• 설비공학논문집
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• 제13권7호
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• pp.572-578
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• 2001

This study conducts a laboratory measurement on a cylindrical electrostatic precipitator(ESP) with a 30mm-diameter cylinder. Several kinds of test aerosols are generated with an atomizer and a diffusion dryer. The effects of applied voltage, flow state, gas velocity, and gas temperature on the electrical characteristics of the precipitator and onset of corona are experimentally investigated. The corona onset voltage is decreased, as diameter of discharge electrode wire becomes small or temperature of the precipitator increases. As the fluid velocity or particle load in the precipitator increases, the corona current is decreased.

• 한국세라믹학회지
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• 제26권4호
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• pp.493-498
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• 1989

High purity, submicron BaTiO3 powder was prepared by a hydrothermal technique using Ba(OH)2.8H2O, TiCl4 and NH4OH as starting raw materials. The submicron BaTiO3 powder was synthesized at 130~23$0^{\circ}C$ for 2.5h to yield highly crystalline particles with a narrow particle distribution. The mole ratio of Ba(OH)2.8H2O/TiO(OH)2 was 1.5. It is possible to obtain BaTiO3 with Ba : Ti=1.00$\pm$0/01. The samples densified well at 13$25^{\circ}C$, showing a uniform and fine grain structure. The grain size ranged between 0.3 and 0.5${\mu}{\textrm}{m}$. The products obtained by hydrothermal treatment at various temperatures from 130 to 23$0^{\circ}C$ were characterized by XRD, DTA, BET and SEM etc.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1891-1896
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• 2010

Submicron-sized polymeric colloidal particles can self assemble into 3-dimensional (3D) opal structure which is a useful template for photonic crystal. Narrowly dispersed polymer microspheres can be synthesized by emulsion polymerization in water using water-soluble radical initiator. In this report, we demonstrate a facile and reproducible emulsion polymerization method to prepare various polymeric microspheres within 200 - 400 nm size ranges which can be utilized as colloidal photonic crystal template. By controlling the amount of monomer and surfactant, monodisperse polymer colloids of polystyrene (PS) and acrylates with various sizes were successfully prepared without complicated synthetic procedures. Such polymer colloids self-assembled into 3D opal structure exhibiting bright colors by reflection of visible light. The colloidal particles and the resulting opal structures were rigorously characterized, and the wavelength of the structural color from the colloidal crystal was confirmed to have quantitative relationship with the size of constituting colloidal particles as predicted by Bragg equation. The tunability of the structural color was achieved not only by varying the particle size but also by infiltration of the colloidal crystal with liquids having different refractive indices.

• 청정기술
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• 제16권2호
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• pp.80-87
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• 2010

본 연구에서는 초음파가 결합된 초임계유체 입자 제조 기술인 SAS-EM 공정을 이용하여 난용성 항진균제인 이트라코나졸의 미세입자를 제조하였다. 실험에 사용된 SAS-EM 장치의 경우 초음파가 분사노즐에 직접 적용되었다는 점에서 기존의 SAS-EM 공정과 차이가 있으며, 초음파 세기, 공정온도, 용매 등의 여러 공정변수가 미세입자 형성에 미치는 영향을 고찰하였다. 초음파의 세기가 증가할수록 더 작은 크기를 가지는 입자의 생성률이 증가하였으며, SAS-EM 공정으로 제조된 미세입자도 원시료와 마찬가지로 결정구조를 가짐을 확인하였다. 초음파의 영향을 고찰하기 위해 기존의 초임계 ASES 공정과 비교하였으며, SAS-EM 공정에 의해 크기가 더 작은 입자가 형성됨을 확인하였다.

