• 한국세라믹학회지
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• 제42권6호
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• pp.432-436
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• 2005

Nickel powders synthesized by the reduction of hydrazine of nickel salts fiom diethanolamine(DEA) solution, and investigated the morphological characteristics of nickel powders with the addition of hydrazine, reaction temperature, the composition of mixed solvents. The addition of hydrazine in DEA solution largely affected on size control of nickel powders. Under $N_2H_4/Ni^{2+}$ molar ratio= 1.5 and 2.0 conditions, spherical nickel powders in the submicron range obtained, owing to higher the reduction rate. An increase of temperature increased the size of nickel particles. At $220^{\circ}C$ for 40 min, the nickel powders composed of polyhedral particles with high crystalline in the submicron range. The mixed volume ratio of TEA to DEA affected on the increase of particle size and the inhibition of agglomerate between particles.

• 한국세라믹학회지
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• 제30권4호
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• pp.325-331
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• 1993

Aqueous solutions of metallic salts, ZrO(NO3)2.2H2O and Y(NO3)3.5H2O were used as raw materials to synthesize crystalline submicron spherical powders of Zr0.94Y0.06O1.97 with tetragonal crystal phase. Each aqueous solution was mixed on the magnetic stirrer to homogenize for 12 hours. The concentration of the mixed solutionwas changed from 0.01mol/$\ell$ to 0.1mol/$\ell$ calculated as the concentration of Zr0.94Y0.06O1.97. Ultrafine droplets of starting mixed solution were sprayed by the ultrasonic vibrator and carried into the furnace kept at 55$0^{\circ}C$, $650^{\circ}C$, 75$0^{\circ}C$ and 85$0^{\circ}C$ using carrier gas of air (10$\ell$/min) and pyrolysed to form Y-TZP fine powders. The results of this exeriment were as follows. 1) Synthesized powders were nonagglomerated and spherical type. 2) Particle size distribution was narrow between 0.1${\mu}{\textrm}{m}$ and 1${\mu}{\textrm}{m}$. 3) Forming reaction Y-TZP was finished above synthetic temperature 75$0^{\circ}C$. 4) As the synthetic temperature rised from 55$0^{\circ}C$ to 85$0^{\circ}C$, the mean particle size decreased from 0.35${\mu}{\textrm}{m}$ to 0.22${\mu}{\textrm}{m}$ in the concentration of starting solution with 0.02mol/$\ell$. 5) At 75$0^{\circ}C$ of synthetic temperature, the concentration changes of starting solution from 0.01mol/$\ell$ to 0.1mol/$\ell$ increased the mean particle size from 0.24${\mu}{\textrm}{m}$ to 0.38${\mu}{\textrm}{m}$. 6) Chemical compositions of each synthesized particle were homogeneous nearly.

• 한국세라믹학회지
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• 제23권2호
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• pp.21-30
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• 1986

Pure submicron $SrTiO_3$ powders had been synthesized with chemical wet process that $5N-NH_4OH$ solution was sprayed into the mixed solution of $SrTiO_3$, $TiCl_4$ and $H_2O_2$ with $N_2$ carrier gas. The characteristic properties of powders obtained from this experiment were as follows. The optimum synthesis condition in reaction bath was above PH 8.5 and under $25^{\circ}C$ The particle size of precipitated SrTiO(OH) powders dried at 6$0^{\circ}C$ was under 0.01${\mu}{\textrm}{m}$ and uniform. Amorphous precipitated complex powders emitted adsorbed water at 15$0^{\circ}C$ less that and crystalline $SrTiO_3$powders was produced from calcining the complex at 30$0^{\circ}C$. Sintered body of SrTiO3 fired at 133$0^{\circ}C$ showed that relative dielectric constant was 228 at 1MHZ and bulk density was 4.73g/$cm^3$.

• 동굴
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• 제76호
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• pp.49-55
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• 2006

The submicron $YBa_2Cu_3O_x$ powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to 1.0 ${\mu}m$, which benefits to eliminate the micro-cracks formed in the $YBa_2Cu_3O_x$ films deposited by electrophoresis. The powder was single phase of $YBa_2Cu_3O_x$ examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of $Y_2O_3$, $Ba(NO_3)_2$ and CuO. When pH values were adjusted to 6.4-6.7, $Ba(NO_3)_2$ could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. Acetone is used as electrophoreticsolution, in which some water and iodine (0.2 g/1) and polyethylene glycol (2 vol. %) are added. The concentrations of $YBa_2Cu_3O_x$ powders is 20g/l. The thickness of deposited film could be more than 50 ${\mu}m$ in 3 minutes of depositing time. The most EPD films could be 90K zero resistance and the Jc values were over 1000A/cm2 (0 H, 77 K).

