• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.20-26
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• 2008

Behavior of micro stickies was analyzed using model micro stickies prepared with PVAc emulsion adhesive. Flocculation of micro stickies increased with temperature. Acidic state also induced greater flocculation of micro stickies since they became more unstable under these conditions. Flocculation of micro stickies increased as calcium ion concentration increased. But the presence of calcium carbonates made micro stickies dispersed indicating that calcium carbonates cause two different effects on the behavior of micro stickies. Talc increased flocculation of micro stickies because of its hydrophobic nature. Cationic polymer increased flocculation of micro stickies. Especially cationic starch has far greater effect in flocculating sticky particles by forming bridging flocculations.

• Polymer(Korea)
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• v.31 no.5
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• pp.410-416
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• 2007

Monodisperse polymer particles were prepared via one- step seeded polymerization using PMMA as seed particles, and HDDA, triEGDMA or EGDMA as crosslinking monomer. For the study, the effects of 1) the ratio of the absorbed monomer to the seed polymer particles (swelling ratio), 2) the characteristics of crosslinking monomer, 3) electroless Ni plating, and 4) electroless Au Plating on the variation of mechanical properties of polymer particles, such as recovery rate, K-values, breaking strength and breaking displacement were investigated by using MCT (micro compression test). It was observed that swelling ratio of polymer particles influenced only on breaking strength of polymer Particles, while electroless plating did on recovery rate, K-values ($K_{10}\;and\;K_{20}$) and breaking strength of electroless plated polymer particles. However, breaking displacement and K-values ($K_{30}{\sim}K_{50}$) were more or less insensitive to electroless plating.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.596-610
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• 2021

For application in adsorption process, we synthesized silica nanospheres by Stober method, and silica particles with wrinkled surface as well as macroporous silica particles were also fabricated by utilizing emulsion droplet as micro-reactors, followed by modification of the particle surface using suitable coupling agents containing amine groups. These particles exhibited improved adsorption capacity for heavy metal ions and anionic dyes, which were difficult to be removed by conventional silica particles without surface modification. Anionic dye, methyl orange could be removed almost completely by adsorption using porous silica particles modified using APTES. The adsorption efficiency of heavy metal like copper ions was close to 100%, when porous silica was used as adsorbent particles modified with AAPTS.

• Membrane and Water Treatment
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• v.14 no.4
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• pp.147-153
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• 2023

Urbanization has been causing such new pollutants as micro-plastic, thus the environmental impact of new pollutants on ecosystem is rapidly increasing. When it comes to micro-plastic, a representative artificial trace pollutant, its risk has been increased at a much faster rate, however the depth study associated with stormwater sediment and wetland was relatively rare. In this research, soil samples from storm water sediment were analyzed for distribution characteristics of micro-plastics in the J wetland (registered as Ramsar wetland, May 2021 and a representative environmental site in South Korea). Analyzed soil samples found approximately 201 ± 93 particle/kg (based on unit weight, Total micro plastic particles / Total Sample weight) micro-plastics in the samples. When considering the total quantitative numbers in stormwater sediment in the entire area of the J wetland, over 15,000 micro-plastics were estimated to be contaminating such area. In addition, in terms of qualitative numbers, micro-plastics were contaminating the J wetland with 94.7 % ratio of styrofoam type (43.9%) and polyethylene type (50.8%). These research results can be used as base data sets for controlling micro-plastics in the J wetland.

• 한국가시화정보학회:학술대회논문집
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• 2004.12a
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• pp.111-118
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• 2004

A new micro-resolution PIV (Particle Image. Velocimetry) has been developed. To investigate transient phenomena in a microfluidic device, Dynamic micro-PIV system was realized by combining a high-speed camera and a CW(Continuous Wave) laser. The technique was applied to a micro-counter-current flow, consisting of water and butyl acetate. The velocity fields of water in the micro counter-current flow were visualized for a time resolution of 500 $\{mu}s$ and a spatial resolution of 2.2 x 2.2 $\{mu}m$. Using the Dynamic micro-PIV technique, the vortex-like motions of fluorescent particles at the water-butyl acetate interface were captured clearly

