• Journal of Microbiology and Biotechnology
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• 제29권6호
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• pp.952-961
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• 2019

Chlorella spp. are green algae that are found across wide-ranging habitats from deserts to arctic regions, with various strains having adapted to survive under diverse environmental conditions. In this study, two novel Chlorella strains (ABC-002, ABC-008) were isolated from a freshwater lake in South Korea during the winter season and examined for possible use in the biofuel production process. The comparison of ABC-002 and ABC-008 strains with Chlorella vulgaris UTEX265 under two different temperatures ($10^{\circ}C$, $25^{\circ}C$) revealed their cold-tolerant phenotypes as well as high biomass yields. The maximum quantum yields of UTEX25, ABC-002, and ABC-008 at $10^{\circ}C$ were 0.5594, 0.6747, and 0.7150, respectively, providing evidence of the relatively higher cold-resistance capabilities of these two strains. Furthermore, both the biomass yields and lipid content of the two novel strains were found to be higher than those of UTEX265; the overall lipid productivities of ABC-002 and ABC-008 were 1.7 ~ 2.8 fold and 1.6 ~ 4.2 fold higher compared to that of UTEX265, respectively. Thus, the high biomass and lipid productivity over a wide range of temperatures indicate that C. vulgaris ABC-002 and ABC-008 are promising candidates for applications in biofuel productions via outdoor biomass cultivation.

• 농업과학연구
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• 제47권4호
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• pp.829-844
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• 2020

A vacuum metering device for garlic seeds was developed, and its metering performance was tested according to the design factors. Three design factors were as follows: suction surface diameter (Edge), suction surface curvature (Type), and guide height (Guide). The suction surface curvature represents the distance between the center of the grooved suction plate and the bottom of suction plate. The metering rate and multiple metering rate were analyzed as the metering performance of the developed device with two varieties of garlic seeds: Namhae (warm region-adapted garlic) and Uiseong (cold region-adapted garlic). The best metering performance for the Namhae seeds were found with the following conditions: An Edge, Guide and Type of 40, 4, and 35 mm, respectively. In the case of the Uiseong seeds, the best conditions were as follows: An Edge, Guide and Type of 35, 4, and 30 mm, respectively. The guide height was found to be the most influential design factor on the metering performance of the metering rate and multiple rate for both Namhae seeds and Uiseong seeds. Additionally, the interaction between the area of the suction surface and the curvature of the suction surface had some effects on the multiple rate for the Uiseong seeds. It was concluded that the guide height should be 4 mm or higher so that more than 90% of the metering rate could be achieved for the tested garlic seeds with the developed metering device.

• 생태와환경
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• 제54권1호
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• pp.71-77
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• 2021

Using data from flies collected with pitfall traps in 365 forests on a nationwide scale in Korea, the abundance and distribution changes of two families (Phoridae and Lauxaniidae) in Korean forests were predicted at the genus level according to two climate change scenarios: RCP 4.5 and RCP 8.5. The most suitable temperature for the 17 major genera was estimated using a weighted average regression model. Stichillus and Anevrina displayed the lowest optimum temperature with 7.6℃ and 8.5℃ in annual mean temperature, respectively, whereas Chonocephalus had the highest optimum temperature with 12.1℃. Among thirty genera, seven genera (four from Phoridae and three from Lauxaniidae), which showed their abundance in a bell-type or linear pattern along the temperature gradient, were used for predicting the distribution changes according to the future climate change scenarios. All the taxa of this study are expected to decrease in abundance and distribution as a function of temperature increase. Moreover, cold-adapted taxa were found to be more affected than warm-adapted taxa.

• ALGAE
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• 제31권3호
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• pp.231-241
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• 2016

We examined the genetic diversity and abundance of picocyanobacteria using barcoded amplicon sequencing approaches and flow cytometry in the East Sea and the East China Sea to determine the distribution patterns of diversity during spring in seas adjacent to the Korean Peninsula. Synechococcus clades I and IV, which have been known as cold-adapted ecotypes, dominated at most stations. However, the relative abundances of the two dominant clades differed in their spatial patterns. Clade I was exclusively dominant in the shelf area of the East China Sea and the north East Sea. However, the dominant genotypes belonging to clade I had different spatial distributions in the two areas and responded oppositely to seawater temperature. The dominance of distinct genotypes under the different ecological conditions suggests the presence of ecologically different ecotypes within the clade. Abundances of clade IV were greater than those of clade I at most stations in the southwest East Sea, showing an apparently different pattern from that of the other areas. A warm-water adapted clade II was observed at significant levels only at stations located in the eastern East China Sea affected by a branch of the warm Kuroshio Current. These results suggest that the physicochemical properties of influencing water masses play an important role in determining the distribution of Synechococcus genotypes.

