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오동욱(Dong-Wook Oh),남기언(Ki Ean Nam),송찬호(Chan Ho Song),윤석호(Seok Ho Yoon),이공훈(Kong Hoon Lee),김욱중(Ook Joong Kim) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.6
In this paper, heat transfer and pressure drop characteristic of plate-fin heat exchangers for evaporative cooling system is investigated. Thermal performance and pressure drop of heat exchangers with different louver fin pitches are compared. Experiments are conducted for heat exchangers with different louver fins at the average air flow velocity of 3 m/s . 5.5 m/s. The thermal performance data are analyzed by using the effectiveness-NTU method. Pressure drop and overall heat transfer coefficient are measured as a constant temperature condition is given to the heat exchanger unit.
( Myo-deok Kim ),( Dong-hyun Jung ),( Dong-ho Seo ),( Jong-hyun Jung ),( Ean-jeong Seo ),( Nam-in Baek ),( Sang-ho Yoo ),( Cheon-seok Park ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.11
The transglycosylation activity of amylosucrase (ASase) has received significant attention owing to its use of an inexpensive donor, sucrose, and broad acceptor specificity, including glycone and aglycone compounds. The transglycosylation reaction of recombinant ASase from Deinococcus radiopugnans (DRpAS) was investigated using various phenolic compounds, and quercetin-3-O-rutinoside (rutin) was found to be the most suitable acceptor molecule used by DRpAS. Two amino acid residues in DRpAS variants (DRpAS Q299K and DRpAS Q299R), assumed to be involved in acceptor binding, were constructed by site-directed mutagenesis. Intriguingly, DRpAS Q299K and DRpAS Q299R produced 10-fold and 4-fold higher levels of rutin transglycosylation product than did the wild-type (WT) DRpAS, respectively. According to in silico molecular docking analysis, the lysine residue at position 299 in the mutants enables rutin to more easily position inside the active pocket of the mutant enzyme than in that of the WT, due to conformational changes in loop 4.
핀 형상에 따른 plate-fin 열교환기의 열전달 및 압력 강하 특성에 관한 실험적 연구
남기언(Ki Ean Nam),오동욱(Dong Wook Oh),송찬호(Chan Ho Song),윤석호(Seok Ho Yoon),이공훈(Kong Hoon Lee),김욱중(Ook Joong Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
이 논문은 공기측 열전달과 압력강하의 특성관계를 다양한 핀 형상에 대하여 난방조건에서 실험적으로 조사하였다. 핀 형상 parameter 인 핀 type(offset or louver), 핀 피치 그리고 핀 높이 등을 변화시켜 4개의 알루미늄 시료에 대하여 실험을 수행 하였다. 저속(1.3㎧)에서 고속(4㎧)까지 10case의 평균 유속과 각 속도에 대하여 압력강하(△p) 그리고 총합열전달 계수(UA)를 실험적으로 구하였다. 또한, 실험 데이터에 근거하여, f-factor와 j-factor를 구하여, 측정된 실험값과 기존 문헌의 결과값을 비교하여 데이터 값의 신뢰성을 검증 하였다. 본 연구에서는 열 교환 능력에 큰 영향을 미치는 fin parameter를 도출하고 최적조건의 핀 설계조건을 제시하였다. In this paper, heat transfer and pressure drop characteristics of plate-fin heat exchangers with different fin geometry are investigated. Tested fin geometry parameters are fin type(offset or louver), fin pitch, fin height and louver angle. The average air flow velocity at the sample heat exchanger is set to vary from 1.3 ㎧ to 4.0 ㎧. Pressure drop and overall heat transfer coefficient are measured as a constant heat flux is given to the heat exchanger unit. Friction f-factor and Colburn j-factor of each sample are calculated.
Park, Yeo-Ul,Jung, Jong-Hyun,Seo, Dong-Ho,Jung, Dong-Hyun,Kim, Jae-Han,Seo, Ean-Jeong,Baek, Nam-In,Park, Cheon-Seok Elsevier 2018 Enzyme and microbial technology Vol.114 No.-
<P><B>Abstract</B></P> <P> <I>Desulfurococcus amylolyticus</I> is an anaerobic and hyperthermophilic crenarchaeon that can use various carbohydrates as energy sources. We found a gene encoding a glycoside hydrolase family 57 amylolytic enzymes (DApu) in a putative carbohydrate utilization gene cluster in the genome of <I>D. amylolyticus</I>. This gene has an open reading frame of 1,878 bp and consists of 626 amino acids with a molecular mass of 71 kDa. Recombinant DApu (rDApu) completely hydrolyzed pullulan to maltotriose by attacking α-1,6-glycosidic linkages, and was able to produce glucose and maltose from soluble starch and amylopectin. Although rDApu showed no activity toward α-cyclodextrin (CD) and β-CD, maltooctaose (G8) was detected from reaction with γ-CD. The highest activity of rDApu was measured at pH 5.0 and 95 °C. The half-life of rDApu was 12.7 h at 95 °C and 27 min at 98 °C. Interestingly, rDApu was able to transfer a maltose unit to 6-<I>O</I>-α-maltosyl-β-CD via transglycosylation. Structure analysis using MALDI-TOF/TOF MS and nuclear magnetic resonance revealed that the new transglycosylated products were 6<SUP>1</SUP>, 6<SUP>4</SUP>-di-<I>O</I>-maltosyl-β-CD and 6<SUP>1</SUP>, 6<SUP>3</SUP>, 6<SUP>5</SUP>-tri-<I>O</I>-maltosyl-β-CD.</P> <P><B>Highlights</B></P> <P> <UL> <LI> GH57 amylopullulanase from <I>Desulfurococcus amylolyticus</I> (DApu) was characterized. </LI> <LI> DApu exhibits not only hydrolysis activity but also transglycosylation activity. </LI> <LI> Branched cyclodextrins were formed by transfer of a maltose unit by DApu. </LI> </UL> </P>