• 설비공학논문집
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• 제13권4호
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• pp.289-294
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• 2001

A well defined electro-spraying and electro-static precipitator(ESP) experiment is carried out to investigate the charging characteristics of the submicron particles and the monodisperse particles. The basic idea is that the highly charged electro-sprayed droplets will be produced into the gas when the Coulombic repulsive force on the surface is higher than the surface tension of the spraying liquid. During this process many highly charged smaller droplets or ions, if the droplets are completely dried out, will be produced in the space. These charged species will be attached ion the particles and then eventually charge the particles. These charged particles will be easily collected with ESP. The experimental results show that the atomizer generated particles with geometric mean diameter (GMD) of 62nm are charged more than 90% even at the mean face velocity of 2.5m/s at the charging zone.

• The Korean Journal of Ceramics
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• 제6권1호
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• pp.58-63
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• 2000

The preparation of Y-doped $SrZrO_3$powder by ultrasonic spray pyrolysis was investigated as a representative system, in order to produce fine, single phase multicomponent oxide powders. A precursor solution containing metal nitrates, citric acid and ethylene glycol was atomized glycol was atomized with an ultrasonic spray nozzle. Gel particles formed by organic functional groups were pyrolyzed and subsequently calcined at $800^{\circ}C$ to obtain well-crystallized, single perovskite phase. Most of large particles exhibited macroscopic pores and weak agglomeration between primary particles. However, strong agglomeration was observed in the surfaces of large particles. The effect of the microstructures of these particles on size reduction to submicron particles was described.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1684-1689
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• 2003

Dielectric Barrier Discharges (DBD) in oxygen and air are well established for the production of large quantities of ozone and are more recently being applied to a wider range of after treatment processes for HAPs(Hazardous Air Pollutants). The potential use as a charger for particle collection are not well known. In this work, we measured charge distribution of nanometer or submicron sized particles passing through the dielectric barrier discharge reactor. The bipolar charge characteristics of particles passing DBD reactor were investigated. Fluorometric method using uranine particles and a fluorometer was employed to examine the bipolar charging characteristics of the charged particles by DBD reactor. Finally, the charge distributions of particles were determined from the electrical mobility classification using DMA.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.93-96
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• 2012

In the industrial furnaces or reactors, entrainment of the material particles is one of the important issues from the point of view of efficient material-use. The particles of solid phase which has submicron unit are easily entrained with gas phase as a reacting agent or product, and it causes a loss of the material. In this study, wind-tunnel experiment is carried out to interpret the distribution of the particles entrained along the tunnel length. Through CFD-based computational analysis of the experiment, availability of result from the CFD analysis associated with particle size distribution and gaseous velocity to practical system is evaluated.

• 공업화학
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• 제29권6호
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• pp.782-788
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• 2018

서브 미크론 구리-은 코어-쉘 Cu@Ag 입자를 초음파화학과 결합된 금속교환 반응으로 합성하고 인쇄용 전자부품을 위한 저렴한 전도성 페이스트 적용을 평가하였다. 코어-쉘의 합성을 위한 반응에서 코어로 사용된 $Cu_2O/Cu$ 복합체의 $Cu_2O$는 초음파화학 반응으로 Cu로 환원되고 Cu 원자는 Ag의 금속교환 반응의 환원제로 작용하여 코어 표면에 Ag가 코팅된 코어-쉘 구조를 얻었다. TEM-EDS와 TG-DSC를 이용하여 서브 미크론 입자의 코어-쉘 구조를 확인하였다. 70 wt% Cu@Ag를 용매에 분산시킨 전도성 페이스트를 결합제와 습윤제를 사용하여 제조하고, 스크린 인쇄법을 사용하여 폴리아미드 필름상에 코팅하였다. Ag 함량이 8 at%와 16 at%인 Cu@Ag 입자를 함유하는 인쇄된 페이스트 필름은 공기 중의 $180^{\circ}C$에서 소결한 후 각각 96.2와 $38.4{\mu}{\Omega}cm$의 낮은 비저항 값을 나타내었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.847-848
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• 2004

We studied a low density 8CB liquid crystal-hydrophobic aerosil dispersions imbedded in submicron-size cylindrical pores. The nanosize spherical aerosil particles are adsorbed at the pore wall and hinder the planar anchoring. The adsorption is temperature dependent, and an axial to radial molecular configuration transition occurs within the cylindrical pores.