• Title, Summary, Keyword: particle size

Search Result 6,692, Processing Time 0.133 seconds

A Continuous Particle-size Sorter Using Negative a Dielectrophoretic Virtual Pillar Array (음의 유전영동에 의한 가상 기둥 어레이를 이용한 연속적 입자 크기 분류기)

  • Chang, Sung-Hwan;Cho, Young-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.32 no.11
    • /
    • pp.824-831
    • /
    • 2008
  • We present a continuous size-dependent particle separator using a negative dielectrophoretic (DEP) virtual pillar array. Two major problems in the previous size-dependent particle separators include the particle clogging in the mechanical sieving structures and the fixed range of separable particle sizes. The present particle separator uses the virtual pillar array generated by negative DEP force instead of the mechanical pillar array, thus eliminating the clogging problems. It is also possible to adjust the size of separable particles since the size of virtual pillars is a function of a particle diameter and applied voltage. At an applied voltage of 500 kHz $10\;V_{rms}$ (root mean sqaure voltage) sinusidal wave and a flow rate of $0.40\;{\mu}l\;min^{-1}$, we separate $5.7\;{\mu}m$-, $8.0\;{\mu}m$-, $10.5\;{\mu}m$-, and $11.9\;{\mu}m$-diameter polystyrene (PS) beads with separation purity of 95%, 92%, 50%, and 63%, respectively. The $10.5\;{\mu}m$- and $11.9\;{\mu}m$-diameter PS beads have relatively low separation purity of 50% and 63%. However, at an applied voltage of $8\;V_{rms}$, we separate $11.9\;{\mu}m$-diameter PS beads with separation purity over 99%. Therefore, the present particle separator achieves clog-free size-dependent particle separation, which is capable of size tuning of separable particles.

Effect of Dispersion Stability of Particles on Detergency of Particulate Soil(Part 1) - The Dispersion Stability of α-Fe2O3 Particles in the Nonyl Phenol Polyoxyethylene Ether Solution - (입자의 분산안정성이 고형오구의 세척성에 미치는 영향(제1보) - Nonyl Phenol Polyoxyethylene Ether 용액 내에서 α-Fe2O3 입자의 분산안정성 -)

  • Kang, In-Sook
    • Fashion & Textile Research Journal
    • /
    • v.4 no.1
    • /
    • pp.86-91
    • /
    • 2002
  • To estimate dispersion stability of particles, suspending power and particle size were examined as functions of pHs, surfactants, electrolytes and ionic strengths using ${\alpha}-Fe_2O_3$ particle as the model of particulate soil. Suspending power and particle size were determined by UV-Vis spectrumeter and by light scattering using the polarization ratio method, respectively. The suspending power was relatively high with polyanion electrolytes and was low with neutral salts. The suspending power was biphasis, minimum pH 6~7, and the effect of surfactant on the suspending power was insignificant. Generally suspending power increased with decreasing the particle size governed aggregation of dispersed particles regardless of solution conditions. Hence the suspending power was inversely related to the particle size.

Experimental Studies on Plasmon Resonance of Ag Nanoparticles on Highly Ordered Pyrolytic Graphite (HOPG)

  • Lopez Salido, Ignacio;Bertram, Nils;Lim, Dong-Chan;Gantefor, Gerd;Kim, Young-Dok
    • Bulletin of the Korean Chemical Society
    • /
    • v.27 no.4
    • /
    • pp.556-562
    • /
    • 2006
  • Studies on Ag nanoparticles grown on Highly Ordered Pyrolytic Graphite (HOPG) using HREELS provide different results for smaller and larger particle sizes corresponding to Ag coverages below and above 4 monolayers, respectively. For the larger particles, a positive frequency shift with decreasing particle size and a broadening of the plasmon resonance were observed with decreasing particle size, in line with previous studies on Ag on alumina. For the smaller particles, in contrast, a shift to lower energy with decreasing particle size, and a narrowing of the plasmon resonance with decreasing particle size can be found. The asymmetry of the Ag-features present for Ag coverages above 4 monolayers disappears for Ag coverages below 4 monolayers. The result for the smaller particles can be rationalized in terms of change of the particle growth mode with increasing particle size, which corroborates our STM data, as well as electronic effects due to the metal/support charge transfer.

Characterization of Surface Properties of $BaTiO_3$ Powder by XPS

  • Chun, Myoung-Pyo;Cho, Jung-Ho;Kim, Byung-Ik
    • Proceedings of the Korean Powder Metallurgy Institute Conference
    • /
    • /
    • pp.678-679
    • /
    • 2006
  • The effects of particle size on the surface properties of hydro-thermally synthesized barium titanate powders were investigated by means of particle size analysis, specific surface area, SEM, zeta potential and XPS. Particle sizes were measured by laser light scattering and are in the range of 150 to 1100nm. Zeta potential increased with increasing particle size and it was large minus value in the range of particle size from 500 to 900nm, which seems to be related with the dissolution of $Ba^{2+}$ ion in these particle sizes from the analysis of surface properties by XPS.

