• Transactions on Electrical and Electronic Materials
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• 제4권1호
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• pp.29-33
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• 2003

Europium doped yttrium oxide submicron-sized particles were prepared by ultrasonic aerosol pyrolysis. To examine the size effect of submicron-sized-particle, the photoluminescence of the particles was investigated. The particle size was controlled by pH, reaction temperature, molar concentration of yttrium in precursor solution. The PL intensity of submicron-sized particles was decreased with particles size. When the particle size is above about 150 times of Bohr radius of Y$_2$O$_3$, the optical property of the particles shows the bulk characteristics.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 하계학술발표대회
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• pp.22-22
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• 2005

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2005년도 추계학술대회 논문집
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• pp.315-316
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• 2005

• Asian Journal of Atmospheric Environment
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• 제11권2호
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• pp.131-137
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• 2017

A cyclone is an effective tool to facilitate the collection of aerosol particles without using filters, and in cell exposure studies is able to collect a sufficient amount of aerosol particles to evaluate their adverse health effect. In this study, we examined two different methods to improve the aerosol particle collection efficiency of a cyclone. The individual and combined effects of reducing the surface roughness of the inner wall of the cyclone and of using a circular cone attachment were tested. The collection efficiency of particles of diameter $0.2{\mu}m$ was improved by approximately 10% when using a cyclone with a smoothened inner wall (average roughness $Ra=0.08{\mu}m$) compared with the original cyclone ($Ra=5.1{\mu}m$). A circular cone attachment placed between the bottom section of the cyclone and the top section of a collection bottle, resulted in improved collection of smaller particles without the attachment. The 50% cutoff diameter of the modified cyclone (combined use of smoothened inner wall and attachment) was $0.23{\mu}m$ compared to $0.28{\mu}m$ in the original model. The combined use of these two techniques resulted in improved collection efficiency of aerosol particles.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.316-319
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• 2006

Monthly-mean aerosol parameters derived from the 1998-2004 SeaWiFS observations over East Asian waters are analyzed. SeaWiFS GAC Level 1 data covering the Northeast Asian area are collected and processed by the standard atmospheric correction algorithm released by the SeaWiFS Project to produce daily aerosol optical thickness (AOT) and ${{\AA}}ngstr{\ddot{o}}m$ exponent imageries. Monthly mean AOT and ${{\AA}}ngstr{\ddot{o}}m$ exponent values are extracted from the daily composite images for six study areas chosen from the surrounding waters of Japan. A slight increasing trend of ${{\AA}}ngstr{\ddot{o}}m$ exponent is found and interpreted as about 4-5% increase in submicron fraction of aerosol optical thickness at 550nm. Two cloud screening methods, including the standard cloud masking method of SeaWiFS and the one based on the local variance method, are applied to the SeaWiFS data processing, in an attempt to inspect the influence to the observed statistical uptrend which probably induced by different cloud mask algorithms. The variability comes from the different cloud masking algorithms are discussed.

• 설비공학논문집
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• 제18권9호
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• pp.745-752
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• 2006

DOS and NaCl aerosol particles were used to determine collection efficiencies of a 2-stage electrostatic wet scrubber with respect to particle size. The DOS and NaCl aerosols have geometric mean diameters of 0.1-3.0 urn, geometric standard deviations of $1.1{\sim}1.8$ and total number concentrations of $450{\sim}2,400\;particles/cm^3$. The tested operating variables for the electrostatic wet scrubber included air velocity and water injection rate. It was shown from the experimental results that particle collection efficiencies increased in the submicron particle size range when different polarities were applied on the water nozzle and corona wire, respectively. This increase in the collection efficiency is attributed to strong electrostatic attraction between the negative water droplets and positive submicron particles. The collection efficiencies also increased when water injection rate was increased or air velocity was decreased. Meanwhile, the pressure drop across the wet scrubber decreased by 90% compared with the existing mechanical wet scrubber. Finally, ammonia gas was used to determine gas removal efficiencies. It was observed that the gas removal efficiencies increased when the air velocity was decreased or the water injection rate was increased.

