• 제목/요약/키워드: Stagnation

검색결과 935건 처리시간 0.023초

Prediction of Air Movement and Temperature Distribution at Different Store Methods Using 3-D CFD Simulation in Forced-Air Cooling Facility

  • Yang, G.M.;Koh, H.K.
    • Agricultural and Biosystems Engineering
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    • 제3권2호
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    • pp.65-72
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    • 2002
  • Temperature is the most influential environment parameter which affects the quality change of agricultural products in cold storage. Therefore, it is essential to keep the uniform temperature distribution in the storage room. This study was performed to analyze the air movement and temperature distribution in the forced recirculating cold storage facility and to simulate optimum storage method of green groceries using 3-D CFD(three dimensional computational fluid dynamics) computer simulation which applied the standard $textsc{k}$-$\varepsilon$ turbulence model and FVM(finite volume method). The simulation was validated by the experimental results for onion storage and the simulation model was used to simulate the temperature and velocity distribution in the storage room with reference to the change of storage method such as location of storage, no stores, bulk storage, and pallet storage. In case of no stores, internal airflow was circulated without stagnation and consequently air movement and temperature distribution were uniform. In case of bulk storage, air movement was stagnated so much and temperature distribution of onion was not uniform. Furthermore, the inner temperature of onion roses more than the initial temperature of storage. In case of pallet storage, air movement and temperature distribution of onion were so uniform that the danger of quality change was decreased.

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응축충격파와 경계층 간섭의 피동제어(II) (A Passive Control of Interaction of Condensation Shock Wave anc Boundary Layer(II))

  • 최영상;권순범;김병지
    • 대한기계학회논문집B
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    • 제21권2호
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    • pp.329-340
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    • 1997
  • A passive control of interaction of condensation shock wave / boundary layer for reducing the strength of condensation shock was conducted experimentally in a 2.5 * 8 cm$^{2}$ indraft type supersonic wind tunnel. The effects of following factors on passive control were investigated: 1) the thickness of porous wall, 2) the diameter of porous hole, and 3) the orientation of porous hole. On the other hand, the location of nonequilibrium condensation region and condensation shock wave was controlled by regulation of the stagnation conditions. Surface static pressure measurements as well as Schlieren observations of the flow field were obtained, and their effects were compared with the results the cases of without passive control. It was found that thinner porous wall, smaller porous hole and FFH orientation for the same cavity size and porosity of 12% are more favourable than the cases of its opposite.

Agriculture in China

  • Pretty, K.M.
    • 한국토양비료학회지
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    • 제17권4호
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    • pp.314-318
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    • 1984
  • China has made rapid strides in agricultural production during the past few years. Although the absence of any serious climatic disturbances is a contributing factor, implementation of the responsibility system to reward peasant families for their initiatives has been by far the most significant. This has resulted in increased specialization, a greater requirement for technical adivsory services, and a much higher demand for farm equipment and production inputs. The revamped system has brought with it some problems such as differences in income between the most progressive producers and their less successful neighbours and urban workers, a shortage of storage, transport and processing facilities, and a strain on the national treasury to continue to subsidize farm prices. Demand for fertilizers has been increasing at a fast rate, especially for nitrogen. This has led to a serious imbalance in nutrient use which must be corrected if the current momentum in improving crop yields is to be maintained. Following a decade of total stagnation during the Cultural Revolution, agricultural research and education facilities are being strengthened. Younger scientists, many with overseas training, are being placed in key positions. China is still a developing country, and much remains to be done; however, progress in the last decade, and especially in the past five years, has been remarkable.

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기허증(氣虛證)의 임상 질환 범위에 대한 고찰 (Study on Clinical Diseases of Qi Deficiency Pattern)

  • 박미선;김영목
    • 동의생리병리학회지
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    • 제27권5호
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    • pp.487-496
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    • 2013
  • This article is a study on to which categories of modern diseases qi deficiency pattern types are assigned by reference to modern clinical papers to analyze and understand modern diseases with the perspective of Korean Medicine. Clinical papers were searched in China Academic Journals(CAJ) of China National Knowledge Infrastructure(CNKI) from 1994 to 2013. Conclusions are as follows. First, qi deficiency pattern types are roughly classified as qi deficiency pattern, qi-yin dual deficiency pattern and qi deficiency pattern related with viscera and bowels. Second, there are many patterns combined with static blood, qi stagnation, phlegm, dampness, heat, toxin, water or fluid deficiency and the level of pattern designation is more specific than pattern types in Korean Standard Classification of Diseases(KCD), which makes the pattern types more useful to clinical application. Third, static blood due to qi deficiency is the most frequent combined pattern and diseases related with blood circulation such as angina, atherosclerosis, hyperlipidemia and chronic obstructive pulmonary disease(COPD) were reported on that pattern. The detailed relation between modern diseases and pattern types can be an another topic.

