• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.547-548
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• 2007

• Journal of ILASS-Korea
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• v.11 no.3
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• pp.131-139
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• 2006

An experimental study was performed to investigate the liquid breakup and atomization characteristics in electrohydrodynamic atomization according to the changing of experimental parameters such as nozzle size, fluid flow, and electrical intensity. An original electrohydrodynamic atomizer equipment was designed and manufactured for the analysis of spray visualization and the exploration of relationship between applied power and the behavior of liquid atomization. The image processing technique by using the back-illumination method was applied to visualize the distilled liquid breakup process and to examine the variation of the droplet size distribution. The results show that the spray modes of electrohydrodynamic atomization are closelyconnected by the strength of the electric stresses at the surface of the liquid film and the kinetic energy of the liquid jet leaving the needle tip.

• Journal of ILASS-Korea
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• v.14 no.2
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• pp.65-70
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• 2009

An experimental study was performed to explore the atomization characteristics as the drop formation and the liquid breakup of an ethanol fuel using an electrohydrodynamic atomizer. A developed electrohydrodynamic atomizer controlled by a high AC power, a variable frequency, and a liquid feeding was used for the experiments. The test had been considered a disperse atomization processing at $450{\sim}4200V$ applied power, $200{\sim}400\;Hz$ frequency, and $1{\sim}3\;ml/min$ ethanol feeding to achieve an uniformed droplet formation. The goal of the research was to investigate the possibility of the liquid breakup for an ethanol fuel in an electrohydrodynamic atomizer. The results showed that the mean droplet radius decreased as the applied voltage increased or as the applied AC frequency increased. The whipping motion had been grown at the specified voltages due to the applied frequency.

• Polymer(Korea)
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• v.35 no.5
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• pp.424-430
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• 2011

Biodegradable poly[(glycine ethyl ester)-(phenylalanine ethyl ester) phosphazene](PGPP) microparticles were fabricated by electrohydrodynamic atomization to apply drug release test. Atomization parameters such as applied voltage, polymer concentration, and molecular weight were investigated to inspect their effects on the size and morphology of microparticles. The average diameter of PGPP microparticles decreased as increasing applied voltage and solution flow rate. Dichloromethane/dioxane mixture shows better results for the preparation of microparticles than single solvent owing to the different PGPP solubility in solvent. Blending PGPP polymers with proper molecular weights not only favored the production of spherical PGPP microparticles via electrohydrodynamic atomization, but also provided a way to adjust drug (rifampicin) release behavior. Drug-loaded biodegradable polyphosphazene microspheres can be fabricated via electrohydrodynamic atomization, which has potential use in biomedical applications.

• Journal of the Korean Society of Visualization
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• v.16 no.3
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• pp.47-51
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• 2018

The stable deposition of impinging droplets on non-wetting substrates is of great importance for numerous industrial and scientific applications such as coating techniques, inkjet printing, spray cooling of heated surfaces. In this work, we systematically investigate impinging behaviors of non-Newtonian and viscous droplets ejected by electrohydrodynamic atomization.

• Journal of ILASS-Korea
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• v.8 no.2
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• pp.24-30
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• 2003

An experimental study was performed to investigate the influence factors of drop formation in electrohydrodynamic atomization. The mode of electrohydrodynamic atomization depended on the various factors such as the flow rate of the liquid, the inner diameter of the nozzle, the distance between the nozzle tip and the ground electrode, the shape of the ground electrode. and the applied high voltage. This work was performed to investigate the experimental analysis for the flow pattern visualization of droplets, and the relationship between voltage application and the behavior of liquid atomization. Uniform drops of different sizes can be obtained at the inception of the spindle mode by charging the flow rate and the electric field. The drop size also decreased when the flow rate was raised for the spindle mode. The whipping motion occurred beyond 7kV and before the corona started to take effect.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.555-556
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• 2010

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1807-1811
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• 2008

In this paper, the meniscus formation/deformation processes and conduction characteristics of the needle-centered ceramic nozzle electrode as an effective electrohydrodynamic (EHD) flow driving mechanisms for de-ionized water and silicone oil have been investigated. Results showed that the applied high voltage affected significantly on the processes, such as the drop formation mode, the deformation mode, the dripping mode, the jet mode, and the atomization mode. There was the EHD atomization mode for the de-ionized water while it was not occurred for the silicone oil, which, however, might be due to the lower electric conductivity and dielectric property of the oil than that of the water.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1747-1751
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• 2008

Electrohydrodynamic jet printing (EHDP) technique is widely used for the direct writing. However, in the existing EHDP method, the printing characteristics are affected by the printing substrate used, and the line width of the printed is determined by the geometry of the nozzle. We propose an EHDP method which is capable of (1) removing the effect from the substrate, and (2) controlling the line width through the ON/OFF control of the each nozzle in the nozzle array. Printing characteristics of our EHDP system were examined and successful ON/OFF control of the nozzle array were demonstrated. By using the proposed EHDP, it is expected that stable meniscus regardless of the substrate and different line widths even using the same nozzle can be achieved.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1913-1916
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• 2008

Electrohydrodynamic (EHD) printing has gained significant interest after a direct writing with a resolution of a few tens nanometer was demonstrated using EHD. Basically, EHD use the electric field to generate droplet which is much smaller than nozzle diameter, so that high resolution printing is possible and the clogging problem can be alleviated as well. However, to adapt this technology to the real application, the fundamental studies are necessary to stabilize EHD jetting, to maximize jetting frequency, and to optimize the design of multi EHD nozzle, etc. In this study, by imaging EHD jetting using high speed camera and measuring the current, the effect of electric field intensity and back pressure on jetting frequency and jetting diameter were studied.