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Aerodynamic performance of flexible airfoil in plunge motion
르광투엔(Tuyen Quang Le),김지웅(Jee Woong Kim),고진환(Jin Hwan Ko),박수형(Soo Hyung Park),박훈철(Hoon Choel Park),변도영(Doyoung Byun) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Dependence of thrust, lift and propulsion efficiency on the reduced frequency was investigated in plunge motion with both rigid and chordwise flexibility. Unsteady viscous flows over NACA airfoils in plunge motions were computed by using a time-accurate preconditioned Navier-Stokes solver. An effect of reduced frequency on performance parameters is investigated with various amplitudes and there is a critical value of reduced frequency for optimal propulsion efficiency. Flapping parameters are increased with the chordwise flexibility, whereas their variations with reduced frequency are almost similar to that of rigid case.
Bach, Quang-Vu,Le, Van Tam,Yoon, Yong Soo,Bui, Xuan Thanh,Chung, Woojin,Chang, Soon Woong,Ngo, Huu Hao,Guo, Wenshan,Nguyen, Dinh Duc Elsevier 2018 Journal of Cleaner Production Vol.178 No.-
<P><B>Abstract</B></P> <P>A new hybrid pilot plant configuration based on a modularized rolled pipe system (RPS) combined with a submerged flat sheet membrane bioreactor (MBR) was investigated to enhance the sewage treatment and membrane performance. The system was operated under actual conditions for more than four months, that is, at a constant flow rate of 30 m³/d and with two internal recycling ratios. The results indicate that the hybrid system produces an excellent effluent quality and considerably mitigated membrane fouling. The average concentrations of SS, COD, TN, NH<SUB>4</SUB> <SUP>+</SUP>-N, NO<SUB>3</SUB> <SUP>−</SUP>-N, and PO<SUB>4</SUB> <SUP>3-</SUP>-P remained below 2.81, 8.29, 8.77, 0.15, 8.17, and 1.49 mg/L, respectively. It was estimated that the periodic chemical cleaning of the membrane could be extended to approximately six months. The MBR and RPS can virtually complete nitrification and denitrification, respectively. The highest average denitrification rate of the RPS is 116.95 mg NO<SUB>3</SUB>-N/(g MLVSS d), with a hydraulic retention time of 1.05 h. Therefore, the RPS–MBR hybrid system has potential to improve the sewage treatability. The emerging RPS technique can obtain high rates of denitrification coupled with a compact design, ease of installation, and small footprint.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new hybrid sewage treatment system was explored. </LI> <LI> Excellent denitrification is achieved with the novel rolled pipe system. </LI> <LI> High rates of simultaneous nitrification and denitrification are obtained. </LI> <LI> The hybrid system performs well in removing organic and nitrogen compounds. </LI> <LI> The membrane fouling rate of the hybrid system is significantly low. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Life Science : Obovatol improves cognitive functions in animal models for Alzheimer`s disease
( Dong Yong Chou ),( Jae Woong Lee ),( Jin Peng ),( Young Jung Lee ),( Jin Peng ),( Young Jung Lee ),( Jin Yi Han ),( Yeon Hee Lee ),( Im Seop Choi ),( Sang Bae Han ),( Jae Kyung Jung ),( Woong Soo Le 영남대학교 약품개발연구소 2012 영남대학교 약품개발연구소 연구업적집 Vol.22 No.0
Etiology of Alzheimer`s disease (AD) is obscure, but neuroinflammation and accumulation of β-amyloid (Aβ) are implicated in pathogenesis of AD. We have shown anti-inflammatory and neurotrophic properties of obovatol, a biphenolic compound isolated from Magnolia obovata. In this study, we examined the effect of obovatol on cognitive deficits in two separate ADmodels: (i) mice that received intracerebroventricular (i.c.v.) infusion of Aβ(1-42) (2.0 μg/mouse) and (ii) Tg2576 mice-expressing mutant human amyloid precursor protein (K670N, M671L). Injection of Aβ(1-42) into lateral ventricle caused memory impairments in the Morris water maze and passive avoidance tasks, being associated with neuroinflammation. Aβ(1-42) -induced abnormality was significantly attenuated by administration of obovatol. When we analyzed with Tg2576 mice, long-term treatment of obovatol (1 mg/kg/day for 3 months) significantly improved cognitive function. In parallel with the improvement, treatment suppressed astroglial activation, BACE1 expression and NF-κB activity in the transgenic mice. Furthermore, obovatol potently inhibited fibrillation of Aβin vitro in a dose-dependent manner, as determined by Thioflavin T fluorescence and electron microscopic analysis. In conclusion, our data demonstrated that obovatol prevented memory impairments in experimental AD models, which could be attributable to amelioration of neuroinflammation and amyloidogenesis by inhibition of NF-κB signaling pathway and anti-fibrillogenic activity of obovatol.
고진환(Jin Hwan Ko),김지웅(Jee Woong Kim),박수형(Soo Hyung Park),투엔르광(Tuyen Quang Le),변도영(Doyoung Byun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
As a novel bio-mimetic technology, flapping foils have attracted much attention, owing to their capacity of producing thrust with high efficiency. Flapping foils may fine applications on autonomous underwater vehicle, flapping micro-air vehicle and etc. In design stage of the new type vehicles, computational fluid dynamics (CFD) can be used to explore performance of the flapping foils. One of challenging problems in CFD is known to be the development of robust, efficient grid deformation algorithms for the large deformation of the foils. In this paper, a volume grid deformation is developed based on Finite Macro-Element and Transfinite Interpolation and then interfaces a structured multi-block Navier-Stokes code. As demonstrated by airfoils with pitching or heaving motion, the force results of presented method is in good agreement with those of a conventional method and is also close to experimental results.
WeiQiang Jia,Sug-Won Roh,Sung Hwan Choi,Jong Chan Won,Soo Yong Shim,Jung-Sung Chung,Le Thi Hien,Aung Bo Bo,Kee Woong Park,Jeung Joo Lee 한국잡초학회·한국잔디학회 2021 Weed & Turfgrass Science Vol.10 No.1
Continuous use of acetolactate synthase (ALS) inhibitors has led to the selection of herbicide-resistant Sagittaria trifolia in paddy fields. Herbicide-resistant (R) S. trifolia was first reported in 2011 in Korea. The objective of this study was to investigate the level and mechanism of resistance and understand the fitness of R biotypes using R and susceptible (S) S. trifolia biotypes originated from seeds and tubers. Whole plant dose-response showed that the R biotypes originated from tubers were highly resistant to cyclosulfamuron and moderately resistant to penoxsulam and imazaquin, with R/S ratios of 250, 13 and 8, respectively. Compared to the S biotype, the R biotype originated from tuber had an amino acid substitution at the position of a Pro197-Leu residue of als gene, a well-known mutation site that could confer resistance to sulfonylurea, triazolopyrimidine, and imidazolinone herbicides. Additionally, the germination rate and growth of the S biotypes originated from seeds were lower than those of the R biotypes. The growth of the S biotypes originated from tubers was more vigorous than that of the R biotypes. Once the seed of R biotypes move to uninfected paddy fields, the germination rate of R biotypes is probably more than that of existing S biotypes. If ALS inhibitors are applied into paddy fields, R biotypes can survive and even produce tubers that can continually propagate and probably become dominant in the population in uninfected paddy fields. Thus, increasing the application rate of ALS inhibitors to kill R biotypes probably can enhance ALS-inhibitors’ selection-pressure.