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Baek Keon-Hee Jeong Nak-Tak Hong Hee-Rok Choi Su-bin Lee Eun-Seong Kim Hyung-Min Kwon Ji-Woon Song Seok-Yong Jang Hong-Seok Lee Ho-Yong Suh Myung-Won 《Journal of Mechanical Science and Technology》2019,33(4):1689-1702
Journal of Mechanical Science and Technology - Threaded fasteners are widely used in mechanical structures primarily owing to their easy disassembly for maintenance and low cost. However, the... 相似文献
2.
Ryu Hwa-Ja Seo Eun-Seong Kang Hee-Kyoung Kim Young-Min Kim Doman 《Food science and biotechnology》2011,20(2):561-565
A gene encoding human intestinal maltase (HMA) was successfully expressed in Pichia pastoris under the control of the methanol-induced alcohol oxidase (AOX1) promoter. The secreted recombinant HMA fused with a His6-tag was produced (150 U/L) and was easily purified from culture supernatants in a 3-step diafiltration, ultrafiltration,
and affinity column chromatography protocol. The specific activity of the purified HMA was 16.8 U/mg. Endoglycosidase H digestion
of the protein showed that the recombinant HMA was N-glycosylated. The purified HMA was maximally active at pH 6.5 and stable (≥90%) up to 65°C. The kinetic parameters K
m
and V
max
were 3.3±0.25 mM maltose and 61.9±2 U/mg, respectively. 相似文献
3.
Lean premixed combustion is a well known method in gas turbine combustors that can reduce fuel consumption and decrease flame
temperature. In lean premixed flames, flame instabilities can occur because the combustion takes place near the lean flammable
limit. For the purpose of increasing flame stability, a small amount of hydrogen was added into a fuel, which has ultra low
lean flammable limit. The extinction stretch rate increased and total equivalence ratio at extinction decreased with hydrogen
addition; consequently, ultra lean premixed combustion was possible and flame stability could be achieved at low temperature
conditions. The NOx emission increased with hydrogen addition for the same stretch rate and equivalence ratio, but the extinction stretch rate
and lean flammability limit was enlarged. Consequently, NOx emission decreased with hydrogen addition in the near extinction conditions. Hydrogen addition could improve flame stability
and reduce NOx emission in ultra lean premixed combustion.
This paper was recommended for publication in revised form by Associate Editor Ohchae Kwon
Dr. Eun-Seong Cho received his B.S. and M.S. degrees in Mechanical Engineering from Hanyang University, Korea, in 1996 and 1998, respectively.
He then received his Ph.D. degree from Seoul National University, Korea, in 2005. He was a principal engineer of KD Navien
research center and currently a research associate at Delft University of Technology, The Netherlands. His research interests
include eco-friendly clean combustion technology, new and renewable energy systems.
Prof. Suk Ho Chung received his B.S. degree from Seoul National University, Korea, in 1976 and Ph.D. degree in Mechanical Engineering from Northwestern
University, USA, in 1983. He is a Professor since 1984 in the School of Mechanical and Aerospace Engineering at Seoul National
University in Seoul, Korea. His research interests cover combustion fundamentals, pollutant formation, laser diagnostics,
and plasma-assisted combustion. 相似文献
4.
The control of nitrogen oxides (NOx) has been a major issue in designing combustion systems, since NOx play a key role in ozone depletion and the generation of photochemical smog. The characteristics of NOx emission can be essential information for the development of a clean combustor having suitable reduction methodologies. In
the present study, NOx emission characteristics were evaluated numerically, accounting for the effect of equivalence ratio, stretch rate, pressure,
and initial temperature. In general, peak NOx emission appeared near the equivalence ratio of unity case, and NOx emission increased with pressure and initial temperature due to the temperature sensitivity in NOx mechanism. NOx decreased with stretch rate due to the decrease in residence time in high temperature region. Furthermore, the thermal and
prompt mechanisms were evaluated with equivalence ratio for two calculation methods. The conventional methods ignore the interaction
of coupled mechanism of thermal and prompt NOx. The reaction path diagram was introduced to understand effective reaction pathways in various conditions.
This paper was recommended for publication in revised form by Associate Editor Kyoung Doug Min
Dr. Eun-Seong Cho received his B.S. and M.S. degrees in Mechanical Engineering from Hanyang University, Korea, in 1996 and 1998, respectively.
He then received his Ph.D. degree from Seoul National University, Korea, in 2005. He was a principal engineer of KD Navien
research center and currently a research associate at Delft University of Technology, The Netherlands. His research interests
include eco-friendly clean combustion technology, new and renewable energy systems.
Prof. Suk Ho Chung received his B.S. degree from Seoul National University, Korea, in 1976 and Ph.D. degree in Mechanical Engineering from Northwestern
University, USA, in 1983. He is a Professor since 1984 in the School of Mechanical and Aerospace Engineering at Seoul National
University in Seoul, Korea. His research interests cover combustion fundamentals, pollutant formation, laser diagnostics,
and plasma-assisted combustion. 相似文献
5.
