• 제목/요약/키워드: Stagnation

검색결과 935건 처리시간 0.023초

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

  • 이기백;손창민;김봉환
    • 대한기계학회논문집
    • /
    • 제15권6호
    • /
    • pp.1919-1932
    • /
    • 1991
  • 본 연구에서는 고강도 알루미늄 합금으로 제작된 평판보의 받음각(.alpha.)를 10˚ 에서 30˚까지 10˚씩 변화시킨 3가지의 모델에 대해, 각 모델의 Re$_{d}$수 변화에 대한 후류의 스펙트럼분석, 레이저 도플러 유속계(laser doppler velocimetry)를 이용 한 유동장 해석 및 평판보의 응답을 실험을 통해 조사, 분석하고 유동장과 측정이 용 이하지 않은 얇은 평판주위의 압력분포에 대한 전산해석을 수행함으로써 유동 여기진 동 구조의 규명을 시도하였다.다.

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

  • 박태선;성형진
    • 대한기계학회논문집
    • /
    • 제15권6호
    • /
    • pp.2132-2146
    • /
    • 1991
  • 본 연구에서는 기존 유속계에 의한 측정이 어려운 점을 감안하여 나프탈렌 승 화법을 이용하여 열교환기 시스템의 한 모델인 원봉에 유한한 길이의 환상핀이 부착된 경우 환상핀과 원봉이 만나는 부분에서 와류들 특히 V2, V3등 구석와류가 물질전달을 증가시키는 구조에 대해 고찰한다. 이는 원봉 주위의 환상핀에 의한 대류 물질전달 에 영향을 줄수 있는 레이놀즈수, 환상핀의 크기에 따른 형상비, 그리고 경계층 두께, 배제 두께 등의 유동변수를 변화시켜 가며 물질전달률과의 관계를 규명하여 열교환기 설계의 기본자료를 제공한다. 또한 환상핀 사이의 원봉표면에 대한 전체물질전달률 을 측정하며, 환상핀에 인접한 곳에서 구석와류에 대한 환상핀의 끝 벽면 영향을 알아 보고 이를 근거로 하여 말굽와류의 3차원 박리 유동구조를 정성적으로 규명하고자 한 다.

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

  • 전세종;홀거노박;캠트로피아;성형진
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2004년도 추계학술대회
    • /
    • pp.1546-1551
    • /
    • 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.

  • PDF

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

  • 오동진;류정인
    • 에너지공학
    • /
    • 제11권3호
    • /
    • pp.276-282
    • /
    • 2002
  • 본 논문에서는 압축공기를 작동매체로 한 저압용 vortex tube에 대한 에너지분리 과정을 상세히 연구하였다. 먼저 vortex tube에서 에너지 분리되어 나오는 온공기와 냉공기의 온도변화에 대하여 실험하였고, vortex tube의 안쪽표면의 최대벽면온도 변화와 vortex tube내의 온도분포를 통하여 vortex tube내 유동장에서의 정체점의 위치에 대한 유용한 정보를 얻게되었다. 이를 바탕으로 vortex tube의 최적 길이와 throttle의 형상, sleeve에 따른 에너지분리과정 등을 실험을 통하여 알아보았다. 또한 본 연구에서는 디젤기관의 배기에 적용하기 위한 외통을 사용하였다. 이때 vortex tube에서 나오는 은공기가 180$^{\circ}$돌아 나오면서 vortex tube의 바깥쪽 벽면을 가열하게 된다. 이러한 기하학적 형상을 통하여 에너지분리효과가 증대됨으로 인하여 디젤기관의 배기가스에 적용 시 고온유동의 온도를 높이고자함에 본 연구의 목적을 두고자한다.

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

  • 이종욱;이두환;최윤호
    • 에너지공학
    • /
    • 제11권1호
    • /
    • pp.26-33
    • /
    • 2002
  • 본 연구에서는 butterfly valve주위의 비압축성 및 압축성유동 특성을 수치해석을 통하여 조사하였다. 밸브는 문제를 단순화시키기 위하여 평판 디스크로 간주하였으며, 다양한 디스크 각도 및 압력비 변화에 대한 계산을 수행하였다. 각도가 증가함에 따라 디스크 상류면의 정체점은 디스크의 중심으로 이동하는 것을 볼 수 있었고, 입구공기의 유입 속도는 감소함을 볼 수 있었다. 최고 유속은 디스크와 벽면사이에 형성되는 vena contracta 효과에 의해 생기는 목의 하류에서 형성됨을 볼 수 있었다. 압력비를 감소함에 따라 압축성 효과는 증대되며 유동이 초음속화 되면서 생성되는 강한 wall jet에 의해 shock cell structure가 형성되는 것을 볼 수 있었다. 입구유량은 디스크 각도와 압력비의 증가에 따라서 감소하며, 압력손실계수는 디스크 각도의 증가 및 압력비의 감소에 따라 증가하였다.

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

  • 이덕자;조정순;박진영;박성혜
    • 한국식품영양학회지
    • /
    • 제25권4호
    • /
    • pp.697-705
    • /
    • 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.

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

  • 류영수;박진성;황시영
    • 동의신경정신과학회지
    • /
    • 제8권2호
    • /
    • pp.85-95
    • /
    • 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.

  • PDF

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

  • 강경화;김인진;이용태
    • 동의생리병리학회지
    • /
    • 제18권5호
    • /
    • pp.1285-1290
    • /
    • 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).

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

  • 이승현;박단서
    • 동의생리병리학회지
    • /
    • 제21권5호
    • /
    • pp.1346-1351
    • /
    • 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.

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

  • 이원철;선승호
    • 동의생리병리학회지
    • /
    • 제27권1호
    • /
    • pp.34-42
    • /
    • 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.