• Title/Summary/Keyword: Different particle size

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Effects of Particle Size Distribution of Alumina on Behaviors of Tape Casting (테이프 케스팅 거동에 미치는 알루미나의 입도분포의 영향)

  • 윤원균;김정주;조상희
    • Journal of the Korean Ceramic Society
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    • v.34 no.11
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    • pp.1173-1181
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    • 1997
  • Effects of particle size distribution of alumina ceramics on behaviors of tape casting were investigated with emphases on the rheological characteristic of slurry, green density, green sheet strength, and sintering density. For the control of particle size distribution of alumina, the commercial grade low soda alumina, which had different mean particle size of 3.58 ${\mu}{\textrm}{m}$ and 0.42 ${\mu}{\textrm}{m}$, were chosen and blended together. As results, the mixing of 80 wt% fine powder and 20 wt% coarse powder(designated to FC20) led to the increase of packing density and strength of green sheet, and made it easy to handle during processing without lowering of sintering density. Besides, the pseudoplastic behavior of slurry decreased with increase of the fraction of coarse alumina powder.

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Comparison of Heat Transfer in Both the Riser and Downcomer of a Circulating Fluidized Bed

  • Hassanein, Soubhi A.;Dahab, O.M.
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.24-32
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    • 2004
  • The characteristics of heat transfer from horizontal cylinder immersed in both a riser and downcomer of a circulating fluidized beds were investigated experimentally under different values of solids mass flux, superficial air velocity, particle size diameter, and different bed materials. The test results indicated that local heat transfer coefficients in both riser and downcomer are strongly influenced by angular position, and mass flux, as well as by particle size and bed materials. The local heat transfer coefficients around a circumference of the cylinder inside a riser and downcomer of a CFB exhibited a general tendency to increase with decreasing particle size and increasing solids mass flux and vary with different bed materials. Also the averaged heat transfer coefficient calculated from local heat transfer coefficient exhibited the same trend as a local i.e increase with decrease particle size and increasing solids mass flux and vary with varying bed materials. The general trend for a riser local heat transfer coefficient is decrease with increase angle until ${\Phi}$ = 0.5-0.6 (Where at angle =180$^{\circ}$ ${\Phi}$ =1). Also the general trend for a local heat transfer coefficient in downcomer is to increase with increase the angle until ${\Phi}$= ${\theta}/{\Pi}$ = 0.3-0.5 (Where at angle =180$^{\circ}$ ${\Phi}$ =1). Comparison the results of the heat transfer in the riser and downcomer of a circulating fluidized beds shows that they have approximately the same trend but the values of heat transfer coefficients in riser is higher than in downcomer.

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Comparison of different measuring methods for the determination of the particle size of powders for plasma spraying

  • 석한길
    • Proceedings of the KWS Conference
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    • 2001.10a
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    • pp.220-222
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    • 2001
  • The average grain size, the grain-size distribution, the morphology and the microstructure are fundamental characteristics of a spraying powder. Now that the significance of the grain size for the pattern of properties of the powder has been recognised, greater consideration is also being given to it in standards and regulations. However, unfortunately, the processes according to which the grain size and the grain-size distribution must be determined are specified in the rarest of cases. The contribution therefore dealt with the comparison of different particle-size measuring techniques, such as diffraction spectroscopy, sedimentation, sieving and microscopic measurement. The comparability of the measured results was investigated on twelve plasma spraying powders with different compositions, nominal sizes and morphologies.

