• Title/Summary/Keyword: Stagnation

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A Study on Flow Induced Vibration of Cantilever Plate with Angle of Attack (받음각을 갖는 평판보의 유동 여기진동에 관한 연구)

  • 이기백;손창민;김봉환
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.6
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    • pp.1919-1932
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    • 1991
  • Experimental studies are conducted to investigate the Flow-Induced Vibration mechanism for cantilever plate model with the angle of attack (.alpha.=10.deg., 20.deg., 30.deg.). Research is divided into two parts. First, the flow fields around two dimensional flat plate model are investigated using LDV system. Second, the vortex shedding frequency and response spectra of cantilever plate are obtained experimentally using gap sensor and hot wire anemometer. Finite element method program was used in order to predict the flow field and pressure field around thin flat plate. And some predicted results were compared with the experimental data. The aspect ration of test model is d/t=25 (d; width, t; thickness). From the measurement of the flow field it was found that in the case of small inclined (.alpha.=10.deg., 20.deg.) relatively, the separated boundary layer at sharp leading edge developed smoothly downstream. With increasing the angle of attack of the plate, stagnation region was appeared on the back side of the plate and separated boundary layer was extended downstream. These trends are a good agreement with the computational results. It was found by analysis of response spectra of cantilever plate that the influences of vortex shedding frequency were important at the large of attack (.alpha.=30.deg.), and two peak values appear in entire test model at 24Hz, 150Hz.

Local Convective Mass Transfer and Flow Structure Around a Circular Cylinder with Annular Fins (환상핀이 부착된 원봉 주위의 3차원 박리 유동구조 및 물질전달 특성 해석)

  • 박태선;성형진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.6
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    • pp.2132-2146
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    • 1991
  • Extensive experiments were carried out to investigate the mass transfer and flow structures around a circular cylinder with annular fins in crossflow. The naphthalene sublimation method was employed to measure the circumferential and longitudinal variations of mass transfer from the circular cylinder between annular fins and H is the height of the fin from the cylinder surface. A remarkable enhancement of mass transfer due to the horseshoe vortices was observed near the corner junction between the annular fin and circular cylinder. The present results indicate that the local circumferential Sherwood number shows the higher values on the front stagnation point. The maximum augmentation of mass transfer rate at the center of cylinder is found near L/H-0.15 due to the separation bubble along the annular fins. The secondary flows, which are the corner vortices V2 and V3 near the end wall of the annular fin, are fairly predicted from the distributions of local Sherwood number in the spanwise direction. The average Sherwood number of overall surface at L/H=0.15 is larger 2.0 times than that of without annualr fins. The correlations of total average mass transfer rate with L/H and Re$_{L}$ can also be obtained.d.

Effect of fringe divergence in fluid acceleration measurement using LDA (레이저 도플러 원리를 이용한 유체 가속도 측정)

  • Chun, Se-Jong;Nobach, Holger;Tropea, Cam;Sung, Hyung-Jin
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1546-1551
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    • 2004
  • The laser Doppler technique is well-established as a velocity measurement technique of high precision for flow velocity. Recently, the laser Doppler technique has also been used to measure acceleration of fluid particles. Acceleration is interesting from a fluid mechanics point of view, since the Navier Stokes equations, specifically the left-hand-side, are formulated in terms of fluid acceleration. Further, there are several avenues to estimating the dissipation rate using the acceleration. However such measurements place additional demands on the design of the optical system; in particular fringe non-uniformity must be held below about 0.0001 to avoid systematic errors. Relations expressing fringe divergence as a function of the optical parameters of the system have been given in the literature; however, direct use of these formulae to minimize fringe divergence lead either to very large measurement volumes or to extremely high intersection angles. This dilemma can be resolved by using an off-axis receiving arrangement, in which the measurement volume is truncated by a pinhole in front of the detection plane. In the present study an optical design study is performed for optimizing laser Doppler systems for fluid acceleration measurements. This is followed by laboratory validation using a round free jet and a stagnation flow, two flows in which either fluid acceleration has been previously measured or in which the acceleration is known analytically. A 90 degree off-axis receiving angle is used with a pinhole or a slit.

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An Experimental Study on the Energy Separation in the Geometric Setup of a Low Pressure Vortex Tube (저압용 vertex tube의 기하학적형상에 따른 에너지 분리특성에 관한 실험적 연구)

  • 오동진;류정인
    • Journal of Energy Engineering
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    • v.11 no.3
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    • pp.276-282
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    • 2002
  • The process of energy separation in a low Pressure vortex tube with compressed air as a work-ing medium is studied in detail. Experimental data of the temperature of the cold and hot air leaving the vortex tube are presented. The variation of the maximum wall temperature along the inner surface of the vortex tube and the temperature distribution in a vortex tube provide useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. Analysis of the results enabled to find the optimum length of the vortex tube, the optimum shape of the Throttle and the usefulness of the Sleeve. In this study Outer tube is used for the exhaust application. The hot gas flow is turned 180$^{\circ}$and passes the out-side of the vortex tube a second time heating it. From this geometric setup of a vortex tube He effects of energy separation and the prediction of the ignition of Diesel Soot is presented by experimental data.

