• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.426-427
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• 2006

Mono-sized silicon particles were effectively fabricated by a novel way named pulsated orifice ejection method (POEM). The particles are with very narrow particles size distribution and very small standard deviation of mean particle size. There are two different types spherical silicon particles were found. One consists of many grains mainly in random boundaries. The other consists of two or three grains with only twin orientation relationships, even single crystal in cross-section was also found within this type of spherical silicon particles.

• 한국염색가공학회지
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• 제23권2호
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• pp.146-153
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• 2011

Silver nano-particles have been synthesized by liquid phase reduction method and alcohol reduction process. Silver nano-particles of the size 30 ~ 40 nm were formed successfully by alcohol reduction process. The formation, structure, morphology and size of silver nano-particles have been studied using FE-SEM, TEM, XRD, UV-visible spectroscopy. In particular high dispersion stability of the synthesized silver nano-particles could be obtained by PVP binding. Antibacterial activity of Ag/PET master batch sample made from its nano-silver particles showed excellent antibacterial activity against S. aureus and E. coli.

• 대한기계학회논문집B
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• 제28권7호
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• pp.741-746
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• 2004

Agglomerated and non-agglomerated SiO$_2$ particles are synthesized in a furnace by oxidation of TEOS vapor. These polydispersed particles are classified with DMA to extract particles. Then these particles are introduced into a thermal precipitator through the ESP(Electrostatic Precipitator) to investigate the themophoretic particle deposition using CNCs(Condensation Nuclei Counter). The efficiency of themophoretic particle deposition according to agglomerated and non-agglomerated particles in the thermal precipitator has been studied as a function of particle size and TEOS mole concentration using monodisperse particles classified by DMA. The results show that the particle deposition efficiency decreases as TEOS mole concentration increases and particle size increases. Thereffre, it is concluded that the thermophoretic deposition efficiency is dependent of the particle morphology.

• 한국세라믹학회지
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• 제39권10호
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• pp.1007-1010
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• 2002

마이크로파 가열을 이용하여 ${\gamma}-Al_2O_3와\;Na_2SO_4$ 분말 혼합물로부터 알파 알루미나 판상체 입자를 합성하였다. 마이크로파를 이용하여 합성된 알루미나 입자의 크기와 입자분포를 마이크로파 이용 없이 동일한 혼합물로부터 합성된 분말과 비교하였다. 마이크로파를 이용하여 합성된 시료는 마이크로파 사용 없이 합성된 시료에 비하여 입자크기가 작고 입자분포가 좁음을 알 수 있었다.

• Journal of Korean Society for Atmospheric Environment
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• 제22권E2호
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• pp.78-88
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• 2006

In order to study the characteristics of cloud, a real-scale experiment for cloud generation was carried out using an extinct vertical mine (430 m height) located in the northeastern Honshu, Japan. The dry particles generated from the three-step concentrations of NaCl solutions were used for cloud generation. The number size distributions of initial dry particles and cloud droplets were monitored by Scanning Mobility Particle Sizer (SMPS) and Forward Scattering Spectrometer Probe (FSSP) at bottom and upper sites of pit, respectively. The polymeric water absorbent film (PWAF) method was employed to measure liquid water content ($W_L$) as a function of droplet size. Moreover the chemical properties of individual droplet replicas were determined by micro-PIXE. The CCN number concentration shows the lognormal form in dependence of the particle size, while the number size distributions of droplets are bimodal showing the peaks around $9{\mu}m$ and $20{\mu}m$ for every case. In comparison to background mineral particles, right shifting of size distribution line for NaCl particles was occurred. When NaCl solutions with three-step different concentrations were neulized, $W_L$ shows the strong droplet size dependence. It varied from $10.0mg\;m^{-3}$ up to $13.6mg\;m^{-3}$ with average $11.6mg\;m^{-3}$. A good relationship between $W_L$ and cloud droplet number concentration was obtained. Both chemical inhomogeneities (mixed components with mineral and C1) and homogeneities (only mineral components or C1) in individual droplet replicas were obviously observed from micro-PIXE elemental images.

• 상하수도학회지
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• 제19권1호
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• pp.16-24
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• 2005

Mathematical model was developed to verify a sequential particle removal taking place in a granular media gravity filter. Consequential multi-layer filtration cycle model was applied to verify the fraction of filter effluent particles that are filter influent particles that were never removed as well as the fraction of filter effluent particles that were detached after deposition were performed through laboratory experiments. Three sizes of marker particles were injected ahead of the filter column as a pulse in the presence of four sizes of polystyrene particles that were used as a primary source of particles in the raw suspension to investigate particle attachment alone in contrast to net removal from attachment and detachment. Microscopic counting of filter effluent particles was assumed to reflect attachment. Experimental results indicated that particle detachment is significant beginning from the early phase of filtration. For each size of fluorescent microspheres at one filter depth, fluorescent microsphere removal increased with filter runtime to a maximum due to ripening. The detached fraction of effluent particles increased with particle size and filter depth. The presence of detached particles and the increasing fraction of detached particles in deeper bed were confirmed.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.61-66
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• 2006

