• Title/Summary/Keyword: blockage effects

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Analysis of Aerodynamic Performance in an Annular Compressor Bowed Cascade with Large Camber Angles

  • Chen, Shaowen;Chen, Fu
    • International Journal of Fluid Machinery and Systems
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    • v.2 no.1
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    • pp.13-20
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    • 2009
  • The effects of positively bowed blade on the aerodynamic performance of annular compressor cascades with large camber angle were experimentally investigated under different incidences. The distributions of the exit total pressure loss and secondary flow vectors of compressor cascades were analyzed. The static pressure was measured by tapping on the cascade surfaces, and the ink-trace flow visualizations were conducted. The results show that the value of the optimum bowed angle and optimum bowed height decrease because of the increased losses at the mid-span with the increase of the caber angle. The C-shape static pressure distribution along the radial direction exists on the suction surface of the straight cascade with large r camber angles. When bowed blade is applied, the larger bowed angle and larger bowed height will further enhance the accumulation of the low-energy fluid at the mid-span, thus deteriorate the flow behavior. Under $60^{\circ}$ camber angle, flow behavior near the end-wall region of some bowed cascades even deteriorates instead of improving because the blockage of the separated flow near the mid-span keeps the low-energy fluid near the end-walls from moving towards the mid-span region, and as a result, a rapid augmentation of the total loss is easy to take place under large bowed angle. With the increase of camber angle, the choice range of bowed angle corresponding to the best performance in different incidences become narrower.

EFFECTS OF ALCOHOL AND GLYCEROL INJECTION ON THE RAT INFRAORBITAL NERVE (백서 안와하신경에서 알콜 및 글리세롤 주입의 효과)

  • Yun, Cheon-Ju;Ryu, Sun-Youl
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.27 no.2
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    • pp.150-156
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    • 2001
  • This study was performed to investigate the changes of nerve after the injection of alcohol and glycerol at the infraorbital nerve in rats. Using the eighteen Sprague-Dawley rats, weighing $200{\sim}250g$, 99% alcohol, pure glycerol, and sterile saline was injected to the epineurium of the infraorbital nerve. Glycerol injected rats were devided into 0.01ml, 0.03ml and 0.05ml groups. The alcohol and control group were injected 0.03ml at the left infraorbital nerve. The following results were obtained by histopathological examination after 1 week, 1 month, and 3 months. A few inflammatory cell infiltration and no signs of nerve degeneration were noted in control group. Total nerve degeneration was noted in the alcohol group and no regeneration was noted in 1month, and partial regeneration was noted at 3month. The nerve degeneration was noted at the periphery of nerve bundle in 0.01ml glycerol injection group. Total degeneration was noted in the 0.03ml and 0.05ml glycerol injection group and the degree was propotional to dose. These results suggest that injection of alcohol and glycerol are effective to nerve blockage by nerve degeneration, and nerve degeneration by glycerol injection is propotional to dose and nerve regeneration by glycerol injection is inversely propotional to dose.

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A Study of External Treatment History in Wei(魏) Dynasty and Jin(晋) Dynasty (위진시대(魏晋時代)의 외치요법(外治療法)에 관한 연구)

  • Moon, Woo-Sang;Kim, Eun-Ha;Lee, Byung-Wook
    • Journal of Korean Medical classics
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    • v.18 no.3 s.30
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    • pp.70-80
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    • 2005
  • 1) Objective External treatments have various curative effects. So it had been used to cure various patients. But, it has a limited sphere of application in the present South Korea. Therefore we would like to bring out its sphere of application and detailed method in the oriental medicine classics. 2) Conclusions From long time ago people have used external treatment to cure various disease. According to the ${\lceil}Nei-Jing{\rfloor}$, hot compress therapy, fumigation therapy and bathing therapy had been used to cure blockage syndrome, muscle disease, carbuncle and cellulitis. Thereafter, a sphere of external treatment had gradually enlarged. (1) After all its sphere had included dermatologic, psychologic, internal, ophthalmic, otolaryngologic, obstetrics, gynecologic, pediatric and surgical diseases. (2) External treatment methods have contained hot compress therapy, fumigation therapy, bathing therapy, application therapy, medication bag therapy, medication plug therapy, medication massotherapy, aroma therapy and so on. (3) Medication types of external treatment have contained ointment, juice, infusion, powder, suppository and so on.