• 한국결정성장학회지
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• 제28권1호
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• pp.14-20
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• 2018

에어로졸 증착법에 의해서 상온에서 $6{\mu}m/min$의 속도로 $5{\sim}10{\mu}m$ 두께의 PZT-PZN(0 %, 20 %, 40 %) 복합체의 막을 실리콘/사파이어 기판위에서 제조하였다. 에어로졸 증착에 사용된 PZT, 2PZN-8PZT, 4PZN-6PZT 초기분말입자는 불규칙한 형상을 가지고 있으며 submicron 크기임을 확인하였다. 증착된 막은 어떠한 뜯김이나 기공도 없는 치밀한 막임을 확인하였고 나노크기의 입자를 가진 페로브스카이트 단상이었다. 실리콘기판 및 사파이어 기판위에서 증착된 막은 전기로에서 $700^{\circ}C$ 및 $900^{\circ}C$에서 각각 어닐링처리 하였으며 PZT에 40 %의 PZN이 첨가된 조성의 막의 경우 pyrochlore의 2차상이 형성되었다. 미세구조에 미치는 PZN 첨가의 영향을 관찰하기 위해 FE-SEM 및 HR-TEM이 사용되었다.

• 대기
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• 제20권3호
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• pp.221-228
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• 2010

Aerosol particles with different size-cuts ($PM_{10}$, $PM_{2.5}$, and $PM_{1.0}$) were collected at Gosan Superstation on Jeju Island from August 2007 to June 2008. Mean concentrations of $PM_{10}$, $PM_{2.5}$ and $PM_{1.0}$ were $29.28{\mu}gm^{-3}$, $17.83{\mu}gm^{-3}$, and $14.30{\mu}gm^{-3}$, respectively. Soluble ions comprised 45.7%, 53.9%, and 60.3% of the total mass of $PM_{10}$, $PM_{2.5}$, and $PM_{1.0}$, respectively. While sulfate was the most dominant species of fine mode ($PM_{1.0}$), nitrate was enriched in coarse mode ($PM_{1.0-10}$). When the concentrations of coarse mode particles were greatly increased, nitrate tended to be enhanced in coarse mode with high calcium but low sulfate concentrations. During the high $PM_{1.0}$ events, however, nitrate was increased with sulfate at fine mode. Particularly, nitrate concentrations were substantially enhanced during high particle episodes, leading high ratios of nitrate to sulfate in air under northwest wind during wintertime. On the other hand, the levels of nitrate were lower than those of sulfate at average particle concentrations. The backward air mass trajectories indicated that nitrate concentrations were elevated in air arriving Gosan passing through Santung peninsula or near South Korea.

• 대한기계학회논문집B
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• 제28권9호
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• pp.1066-1074
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• 2004

With a diode corona charger, which is a component of ELPI(Electrical Low Pressure Impactor), aerosol particles are charged to make electrical detection possible before they are collected by the impactor. We designed and evaluated two cylindrical corona chargers, each of which had a central corona needle electrode. For the performance evaluation of each corona charger the polydisperse dioctyl sebacate(DOS) particles, with diameters of 0.1∼0.8 $\mu$m and NaCl particles, smaller than 0.1$\mu$m, were used. The particles were then led through an electrostatic classifier (TSI model 3081) to classify monodisperse aerosol with minimal size deviation. After evaluating the wall loss of the particles in the corona charger, we measured the product of penetration and number of charges, Pㆍn, to evaluate the corona charger efficiency at high positive voltages of 4, 5, 6 kV.

• 대한기계학회논문집B
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• 제30권2호
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• pp.186-192
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• 2006

We applied a new charging system using the condensation and evaporation method to charge the submicron particles with a uniform charging performance. The monodispersed NaCl submicron particles were condensed by n-butanol vapor and grew up to micron droplets with a same size, regardless of their initial size. Those condensed droplets were charged in an indirect corona charger. The indirect corona charger consisted of the ion generation zone and the particle charging zone. In the ion generation zone, Ions were generated by corona discharge and some of them moved into the particle charging zone by a carrier gas and mixed with the condensed droplet. And finally, the charged and condensed droplets dried through an evaporator to shrink to their original size. The average charge and penetration rate of the particles before and after evaporation were measured by CPC and aerosol electrometer and compared with those of a conventional corona charger. The results showed that the average charge was $5\~7$ charges and the penetration rate was over $90\%$, regardless of the initial particle size.