• Title/Summary/Keyword: Diameter size

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Spray characteristics on mixing region scale of twin fluid atomizer (이류체 분사노즐의 혼합영역 형상에 따른 분무특성)

  • 김병문;김혁주;이충원
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.6
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    • pp.2147-2159
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    • 1991
  • The effects of principal dimensions of internal mixing twin-fluid atomized and operating conditions on the atomizing characteristics are experimentally investigated. The tests are conducted over the wide range of air/liquid ratio to predict influences of the diameter and length of nozzle, contacting angle between air and liquid in the mixing chamber, and air orifice diameter on the mean drop size(SMD), spray angle, distribution of drop size, and spray dispersion, And also, initial distribution of liquid column by air stream within the mixing chamber are observed through the transparent nozzles. A He-Ne laser particle sizer(MALVERN Model 2604) was used to measure the Sauter.s mean diameter( $D_{321}$) and droplet sizes distribution. In this experiment the air/liquid ratio, mixing length and nozzle diameter have a great influence on SMD, spray angle, droplet sizes distribution and spray dispersion.

Control of morphology and interfacial tension of PC/SAN blends with compatibilizer

  • Kim, J.H.;Kim, M.J.;Kim, C.K.;Lee, J.W.
    • Korea-Australia Rheology Journal
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    • v.13 no.3
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    • pp.125-130
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    • 2001
  • Block copolymers of PC-b-PMMA (polycarbonate-b-polymethylmethacrylate) and PC -b-SAN (polycarbonate-b-(styrene-c-acrylonitrile)), were examined as compatibilizers for blonds of PC with SAN copolymer. The average diameter of the dispersed particles was measured with an image analyser, and the interfacial properties of the blonds were analysed with an imbedded fiber retraction (IFR) technique. The average diameter of dispersed particles and interfacial tension of the PC/SAN blends reached a minimum value when the SAN copolymer contained about 24 wt% AN. Interfacial tension and particle size were further reduced by adding compatibilizer to the PC/SAN blends. PC-b-PMMA was more effective than PC-b-SAN as a compatibilizer in reducing the average diameter of the dispersed particles and interfacial tension of PC/SAN blend. A direct proportionality between the particle diameter and interfacial tension was also observed. The interfacial properties of the PC/SAN blends were optimized by adding a block copolymer and using an SAN copolymer that had minimum interaction energy with PC.

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Characteristic of Evaporation Cooling in Water Droplet Impinging on Steel with Various Surface Roughness and Droplet Diameter (강에서 표면조도의 변화와 액적 직경에 따른 충돌 액적 증발 냉각 특성)

  • Jang, C.S.;Sohn, C.H.;Chung, S.W.;Choi, W.S.
    • Journal of the Korean Society for Heat Treatment
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    • v.19 no.3
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    • pp.141-148
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    • 2006
  • An experimental study is presented for water droplet impingement on a steel surface in the process of heat treatment. The objective of the present work is to examine characteristic of evaporation cooling due to surface roughness and droplet diameter under conductive heat input condition. The surface temperatures varied from $80{\sim}155^{\circ}C$, surface roughness was from $R_a=0.12{\mu}m$ to $R_a=1.14{\mu}m$ and droplet diameter was from 2.4 mm to 3.0 mm. The results show that the total evaporation time is shorter for the larger surface roughness and the smaller droplet size, the time average heat flux has maximum value for the larger surface roughness and the smaller droplet size. The total evaporation time has not influence on the nuclear boiling region.