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.387-393
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• 2013

The crystallization of polypropylene (PP) particles in PP/decalin solution was conducted using the thermally induced phase separation(TIPS). During the control of particles sizes followed by the cooling of PP/decalin solution, particles were formed controllably, the concentrated PP resulted in an increase in the average diameter of PP particles. The effects of surfactants changes on particles sizes were investigated by using a field emission scanning electron microscope (FE-SEM). The PP crystals showed spherical shapes with a diameter 5~18 ${\mu}m$. Additionally, as an effect of concentration of PP, the size distribution of the PP particles became broad with higher concentration of PP in the solution.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.1-6
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• 2023

In CO₂ laser surface machining of plastic films in modern display manufacturing, scattering of fume particles could be a major source of well-recognized film surface contamination. This computational fluid dynamics research investigates the suction air flow patterns over a film surface as well as the dispersion of micron-sized fume particles with low-Reynolds number particle drag model. The numerical results show the recirculatory flow patterns near laser machining point on film surface and also over the surface of vertical suction slot, which may hinder the efficient removal of fume particles from film surface. The dispersion characteristics of fume particles with various particle size have been tested systematically under different levels of suction flow intensity. It is found that suction removal efficiency of fume particles heavily depends on the particle size in highly nonlinear manners and a higher degree of suction does not always results in more efficient particle removal.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1874-1879
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• 2008

It is not easy to detect nano-sized airborne particles (< 100 nm in diameter) in air. Therefore, the condensation of the nanoparticles alongside of the size-classification is needed for their detection. This paper proposes a hybrid (aerodynamic+electrical) particle classification and condensation device using a micro virtual impactor (${\mu}VI$). The ${\mu}VI$ can classify the nanoparticles according to their size and condense the number concentration of nanoparticles interested. Firstly, the classification efficiency of the ${\mu}VI$ was measured for the particles, polystyrene latex (PSL), ranging from 80 to 250 nm in diameter. Secondly, the nanoparticles, NaCl of 50 nm in diameter, were condensed by 4 times higher. In consequence, the output signal was amplified by 4 times (before condensation: 4 fA, after condensation: 16 fA). It is expected that the proposed device will facilitate the detection of nanoparticles.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.1
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• pp.47-54
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• 2004

In this study, the electrorheological (ER) fluid was used as finishing agent. Since the apparent viscosity can be controlled by an electric field, the ER fluid can be one of efficient materials in finishing processes. To finish small 3-dimensional structures such as the aspherical surface in optical elements, the possible arrangement of a tool, part and auxiliary electrode was described. We examined the influence of the addition of a few abrasive particles on the performance of the ER fluid by measuring yield stress and observed the behavior of abrasive particles in the ER fluid by a CCD camera, which had been also theoretically predicted from the electromechanical principles of particles. On the basis of the above results, the steady flow analysis around the rotating micro tool was performed considering the non-uniform electric field. Finally, borosilicate glass was finished using the mixture of the ER fluid and abrasive particles and material removal with field strength and surface roughness were investigated.

• Structural Engineering and Mechanics
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• v.62 no.2
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• pp.163-170
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• 2017

This study presents a particle-wall filtration model for predicting the particle motion behavior in a typical rotational flow field-filtration in blower system of cooker hood. Based on computational fluid dynamics model, air flow and particles has been simulated by Lagrangian-particle/ Eulerian-gas approaches and get verified by experiment data from a manufacturer. Airflow volume, particle diameter and local structure, which are related to the particle filtration has been studied. Results indicates that: (1) there exists an optimal airflow volume of $1243m^3/h$ related to the most appropriate filtration rate; (2) Diameter of particle is the significant property related to the filtration rate. Big size particles can represent the filtration performance of blower; (3) More than 86% grease particles are caught by impeller blades firstly, and then splashed onto the corresponding location of worm box internal wall. These results would help to study the micro-particle motion behavior and evaluate the filtration rate and structure design of blower.