• Journal of ILASS-Korea
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• v.10 no.3
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• pp.9-16
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• 2005

To investigate spray and combustion of emulsified fuel of W/O type, we mixed water with light oil by using ultrasonic energy adding system. We measured the SMD of sprayed droplet to find atomization characteristics of emulsified fuel with using the Malvern 2600D system. Major parameters are the weight ratio of water($0{\sim}30%$ by 10%) in emulsified fuel injection pressure(lobar), and the measurement distance($10{\sim}100mm$ by 10mm). Combustion visualizing system is made up commonly used boiler system and digital camera 1/500s to investigate combustion phenomena. As a result, the more water contents increased, the more SMD increased. The water particle of emulsified fuel made short flame in continuos spray combustion phenomena because of micro explosion.

• Journal of ILASS-Korea
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• v.2 no.3
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• pp.25-31
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• 1997

This experiment was undertaken to investigate the spray characteristics of the conventional injection system and the ultrasonic energy added injection system. Test fuels include light oil and mixed light-BC oil. The mixed light-BC oil was injected at the normal temperature$(20^{\circ}C)$ and the high temperature$(95{\pm}2^{\circ}C)$ and injection pressure was $120kg/cm^2$. Sauter mean diameter was measured under the variation of the spray distance. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. It is also found that the condition of the ultrasonic energy added injection and high temperature injection generates the smaller droplets than that of the conventional injection.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.469-474
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• 2015

In ultrasonic spray pyrolysis deposition, a precursor solution is evaporated by an ultrasonic atomizer, then gas-carried into a furnace where the solute is separated from the water vapor. After condensation, polymerization, and nucleation, the solute oxide forms a thin film. To improve the deposition efficiency, the ultrasonic atomizer was studied to optimize the evaporated gas flow. The vat cover was redesigned, using three versions with different inlet factors being tested through a computational fluid dynamic analysis as well as a water evaporation experiment. The atomization rate with a hemispherical cover with a $30^{\circ}$ inlet was found to be 2.4 times higher than that with the original. This improvement was verified with fluorine-doped tin oxide spray pyrolysis deposition. The film obtained with the modified vat cover was 2.4 times thicker than that obtained with the original vat cover.

• The Journal of the Acoustical Society of Korea
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• v.41 no.1
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• pp.9-15
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• 2022

In order to overcome the limitation of conventional nanoparticle dispersion methods such as sonicator or homogenizer, a filtration method using an ultrasonic atomization effect and cyclones was proposed in this study. A 0.5 wt% suspension was made with Al₂O₃ powder with an average diameter of 250 nm. The suspension was filtered by the proposed method after pre-dispersing using a sonicator and a homogenizer, respectively. As the result, in the case of the suspension after pre-dispersing with a sonicator, the particle size distribution of the filtered suspension started showing up a single normal distribution indicating the mode of the average diameter only after the 3rd cyclone process. On the other hand, in the case of the suspension with the homogenizer pre-dispersion, similar results appeared from the 2nd cyclone process. Filtration of various types of nanoparticles is expected to be possible by adjusting ultrasonic atomization frequency and manipulating the design of the cyclone.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.732-737
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• 2000

The purpose of this study is to compare the SMD(Sauter mean diameter) with different vibrant plates. Each vibrant plates have different surface roughness. Also liquid film thickness are measured for explanation how to concern atomization. Ultrasonic waves is used for vibration. Immersion liquid method is used for the measure of SMD and also liquid film thickness is measured using of point needle method. Distilled water and gasoline fuel are used to liquids. Supplied liquid flow rates are $18{\sim}296cc/min$. Centerline average roughness of vibrant plates are 0.5, 2.0, 4.7, $9.5\;{\mu}m$ and diameter of vibrant plate is 60mm. In result, good atomization of liquid is obtained in widen flow rates. The mean droplet size is increased in orders of 4.7, 2.0. 9.5, $0.5\;{\mu}m$ surface roughness. Distilled water has a big mean droplet size than gasoline fuel in low flow rate. Above the 78cc/min flow rates, distilled water has a small mean droplet size than gasoline fuel. Liquid films changes are measured with ultrasonic power. Also, cavitation effect on sprays is observed.