• Food Science and Biotechnology
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• 제17권6호
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• pp.1391-1395
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• 2008

Leuconostoc citreum HJ-P4 is a strain isolated for kimchi fermentation with its low temperature-adapted growth feature and its high dextransucrase activity. The detailed characteristics of cell growth and dextran sucrase activities were investigated at various environmental conditions such as temperatures, pHs, salts, and raw ingredients. This strain showed almost 2-fold higher maximal cell concentration ($X_{max}$) than that of the type culture Leuconostoc mesenteroides B-512F at $10^{\circ}C$. The $X_{max}$ of the strain was maximum at pH 7 and the cell growth was inhibited by salts in a dose-dependent mode up to 7%. Addition of pepper (<6%), garlic (<10%), and ginger (<2%) in kimchi gave no inhibition effect on the growth of HJ-P4. Dextransucrase synthesized by this strain retained over 80% of its maximum activity at $10^{\circ}C$ showing a comparable cold-adapted feature to its host microbe. This culture can be used as a starter culture in the industrial kimchi production giving desirable functions and predominance at low temperature.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.730-735
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• 2003

본 실험에서는 분리된 곤충병원성 선충 6종의 온도에 따른 trehalose의 농도와 병원성의 상관관계를 조사하였으며 온도 적응, oil, glycerol을 이용하여 trehaolse 생성량 조절에 대하여 조사하였다. 저온에서는 S. longicaudum G1 종이 $81.92{\mu}g/mg$로 가장 높게 나타났으며, 고온에서는 S. glaseri Agr B3 $71.22{\mu}g/mg$로 가장 높게 나타났다. 또한 S. longicaudum G1을 저온에서 적응 시켰을 경우 병원성과 trehaolserk 향상되었으며 S. glaseri Agr B3 종일 경우 고온에 적응 시켰을 경우 역시 향상되었다. glycerol 20%과 oil 전 농도에서 처리하였을 경우 도 종 모두 다소 향상되는 것으로 나타났다.

• 미생물학회지
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• 제55권1호
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• pp.83-85
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• 2019

남극 연안 툰드라 토양에서 리그닌 분해능이 있는 Pseudomonas sp. PAMC 29040를 분리하였으며, 이후 토양 유기물의 주요 구성성분인 복합유기화합물 부식질 분해능을 확인하였다. 부식질 초기 저분자화 효소(예, dye-decolorizing peroxidase)와 부식질 유래의 다양한 저분자 분해산물들을 분해하는 효소들(예, vanillate O-demethylase)를 탐색하기 위해 PAMC 29040 게놈 염기서열을 분석하였다. 분석을 통해서 최종 확보한 효소유전자 정보는 저온환경에 서식하는 토양 세균의 부식질 분해경로 제안에 활용될 것이다.

• Animal Systematics, Evolution and Diversity
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• 제11권2호
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• pp.159-166
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• 1995

한국산 하루살이과(곤충강: 하루살이목)의 신종인 가는무늬하루살이(Ephemera separigata n. sp.)의 성숙유충과 암.수성충을 기재하였다. 본 신종은 7-9 배마디등판에 한쌍의 세로줄무늬가 매우 가늘고, 각자 옆쪽 가장자리로 치우쳐 있어서 하루살이속의 다른 종들과 구별된다. 본 종의 유충은 수온이 상대적으로 낮은 산간계류(고도 500-700m)의 모래, 왕모래 및 다량의 자갈이 섞인 하천바닥을 파고 서식한다. 한국산 하루살이 유충의 고도에 따른 서식처 적응에 관하여 간략히 논하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.245-249
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• 2005

The numerical simulation of a two-phase flow In a discrete fracture network model is presented in this paper, The purpose of this work is to consider density-driven flows induced by the density difference between hot autochthonous heavy brines and injected cold water. Mechanical consequences of high pressure waves on the fracture permeability and heat exchanges between fluids and rock matrix are neglected in this study. The finite volume method is employed to discretize spatially and the system is solved by using an IMPES(Implicit Pressure-Explicit Saturation) scheme. In order to solve the strong non-linearity of the system, the Newton-Raphson algorithm is used. The well-known Buckeley-Leverett problem is adapted to validate results calculated from the model and a relatively good agreement is obtained.

• Nuclear Engineering and Technology
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• 제28권4호
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• pp.405-414
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• 1996

In this paper, the unsteady 2-dimensional turbulent flow model for thermal stratification in a pressurizer surge line of PWR plant is proposed to numerically investigate the heat transfer and flow characteristics. The turbulence model is adapted to the low Reynolds number K-$\varepsilon$ model (Davidson model). The dimensionless governing equations are solved by using the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm. The results are compared with simulated experimental results of TEMR Test. The time-dependent temperature profiles in the fluid and pipe nil are shown with the thermal stratification occurring in the horizontal section of the pipe. The corresponding thermal stresses are also presented. The numerical result for thermal stratification by the outsurge during heatup operation of PWR shows that the maximum dimensionless temperature difference is about 0.83 between hot and cold sections of pipe well and the maximum thermal stress is calculated about 322MPa at the dimensionless time 28.5 under given conditions.