• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.27-31
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• 1997

액상법에 의한 단분산 ZnS입자의 합성을 60~9$0^{\circ}C$에서 행하여, 반응조건이 ZnS입자의 형태에 미치는 효과를 검토했다. ZnS입자의 형태는 반응 시간의 경과와 더불어 단분산으로부터 다분산 혹은 응집체로 변화하였다. 반응 온도 60~9$0^{\circ}C$에서 초기 농도적이 중간값이고, 반응시간이 짧을 경우 입경 0.2~0.8$\mu\textrm{m}$의 구상 단분산 입자를 얻었다. 또한 Ag$_2$NO$_3$, EtOH용액, $0^{\circ}C$에서, Ag$_2$S에 의한 ZnS의 균일 피복이 가능하였다.

• The Korean Journal of Rheology
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• v.10 no.1
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• pp.24-30
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• 1998

솔젤법을 이용하여 단분산의 실리카 입자를 제조하고 농도변화에 따른 실리카 분산 액의 유변학적 거동을 해석하였다. 단분산 실리카 입자의 제조는 솔젤법을 이용한 액상반으 으로 제조하였고 입자의 안정화를 위하여 입자표면에 실란커플링제를 코팅하여 유기용매에 서 안정성을 갖도록 하였다. 분산액의 농도에 따른 유변학적 거동을 조사하기 위하여 부피 분율( )이 0.05인 희박 분산계로부터 =0.55의 고농도 분산계를 제조하였다. 솔젤법을 통하 여 단분산 실리카 입자를 성공적으로 제조하였으며 실란커플링제인 ${\gamma}$-methacryloxypropyl triethoxysilane로 입자의 표면을 화학적 방법으로 처리하여 유기용매 상에서 알킬기의 작용 에 의한 hard-sphere'특성을 나타내도록 하였으며 동시에 분산안정성을 유지할수 있었다. 입자 분산계는 =0.25이하의 부피농도에서는 분산용매와 같은 뉴톤거동을 보여주었으며 이 이이상의 농도에서는 비뉴톤거동인 전단담화(shear thinning)현상과 high shear limiting viscosity를 나타내었다. 이결과는 Krieger-Dougherty 식을 따름이 확인되었으며 부피분율 =0.50정도까지도 이식이 잘적용됨을 확인하였다. 부피분율 =0.50 이상의 고농도 입자 분산계 는 급격한 점도의 증가와 함께 전단담화와 전단탁화(shear thickening)현상이 모두 관찰되었 다. 특히 전단탁화를 일으키는 특헝전단변형률(cr)이하의 전단변형률에서는 안정되고 빠른 점성반응(viscous response)을 보여주었으나 특성 전단변형률 부근과 이상의 전단변형률 영 역에서는 매우 불안한 거동이 보여짐을 확인하였다. 그러나 이러한 점도 거동은 가역적이며 전단변형률을 증가시킬때와 감소시킬 때의 유변학적 거동이 거의 일치하였다.

• Journal of the korean Society of Automotive Engineers
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• v.6 no.2
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• pp.55-63
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• 1984

Berglund-Liu 진동방식 단분산 분체입자 발생기(Berglund-Liu vibrating orifice monodisperse aerosol generator)에 의하여 제작한 단분산 광흡수성 표준분체입자를 사용하여 레이저 산란광 분체입도 측정기 (Knollenberg active scattering aerosol spectrometer)의 반응특성을 조사하 였다. 실험결과, 기기의 반응특성은 Mie 산란이론에 의하여 계산한 이론치와 매우 잘 일치하며 특히 광흡수성 분체입자는 광통과성 분체입자가 다의적인 특성을 나타내는 것에 반하여 거의 단조증가하는 일의적인 특성을 가지고 있으며 광흡수성 분체입자의 반응특성이 제작자의 교정 치에 가까운 결과를 나타내었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.6
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• pp.2005-2013
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• 1996

Particle paths and flow fields in a prototype differential mobility analyzer (DMA) were numerically analyzed solving Navier-Stokes equation, electric field equation and particle motion considering viscous drag force, Coulomb force and polarization force. Analytically predicted particle diameters for the prototype DMA are in good agreement with the measured particle diameters within $\pm$1%. And the analytically predicted particle diameters are also in good agreement with numerical results for the prototype DMA.

