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Measurement of Developing Turbulent Flow in a U-Bend of Circular Cross-Section
Gun Hyee Lee,Young Don Choi,Seong Ho Han 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.2
Hot-wire measurements of the full mapping of the velocity and Reynolds stress components are reported for developing turbulent flow in a strongly curved 180 deg pipe and its tangents. A slanted wire is rotated into 6 orientations and the voltage outputs from wires are combined to obtain the mean velocity and Reynolds stress components. The strength of secondary flow reaches up to the 28% of bulk mean velocity. The strong counter-rotating vortex pair induced by the transverse pressure gradient and centrifugal force imbalance grows up to θ=67.5°into the bend. But the vortex pair breaks down into two cell pattern after θ=90° Core vortex formation and reversal of secondary flow direction along the bend symmetry plane is cleanly found in the secondary vector plot. At θ=67.5° and 8=90° into bend a large "trough" develops in the longitudinal velocity toward the inside of the bend due to the breakdown of secondary flow. In the bend, the mean longitudinal velocity component changes little after θ=90°, but secondary flow never achieves fully-developed state. Similar behaviors are observed in the radial and circumferential stresses.
오렌지 껍질로부터 분리된 프라보노이드의 화학요법 감작효과
최철익,변익건,차윤정,김선필,민영돈,유진철,송재경 조선대학교 2001 The Medical Journal of Chosun University Vol.26 No.2
Background and Objectives : The overexpression of P-glycoprotein (Pgp) or multidrug resistanceassociated protein (MRP) confers multidrug resistance (MDR) to cancer cells. MDR cells could be sensitized to anticancer drugs when treated concomitantly with a chemosensitizer. In this study, orange peel have been screened for the development of chemosensitizers reversing MDR. Materials and methods : Expression of Pgp in AML-2/WT and AML-2/D100 were determined using western blot analysis and RT-PCR. Candidates for chemosensitizers were isolated, purified from orange peel using sephadex LH-20 column chromatography and silica-gel column chromatography, whose structure was determined using ^1H-NMR, ^13C-NMR, ^1H-^1H-COSY, 13C-NMR, EI-Mass, IR. Chemosensitizing effect of NP-28 on AML-2/DX100 over expressing Pgp and MRP was determined by the MTT assay. Membrane toxicity was evaluated by the RBC hemolysis test. Antioxidant effects were examined by using a fluorescence probe (2’-7’-dichlorofluorescein diacetate). Results : A potent candidate, NP-28, has a flavonoid nucleus with some methoxy moiety. NP-28 is believed to have high therapeutic index, being non-transportable inhibitor and possibly, of inhibiting other efflux pumps such as MRP and antioxidant effects. NP-28 is also unlikely to be a substrate of Pgp. NP-28 did not increase Pgp levels. Conclusion : NP-28 has a Chemosensitizing effect to reverse Pgp-mediated MDR by increasing the intracellular accumulation of drugs. Furthermore, they do not increase expression of Pgp, which can allow a long term use without the concern about Pgp activation. NP-28 is anticipated as an ideal second-generation flavonoid chemosensitizer and/or possibly other therapeutic agents by further investigation.
콘크리트용 혼합골재 표준화를 위한 실태 조사에 관한 연구
최영준(Choi Young Jun),조영근(Cho Young Gun),문규돈(Moon Gyu Don),최영철(Choi Young Chul) 표준인증안전학회 2012 표준인증안전학회지 Vol.2 No.1
Recently, ready-mixed concrete companies are using disqualified aggregates which lack in both grade and grain shape due to the shortage of natural aggregate. However, still there aren t any clear and accurate blending method and quality standard existing. In this paper, we surveyed ready-mix concrete companies about the quality level and blending of aggregates in order to standardize the blended aggregates on concrete. Survey results indicated that blending of aggregates is common for the aim of quality improvement, and usually grade and grain shape were the main cause of the blending. To sum up the ready-mixed concrete companies view point, once the blended aggregate s quality standard is set, the supply shortage and quality problem of aggregates can be solved.