pH 7 and $30^{\circ}C$). In high density resting cell $(3.5g-dcw.1^{-1})$ experiments, the maximal degradation rate was increased to $89.7{\mu}g\;ml^{-1}\;h^{-1}$. Our results suggest that BP-2 has high potential as a catalyst for practical BPA bioremediation.

융합기술분야 공백기술 분석을 통한 추진기술 분야 발굴

권기석,박소연,안주명,서덕록 한국기술혁신학회 2016 한국기술혁신학회 학술대회 발표논문집 Vol.2016 No.10

혼화재 종류에 따른 고강도 콘크리트의 내화성능 평가

권기석,류동우 한국건축시공학회 2015 한국건축시공학회지 Vol.15 No.6

The method of concrete mix design used in this study aims to achieve the identical specified design strength,applying different types and replacement ratio of mineral admixtures and afterwards, fire tests were conducted usingthe standard time-temperature curve specified in the ASTM E119 to identify the influences of the types of mineraladmixtures on the fire resistance performance of high strength concrete(HSC). The least spalling was observed in thetest specimen containing blast furnace slag as a partial replacement of cement, while the most significant spallingphenomena were observed in the blast furnace slag test specimen that silica-fume was added in. In particular, thereasonable volume of spalling was observed when solely replaced by silica fume. However, the influence of the cementreplacement by silica fume and blast furnace slag on the increases of spalling can be explained through blocked poresby the fine particles of silica fume, leading to decreases in permeability. 본 연구에서는 동일 설계기준 강도를 목표로 혼화재의 종류 및 치환율을 달리하여 콘크리트 배합설계를 실시하였으며, 이에 따른 혼화재의 종류가 고강도 콘크리트의 내화성능에 미치는 영향을 검토하고자 ASTM E119의 표준가열온도곡선에 따른 내화시험을 실시하였다. 그 결과, 고로슬래그를치환하는 경우 폭렬량이 현저히 저감되는 것으로 나타났으며, 실리카흄을 추가하여 치환하는 경우 폭렬량이 가장 많은것으로 나타났다. 특히 실리카흄을 단독으로 치환하는 경우비교적 양호한 폭렬량을 나타냈으나, 고로슬래그와 함께 치환한 시험체의 경우 분말도가 높은 실리카흄이 공극을 밀실하게 함으로써 수증기압의 증가로 인해 폭렬량이 증가한 것으로 판단된다. 또한, 실리카흄을 5% 치환한 시험체의 경우,고로슬래그 치환율이 증가함에 따라 상대적으로 큰 공극량은 감소하고 미세공극량이 증가함으로써 폭렬량 또한 증가하는 결과를 나타냈다.

화재시나리오 및 섬유 혼입유무에 따른 콘크리트 터널 라이닝의 열적손상에 관한 실험적 연구

권기석,조범연,채승언,신현준,박경훈 한국방재학회 2015 한국방재학회논문집 Vol.15 No.3

국내에는 지형적 특성으로 인해 많은 터널이 건설되고 있으며, 추후에도 지속적으로 증가할 전망이다. 한편, 최근 10년간 화재추이를살펴보면 전체 화재사고 중 약 13%가 차량에 의한 화재사고인 것으로 나타나 터널은 항상 잠재적인 위험요소를 가지고 있다. 따라서세계적으로 터널 구조물의 화재피해를 줄이기 위해 다양한 연구를 진행하고 있으나, 국내의 경우 터널 라이닝의 내화성능 평가에 관련된 규정조차 전무한 실정이다. 따라서 본 연구에서는 콘크리트 터널 라이닝의 내화시험을 통해 폭렬특성 및 열적손상정도를 파악하여, 터널 구조물의 내화설계에 대한 기초자료로 활용하고자 연구를 진행하였다. 그 결과, 섬유를 혼입한 시험과 섬유를 혼입하지 않은 경우를 비교해 볼 때, 콘크리트는 약 10~30 mm, 철근은 약 20~40 mm 깊이만큼 화재손상범위가 줄어든 것으로 나타났다. Many tunnels are under construction and have been completed due to the topographical characteristic in Korea. Also, further construction will be carried out. Meanwhile, it has been shown that for the fire trend over last 10 years, approximately 13% of overall fire accidents was caused by cars so that the tunnel has the potential risk factor at all times. Therefore, in order to reduce the fire damage of tunnel structures, various studies are under execution in the world but even regulations relating to the evaluation of the fire resistance performance is rarely settled on the tunnel lining in Korea. Therefore, in the study, the explosive spalling and thermal damage will be figured out by the fire resistance test of the concrete tunnel lining so that the results will be utilized as the basic data on the fire resistance design of the tunnel structure. As a result of that, it has been shown that for each case of the test adding the fiber and also without the fiber, the fire damage scope has been reduced as much as approximate 10~30 mm for the concrete and 20~40 mm for the reinforcement.