• Journal of the Korean Ceramic Society
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• v.25 no.5
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• pp.50-50
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• 1988

The controlled Ti(CO2H5)4 hydrolysis reactions for the synthesis of Spherical Monodispersed Titania powders are described. Increasing the concentration of TEOT and the molar ratio of water to TEOT in alcohol solution decrease the reaction time and the particle size. The reaction time is delalyed by increasing the chain length and the number of carbon branches of alcohol as a solvent. The prepared powders with an average diameter of 0.8μ and the spherical monodispersed transfer to Rutile phase at 550℃.

• Polymer(Korea)
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• v.34 no.1
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• pp.25-31
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• 2010

Polymer core and metal shell composite particles have been prepared by the electroless nickel plating on the surface of monodisperse polystyrene microspheres. Various sizes of polystyrene particles with highly monodisperse state could be synthesized by controlling the dispersion medium in dispersion polymerization. Electroless nickel plating was performed on the polystyrene particle with diameter of $3.4\;{\mu}m$. The morphology of polystyrene/nickel composite particles was investigated to see the effect of the plating conditions, such as the $PdCl_2$ and glycine concentrations and the dropping rate of nickel plating solution, on nickel deposition. With $PdCl_2$ and glycine concentrations at more than 0.4 g/L and 1 M, respectively, more uniform nickel layer and less precipitated nickel aggregates were formed. At the given plating time of 2 h, the same amount of plating solution was introduced by varying the dropping rate. Though the effect of dropping rate on particle morphology was not noticeable, the dropping rate of 0.15 mL/min for 60 min showed rather uniform plating.

• Polymer(Korea)
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• v.24 no.3
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• pp.287-298
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• 2000

In preparing micron-sized monodisperse polystyrene beads by dispersion polymerization, the conversion, and the particle size and its distribution were affected by the reaction temperature, concentration of the monomer, solvent and initiator, molecular weight and concentration of the steric stabilizer, amount of oxygen existing in the reactor, and an appropriate combination of these starting materials. Ethanol as a dispersing agent, styrene as a monomer, PVP as a steric stabilizer, AIBN as an initiator, DVB as a cross-linking agent and toluene as a co-solvent were the basic materials for the synthesis. The reaction rate and the conversion were increased with the reaction temperature and the amount of DVB from 1 to 4%, and the conversion was saturated after 10 hours of the reaction time. The optimum reaction recipe for the preparation of the monodisperse PS beads was 25% styrene monomer, 0.5% DVB, 25% toluene, 10-15% PVP, and 2 and 4% AIBN, thereby, 3.9~4 ${\mu}{\textrm}{m}$ and 3.4~9.3 ${\mu}{\textrm}{m}$ of polystyrene beads, respectively, were successfully synthesized.

• Elastomers and Composites
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• v.44 no.3
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• pp.222-231
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• 2009

Shirasu-porous-glass (SPG) membrane emulsification is highly attractive in the field of toner industries, foods and drug delivery systems because of its easy control of particle size in micro-scale, narrow size distribution and multiple emulsion. The particle size and morphology of emulsion droplets can be controlled by changing the type of initiators, additives, monomers, crosslinkers and inhibitors in SPG membrane emulsification. In this paper, principles of SPG membrane emulsification, influence of process parameters and industrial applications have been addressed.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.108.1-108
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• 2000

• The Journal of the Acoustical Society of Korea
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• v.41 no.1
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• pp.9-15
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• 2022

In order to overcome the limitation of conventional nanoparticle dispersion methods such as sonicator or homogenizer, a filtration method using an ultrasonic atomization effect and cyclones was proposed in this study. A 0.5 wt% suspension was made with Al₂O₃ powder with an average diameter of 250 nm. The suspension was filtered by the proposed method after pre-dispersing using a sonicator and a homogenizer, respectively. As the result, in the case of the suspension after pre-dispersing with a sonicator, the particle size distribution of the filtered suspension started showing up a single normal distribution indicating the mode of the average diameter only after the 3rd cyclone process. On the other hand, in the case of the suspension with the homogenizer pre-dispersion, similar results appeared from the 2nd cyclone process. Filtration of various types of nanoparticles is expected to be possible by adjusting ultrasonic atomization frequency and manipulating the design of the cyclone.