• Title/Summary/Keyword: Decrease rate

검색결과 6,181건 처리시간 0.044초

유동공진이 판형 열교환기의 열전달 향상과 압력강하에 미치는 영향 (Effects of Flow Resonance on Heat Transfer Enhancement and Pressure Drop in a Plate Heat Exchanger)

  • 한상규;강병하
    • 설비공학논문집
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    • 제17권2호
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    • pp.165-172
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    • 2005
  • Heat transfer enhancement of three types of brazed plate heat exchangers has been evaluated experimentally. The effects of flow resonance in a plate heat exchanger on the heat transfer rate and pressure drop have been investigated in a wide range of mass flow rates in detail. The problem is of particular interest in the innovative design of a plate heat exchanger by flow resonance. The results obtained indicate that both heat transfer coefficient and pressure drop are increased as mass flow rate is increased, as expected. It is also found that the heat transfer enhancement is increased with an increase in the plate pitch, while the heat transfer is decreased with a decrease in the chevron angle. Pressure drop also increased with an increase in the plate pitch and with a decrease in the chevron angle. Heat transfer enhancement in the plate heat exchangers is maximized by flow resonance and the resonance frequency of the present plate heat exchangers is found to be in the range of $10~15\;Hz$.

수직관내(垂直管內)를 흘러내리는 액막식(液膜式) 흡수기(吸收器)의 흡수(吸收) 및 열전달특성(熱傳達特性) (제(第) 1 보(報), 흡수특성(吸收特性)) (Characteristics of Absorption and Heat Transfer for Film Falling along a Vertical inner Tube (1st Report, Characteristics of Absorption))

  • 엄기찬;백목 효부;서정윤
    • 설비공학논문집
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    • 제5권1호
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    • pp.1-9
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    • 1993
  • Mass transfer coefficients were measured for water vapor absorption into a LiBr-Water solution of 60wt% flowing down an absorber of vertical tube type. The absorber is copper tube of 25mm inner diameter and 1000mm length. The film Reynolds number were varied in the range of 35~130. The solution is fed from the top of the pipe, and the conditions of solution are supercooled liquid and superheated liquid. As results, the flowrates of LiBr solution which takes peak value of average absorption mass flux exist. Mass transfer coefficients decrease with increasing the flowrate of LiBr solution, and the decrease rate in the case of supercooled liquid is large as compared with that in the case of superheated liquid. But the absorption rate of supercooled liquid is decidedly superior to that of superheated liquid.

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한국재래산양(韓國在來山羊)에 있어서 Combelen 투여(投與)가 임상소견(臨床所見) 및 혈액성분(血液成分)에 미치는 영향(影響) (Clinical, Hematological and Blood Chemical Changes in Korean Native Goats Following Administration of Combelen)

  • 장인호
    • 대한수의학회지
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    • 제18권1호
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    • pp.1-7
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    • 1978
  • In order to detect the clinical effect of combelen which is used for sedation of domestic animals, 10 heads of clinically healthy Korean native goats were used in this study. They were divided into two groups; one is dose level of 1ml per 10 kg of body weight with 1% combelen and the other is dose level of 3 ml. Clinical observations and changes in blood components after administration of combelen were made. 1. There was no adverse effect due to combelen, but sedative effect was insufficient. 2. During sedative period the changes in heart rate and respiratory rate showed noticeable change, and body temperature was slightly decreased. 3. In ECG recordings, except for slight changes in T wave, significant change was not observed. 4. Erythrocytes, leukocytes, hemoglobin concentration and packed cell volume showed tendency to decrease during the period of sedation. 5. SGOT activity showed a remarkable increase and BUN showed a great decrease 24 hours after administration in the group of 3ml/10kg. Blood glucose level increased during the period of sedation in both groups.

