• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.76-80
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• 2007

Three nano-sized Fe-N particle samples synthesized by Chemical Vapor Condensation (CVC) were analyzed using $M\"{o}ssbauer$ spectroscopy, XRD and BET. The synthesized nanoparticles consisted of ${\epsilon}-Fe_{2.12}N,\;{\gamma}'-Fe_4N,\;{\alpha}-Fe\;and\;{\gamma}-Fe.\;{\gamma}'-Fe_4N$ was mainly formed at the low decomposition temperature. With increasing decomposition temperature, the phase was changed to ${\gamma}-Fe$ via ${\epsilon}-Fe_{2.12}N$. For synthesizing Fe-N phases, this study implies that the low decomposition temperature is better than high temperature during Chemical Vapor Condensation.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.125-130
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• 2006

The characteristics of boiling heat transfer and critical heat flux (CHF) behavior of nano-fluids were studied by using various sized silver and alumina nanoparticles. The diameter of nanoparticles was from 2 nm to 250 nm for silver and from 20nm to 40nm for alumina. Pool boiling characteristics and CHF enhancement of nano-fluids with different sized nanoparticles were compared with those of pure water and each nano-fluids. The experiment was performed at atmospheric pressure and the temperature of the pool was maintained constantly by using a flat immersed heater. The concentration of nano-fluids was uniform in all experiments as 0.01g/liter. The results showed that the measured boiling curves were shifted to the right. It demonstrated that the occurrence of nucleate boiling regime in nano-fluids retarded, compared with that of pure water. Also, in nano-fluids, the boiling curves showed that CHF of nano-fluids is significantly enhanced and represented the effect of particle size on boiling characteristics.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.35-40
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• 2022

In this study, the average particle size of silver powder was 2㎛, 7㎛, and a mixture of these (50:50wt%), three kinds of silver pastes were prepared. In addition, as a result of examining the viscosity and viscoelasticity of the three silver pastes, TGA measurement, resistance change according to strain, and change in surface structure of the electrode, the following conclusions were obtained. Summarizing these results, it was found that it is most desirable to have a particle size of about 2㎛ in order to minimize the change in resistance due to strain.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1713-1717
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• 2008

We have developed a nanoparticle focusing mask which can generate particle arrays directly on the large area with high resolution. Using this mask, nanomaterials are precisely deposited onto desired positions on a substrate surface. We obtained various sizes of arrays ranging from 80 nm to 6 ${\mu}m$ with silver and copper nanoparticles that are generated by a spark discharge and an evaporation-condensation method. The feather size is much smaller than that of mask openings due to the focusing effects, like electrostatic lens, caused by charge or electric potential on insulator mask surface, which also prevent a mask clogging. The particle array size depends on the size of mask open patterns and focusing effects near the mask relate to ion flow rate and electric potential. We have demonstrated that diverse size of arrays with high resolution could be obtained repeatedly using the same sized mask in atmosphere.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.468-473
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• 2007

In this paper, we discussed about the development of the PBMS(Particle Beam Mass Spectrometer) that can measure the nanoparticles on real-time in low-pressure processes. To calibrate this equipment, a DMA(Differential Mobility Analyzer) was used to generate NaCl particles which are charged to +1. Total aerosols flow rate was 1 lpm and 0.086 lpm of that was introduced into the PBMS through the pressure-reducing critical orifice. Transport efficiency through PBMS was 50$\sim$60 % compared to particle current for DMA and PBMS according to the particle size. Results of mesurements are in good agreement with size distributions obtained by DMA.