• 한국진공학회지
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• 제10권3호
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• pp.361-367
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• 2001

CMP(Chemical Mechanical Polishing)는 반도체 소자 제조공정 중 다층 배선구조의 평탄 경면화에 널리 이용되고 있다. 차세대 웨이퍼로 각광받는 SOI(Silicon On Insulator) 웨이퍼 제조공정 중 웨이퍼 표면 미소 거칠기를 개선하기 위해서 본 논문에서는 여러 가지 가공변수(슬러리와 연마패드)에 따른 CMP 연마능률과 표면 미소 거칠기 변화에 대해 연구하였다. 결과적으로 연마능률은 슬러리의 입자 크기가 증가할수록 이에 따라 증가하였으며, 미소 거칠기는 슬러리의 연마입자보다는 연마패드에 영향이 더욱 지배적이다. AFM(Atomic Force Microscope)에 의한 평가에서 표면 미소 거칠기가 27 $\AA$ Rms에서 0.64 $\AA$ Rms로 개선됨을 확인할 수 있었다.

• 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.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.267-268
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• 2002

Microbeam is a new avenue of radiation research especially in radiation biology and radiation protection. Selective irradiation of an ionizing particle to a targeted cell organelle may disclose such mechanisms as signal transaction among cell organelles and cell-to-cell communication in the processes toward an endpoint observed. Bystander effect, existence of which is clearly evidenced by application of the particle microbeam to biological experiments, suggests potential underestimation in the conventional risk estimation at low particle fluence rates, such as environment of space radiations in ISS (International Space Station). To promote these studies we started the construction of our microbeam facility (named as SPICE) to our HVEE Tandem accelerator (3.4 MeV proton and 5.1 MeV $^4$He$\^$2+/). For our primary goal, "irradiation of single particle to cell organelle within a position resolution of 2 micrometer in a reasonable irradiation time", special features are considered. Usage of a triplet Q magnet for focussing the beam to submicron of size is an outstanding feature compared to facilities of other institutes. Followings are other features: precise position control of cell dish holder, design of the cell dish, data acquisition of microscopic image of a cell organelle (cell nucleus) and data processing, a reliable particle detection, soft and hard wares to integrate all these related data, to control and irradiate exactly determined number of particles to a targeted spot.

• 한국입자에어로졸학회지
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• 제4권2호
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• pp.37-50
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• 2008

Concerns on centrifugal classifiers, of which have cut sizes are below few micrometers, have been increased and it is prospected to be used in extensive industries, such as manufacturing the fine minerals, cosmetics, advanced electric materials, and life science. This paper reviews the recent progress of research and development on the centrifugal classifiers. General categorization of classifiers for feeds was assessed and separation mechanism of the classifiers was followed. History of centrifugal classifiers was explored and some points to be improved were briefly indicated. Fundamental theory of the classification by centrifugal classifiers was pearly studied, and advanced and further understandings on factors affecting the separation or grading efficiency are described. Factors determining the classification precision and efficiency of centrifugal classifiers, such as geometry, rotational speed and inclined angle of rotating vanes, feed and air flow rates, and rotor dimensions are reviewed.

• 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.

• 한국세라믹학회지
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• 제32권5호
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• pp.575-581
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• 1995

Zr0.94Y0.06O1.97 powder was synthesized by the ultrasonic spray pyrolysis with various concentrations of starting solution and the influence of powder characteristics on sintering behavior was investigated. Powders prepared at 75$0^{\circ}C$ were characterized as narrowly distributed submicron spherical particles, which were crystalline, nonagglomerated, and compositionally homogeneous. The changes in concentration from 0.01 to 01. mol/ι increased mean particle size from 0.24 to 0.38${\mu}{\textrm}{m}$ and decreased the specific surface area from 14.2 to 2.9$m^2$/g. The relative density of the specimen from the powders, prepared with the solution concentration of 0.01 mol/ι, was 98% after sintering for 2 hr at 1,45$0^{\circ}C$ and the monoclinic phase was observed after sintering at 1,55$0^{\circ}C$. As the concentration of starting solution was increased, the formation temperature of monoclinic phase was lowered.