• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.676-679
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• 2010

Nano composite particles were synthesized from a bulk ZrVFe alloy ingot by transferred DC thermal plasma. Effects of plasma gas flow rate on the characteristics of the produced nano composite particles were investigated. The characteristics of the synthesized powder were analyzed by field scanning electron microscopy (FE-SEM), light scattering particle size analyzer (PSA), energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), and Brunauer-Emmett-Teller (BET) surface area analyzer. As the flow rate of plasma gas increased from 20 L/min to 40 L/min, the average particle size decreased from 91 nm to 55 nm, the particle size distribution became narrower, the surface area increased from $200\;m^2/g$ to $255\;m^2/g$, the particle composition was nearly unaffected, and the particle crystallinity was improved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1101-1102
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• 2013

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2160-2164
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• 2007

In this study, the mechanism of enhanced thermal conductivity is elucidated on the bases of both electric double layer (EDL) and kinetic theory. A novel expression for the thermal conductivity of nanofluids is proposed and verified by applying to $Al_2O_3$ nanofluids with regard to various temperatures, volume fractions and particle sizes. In dilute nanofluids, the effects of Brownian motion and particle interaction on enhancing the thermal conductivity of nanofluids are quite comparable while the effect of particle interaction due to EDL is more prominent in dense nanofluids. The model presented in this paper shows that particle interaction due to the electrical double layer is the most responsible for the enhancement of thermal conductivity of nanofluids.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.11
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• pp.1542-1547
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• 2003

Although dielectric barrier discharge (DBD) in air has been applied to a wider range of aftertreatment processes for HAPs (Hazardous Air Pollutants), due to its high electron density and energy, its potential use as precharging dust particles is not well known. In this work, we measured size distributions of bimodal aerosol particles and estimated collection efficiency of the particles by an electrostatic precipitator (ESP) using DBD as particle charger. To examine the particle collection with DBD charger, nano size particles of NaCl(20∼100nm) and DOS (50∼500nm) were generated by a tube furnace and an atomizer, respectively. For experimental conditions of 60㎐, 11㎸ and 60 lpm, the particle collection efficiency for the hybrid system was over 85%, based on the number of particles captured.

• 연구논문집
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• s.34
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• pp.21-28
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• 2004

In this study, we report an investigation for the charging and collection of aerosol nanoparticles in an electrostatic precipitator (ESP) according to particle charging and diffusion effects. The competition between charging probability and diffusion effect determines the collection efficiency of nanoparticles in the ESP. In conclusion, collection efficiency continuously decreased with the reduction in the particle size. This indicates that poor partial charging effect of nanoparticles is more dominant than their diffusion effect in the ESP for the nanoparticles in the particle size range of 4-20 nm. Theoretical calculations using a unipolar diffusion charing theory were in good agreement with the experimental data for the nanoparticles less than 20 nm in diameter.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1435-1440
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• 2003

Although Dielectric Barrier Discharge (DBD) in air has been applied to a wider range of aftertreatment processes for HAPs(Hazardous Air Pollutants), due to its high electron density and energy, its potential use as precharging dust particles is not well known. In this work, we measured size distributions of bimodal aerosol particles and estimated collection efficiency of the particles by electrostatic precipitator(ESP) using DBD as particle charger. To examine the particle collection with DBD charger, nano size particles of NaCl($20{\sim}100$ nm) and DOS($50{\sim}800$ nm) were generated by tube furnace and atomizer, respectively. For experimental conditions of 60 Hz, 11 kV, and 60 lpm, the particle collection efficiency for the hybrid system comprising DBD charger and ESP was over 85 %, based on the number of particles captured.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1510-1515
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• 2004

The effects of additive ions on the generation of metallic nanoparticles were evaluated using a corona induced supersonic nozzle. Applying the corona discharge to the nanoparticle generator, a tungsten needle and the supersonic nozzle are used as an anode electrode and a cathode electrode respectively. The corona ions act as nuclei for the silver vapor condensation. The ion density was controlled precisely as varying the applied voltage between electrode and nozzle. The mean diameter of the silver particle decreases as the ion density increases. However, the number concentration of the silver particle tended to increase with the ion density. The size distribution is more uniform as the ion density increases.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2106-2109
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• 2008

Nanofluids have been studied as possible alternatives for heat transfer fluids to improve the efficiency of heat exchangers. There are deviations of measured effective thermal conductivities between research-groups, and the mechanisms of the effective thermal conductivity enhancement of nanofluids are not confirmed yet. In this study, the effects of particle shape on the effective thermal conductivity enhancement are discussed and presented as a possible explanation of the deviations. The particle motion effect is found to be negligible for nanofluids of high aspect ratio cylindrical particles, which is believed to be important for nanofluids of spherical particles, while the percolation network formation and contact resistance play dominant roles in determining the effective thermal conductivity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.152-152
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• 2004

카본나노튜브(Carbon Nanotube)는 다른 물질과 구별되는 날카로움(Sharpness), 고세장비(High Aspect Ratio), 높은 기계적 강성(Stiffness), 고탄성(high Elasticity), 그리고 반도체(semi-conducting)와 도체(Metallic) 성질 때문에, 카본나노튜브는 많은 연구에 적용되고 있으며, 카본나노튜브가 부착된 AFM(Atomic Force Microscope) 팁을 이용한 AFM 측정은 CNT 응용에 있어서 매우 큰 효과를 내는 응용분야 중 하나이다. AEM 팁에 카본나노튜브를 붙이는 이전 연구는 대부분 화학증착법(Chemical Vapor Deposition)에 의해 이루어 졌으며, 매우 효과적인 방법이지만 고가의 장비와 고온의 챔버내에서 이루어진다는 문제점을 가지고 있다.(중략)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.247-247
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• 2009

본 연구에서는 indium-tin oxide (ITO) 나노 입자 용액을 이용하여 간단한 공정을 통해 ITO 나노 패턴을 직접적으로 제작하는 기술에 대한 연구를 진행하였다. 이를 이용하여 300nm급 ITO 나노 dot 패턴을 제작하는데 성공하였으며 이를 glass 표면에 구현하는데 성공하였다.