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Evaluation of Anti-inflammatory Activities and Mechanisms of Microalga Phaeodactylum tricornutum

  • Kim, Jeong Hwa;Kim, Sang Min;Pan, Cheol-Ho;Choi, Joong-Kook;Lee, Jae Kwon
    • Journal of Applied Biological Chemistry
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    • v.56 no.2
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    • pp.61-67
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    • 2013
  • Due to their diversity and abundancy, marine resources have emerged as important biological resources to compensate the limited sources of terrestrial biological materials. Phaeodactylum tricornutum (PT) is one of classical model diatoms most widely studied for its ecology, physiology, biochemistry and molecular biology. In this study, four different PT extracts on lipopolysaccharide (LPS)-stimulated macrophages were compared for anti-inflammatory effect and investigated for the underlying mechanisms. The extracts of PT inhibited nitric oxide production from LPS stimulated RAW 264.7 cells in a dose dependent manner. These extracts also inhibited the expression of mRNA and production of proteins of pro-inflammatory cytokines such as interleukin (IL)-$1{\beta}$, IL-6 and tumor necrosis factor-${\alpha}$. These inhibitory effects were found to be caused by blockage of nuclear factor-${\kappa}B$ activation and phosphorylation of p38 mitogen-activated protein kinases, extracellular signal-regulated kinases 1 and 2 and c-Jun N-terminal kinase.

Oridonin Suppresses Proliferation of Human Ovarian Cancer Cells via Blockage of mTOR Signaling

  • Xia, Rong;Chen, Sun-Xiao;Qin, Qin;Chen, Yan;Zhang, Wei-Wei;Zhu, Rong-Rong;Deng, An-Mei
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.2
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    • pp.667-671
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    • 2016
  • Oridonin, an ent-kaurane diterpenoid compound isolated from the traditional Chinese herb Rabdosia rubescens, has shown various pharmacological and physiological effects such as anti-tumor, anti-bacterial, and anti-inflammatory properties. However, the effect of oridonin on human ovarian cancer cell lines has not been determined. In this study, we demonstrated that oridonin inhibited ovarian cancer cell proliferation, migration and invasion in a dose-dependent manner. Furthermore, we showed oridonin inhibited tumor growth of ovarian cancer cells (SKOV3) in vivo. We then assessed mechanisms and found that oridonin specifically abrogated the phosphorylation/activation of mTOR signaling. In summary, our results indicate that oridonin is a potential inhibitor of ovarian cancer by blocking the mTOR signaling pathway.

Two-Dimensional Analysis of Unsteady Flow Through One Stage of Axial Turbine (II) (1단 축류 터빈의 비정상 내부유동특성에 관한 2차원 해석 (II))

  • Park, Jun-Young;Um, In-Sik;Baek, Je-Hyun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.11
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    • pp.1518-1526
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    • 2001
  • In this paper, the mechanism of unsteady potential interaction and wake interaction in one stage axial turbine is numerically investigated at design point in two-dimensional viewpoint. The numerical technique used is the upwind scheme of Van-Leer's Flux Vector Splitting (FVS) and Cubic spline interpolation is applied on zonal interface between stator and rotor. The inviscid analysis is used to embody the influence of potential interaction only and viscous analysis is used to embody the influences of both potential interaction and wake interaction at the same time. The potential-flow disturbance from the stator into a rotor passage and the periodic blockage effect of rotor produce the unsteady pressure on the blade surface in inviscid analysis. After the wake is cut by rotor, two counterrotating votical patterns flanking the wake centerline in the passage are generated. So, these phenomena magnify the unsteady pressure in viscous analysis than that in inviscid analysis. The resulting unsteady forces on the rotor, generated by the combined interaction of the two effects by potential and wake interaction, are discussed.