• Journal of ILASS-Korea
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• v.9 no.3
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• pp.22-28
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• 2004

This study is concerned about the characteristics of ultrasonic-energy-added W/O type emulsified fuel. The distilled water was mixed with diesel oil by using ultrasonic energy fuel feeding system and then the SMD of sprayed droplets was measured to find out atomization characteristics of emulsified fuel by using the Malvern 2600 system. The capacitance value was measured to verify stability of the same specimen by using the digital LCR meter, EDC1630 additionally. The main results are as follows; 1) The more measuring distance increases between one hole nozzle tip and analyser bearm, the more SMD increases. 2) The more water content increases, the more capacitance value increases depending on the time. Main Parameters of the study are the amount of water content $0{\sim}30%$ by 5% in emulsified fuel, and the measurement distance, $20{\sim}140mm$ by 10mm or 20mm between nozzle tip and analyser beam.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.3
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• pp.211-218
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• 2009

Feasibility study of using $Ti0_2$ mist generated by ultrasonic atomization for photocatalytic degradation of gaseous toluene was attempted in this study. For this, the photocatalytic reactor consisting of mist generator and photo-reactor was designed. Most of experimental results showed that steady state reached about 30 minutes after the start of experiments. The effects of $Ti0_2$ concentration, toluene concentration, and UV wavelength on toluene removal ratio were investigated. It was found that the highest removal efficiency was obtained when $Ti0_2$ concentration was 0.6 g/L in slurry. At this condition, it was found that the toluene removal efficiency increased as toluene concentration in feed decreased. In order to investigate the effect of UV wavelength, experiments were carried out using three UV lamps with different UV wavelength. The results showed that the highest removal efficiency was achieved when the lamp with the shortest wavelength were employed.

• Progress in Superconductivity
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• v.13 no.2
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• pp.127-132
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• 2011

Many research groups have been manufacturing coated conductor by various processes such as PLD, MOD, and MOCVD, but the methods with production cost suitable for wide and massive application of coated conductor did not develop yet. Spray pyrolysis method adopting ultrasonic atomization was tried as one of the possible option. GdBCO precursor films have been deposited on IBAD substrate by spray pyrolysis method at low temperature and converted to GdBCO by post heat treatment. Ultrasonic atomization was used to generate fine droplets from precursor solution of Gd, Ba, and Cu nitrate dissolved in water. Primary GdBCO films were deposited at $500^{\circ}C$ and oxygen partial pressure of 1 torr. After that, the films were converted at various temperatures and low oxygen partial pressures. C-Axis oriented films were obtained IBAD substrates at conversion temperature of around $870^{\circ}C$ and oxygen partial pressures of 500 mtorr ~ 1 torr in a vacuum. Thick c-axis epitaxial film with the thickness of 0.4 ~ 0.5 ${\mu}m$ was obtained on IBAD substrate. C-axis epitaxial GdBCO films were successfully prepared by ex-situ methods using nitrate precursors on IBAD metal substrate. Converted GdBCO films have very dense microstructures with good grain connectivity. EDS composition analysis of the film showed a number of Cu-rich phase in surface. The precursor solution having high copper concent with the composition of Gd : Ba : Cu = 1 : 2 : 4 showed the better grain connectivity and electrical conductivity.

• Journal of Biosystems Engineering
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• v.21 no.4
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• pp.467-473
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• 1996

Ultrasonic energy was applied for atomizing rice-bran oil which is a highly viscous bio fuel. Six different nozzles, an injection simulator, and an ultrasonic generator system were designed and constructed for the experiment. An immersion liquid method was used for the measurement of injection droplet sizes. The characteristics of injection droplets was investigated with respect to the numbers of the droplets with diameters ranging from 5$\mu$m 50$\mu$m and to the Sauter mean diameter. The results showed that the ultrasonic energy was effective for the improvement of the atomization of the injection droplets for all the factors such as type of nozzles, nozzle opening pressures, and collection distances.

• Journal of ILASS-Korea
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• v.9 no.3
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• pp.29-34
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• 2004

To investigate characteristics and micro-explosion of single-droplets of emulsified fuel, water is mixed with diesel oil by using ultrasonic energy fuel feeding system. The fuel characteristics is analysed through H-NMR spectrum and micro-explosion phenomena of the emulsified fuel is also investigated. The life times of droplets of conventional diesel fuel, ultrasonic energy added diesel fuel and emulsified fuel we obtained additionally. According to this study, the micro-explosion phenomena of single-droplets happen in atmospheric pressure condition, a curve form of emulsified fuel's life tim is different from diesel fuel's one and the change of chemical structures is a cause of ultrasonic-energy-added diesel fuel effect.