Numerical Analysis of Incompressible and Compressible Flow Around a Butterfly Valve (버터플라이 벨브 주위의 비압축성 및 압축성유동 특성에 대한 수치해석)

  • 이종욱;이두환;최윤호
    • Journal of Energy Engineering
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    • v.11 no.1
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    • pp.26-33
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    • 2002
  • In this paper, incompressible and compressible flow characteristics around the butterfly valve have been investigated. In order to simplify the problem, a flat disk valve with various valve disk angles and pressure ratios is considered in the present calculations. It was found that as the disk angle increases, the stagnation point on the front surface of the disk moves to the center of the surface and the inflow velocity decreases. The maximum flow velocity occurs at the downstream of throat because of the formation of vents contracta. As the pressure ratio decreases, compressibility effects increase and the jet formed between the throttle body wall and the disk edge becomes supersonic. This flow also builds up as a shock cell structure. The increase of disk angle and pressure ratio makes the mass flow at the inlet decrease, while the increase of disk angle and the decrease of pressure ratio make the pressure loss coefficient increase.

Effects of Kangjieum on Serum Lipids and Active Oxygen Content in Overweight Women Consequential Qi-stagnation and Blood Stasis Patterns (약선차 강지음(降脂飮)이 기체혈어형(氣滯血瘀型) 과체중 성인의 혈청지질 및 활성산소 농도에 미치는 영향)

  • Lee, Deok-Ja;Cho, Jung-Soon;Park, Jin-Young;Park, Sung-Hye
    • The Korean Journal of Food And Nutrition
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    • v.25 no.4
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    • pp.697-705
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    • 2012
  • This research was planned and executed to evaluate how the composition of Yack-sun (oriental diet therapy) tea can effect the health conditions of people who are suffering from diet-related diseases such as being overweight, obese and hyperlipidemic, by taking Yack-sun tea in a form of nutritional supplement with daily meals. We produced Kangjieum with Lycense Mill., Polygonum multflorum Thunb, Cassia tora L., Crataegus pinnatifida Bge and Salvia miltiorrhiza Bge. We evaluated the effects of this tea on serum lipids, on homocysteine concentration, and on active oxygen contents, oxidative stress by clinical practices. We have determined that this tea has a significant effect on decreasing body fat content, decreasing total cholesterol, decreasing LDL-cholesterol, and decreses triglyceride and homocysteine concentrations. In addition, blood active oxygen content and oxidative stress were significantly decreased. We think that scientific and objective evaluation was performed on the components of Kangjieum prescription. We concluded that we could apply the components, not only in a form of tea, but also in other forms of various foods. The information we received from this conclusion will be basic information on how we can apply oriental medicinal resources into other food and will be a steppingstone for medicinal herbs to place a foot in the field of functional food research, which already draws sizable attention world-wide.

Clinical Study on the Auricular Acupuncture Therapy for the Functional Headache (기능성(機能性) 두통(頭痛)에 대한 이침요법(耳鍼療法)의 임상적(臨床的) 연구(硏究))

  • Lyu Young-Su;Park Jin-Sung;Hwang Si-Young
    • Journal of Oriental Neuropsychiatry
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    • v.8 no.2
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    • pp.85-95
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    • 1997
  • After performing the auricular acupuncture therapy for the functional headache, we came to gain the following therapy effects. 1. In the whole of the patients of the functional headache, housewives of forties were most of all. 2. In the classification of mordern medicine on the patients of the functional headache, muscular contractional headache was most of all and in the classification of oriental differentiation of symtoms and signs(辨證), headache due to deficiency of blood(血虛頭痛) was most of all. 3. In the regional auricular acupuncture therapy for the functonal headache, Taiyang of auricular point(太陽點) had an effect on the lateral headache around the area of Taiyang of auricular point(太陽點) though the actions of sedation, analgesia, Neck of auricular point(頸點) had an effect on the muscular contractional headache of the occipital region, and Stomach of auricular point(胃點) had an effect on the headache of stagnation of phlegm(痰濁頭痛) of anterior region with a chronic digestive disease. 4. The average treatment times of the auricular acupuncture therapy in the patients of the functional headache was 4.08 times, if we have them take auricular acupuncture therapy about 4 times it could be thought to take excellent effect of treatment. 5. The effect of auricular acupuncture therapy for functional headache was turned out to be effective in the following orders ; lateral region(Group A), occipital region(Group B), anterior region(group C). Through the clinical consequences of therapy mentioned above, we came to confirm regular therapeuric effects and hereafter, it is considered that a clinical comparative study on oriental cure and auricular acupuncture therapy for headache has to be more progressed than now.