Evaporation Cooling of Water Droplet on Aluminum with Various Surface Roughness and Droplet Diameter in Conductive Condition (전도조건 하에서 표면조도와 액적 직경의 변화에 따른 알루미늄의 액적 증발 냉각)

  • Jang, C.S.;Choi, W.S.
    • Journal of the Korean Society for Heat Treatment
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    • v.18 no.6
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    • pp.375-382
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    • 2005
  • This paper presents the results of experimental investigation for the effect of heat conduction on the evaporation cooling of water droplet in the process of heat treatment. The experiments are mainly focused on the surface temperature, the surface roughness and the droplet diameter at aluminum. The range of surface temperature is from $80^{\circ}C$ to $140^{\circ}C$, surface roughness is from $R_a=0.18{\mu}m$ to $R_a=1.36{\mu}m$ and droplet diameter is from 2.4 mm to 3.0 mm. The results show that the total evaporation time is shorter for the larger surface roughness, the time averaged heat flux has maximum value for the larger surface roughness and exist the critical heat flux. The total evaporation time has a big influence on the evaporation region for the smaller droplet size, but the total evaporation time has not influence on the nuclear boiling region.

Ultrasonographic Appearance of the Gestational Structures throughout Pregnancy in Pet Dogs II. Estimation of Gestational Age and Prediction of Parturition Day by Measurement of the Gestational Structu (애완견에서 임신일령에 따른 임신구조물의 초음파상 II. 임신구조물의 측정에 의한 임신일령의 판정과 분만일의 예시)

  • 손창호;강병규;최한선;서동호;신창록;박인철
    • Journal of Veterinary Clinics
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    • v.14 no.2
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    • pp.287-296
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    • 1997
  • Serial ultrasonographic examinations were daily performed on 8 bitches (5 Maltese and 3 Yorkshire terrier) from day 15 until parturition to determine the size of gestational structures. Gestational age was timed from the day of ovulation (day 0), which was estimated to occur when plasma progesterone concentration was first increased above 4.0 ng/ml. When the size of fetal and extra-fetal structures according to gestational age was measured, there was a difference between Maltese and Yorkshire terrier in extra-fetal structures (P<0.001), and no difference in fetal structrures (P<0.001). The correlations between the gestational age and the growth in fetal and extra-fetal structures were examined by regression analysis. The extra-fetal structure which showed high correlation from day 20 to 35 was inner chorionic cavity diameter in two breeds. The fetal structures which showed high correlation from day 36 until parturition was fetal head diameter in two breeds. In conclusions inner chorionic cavity diameter was the most accurate for estimation of gestational age and prediction of whelping day from day 20 to 35, and fetal head diameter from day 36 to parturitions respectively. Ultrasonography is very useful tool to evaluate the gestational age and to predict the whelping day in pet dogs.

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Determination of the Optimal PTC Receiver Diameter Considering Heat Losses (열손실을 고려한 PTC(Parabolic Trough Concentrator) 흡수기 최적 직경 결정에 관한 연구)

  • Kang, Y.H.;Kwak, H.Y.;Yoon, H.K.;Yoo, C.K.;Lee, D.G.;Seo, T.B.
    • Solar Energy
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    • v.20 no.1
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    • pp.73-80
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    • 2000
  • Considering the optical performance of the reflector and analyzing heat losses from the receiver, the optimal diameter of the absorber for a PTC(Parabolic Trough Concentrator) system was numerically determined. The results of this study were compared with the results of the IST (Industrial Solar Technology)-PTC test to verify the validity of the model. Good agreement was obtained with the deviation range from 0.4 to 7.7%. Generally, the net energy gained by the receiver shows the maximum at the particular absorber diameter and the specific gap size between the absorber and the glass envelop because the heat losses from the receiver becomes the minimum. The results showed that the conductive and convective heat losses became the minimum when the gap size was 7 to 10mm. Finally, it was known that the optimal absorber diameter was 62mm at $100^{\circ}C$, 57mm at $150^{\circ}C$, and 53mm at $200^{\circ}C$ of the absorber surface temperature, respectively.

