• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.53-60
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• 2020

In liquid-fuel spray combustion, an experimental study was conducted to observe the effect of ultrasonic excitation on the ultrasonically-atomized liquid fuel flame by controlling pressure field through an ultrasonic standing wave. Flame of the ultrasonically-atomized kerosene aerosol was visualized by using a high speed camera, DSLR, and Schlieren photography. The amount of fuel consumed was obtained by a precise flow-rate measurement technique during combustion, through which the ratio of carrier gas (air) to fuel mass was able to be obtained, too. As a result, it could be found that the combustion reaction-rate of the liquid-fuel aerosol was increased by applying an ultrasonic standing wave to the secondary flame zone of the flame.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.04a
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• pp.319-320
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• 1999

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.156.1-156
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• 2000

• Journal of the Korean Society of Propulsion Engineers
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• v.27 no.1
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• pp.1-8
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• 2023

A study was conducted to scrutinize the behavior of the ultrasonically-atomized kerosene lifted-flame according to the carrier gas flow-rate and position of ultrasonic standing wave (USW). The combustion region of the kerosene-aerosol generated through a slit-jet nozzle was visualized using a DSLR, ICCD, high-speed camera, and Schlieren technique, and the fuel consumption was measured by using a precision balance. As a result, the flame was confined within the region bounded by the USW-field, and the fuel consumption decreased as the position of the USW field increased.

• Particle and aerosol research
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• v.8 no.2
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• pp.69-74
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• 2012

This study describes how successfully a conventional flame aerosol synthesis was used to continuously synthesize Pt-Ru catalysts supported by carbon agglomerates. Nearly spherical catalysts produced in the flame were mainly composed of metallic Pt and Ru with the molar ratio of 1:1 and those sizes were controllable from ~1.5 nm to ~2.0 nm. Nevertheless, only Pt peaks were found from X-ray diffraction experiments, suggesting that amorphous-like Ru was well mixed in the crystalline Pt lattices. It was found from Cyclo-voltamograms and CO stripping experiments that the electrochemical properties of the catalysts are at least comparable to that of a conventional commercial sample.

• Particle and aerosol research
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• v.5 no.1
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• pp.1-7
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• 2009

Fe- and V-doped titanium dioxide nanoparticles consisting of spherical primary nanoparticles were synthesized from a mixed liquid precursor by using the flame spray pyrolysis. The effects of dopant concentration on the powder properties such as morphology, crystal structure, and light adsorption were analyzed by TEM, XRD, and UV-Vis spectrophotometer, respectively. As the V/Ti molar ratio increased, pure anatase particles were synthesized. On the contrary, rutile phase particles were synthesized as the Fe/Ti ratio increased. Photocatalytic property of as-prepared $TiO_2:Fe,V$ nanoparticles was investigated by measuring the removal efficiency for volatile organic compounds (VOCs) under the irradiation of visible light. After 2 hrs under visible light, the removal efficiencies of benzene, p-xylene, ethylbenzene, and toluene were reached to 21.9%, 21.4%, 19.8% and 17.6% respectively.

• Particle and aerosol research
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• v.4 no.2
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• pp.51-67
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• 2008

In this study, we devoted to kinetic measurement of the catalytic oxidation of iron-containing flame soot particles and better understanding the role of catalytic particles on carbon oxidation in particular at low temperature, targeting on autothermal regeneration of diesel particulate filter by diesel exhaust gas. Carbon-based Fe-containing particles generated by spraying ferrocene-doped diesel fuel in an oxy-hydrogen flame are tested and compared with a commercial carbon black powder for thermogravimetric analysis (TGA), secondary ion mass spectrometry (SIMS), Fourier-transform infrared spectroscopy (FTIR), Induced coupled plasma-Atomic emission spectroscopy (ICP-AES), and High-resolution transmission electron microscopy (HR-TEM). As a result, we found that a small amount of the ferrocene addition led to significant reductions in a on-set temperature and an activation energy of the carbon oxidation as well. An oxygenated surface complex forming at the particle surface could be thought as active species that would be readily consumed in particular at low temperature.

• Particle and aerosol research
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• v.12 no.2
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• pp.37-42
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• 2016

$CeO_2$ nanoparticles were prepared by a flame spray pyrolysis from aqueous solution of cerium nitrate. The morphology, structure crystallinity and specific surface area of as-prepared nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Telle (BET). The $CeO_2$ nanoparticles about 5 nm in diameter showed a cubic fluorite structure and polyhedral morphology. The average particle size increased as the cerium nitrate concentration increased. UV absorption performance of the as-prepared nanoparticles was measured by UV-visible spectroscopy. UV absorption of $CeO_2$ nanoparticles was more effective than that of commercial $TiO_2$ nanoparticles. Effect of dopants such as Ti and Zn to $CeO_2$ nanoparticles on UV absorption properties was also investigated. In case of $Ti/CeO_2$, and $Zn/CeO_2$ nanoparticles, they showed a little higher UV absorption values compared with $CeO_2$ nanoparticles. The as-prepared nanoparticles can be promising materials with high UV absorption value.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.156-161
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• 1998

We developed aerosol flame deposition method and made stress-free Pyrex-based optical waveguide on silicon substrate using this method. Zr is doped to control the refractive index of Pyrex waveguide layers. The refractive index of the film changes from 1.460 to 1.475 as the content of Zr changes from 0 to 3 wt%. Er is doped to see the possibility of applying this Pyrex waveguide as PLC-type (Planar Lightwave Circuit) optical amplifier. The refractive index of the film changes from 1.460 to 1.465 as the content of Zr changes from 0 to 1 wt%. Light launching using a prism coupler to the fabricated waveguide showed good quality for application to PLC. The polarization dependence of refractive-index of the Pyrex film is measured to be less than $2{\times}10^{-4}$.

• Korean Journal of Materials Research
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• v.10 no.11
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• pp.778-783
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• 2000

Effects of the $Al_2$O$_3$surface protective layer, deposited on the SnO$_2$sensing layer by aerosol flame deposition (AFD) method, on the sensing properties of SnO$_2$thin film ags sensors were investigated.Effects of Pt doping to the $Al_2$O$_3$surface protective layer on the selectivity of CH$_4$ gas were also investigated. 0.3$\mu\textrm{m}$ thick SnO$_2$thin sensing layers on Pt electrodes were prepared by R.F. magnetron sputtering with R.F. power of 50 W, at working pressure of 4mTorr, and at 20$0^{\circ}C$ for 30 min. $Al_2$O$_3$surface protective layers on SnO$_2$layers were prepared by AFD using a diluted aluminum nitrade (Al(NO$_3$).9$H_2O$) solution. The sensitivity of CO gas in the SnO$_2$gas sensor with an $Al_2$O$_3$surface protective layer was significantly decreased. But that of CH$_4$gas remained almost same with pure SnO$_2$gas sensor. This result shows that the selectivity of CH$_4$gas is increased because of the $Al_2$O$_3$surface protective layer. In the case of SnO$_2$gas sensors with Pt-doped $Al_2$O$_3$surface protective layers, low sensing property to CO gas and high sensing property to CH$_4$were observed. This results in the increasing of selectivity of CH$_4$gas selectivity are discussed.