인터넷쇼핑몰 選擇時 消費者 信賴 決定要因에 關한 硏究

학위논문(석사)--서울대학교 대학원 :경영학과 경영학전공,2001.Maste

An Experimental Study on Characteristics of Droplet Generation by Electrospraying for Highly Viscous Liquids

Generation characteristics of electrospray droplets for highly viscous liquid have been investigated by measuring size distributions of droplets emitted from the Taylor cone using glycerol solutions with various conductivities. Because of very small volatility of glycerol, droplet sizes can be measured by an aerodynamic size spectrometer (TSI Aerosizer DSP) with negligible evaporation of droplets. For highly conducting and viscous liquid, the sizes of the droplets electrosprayed from the Taylor cone are found to be relatively insensitive to applied voltages and the electrosprays assisted by the corona discharge call produce monodisperse droplets as long as the corona intensity is not too high. Near the minimum flow rate where a liquid cone is stable, the spray tends to consist of a one -peak monodisperse distribution of drop lets. However, at high flow rates, the spray bifurcates into bimodal distributions, which are consistent with the result of the previous study for less viscous liquids than our liquids. For liquid flow rates (Q) below 1 nl/s, the measured droplet diameters by the aerosizer are in the range of 0.30 to 1.2μm for the glycerol solutions. The diameters of monodisperse droplets scale approximately with r*=(Qτ)⅓ where r* is a characteristic length τ and is the electrical relaxation time of the fluid. However, when compared with several represe ntative scaling laws, the droplet diameters are two to six factors greater than those predicted by the scaling laws. This may be closely related to the combined effect of the much higher viscosity and the electrical charge on the jet breakup of glycerol so solution

A Numerical Study on Evaporation of Sludge Particles in a Sludge Dryer

The evaporation of sludge particles in a sludge dryer has been numerically investigated with commercial CFX4.1 code. Gas flow field, gas temperature field, sludge particle trajectories, and the moisture content variation of sludge particles are calculated fort various influencing factors, i. e., gas swirl velocity, initial particle distribution, gas temperature. Evaporation of sludge particles increases with gas swirl velocity, several supplying positions, and gas temperature, respectively due to increased residence time, increased contacting surface area, and increased temperature difference between gas and particle

Basic experiment and theory for the development of a thermo-acoustic refrigerator

학위논문(석사) - 한국과학기술원 : 기계공학과, 1995.2, [ xi, 73 p. ]한국과학기술원 : 기계공학과

The effect of flow rate and physical properties of liquid on electrospraying at atmospheric and low pressures

학위논문(박사) - 한국과학기술원 : 기계공학전공, 2001.8, [ xiii, 124 p. ]한국과학기술원 : 기계공학전공

Measurement of Size Distributions of Submicron Electrosprays Using a Freezing Method and an Image Processing Technique

The size distributions of electrospray droplets from the Taylor cone in cone-jet mode are directly measured by using a freezing method and a transmission electron microscope (TEM) image processing technique. These results are compared with the data obtained by an aerodynamic size spectrometer (TSI Aerosizer DSP). The use of glycerol seeded with NaI and a freezing method make it possible to sample droplets with their original sizes preserved. Since pictures of droplets are taken with TEM with very low vapor pressure of the solution, evaporation is suppressed by freezing. For liquid flow rates below 1 nl/sec, the measured droplet diameters by the TEM image processing technique and the aerosizer are in the range of 0.25 to 0.32 m add 0.3B to 0.40m, respectively. Comparing the TEM data with the aerosizer measurements, it has been revealed that the TEM image processing technique can afford more accurate values of droplet size distributions in the submicron range of 0.1 to 0.4m

스타일화된 얼굴 일러스트레이션

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