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Saccharomyces cerevisiae에서 myo-Inositol 결핍에 의한 Respiratory capacity의 감소

  • 정경환;이준식
    • 한국미생물·생명공학회지
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    • 제24권4호
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    • pp.485-492
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    • 1996
  • myo-Inositol, a growth factor for Saccharomyces cerevisiae (S. cerevisiae), has been known to be incorporated into phosphatidylinositol (PI), which is a kind of phospholipid in the cell membrane, by a membrane-associated PI-synthesizing enzyme. The deficiency of myo-inositol in S. cerevisiae adversely affected the membrane structure and function. On the basis of biochemical functions of myo-inositol, the effect of deficiency of myo-inositol on the aerobic glucose metabolism was investigated by measuring specific oxygen uptake rate (Q$_{O2}$) used as an indicator representing the respiratory capacity of S. cerevisiae in batch and continuous cultures. The respiratory capacity of aerobic glucose metabolism in S. cerevisiae was also monitored after glucose pulse-addition in a continuous culture (D=0.2, 1/hr), in which glucose was utilized through respiratory metabolism. The deficiency of myo-inositol was found to lead to both the decrease of the maximum specific oxygen uptake rate (Q$_{O2max}$) observed from the batch as well as in the continuous culture experiment and the decrease of the respiratory capacity of aerobic glucose metabolism of S. cerevisiae determined from the glucose pulse-addition experiment, in which the glucose flux into respiratory and fermen- tative metabolism was quantitatively analyzed.

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24시간 혈압 변동과 관련 위험 요인 (24 Hours Blood Pressure Variation and Related Risk factors)

  • 최인주;김영미;이해정
    • 기본간호학회지
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    • 제12권3호
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    • pp.307-316
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    • 2005
  • Purpose: The purpose of this study was to identify 24 hours blood pressure variations among adults over 40 years of age. Method: The participants(50 adults) were recruited from P hospital and B company. The participants were divided into normotensive and hypertensive tendency groups and then sub-divided into non-dipper, dipper, and extreme dipper. The data were collected from April, 2003 to September, 2004 and analyzed using SPSS for Window program. Results: 1) There were significant differences in cardiovascular risk factor, systolic and diastolic blood pressures, and LDH, diet between the normotensive and hypertensive tendency groups. 2) Dippers in both groups showed a marked decrease in blood pressure during the night, but non-dippers in both groups didn't show a marked nocturnal decrease in blood pressure. 3) There were significant differences in heart rate, WHR, BMI, LDH, triglyceride, glucose, affective-oriented coping strategies between dippers and non-dippers. 4) There were significant differences in heart rate, WHR, BMI, LDH, triglyceride, affective-oriented coping strategies between dipper and non-dipper within hypertensive tendency group. Conclusion: Further studies are needed to provide effective intervention in hypertension when applying 24 hour blood pressure monitoring.

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구개열 언어의 비음화에 관한 공기역학 및 음향학적 연구 (An Aerodynamic and Acoustic Study of Nasalization in Cleft Palate Speakers.)

  • 이종한;신효근
    • 음성과학
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    • 제5권1호
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    • pp.105-119
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    • 1999
  • Cleft palate patients have general speech problems with resonance disorders and articulation disorders. The aim of this study is to find the aerodynamic and acoustic characteristics of the nasalization in cleft palate speakers. Thirteen control groups and three cleft palate patients pre- and post operation were selected for these studies. The test words are composed by polysyllabic words: consonants between high vowel /i/ analysis. The cleft palate patients repeated test words pre- and post-operation from one, three and six month periods. The subjects repeated test words on Macquirer and on Nasometer Model 6200-3. The aerodynamic and acoustic results of nasalization show as follows: (1) The nasal rate in overall airflow of aspirated consonant for cleft palate patients shows higher levels than that of the control group. It had decreased since one month after operation. (2) The overall airflow of cleft palate patients is higher than in the control group, however oral air pressure is lower than control group. (3) The nasal airflow and the nasal rate in overall airflow of cleft palate patients has higher than the control group, however its decreased after operation. (4) The nasalance scores of cleft palate patients were 40% higher than that of the control group. The scores did not decrease after operation. The nasalance score of lateral and fricative sounds did not decrease after operation.

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활성탄을 첨가한 콘크리트벽돌의 물리적 특성 및 환경 성능 평가에 관한 연구 (A Study on the Physical Properties and Environment Efficiency Evaluation in Activated Carbon Concrete Bricks)

  • 우종권;홍상희;전경빈;류현기
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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    • pp.47-51
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    • 2006
  • Modern residing equipment developed much quantitatively along with economic growth but improvement for agreeable residing space of indoor environment is insufficient situation yet. Also, the latest sick-building syndrome discharging room contaminant such as Formaldehyde, toluene, radon etc. built house or buildings newly human body threaten. Radon of them is real condition that raise origination of lung cancer next to smoke. So, wish to in this research by one of solution way of these problems adsorption performance and specie performance excellent activated carbon to concrete bricks for deconstipating suppository that is room finish fare mix and examine closely after grasp physical, mechanical special quality, hazardous substance and specie performance effect. According to result that estimate environment efficiency evaluation, the $CO_2$ absorption amount displayed decrease effect more than about 90% in activated carbon metathesis rate 40% and radon release amount displayed tendency that decrease about $76{\sim}96%$ in activated carbon metathesis rate 40%.