Flue gas recirculation (FGR) is a method widely adopted to control NOx in combustion system. The recirculated flue gas decreases flame temperature and reaction rate, resulting in the decrease
in thermal NO production. Recently, it has been demonstrated that the recirculated flue gas in fuel stream, that is, the fuel
induced recirculation (FIR), could enhance a much improved reduction in NOx per unit mass of recirculated gas, as compared to the conventional FGR in air. In the present study, the effect of FGR/FIR
methods on NOx reduction in turbulent swirl flames by using N2 and CO2 as diluent gases to simulate flue gases. Results show that CO2 dilution is more effective in NO reduction because of large temperature drop due to the larger specific heat of CO2 compared to N2 and FIR is more effective to reduce NO emission than FGR when the same recirculation ratio of dilution gas is used. 相似文献
6.
Jin Ha Lee Seong Hee Nam Hyen Joung Park Young-Min Kim Nahyun Kim Ghahyun Kim Eun-Seong Seo Seong-Soo Kang Doman Kim 《Food science and biotechnology》2010,19(3):757-762
Appreciably elevated levels of dextranase from Arthrobacter oxydans (AODex) isolated from sugar-cane farm soil was resulted from the culture on the Luria-Bertani (LB) medium containing 1%(w/v)
soluble starch, glycerol, or dextran. The responsible gene (aodex) was cloned, its nucleotide sequence was determined, and expression of the encoded protein was achieved in Escherichia coli. An open reading frame was composed of 1,863 bp putatively encoding a 68.3 kDa protein. Recombinant A. oxydans dextranase (rAODex) was purified about 16 fold by nickel-nitrilotriacetic acid affinity column chromatography; K
m value for dextran T2000 was 0.85 mg/mL (w/v). AODex treatment of stale sugar cane juice resulted in a yield of square and
light-colored sugar crystals. 相似文献
7.
Sang Kyu Choi Eun-Seong Cho Suk Ho Chung 《Journal of Mechanical Science and Technology》2014,28(9):3863-3871
The extinction mechanisms of stretched premixed flames have been investigated numerically for the fuels of CH4, C3H8, H2, CO and for the mixture fuels of CH4+H2 and CO+H2 by adopting symmetric double premixed flames in a counterflow configuration. The local equilibrium temperature concept was used as a measure of energy loss or gain in order to quantify the extinction mechanism by preferential diffusion and/or incomplete reaction. The energy loss ratio from preferential diffusion arising from non-unity Lewis number and the loss ratio from incomplete reaction were calculated at various equivalence ratios near flame extinction. The results showed that the extinction of lean H2, CH4, CH4+H2, CO+H2, and rich C3H8 premixed flames was caused by incomplete reaction due to insufficient reaction time, indicating that the effective Lewis number was smaller than unity, while the effect of preferential diffusion resulted in energy gain. However, the extinction of rich H2, CH4, CH4+H2, CO+H2, and lean C3H8 premixed flames was affected by the combined effects of preferential diffusion and incomplete reaction indicating that the effective Lewis number was larger than unity. In CO premixed flames, incomplete reaction was dominant in both lean and rich cases due to the effective Lewis number close to unity. The effect of H2 mixing to CO is found to be quite significant as compared to CH4+H2 cases, which can alter the flame behavior of CO flames to that of H2. 相似文献
8.
Kook-Young Ahn Han-Seok Kim Eun-Seong Cho Jin-Hyuk Ahn Yong-Mo Kim 《Journal of Mechanical Science and Technology》1999,13(6):477-486
The combustion processes and emission characteristics in air-staged burner have been experimentally studied. The light fuel
oil doped with pyridine(C5H5N) is used to investigate the fuel NOX emission characteristics. Experiments are carried out for a wide range of operating conditions of single-staged and multi-staged
burner. The detailed discussions are made for the flame structure of the air-staged burner as well as effects of excess air
ratios, staged air flow percentage, and spray conditions on flame pattern and NOX emission characteristics. 相似文献
9.
Flue gas recirculation (FGR) is widely adopted to control NO emission in combustion systems. Recirculated flue gas decreases
flame temperature and reaction rate, resulting in the decrease in thermal NO production. Recently, it has been demonstrated
that the recirculated flue gas in fuel stream, that is, the fuel induced recirculation (FIR), could enhance much improved
reduction in NO per unit mass of recirculated gas, as compared to conventional FGR in air. In the present study, the effect
of dilution methods in air and fuel sides on NO reduction has been investigated numerically by using N3 and CO2 as diluent
gases to simulate flue gases. Counterflow diffusion flames were studied in conjunction with the laminar flamelet model of
turbulent flames. Results showed that CO2 dilution was more effective in NO reduction because of large temperature drop due
to the larger specific heat of CO2 compared to N2. Fuel dilution was more effective in reducing NO emission than air dilution when the same recirculation ratio of dilution
gas was used by the increase in the nozzle exit velocity, thereby the stretch rate, with dilution gas added to fuel side. 相似文献
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