Validation of the numerical simulations of flow around a scaled-down turbine using experimental data from wind tunnel

  • Siddiqui, M. Salman;Rasheed, Adil;Kvamsdal, Trond
    • Wind and Structures
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    • v.29 no.6
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    • pp.405-416
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    • 2019
  • Aerodynamic characteristic of a small scale wind turbine under the influence of an incoming uniform wind field is studied using k-ω Shear Stress Transport turbulence model. Firstly, the lift and drag characteristics of the blade section consisting of S826 airfoil is studied using 2D simulations at a Reynolds number of 1×105. After that, the full turbine including the rotational effects of the blade is simulated using Multiple Reference Frames (MRF) and Sliding Mesh Interface (SMI) numerical techniques. The differences between the two techniques are quantified. It is then followed by a detailed comparison of the turbine's power/thrust output and the associated wake development at three tip speeds ratios (λ = 3, 6, 10). The phenomenon of blockage effect and spatial features of the flow are explained and linked to the turbines power output. Validation of wake profiles patterns at multiple locations downstream is also performed at each λ. The present work aims to evaluate the potential of the numerical methods in reproducing wind tunnel experimental results such that the method can be applied to full-scale turbines operating under realistic conditions in which observation data is scarce or lacking.

Numerical study on the effect of three-dimensional unsteady tunnel entry flow characteristics on the aerodynamic performance of high-speed train (터널진입시 비정상 유동특성이 고속전철의 공력성능에 미치는 영향에 관한 수치해석적 연구)

  • 정수진;김태훈;성기안
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.5
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    • pp.596-606
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    • 2002
  • The three-dimensional unsteady compressible Euler equation solver with ALE, CFD code, PAM-FLOW based on FEM method has been applied to analyze the flow field around the high speed train which is entering into a channel. From the present study, the pressure and flow transients were calculated and analyzed. The generation of compression wave was observed ahead of train and the high pressure in the gap between the train and the tunnel was also found due to the blockage effects. It was found that abrupt fluctuation in pressure exists in the region from train nose to shoulder of train corresponding to 10% of total length of train during tunnel entry. Computed time history of aerodynamic forces of train during tunnel entry show that drag coefficient rapidly rises and saturates at about non-dimensional time 0.31. The total increase of drag coefficient before and after tunnel entry is about 1.1%. Transient profile of lift force shows similar pattern to drag coefficient except abrupt drop after saturation and lift force in the tunnel increases 0.08% more than that before tunnel entry.

Treatment of Lung Cancer-Related Intractable Hiccups Using Pulsed Radiofrequency: Clinical Experience

  • Cho, Suk Ju
    • Journal of Hospice and Palliative Care
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    • v.21 no.3
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    • pp.104-107
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    • 2018
  • While most benign hiccups can be controlled with empirical therapy, intractable hiccups lasting longer than one month tend to have significant adverse effects with obscure etiology. Treatment strategies for intractable hiccups have not been established. Only a few sporadic cases of bilateral phrenic nerve blockage have been reported. Here, we report a case of intractable hiccups that lasted five weeks in a 56-year-old male patient with a lung cancer above the right diaphragm. We hypothesized that his intractable hiccups were caused by irritation and mass effect caused by the lung cancer. We performed an ultrasound-guided right unilateral phrenic nerve pulsed radiofrequency treatment, and the patient's intractable hiccups were successfully managed without complication.

A numerical and experimental study on the drag of a cavitating underwater vehicle in cavitation tunnel

  • Choi, Jung-Kyu;Ahn, Byoung-Kwon;Kim, Hyoung-Tae
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.5
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    • pp.888-905
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    • 2015
  • For Super-Cavitating Underwater Vehicles (SCUV), the numerical analyses and experiments in a large cavitation tunnel are carried out at relatively large Reynolds numbers. The numerical results agree well with experiments and the drag coefficient of SCUV is rarely changed by the Reynolds number. As the cavitation number is decreased, the cavity occurs and grows, the cavitator drag decreases and the body drag is affected by the degree of covering the body with the cavity. The tunnel effects, i.e. the blockage and the friction pressure drop of the tunnel, on the drag and the cavitation of SCUV are examined from the numerical results in between the tunnel and unbounded flows. In the tunnel, a minimum cavitation number exists and the drag of SCUV appears larger than that in unbounded flow. When the super-cavity covers the entire body, the friction drag almost disappears and the total drag of SCUV can be regarded as the pressure drag of cavitator.