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Study on the evaporation Heat Transfer Characteristics of R-134a in Small Diameter Tubes

  • Roh, Geon-Sang;Oh, Hoo-Kyu
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.3
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    • pp.224-234
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    • 2007
  • Large diameter tubes have been used until comparatively lately. However, small diameter tubes are largely used because of their high efficiency in heat transfer and low cost, recently. This study focuses on the experimental research of the heat transfer coefficients during evaporation process of R-22 and R-134a in small diameter tubes. The evaporation heat transfer coefficients were measured in smooth horizontal copper tubes with ID 1.77, 3.36 and 5.35 mm. The evaporation heat transfer coefficients in the small diameter tubes (ID <7 mm) were observed to be strongly affected by the size of tube diameters and to differ from those of general predictions in the large diameter tubes. The heat transfer coefficients of ID 1.77 mm copper tube were higher by 20 and 30 % than those of ID 3.36 mm, ID 5.35 mm copper tubes respectively. Also, it was found that it was very difficult to apply some well-known previous predictions (Shah's, Jung's. Kandlikar's and Oh-Katsuda's correlation) to small diameter tubes. Based on the data, the new correlation is proposed to predict the evaporation heat transfer coefficients of R-22 and R-134a in small diameter tubes.

An Experimental Study on the Atomization Characteristics of a Two-Phase Turbulent Jet of Liquid Sheet Type Co-Axial Nozzle (액막형 동축노즐의 2상 난류분사의 미립화 특성에 관한 실험적 연구)

  • 노병준;강신재;오제하
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.6
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    • pp.1529-1538
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    • 1995
  • In this study, a liquid sheet type co-axial nozzle has been used to investigate the turbulent atomization characteristics which could result in the experimental data to be used in designing a jet nozzle with high performance. Image processing technique and immersion sampling method were employed to measure droplet size. In atomizing characteristics, droplet size distributions and absolute droplet sizes, SMD(Sauter Mean Diameter) have been investigated in the wide ranges of flow field depending upon the air-water mass ratios. And the comparisons between the present data and the semi-empirical curves have been conducted semi-empirical correlation for SMD has been derived in the present analysis.

Printed Type Half-wavelength Small Loop Antenna (프린트형 반파장 소형 루프 안테나)

  • Ryu, Hong-Kyun;Woo, Jong-Myung
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2005.11a
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    • pp.245-248
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    • 2005
  • In this paper, small sized half-wavelength circular loop antenna which attached beneath a visor of helmet is designed and fabricated at the resonant frequency of 449MHz. To reduce the size of the antenna, double series-shorted stubs are inserted inside the loop for practical use of a vacant space of loop inside. Also, It is designed for the printed type to install the helmet easily. The size of antenna on helmet is reduced to 87.75%(diameter : 70mm, height :.36mm) compare with general type antenna(diameter : 200mm height 101mm). The return loss, -10dB bandwidth and gain are -13.2dB, 17.6MHz(3.9%), and -1.78dBd. And, radiation pattern is omni-directional pattern at H-plane. Therefore, it can be seen that the half-wavelength circular loop antenna using double series-shorted stubs is proper structure for the miniaturization and the installed antenna of the helmet.

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Effects of the Block Distance of Collecting Plate and Particle Size on the particle Deposition Efficiency in the Two-Stage Electrostatic Precipitator (2단식 전기집진기의 집진판 블록간격 및 입자크기가 입자의 부착효율에 미치는 영향)

  • 박청연
    • Journal of Korean Society for Atmospheric Environment
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    • v.16 no.2
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    • pp.165-178
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    • 2000
  • In this study the effects of block distance have been investigated on the particle deposition efficiency in the collecting cell of two-stage electrostatic precipitator by numerical analysis. Particle trajectories have been changed by the electrostatic and inertial force of particle with the inlet velocity electrostatic number and particle diameter. The total deposition efficiency has a minimum value by the interaction between the effect of particle inertial force and electrostatic force in the collecting cell. The increase of block distance makes the total deposition efficiency decrease under the range of the particle size which has the minimum deposition efficiency. However beyond the range of particle size which has minimum deposition efficiency total deposition efficiency has no trend with the variation of block distance.

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