  • PDF

Experimental Study on the Effect of Particle Size Distribution of Soil to the Liquefaction Resistance Strength (입도분포가 액상화 저항강도에 미치는 영향에 관한 실험적 연구)

  • Choi, Mun-Gyu;Seo, Kyung-Bum;Park, Seong-Yong;Kim, Soo-Il
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • /
    • pp.1126-1133
    • /
    • 2005
  • The effects of mean particle size and uniformity coefficient of dredged soils to the liquefaction resistance strength and dynamic characteristics are experimentally studied in this paper. Representative 4 mean particle sizes and 3 uniformity coefficients were selected and 12 representative particle size distribution curves which have different mean particle sizes and uniformity coefficients, were artificially manufactured using the real dredged river soil. Cyclic triaxial tests and torsional shear tests were carried out to analyze the effect of mean particle size and uniformity coefficient to the liquefaction resistance strength and dynamic characteristics of soils.

  • PDF

Size Distribution Characteristics of Particulate Matter Emitted from Cooking (조리과정에서 생성된 미세먼지의 크기분포 특성)

  • Joo, Sang-Woo;Ji, Jun-Ho
    • Particle and aerosol research
    • /
    • v.16 no.1
    • /
    • pp.9-17
    • /
    • 2020
  • The characteristics of particulate matter made from daily cooking at a Korean residential apartment house with three dwellers had been investigated for about 3 months. All data were recorded by an optical particle counter every minute at the kitchen. Types of cooking such as boiling, frying, and grilling that performed in the house were listed. Boiling only was used in 32% cases among total 234 meals. Frying and grilling were 14% and 11%, respectively. From an initial indoor particulate matter smaller than 10 ㎛ in diameter, the increases due to cooking are reported by size. In case of boiling, PM at 1-10 ㎛ size and under 1 ㎛ size little increased. Normally, particles from oil or combustion in a process of frying or grilling increased indoor PM. In a case of grilling, particle mass concentration in a region of 1-10 ㎛ in diameter increased as much as 295 ㎍/㎥. Mass concentration of particles smaller than 1 ㎛ increased as much as 33 ㎍/㎥.

Deposition of Polydisperse Particles in a Falkner-Skan Wedge Flow (포크너-스캔 경계층유동에서의 다분산 입자부착에 대한 연구)

  • 조장호;황정호;최만수
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.19 no.9
    • /
    • pp.2342-2352
    • /
    • 1995
  • Deposition of flame-synthesized silica particles onto a target is utilized in optical fiber preform fabrication processes. The particles are convected and deposited onto the target. Falkner-Skan wedge flow was chosen as the particle laden flow. Typically the particles are polydisperse in size and follow a lognormal size distribution. Brownian diffusion, thermophoresis, and coagulation of the particles were considered and effects of these phenomena on particle deposition were studied. A moment model was developed in order to predict the particle number density and the particle size distribution simultaneously. Particle deposition with various wedge configurations was examined for conditions selected for a typical VAD process. When coagulation was considered, mean particle size and its standard deviation increased and particle number density decreased, compared to the case without coagulation. These results proved the fact that coagulation effect expands particle size distribution. The results were discussed with characteristics of thermal and diffusion boundary layers. As the boundary layers grow in thickness, overall temperature and concentration gradients decrease, resulting in decrease of deposition rate and increase of particle residence time in the flow and thus coagulation effect.

Studies on The Paper Making Technique and TsaiLun (제지술과 채륜에 관한 연구)

  • JongchanLee
    • Journal of the Korean Printing Society
    • /
    • v.14 no.2
    • /
    • pp.81-99
    • /
    • 1996
  • The characteristics of printing inks are affected, to a greater or lesser extent, by the size and distribution of the pigment particles in the dispersion. Color strength, transparency and gloss increase with a decrease in particle size of pigments and with an increase in surface area of pigments. On the contrary, opacity and lightfastness tend to increases with an increase in particle size of pigments and with a decrease in surface are and particle size if pigments on the physical properties of printing ink which made up vehicles for sheet fed and organic pigment Lake Red C(C.I Pigment Red 53:1) that different surface area and particle size.

  • PDF

Influence of Atomizing Condition on Particle Size Distributions for High Pressure Water Atomized Powder

  • Nakabayashi, Koei;Tanaka, Yoshinari;Hirai, Masazumi
    • Proceedings of the Korean Powder Metallurgy Institute Conference
    • /
    • /
    • pp.18-19
    • /
    • 2006
  • To improve the properties of fine metal powder, such as particle size distribution and geometric standard deviation, this work was done at various atomizing conditions. The new atomization mechanism and the correlation equation were proposed to estimate the mean particle diameter.

  • PDF

Influence of Particle Size of Quartz on the Strength of Porcelain Body (자기질 요지의 강도에 미치는 석영입도의 영향)

  • 이은상;김진영
    • Journal of the Korean Ceramic Society
    • /
    • v.21 no.3
    • /
    • pp.209-216
    • /
    • 1984
  • The influence of the particle size of quartz and the change of cooling rate to the strength of conventional triaxial porcelain was studied, . The results indicate that 1. The residual quartz content was increased by particle size increasing. And the strength was increased by increas-ing residual quartz content which increased the total stress in the specimen. But the influence of residual quartz was lessened by the extent of crack between quartz particle and glass matrix 2. In order to increase the strength of the body fast cooling is suitable to small quartz particle and slow cooling is suitable to large quartz particle.

  • PDF