Over the past 20 years there has been a revolution involving the use of nano or macro size particles as drainage and retention systems during the manufacture of paper. More recently a group of patented technologies called Synthetic Mineral Microparticles (SMM) has been invented and developed. This system has potential to further promote the drainage of water and retention of fine particles during papermaking. Prior research, as well as our on preliminary research showed that the SMM system has advantages in both of drainage and retention compared with montmorillonite (bentonite), which one of the most popular materials presently used in this kind of application. In spite of the demonstrated advantages of this SMM system, the properties and activity of SMM particles in the aqueous state have not been elucidated yet. Streaming current titrations with highly charged polyelectrolytes were used to measure the charge properties of SMM and to understand the interactions among SMM particles, fibers, fiber fines, and cationic polyacrylamide (cPAM) as a retention aid. It was found that pH profoundly affects the charge properties of SMM, due to the influence of Al-ions and the Si-containing particle surface. SEM pictures, characterizing the morphology, geometry and size distribution of SMM, showed an broad distribution of primary particle size. Dilution of SMM mixturee appeared to wash out particles smaller than 100 nm from the surface of larger particles, which themselves appeared to be composed of fused primary particles. DSC thermoporometry was used to measure the size distribution of nanopores within SMM particles.

• 한국자기학회지
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• 제6권5호
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• pp.334-339
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• 1996

도포형 자기기록매체에 있어서 자성분의 size와 특성이 자기기록 특성에 미치는 영향을 조사하기위하여 size가 다른 각각의 자성분으로 만든 도료를 이용하여 자기 tape를 제조하고 자성분의 분산성 및 전자 변환 특성을 측정하였다. 자성분의 분산성은 입자 size의 영향보다 입자의 형태 및 자성분의 표면화학특성에 크게 의존하며 자성분의 입자 size가 작아질 수록 자성분의 충진성은 향상 되고 tape의 remanence 특성과 출력 특성 및 noise 특성이 향상되어 고출력, 저 noise의 넓은 dynamic range의 출력이 나타남을 확인하였다. 따라서 고출력의 자기 tape를 제조하기 위하여는 자성분의 size, 형상, 표면화학 특성 및 자기특성이 자성분 선정의 중요한 요건임을 확인하였다.

• Asian Journal of Atmospheric Environment
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• 제4권3호
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• pp.189-197
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• 2010

An orchestrated attempt was made to analyze samples of bulk and individual particulate matters (PM) collected at the Gosan ground-based station on the west coast of Jeju, Korea. A two-stage filter pack sampler was operated to collect particles in both large (> $1.2\;{\mu}m$) and small size fractions (< $1.2\;{\mu}m$) between the Asian dust (hereafter called "AD") storm event and non-Asian dust period. Elemental components in bulk and individual particles were determined by PIXE and synchrotron XRF analysis systems, respectively. To assess the transport pathways of air parcels and to determine the spatial distribution of PM, the backward trajectories of the Meteorological Data Explorer (Center for Global Environmental Research, 2010) and the NOAA's HYSPLIT dispersion-trajectory models were applied. In line with general expectations, Si and other crustal elements in large size particles showed considerably higher mass loading on AD days in comparison with non-AD days. Computation of the crustal enrichment factors [(Z/Si)$_{particle}$/(Z/Si)$_{desert}$ sand] of elements in large size particles (> $1.2\;{\mu}m$) allowed us to estimate the source profile and chemical aging of AD particles as well as to classify the soil-origin elements. On the basis of a single particle analysis, individual AD particles are classified into three distinct groups (neutralized mineral particles, S-rich mineral particles, and imperfectly neutralized particles).

• Advances in nano research
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• 제3권3호
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• pp.169-176
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• 2015

Iron nanoparticles were made by using the modified coprecipitation technique. Usually the characteristics of synthesised particles depend upon the process parameters such as the ratio of the iron ions, the pH of the solution, the molar concentration of base used, type of reactants and temperature. A modified coprecipitation method was adopted in this study. A magnetic stirrer was used for mixing and the morphology and nature of particles were observed after synthesis. Nanoparticles were characterised through XRD. Obtained nanoparticles showed the formation of magnetite and maghemite under citric acid and oxalic acid as stabilisers respectively. The size of nanoparticle was greatly affected by the use of different types of stabilisers. Results show that citric acid greatly reduced the obtained particle size. Particle size as small as 13 nm was obtained in this study. The effects of different kinds of nucleating agents were also observed and two different types of nucleating agents were used i.e. potassium hydroxide (KOH) and copper chloride ($CuCl_2$). Results show that the use of nucleating agent in general pushes the growth phase of nanoparticles towards the end of coprecipitation reaction. The particles obtained after addition of nucleating agent were greater in size than particles obtained by not utilising any nucleating agent. These particles have found widespread use in medical sciences, energy conservation and electronic sensing technology.