저압용 보텍스튜브의 노즐면적비에 따른 에너지 분리특성에 관한 실험적 연구 (An Experimental Study on the Energy Separation in the Ratio of Nozzle Area of a tow Pressure Vortex Tube)

  • 오동진;최정원
    • 에너지공학
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    • 제13권1호
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    • pp.34-39
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    • 2004
  • 본 논문에서는 압축공기를 작동매체로 한 저압용 보텍스튜브에 대한 에너지 분리과정을 상세히 연구하였다 먼저 보텍스튜브에서 에너지 분리되어 나오는 온공기와 냉공기의 온도변화에 대하여 실험하였고, 보텍스튜브의 안쪽표면의 최대벽면온도 변화와 보텍스튜브 내의 온도분포를 통하여 보텍스튜브 내 유동장에서의 정체점의 위치에 대한 유용한 정보를 얻게 되었다. 이를 바탕으로 보텍스튜브의 노즐면적비와, 오리피스의 크기에 따른 에너지분리 과정 등을 실험을 통하여 알아보았다. 이러한 기하학적 형상의 변화실험을 통하여 저압용?대형 보텍스튜브의 에너지 분리과정이 고압형\ulcorner소형 보텍스튜브 보다 에너지 분리효과가 증대됨으로 인하여 최적의 노즐면적비와 오리피스지름비가 차이가 있음을 알 수 있었다.

부품승인(PMA/EPA) 제도와 항공부품시장 동향 (Status of Aviation Part Market and PMA/EPA)

  • 정봉구;진영권
    • 항공우주산업기술동향
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    • 제7권2호
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    • pp.106-114
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    • 2009
  • 그 동안 항공부품시장은 높은 신뢰성과 안전성을 요구하는 항공산업의 특성로 인해 OEM(Original Equipment Manufacturer) 부품이 주도하여 왔다. 그러나 제조기술의 발전, 경기침체, 유가상승 및 아시아-태평양 신흥 시장의 부각 등의 환경적 변화로 인해, 최근, 항공시장에서의 PMA 부품에 대한 관심이 지속적으로 증대되고 있다. 실제로 2006년 이후 FAA PMA 승인부품은 매년 40,000 개씩 증가하고 있으며, PMA 부품 보급률(아시아-태평양 시장)은 2007년 2.5%에서 2017년 8%까지 증대될 것으로 예상되고 있다. 따라서, 본 논문에서는 항공부품 승인제도에 대한 이해를 도모하고, 새로운 PMA 시장을 살펴보기 위해 FAA PMA/EASA EPA의 절차상 요건과 PMA 부품시장 현황을 소개하였다.

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칩 특성을 고려한 UHF RFID 태그 설계 (Design of UHF RFID Tag Considering Chip Characteristic)

  • 이홍주;황건용;이응주
    • 한국멀티미디어학회논문지
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    • 제14권2호
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    • pp.194-200
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    • 2011
  • RFID(Radio Frequency IDentification) 산업의 시장 동향은 가격 문제로 인하여 정체성을 보이고 있다. 근래에는 칩 가격의 하락으로 인해 칩을 제외한 태그 인레이 가격이 상대적으로 높아지고 있는 실정이며 태그 저 가격화를 실현하기 위해서는 빠르고 간단하면서도 저비용의 RFID 태그 설계 기술이 필수적이다. 따라서 본 논문에서는 안테나 설계를 위한 기반기술 중 하나인 칩 임피던스를 고려하여 태그를 설계하여 보다 정확하고 빠른 설계가 가능한 시스템 개발을 제안하였다. 제안한 시스템의 성능평가 결과 기존 시스템보다 20Mhz 내에서 공진 범위오차가 줄어들었으며, 판독 오류도 1.5m 이내로 줄어드는 성능개선 효과가 있었다.