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Higher levels of serum triglyceride and dietary carbohydrate intake are associated with smaller LDL particle size in healthy Korean women

  • Kim, Oh-Yoen;Chung, Hye-Kyung;Shin, Min-Jeong
    • Nutrition Research and Practice
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    • v.6 no.2
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    • pp.120-125
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    • 2012
  • The aim of this study was to investigate the influencing factors that characterize low density lipoprotein (LDL) phenotype and the levels of LDL particle size in healthy Korean women. In 57 healthy Korean women (mean age, $57.4{\pm}13.1$ yrs), anthropometric and biochemical parameters such as lipid profiles and LDL particle size were measured. Dietary intake was estimated by a developed semi-quantitative food frequency questionnaire. The study subjects were divided into two groups: LDL phenotype A (mean size: $269.7{\AA}$, n = 44) and LDL phenotype B (mean size: $248.2{\AA}$, n = 13). Basic characteristics were not significantly different between the two groups. The phenotype B group had a higher body mass index, higher serum levels of triglyceride, total-cholesterol, LDL-cholesterol, apolipoprotein (apo)B, and apoCIII but lower levels of high density lipoprotein (HDL)-cholesterol and LDL particle size than those of the phenotype A group. LDL particle size was negatively correlated with serum levels of triglyceride (r = -0.732, $P$ < 0.001), total-cholesterol, apoB, and apoCIII, as well as carbohydrate intake (%En) and positively correlated with serum levels of HDL-cholesterol and ApoA1 and fat intake (%En). A stepwise multiple linear regression analysis revealed that carbohydrate intake (%En) and serum triglyceride levels were the primary factors influencing LDL particle size ($P$ < 0.001, $R^2$ = 0.577). This result confirmed that LDL particle size was closely correlated with circulating triglycerides and demonstrated that particle size is significantly associated with dietary carbohydrate in Korean women.

Effects of particle size on processing variables and green microstructure in gelcast alumina green bodies (겔-케스팅한 알루미나 성형체에서 출발입도가 공정변수 및 성형 미세구조에 미치는 영향)

  • Ha, Chang-Gi;Kim, Jae-Won;Jo, Chang-Yong;Baek, Un-Gyu;Jeong, Yeon-Gil
    • Korean Journal of Materials Research
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    • v.11 no.10
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    • pp.869-878
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    • 2001
  • Alumina $(Al_2O_3)$ green bodies were fabricated by gel-casting using three kinds of alumina with different particle size (mean particle size: 4.6 $\mu\textrm{m}$, 0.32 $\mu\textrm{m}$, 10nm). The effects of particle size on gel-casting process and green microstructure were investigated. The optimum dispersion conditions using ammonium salt (D-3019) as dispersant were 0.2 wt% (4.63 $\mu\textrm{m}$), 0.5 wt% (0.32 $\mu\textrm{m}$), and 5.0 wt% (10 nm), in high solid loading. The optimum solid loading of each starting material for gel-casting was obtained as 59 vol% (4.63 $\mu\textrm{m}$), 57 vol% (0.32 $\mu\textrm{m}$), 15 vol% (10 nm), depending on particle size, indicating that nano-size particle (10 nm) represent lower solid loading as high specific surface area than those of other two starting materials. The drying at ambient conditions (humidity; $\thickapprox$90%) was performed more than 48hrs to enable ejection of the part from the mold and then at $120^{\circ}C$ for 2hrs in an air oven, showing no crack and flaw in the dried green bodies. The pore size and distribution of the gelcast green bodies showed the significant decrease with decreasing particle size. Green microstructure was dependent on the pore size and distribution due to the particle size, and on the deairing step. The green density maximum obtained was 58.9% (4.63 $\mu\textrm{m}$), 60% (0.32 $\mu\textrm{m}$), 47% (10 nm) theoretical density (TD), and the deairing step applied before gel-casting did not affect green density.

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Influence of the Morphology and the Particle Size on the Processing of Bronze 90/10 Powders by Metal Injection Moulding (MIM)

  • Contreras, Jose M.;Jimenez-Morales, Antonia;Torralba, Jose M.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.503-504
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    • 2006
  • The MIM technology is an alternative process for fabricating near net shape components that usually uses gas atomised powders with small size $(<\;20\;{\mu}m)$ and spherical shape. In this work, the possibility of changing partially or totally spherical powder by an irregular and/or coarse one that is cheaper than the former was investigated. In this way, different bronze 90/10 components were fabricated by mixing three different types of powder, gas and water atomised with different particle sizes, in order to evaluate how the particle shape and size affect the MIM process.