• Journal of the Korean Magnetics Society
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• v.15 no.3
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• pp.172-176
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• 2005

Four nano-sized Fe-nano particle samples synthesized by Chemical Vapor Condensation (CVC) were analyzed using $M\ddot{o}ssbauer$ spectroscopy, XRD, BET and TEM. The samples were consisted as functions of carrier gas and decomposition temperature. The synthesized nanoparticles consisted of two- or three-layers with the circular shape. The average particle size was increased with increasing the decomposition temperature. At $500^{\circ}C$ for the decomposition temperature, $Fe_3C$ was formed more under the environment of CO carrier gas than that of $CH_4$. However, at $1,100^{\circ}C$, almost of Fe-nano particles were transformed into $Fe_3C$ with using both carrier gas.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.701-706
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• 2008

Nano-sized nickel powders were prepared by evaporating the bulk nickel metarial using transferred arc thermal plasma. Nitrogen gases are easily dissociated to atomic nitrogen in thermal plasma and they are quickly dissolved in molten nickel. Super-saturated atomic nitrogen in molten nickel is recombined to nitrogen gas because of the relatively low temperature of nickel surface. Generally, the recombine reaction of atomic nitrogen is exothermic, so bulk nickel is quickly evaporated to nickel vapor due to the thermal energy of recombine reaction. The particle size of nickel powder was controlled by $N_2$ used as the diluting gas. It was observed that as the diluting gas flow rate was increase, the particle size was decreased and the particle size distribution was narrowed. The average particle size at 250 l/min of the diluting gas was 202 nm analyzed by means of the particle size analyzer (PSA).

• Resources Recycling
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• v.13 no.6
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• pp.16-25
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• 2004

In this study, nano-sized indium oxide powder with the average particle size below 100 nm is prepared from the indium chloride solution by the spray pyrolysis process. The effects of the concentration of raw material solution, the nozzle tip size and the air pressure on the properties of powder were studied. As the indium concentration of the raw material solution increased from 40 g/l to 350 g/l, the average particle size of the powder gradually increased from 20 nm to 60 nm, yet the particle size distribution appeared more irregular, the intensity of a XRD peak increased and specific surface area decreased. As the nozzle tip size increased from 1 nm to 5 nm, the average particle size of the powder increased from 40 nm to 100 nm, the particle size distribution was much more irregular, the intensity of a XRD peak increased and specific surface area decreased. As the air pressure increased from 0.1 kg/cm$^2$ to 0.5 kg/cm$^2$, the average particle size of the powder varies slightly upto 90~100 nm. As the air pressure increased from 1 kg/cm$^2$ to 3 kg/cm$^2$, the average particle size decreased upto 50~60 nm, the intensity of a XRD peak decreased and the specific surface area increased.

• Particle and aerosol research
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• v.6 no.3
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• pp.107-121
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• 2010

The number of nanotechnology based consumer products are growing rapidly. Thus, the customer likely to be exposed to such products continues to increase as the applications expand. This article describes the international and Korea's policies on the EHS(Environment, Safety and Health) issues of nanotechnologies. The strategic plan and coordination of OECD and ISO were summarized. This article also examines several new findings of Korean researchers as well as current and future challenges in the aerosol application study of EHS issues on the nanotechnologies.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.391-392
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• 2013

반도체 집적회로의 고집적화 및 고성능화를 위한 기본 소자(MOSFET)의 미세화 및 단위공정의 물리적 한계를 극복하기 위해 기존의 Top-down 방식에서 buttom-up 방식의 공정에 대한 연구가 진행되고 있다. 그 중 nanoparticles를 이용한 나노소자 제작 연구가 이루어지고 있다. 하지만 이러한 nanoparticles를 이용한 나노소자의 제작에 있어서 원하는 위치에 nanoparticles를 배열하고 정렬하는데 어려움을 겪고 있다. 이 문제를 해결하기 위해서 자기조립 특성을 가지고 있는 DNA분자와 기능화를 통하여 표면에 positive charge를 띄고있는 Gold nanoparticles를 상호결합 시키는 실험을 하였다. Au-DNA nanowire는 backbone에 있는 phosphate부분에서 negative charge를 띠고 있는 DNA와 positive charge를 띠고 있는 Gold nanoparticles가 결합하는 원리로 형성된다. 그렇지만 Gold particles를 표면이 아닌 DNA에만 붙이는 것은 아직 해결해야 할 부분으로 남아있다. 본 연구에서는 이 문제를 해결하기 위하여 pH 조절을 통하여 기능화된 Gold particles의 charge의 변화를 주고 이를 Zeta potential 측정기로 측정한 후에 이 particles와 DNA를 결합시켜서 FE-SEM과 AFM 으로 확인하는 실험을 하였다.