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Study on Depressive Syndrome in Hyungsang Medicine (울증의 형상의학적 고찰)

  • Kang Kyung Hwa;Kim In Jin;Lee Yong Tae
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.18 no.5
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    • pp.1285-1290
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    • 2004
  • From a view point of Hyungsang medicine a study is made on depressive syndromes through 'Donguibogam(東醫寶鑑)' ,'Clinical lectures by Mr. Jeesan(芝山先生 臨床學特講)' and other literature. Depressed energy(?) originally meant the disorder of vital energy in the circulation of nature with the lapse of time. In later, it has been changed to mean the disease of man, especially related to the mind. Depressive syndromes come from the stagnation of the Ki or the abnormal circulation(rising, falling, coming and going), which happens when man cannot adjust oneself to the circumstances due to the disharmony between internal and external conditions. Depressive syndrome easily attacks the following types of persons; Dam type person with excessive Ki and deficient Hyung(形), manly woman, womanly man, Bird type person who shows a great variety of emotion, Turtle type person declined to melancholy, Ki type person apt to be depressive, and Shin type person with upward gush of the fire. It also attacks the persons who have smudgy face with the scar between eyebrows, those whose pulses are mixture of two different kinds and those whose pulses extend on two ranges in Jeesan's diagram. Depressive syndromes recorded in 'Donguibogam' are globus hystericus, chest congestion, gastric discomfort, cough and asthma caused by depressed Ki, abdominal mass, edema, and tympanites. The most effective prescriptions for depressive syndromes are Eajintang(二陳湯), Guibitang(歸脾湯), Hyangsosan(香蘇散), and Gamisachiltang(加味四七湯).

Clinical Study on 1 Case of Soyangyin Patient Diagnosed as Crohn's Disease (크론씨병으로 진단된 소양인 환자 치험 1 례)

  • Lee, Seung-Hyun;Park, Darn-Seo
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.21 no.5
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    • pp.1346-1351
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    • 2007
  • Crohn' disease is an auto-immune disease characterized by intermittent chronic diarrhea, high fever, weight loss, abdominal spastic pain or abdominal discomfort which is followed by granulomatous necrosis and cicatrical inflammation. It is also called segmental enteritis or granulomatous enteritis. In western medicine the exact cause is undefined, however it is presumed as an immunological unbalance in alimentary tract commoonly occured in ileum portion of small intestitine or ascending colon and therefore immuno suppressive agents(usually steroids) and anti-inflammatory drugs are prescribed. In case of emergency such as ileus, perforation of intestinal wall surgical methods are considered. In oriental medicine this falls under the category of diarrhea(泄瀉), dysentery(痢疾), splenic diarrhea(脾泄). As to the pathological mechanism the abnormal ascending and descending circulation of stomach and splenic energy(脾不升淸, 胃不下降) the hepatic stagnation(肝鬱氣滯) and dysfunction of small intestine in expelling urine and feces(小陽淸獨不利) all together causes such condition. Main treatments are inducing diuresis(利小便), warming kindey to reinforce yang(溫賢助陽), nourishing the middle energy to invigorate spleen(補中健脾), elimination of the dampness by cooling(淸熱燥濕). In this case the patient was diagnosed as soyangyin(少陽人) constitution and herb medicine soyangyin Hyongbangjihwan-tang(少陽人 荊防地黃湯), Sa-am acupuncture Sojangjeonggyeok(小腸政格) was applied. There was an significant improve in chief complaints and general conditions.

Literature Review on Alternative Traditional Treatment of Spasmodic Torticollis - focusing on Chinese Traditional Medicine's Journals - (연축성 사경 치료에 관한 문헌적 고찰 - 중국 논문 중심으로 -)

  • Lee, Won Chul;Sun, Seung Ho
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.27 no.1
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    • pp.34-42
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    • 2013
  • Our study is to review Chinese traditional medicine's journals about the diagnosis and treatment of spasmodic torticollis such as category, syndrome differentiation, acupoints of treatment, and herbal medicine. The journal search was performed using the search engine of China Academic Journal (CAJ) and China Doctor/Master's Dissertation (CDMD) in China National Knowledge Infrastructure (CNKI) from January 1982 to October 2012. Searching key words were the diverse combination of "spasmodic torticollis", "cervical dystonia", "Chinese traditonal medicine", "herbal medicine", "acupuncture", and "syndrome differentiation". The inclusion criteria was all kinds of journals including Chinese traditional medicine approach except for experiment study. The category, syndrome differentiation, acupoints of treatment, and herbal medicine from finally selected journals were extracted and summarized. The fourty-seven Chinese journals were selected finally. The category was divided into wind syndrome, trembling syndrome, convulsive syndrome, and convulsions. The syndrome differentiation was classified as internal stirring of liver wind, yin-blood depletion, invasion of external contraction, uncontrol of governor vessel, internal obstruction of phlegm turbidity, dual deficiency of qi and blood, and blood stasis due to qi stagnation. The combination of acupoints to unblock the meridian and dissipate binds and to tonify governor vessel and repel tremor was mainly used in acupuncture treatment. Galgun-tang or galgun-tanggami was primarily used and the others were the prescriptions to tonify liver and kidney, to calm convulsion, and to dispeling wind-phlegm. We suggests that spasmodic torticollis could be treated using Korean medicine's approach in Korea.