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The calculation of stress-strain behavior of Ti-10V-2Fe-3Al alloys (Ti-10V-2Fe-3Al 합금의 응력-변형거동 계산)

  • 오택열
    • Journal of the korean Society of Automotive Engineers
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    • v.11 no.6
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    • pp.38-47
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    • 1989
  • The Finite Element Method has been employed to calculate the effect of particle size, matrix, and volume fractions on the stress-strain relations of .alpha.-.betha. titanium alloys. It was found that for a given volume fraction, the calculated stress-strain curve was higher for a finer particle size than for a coarse particle size within the range of the strains considered, and this behavior was seen for all the different volume fraction alloys considered. The calculated stress-strain curves for three vol. pct .alpha. alloys were compared with their corresponding experimental curve, and in general, good agreement was found.

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Performace of a Cyclone and an impactor Using Monodisperse and Polydisperse Particles (단분산 입자와 다분산 입자를 이용한 싸이클론 및 임팩터의 성능평가)

  • Im Gyeong-Su;Lee Gyu-Won
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2001.11a
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    • pp.101-102
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    • 2001
  • Monodisperse aerosols containing spherical particles of known size, shape and density are the most widely used to calibrate particle-size measuring instruments and to determine the effects of particle size on the sampling device. However, these tests are time-consuming because monodisperse aerosols with different particle sizes are generated and tested in a series of experiments. Polydisperse aerosols may be used to determine the calibration or to simulate equipment under controlled laboratory condition. (omitted)

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A study on analysis of particle size distribution

  • Min, Shin-Hong
    • Archives of Pharmacal Research
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    • v.3 no.2
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    • pp.65-74
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    • 1980
  • Analysis of particle size distribution of a sample of fine aluminum hydroxide powder was carried out by four different methods, i. e., conductivity, air permeability, gas-adsorption and sedimentation. Each method was reproducible. The results obtained by Coulter counter and sedimentation balance were similar, and the data obtained by Lea and Nurse permeameter and Stroehlein areameter were also similar. But the results differ considerabley between the former and the latter. The advantages and disavantages of each method were discussed briefly and a means of comparing the results with those obtianed by surface area measurements was shown.

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Quality Characteristics of Korean Red Ginseng Powder with Different Milling Methods (분쇄방법에 따른 고려홍삼분말의 품질특성)

  • 서창훈;이종원;도재호;김나미;양재원;장규원
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.32 no.3
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    • pp.370-374
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    • 2003
  • Cell cracking method using a non-collision was evaluated for the possibility of new red ginseng grinding technique. Based on particle size distribution analysis by 1size shaker, the ratios of 100 mesh penetrated particles were 94.9% for hammer mill (group A) and 95.6% for cell crack (group B). The ratio of 120 mesh penetrated particle of group A was higher than that in group B. The particle size distributions for 100 mesh non-penetrated Powder between 2 groups were not significantly different, and particle size distribution analysis by laser scattering analyzer showed that the particle size ranges were 0.77~128.07 ${\mu}{\textrm}{m}$ for group A and 4.24~180.07 ${\mu}{\textrm}{m}$ for group B. The Particle size distribution in group A was more broad than that in group B. The mean particle size in group B was larger than that in group A, while the standard deviation of particle size distribution in group B was less than that in group A. Structural surface characteristics, in group A, particle size distribution was broad and the distribution curve was amorphous. The structure of individual particles was similar to unequal stone which was roughly grinded and had soft cotton-like surface. In the contrary, in group B, particle size distribution was relatively narrow and also individual size particles were ubiquitously distributed. The structure of individual particles was unequal cut stone shape.