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활성탄을 잔골재로 이용한 친환경 모르타르 개발에 관한 연구 (A Study on the Development of Friendly Environment Mortar by Using Activated Carbon as Fine Aggregate)

  • 우종권;홍상희;전경빈;류현기
    • 한국건축시공학회지
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    • 제6권2호
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    • pp.105-109
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    • 2006
  • Modern residing equipment developed much quantitatively along with economic growth but improvement for agreeable residing space of indoor environment is insufficient situation yet. Also, the latest sick-building syndrome discharging room contaminant such as Formaldehyde, toluene, radon etc. built house or buildings newly human body threaten. Radon of them is real condition that raise origination of lung cancer next to smoke. So, wish to in this research by one of solution way of these problems adsorption performance and specie performance excellent activated carbon to mortar for deconstipating suppository that is room finish fare mix and examine closely after grasp physical, mechanical special quality, hazardous substance and specie performance effect. According to result that estimate friendly-environment performance, the $CO_2$ absorption amount displayed decrease effect more than about 90% in activated carbon metathesis rate 80% and radon release amount displayed tendency that decrease about $75{\sim}85%$ in activated carbon metathesis rate 80%.

베이즈 분류기를 이용한 수냉식 냉동기의 고장 진단 방법에 관한 실험적 연구 (An Experimental Study on Fault Detection and Diagnosis Method for a Water Chiller Using Bayes Classifier)

  • 이흥주;장영수;강병하
    • 설비공학논문집
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    • 제20권7호
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    • pp.508-516
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    • 2008
  • Fault detection and diagnosis(FDD) system is beneficial in equipment management by providing the operator with tools which can help find out a failure of the system. An experimental study has been performed on fault detection and diagnosis method for a water chiller. Bayes classifier, which is one of classical pattern classifiers, is adopted in deciding whether fault occurred or not. Failure modes in this study include refrigerant leakage, decrease in mass flow rate of the chilled water and cooling water, and sensor error of the cooling water inlet temperature. It is possible to detect and diagnose faults in this study by adopting FDD algorithm using only four parameters(compressor outlet temperature, chilled water inlet temperature, cooling water outlet temperature and compressor power consumption). Refrigerant leakage failure is detected at 20% of refrigerant leakage. When mass flow rate of the chilled and cooling water decrease more than 8% or 12%, FDD algorithm can detect the faults. The deviation of temperature sensor over $0.6^{\circ}C$ can be detected as fault.

정기적인 찜질노출이 농업인의 생리반응에 미치는 영향 (Influence of Regular Jjimjilbang Exposure on Farmers' Physiological Responses)

  • 최정화;송은영;박준희
    • 대한가정학회지
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    • 제46권1호
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    • pp.39-45
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    • 2008
  • We analyzed the effects of regular Jjimjilbang(Korean sauna) exposure on the physiological responses in seven elderly farmers(Male=3, Female=4). Jjimjil training group took a bath in Jjimjilbang 8 times twice a week. Jjimjibang exposure was limited three times per day. Rectal temperature, total sweat rate, body fat (%), blood pressure, pulse, $Na^+$ concentration in sweat, and subjective sensation were measured during Jjimjil training exposure. The results are as follow: During Jjimjil exposure, changes of rectal temperature in male farmers were more stabilized than female farmers. The gradual decrease in total sweat rate and Na+ concentration in sweat was observed in both sexes. After Jjimjil exposure, the decrease in blood pressure was observed in both sexes, but not observed changes according to regular Jjimjil exposure. Subjective thermal comfort sensation was changed positively. In conclusion, the regular Jjimjil exposure has positive effects upon improvement in regulation of body temperature, blood pressure, and $Na^+$ concentration especially in heat tolerance.