편타성 손상후 발생한 뇌진탕증 2례 (Two cases of concussion after whiplash injury)

  • 한을주;김봉찬;이명종
    • 한방안이비인후피부과학회지
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    • 제14권1호
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    • pp.87-93
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    • 2001
  • Object : This study was focused on finding out the better method of medical treatment of concussion after whiplash injury. Methods : This study has been carried out for two cases of concussion after whiplash injury which had been hospitalized at the Kangnam Oriental medical Hospital of the Dongguk University Results and conclusions : The concussion is caused by whiplash injury about $47\%. In the symptoms of concussion, there are lightheadedness, dizziness, neck pain, headache, photophobia, phonophobia, anamnesis disorder, concentration disorder, tinnitus, irritability, etc. It is considered more important that the treatment of nausea and vomiting than the removal of stagnation of blood. Oriental medical treatments including of herb-medicine, acupuncture, moxibustion, cupping, chuna, taping have more economic favor and rapid effects than the others. so we report on two cases.

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음아의 원인(原因)에 대(對)한 문헌적(文獻的) 고찰(考察) (A Bibliographic Study on the Cause of Aphasia)

  • 한대길
    • 대한한방내과학회지
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    • 제11권2호
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    • pp.137-147
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    • 1990
  • I studied some important medical liter atures in order to examine the cause of Aphasia and found out some facts as follows : 1. Hwang Je Nae Kgong(黃帝內經) is more referred exogenous causes of disease of Aphasia than endogenous causes of disease. 2. Among many causes of Aphasia, exogenous causes of disease was cinsidered to be most common in Soh Shi Je Byong Won Hu chong Rhon(巢氏諸病源喉總論), which has had a wide influence down the ages. 3. Chon Keum Yo Bang(千金要方), Chi Tae Bhi Yo(外臺秘要), Tae Pyong Song Hye Bang(太平聖惠方), Song Je Chong Rok(聖濟總綠). Bu In Yang Bang(婦人良方) and so forth had been quoted from Hwang Je Nae Kyong and Soh Shi Je Byong Won Hu Chong Ron(巢氏諸病源喉總論). 4. In the ming dynasty had been quoted non-exo-endogenous causes of disease and the Kinds of Aphasia and prescription. 5. In the Choeun dynasty and the Ching dynasty, exogenous causes of disease was confined to the quotation of the books referred to above as well, but endogenous causes of disease was developed. 6. Today is refered kidney and Aphasia. The cause of Aphasia obtained was as follows. The exogenous cause of disease is wind, wind and cold, wind and heat. The endogenous cause of disease is pregnancy, heart block of postpartum, weakness of heart and kidney, impairment of seven modes of emotions, stagnation of phlegm and phlegm-fire, hemorrhage. The non exo-endogenous causes of disease is sing ballads and call out.

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전증(癲證)을 동반한 졸중풍(卒中風) 환자 치험1례 (A clinical report of cerebral infarction patient with schizophrenia)

  • 오경민;양동호;김보경
    • 동의신경정신과학회지
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    • 제18권3호
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    • pp.209-224
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    • 2007
  • Metabolic syndrome consists of several risk factors of metabolic origin like elevated blood pressure, abdominal obesity, elevated triglyceride concentrations, decreased HDL-cholesterol concentrations, and elevated fasting glucose. It appear to directly increase the development of atherosclerotic cardiovascular diseases which leading to cardiovascular diseases in later life. This 39 years female patient was diagnosed schizophrenia at the age of 17. but she didn't take reasonable treatments. during 20 years, she stayed in home and lived unsuited life with her family. As a result she gains heavy weight and centeral obesity, diabetic mellitus and hypertention, and developed cerevral vascular accident twice. This patient was treated with herb medication, acupuncture, western medication, psychotherapy primarily in focusing of pre-illness state(未病) as well as the stagnation of phelm. During 140 days of treatment from admission, before 2nd attack tbe patient showed improvement of Lt. hemiparesis but after second attack improved a little. And symptom of schizophrenia improved considerably. Also diet habit changed.

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