• Particle and aerosol research
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• v.10 no.3
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• pp.99-108
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• 2014

Liquid filtration by membrane filters is essential for the preparation of ultrapure water in semiconductor manufacturing processes. The separation of submicrometer particles suspended in ultrapure water with a laminated fibrous membrane filter was studied numerically and experimentally in the present work. We found that an electrical double layer around a single fiber expanded to a large extent at a low ion concentration, as in ultrapure water, and deformed toward the upstream of the fiber with increasing filtration velocity. Since an increase in the electrical double-layer thickness leads to a decrease in the electrical potential gradient, particles with the same polarity as the fiber approach the fiber more easily and are captured at a high filtration velocity. Experimental results also confirmed that the collection efficiency of polystyrene latex(PSL) particles through a PTFE filter became higher as the filtration velocity increased.

• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.600-603
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• 1997

Spherical, submicrometer particles of barium-titanyl oxalate were homogeneously precipitated by thermal decomposition of diethyl oxalate in acidic aqueous solutions. The rates of oxalate ion generations, determined by various combinations of temperature and initial concentration of diethyl oxalate had a very important effect on the particle size distribution. Monosized, bimodal, or broad unimodal powders were obtained under certain combinations of experimental variables.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.1-6
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• 1995

Submicrometer, monosized ceramic powder of $Al_2TiO_5$$Al_2O_3$ ethanolic solutions. All particles produced by sol-gel-process were amprphous, monodispersed and with a narrow particle-size distribution. Compacts fired above $1300^{\circ}C$ formed aluminium titanate. Mullite formed first at $1480^{\circ}C$. After decomposition test at $1100^{\circ}C$, and cyclic thermal decomposition test at 750-1400-$750^{\circ}C$ for 100hrs., aluminium titanate was well stablized by composition with mullite.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.133-137
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• 2014

As a preceding process for preparing several micrometer sized Ag-coated Cu flakes, ball milling of submicrometer-sized Cu particles synthesized through a wet chemical method was performed in order to convert the particles into flakes. To suppress oxidation and aggregation of the particles during ball milling, ethylene glycol and ethyl acetate were used as a medium and a surface modifying agent, respectively. Results obtained with different rotation speeds of a jar indicated that the rotation speed changes a rotating mode, and strikingly alters the final shapes and shape uniformity of Cu particles after milling. The diameter of zirconia ball was also confirmed. Although there was aggregates in the initial submicrometer-sized Cu particles, therefore, well-dispersed Cu flakes with a size of several micrometers were successfully prepared by ball milling through optimization of rotation speed, amount of ethyl acetate, and diameter of zirconia ball.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.2
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• pp.73-79
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• 2002

The polyol process which applies to cobalt, nickel. copper and precious metals is a interesting and unexpected example of such a method for preparing uniform metal powders. The reaction proceeds via dissolution, and the polyol acts simultaneously as a solvent, a reducing agent, and to some extent a protective agent. Submicrometer uniform cobalt particles can be obtained by seeding the reactive medium ($AgNO_3$) to achieve a complete substitution of homogeneous by heterogeneous nucleation. By varying the number of nuclei it is possible to control to some extent the average particle size in the submicrometer (0.5$\mu$m) range.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.743-746
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• 2000

The removal of contaminants of silicon wafers has been investigated by various methods. Laser cleaning is the new dry cleaning technique to replace wafer wet cleaning in the near future. A dry laser cleaning uses inert gas jet to remove contaminant particles lifted off by the action of a KrF excimer laser. A laser cleaning model is developed to simulate the cleaning process and analyze the influence of contaminant particles and experimental parameters on laser cleaning efficiency. The model demonstrates that various types of submicrometer-sized particles from the front sides of silicon wafer can be efficiently removed by laser cleaning. The laser cleaning is explained by a particle adhesion model. including van der Waals forces and hydrogen bonding, and a particle removal model involving rapid thermal expansion of the substrate due to the thermoelastic effect. In addition, the experiment of wafer laser cleaning using KrF excimer laser was conducted to remove various contaminant particles.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.5
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• pp.657-665
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• 1999

Particulate matter produced by diesel engines is of concern to cngine manufactures because of its environmental impact. The majority of diesel particles are in the range of smaller than 1 ${\mu}{\textrm}{m}$. Because of their tiny volume, ultrafine diesel particles contribute very little to the total mass concentration which is currently regulated for automobile emissions. Ultrafinc particles are known to have deleterious effects upon human health cspecially because they penetrate deeply human respiratory tract and have negative effects on the health. In this study, the engine exhaust gas was diluted in a dilution tunnel and the particle size distribution was measured using the scanning mobility particel sizer system. Measurements of the number and the mass concentrations of the diesel exhaust were made under different engine ooperating conditions. The dilution sampling system provided a common basis for collection of the exhaust by cooling and diluting the source emission prior to the measurement. The measurement results showed that the particle size distributions of the exhaust from the diesel vehicles equipment with either heavy-duty or lignt-duty diesel engines, were similar in the particle size range of 0.08~0.2${\mu}{\textrm}{m}$.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.330-330
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• 2006

The elaboration of fluorescent submicronic polymer particles exhibiting narrow particle size distribution as well as good photostability is of particular interest in various biomedical applications. In the frame of this work, labeled polystyrene latexes have been synthesized by miniemulsion polymerization using luminescent semiconductor nanoparticles (quantum dots, QD). The influence of incorporation of QDs on the polymerization kinetics as well as on the optical properties of the obtained latexes will be discussed.

• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.600-604
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• 2003

The light pressure force from an optical standing wave (SW) can focus an atomic beam to submicrometer dimensions. To make the best of this technique it is necessary to find a set of optimal experimental parameters. In this paper we consider theoretically the chromium atoms focusing and demonstrate that the focusing performance depends not only on the strength of but also on the time atoms take to traverse the force field. The general conclusions drawn can easily be applied to other atoms. To analyze the problem we numerically integrate a coupled time-dependent $Schr{\"{o}}dinger$ equation over a wide range of experimental parameters. It is found that an optimal atomic beam speed-laser intensity pair does exist, which could give substantially improved focusing over the one with the experimental parameters given in the literature. It is also shown that the widely used classical particle optics approach can lead to erroneous predictions.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.200-206
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• 2000

We have investigated the activation magnetic moment, which characterizes the basis magnetic moment acting as a single magnetic particle during magnetization reversal. The activation magnetic moment was measured from each local area on continuous ferromagnetic thin films, by analyzing the magnetic field dependence of magnetization reversal of the corresponding local area based on a thermally activated relaxation process. It was found that the activation magnetic moment was nonuniform on submicrometer scale; the fluctuation increased with increasing the number of layers in Co/Pd multilayers. The distribution could be well analyzed by exp($\delta$m$\^$3/2/), where $\delta$m is the deviation of the activation magnetic moment from the mean value.