• Title, Summary, Keyword: particle size

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Preparation and Characterization of Microcapsules Containing Perfume Oil. (향 오일을 포함하는 마이크로캡슐의 제조 및 특성분석)

  • 박연흠;백남중;김영준
    • Textile Science and Engineering
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    • v.38 no.11
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    • pp.589-595
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    • 2001
  • Melamine-formaldehyde microcapsules were prepared by conventional interfacial addition polymerization and characterized by Fourier transform(FTIR) spectroscopy, particle size analyzer, and scanning electron microscopy. The effects of polymerization variables such as the nature and concentration of surfactants, agitation speed, and agitation time on the particle size and particle size distribution were investigated. FTIR spectroscopic data shoed that perfume oil was successfully encapsulated in the microcapsule. The nature of surfactants had profound effects on the particle size and particle size distribution. It was also found that the use of poly(vinyl alcohol) was critically important to prevent agglomeration of microcapsule particles.

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Effect of Particle Size of Disperse Dyes on Their Dyeing Properties (분산염료의 입자크기가 염색성에 미치는 영향)

  • 이원재;김재필
    • Textile Science and Engineering
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    • v.35 no.2
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    • pp.100-104
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    • 1998
  • The effect of particle size distribution of disperse dyes on polyester dyeing was investigated using press cakes of C. I. Disperse Orange 30 and C. I. Disperse Blue 60. The particle size of the dyes which were grinded by milling machine was separated into 0.1~1${\mu}{\textrm}{m}$, 1~10${\mu}{\textrm}{m}$ and 5~20 ${\mu}{\textrm}{m}$ of particle size ranges using a centrifuge. Dyeing poperties such as dyeing rate, exhaustion, solubility and compatibility were estimated according to the particle size distribution of the dyes. Dyes having larger particle size showed lower dyeing rate and exhaustion value in polyester dyeing. Solubility and compatibility were also affected by the particle size distribution of dyes.

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The Influence of Magnetic Particle Size and Its Properties on The Electromagnetic Particle in Magnetic Tape (자기 Tape의 전자 변환 특성에 대한 자성분의 Size와 그 특성의 영향)

  • 김상문;김태옥
    • Journal of the Korean Magnetics Society
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    • v.6 no.5
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    • pp.334-339
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    • 1996
  • In order to investigate the influence of the magnetic paticle size and its properties on the particulate magnetic material, we evaluated the dispersion of magnetic particles and the electromagnetic properties in magnetic tape made from the magnetic paints by use of each magnetic particles witch were different from particle size and its propertis. The dispersion of magnetic particles depends on the surface chemical properties rather than particle size. As particle size is smaller, the packing ratio of magnetic particle and the magnetic flux density in tape increase. The output levels in playing back of tape incerase in wide frequency range from 315 Hz to 10 kHz and the noises decrease. It is very important to choose the size, the shape, the surface chemical properties and the magnetic properties of the magnetic particle in producing the high quality magnetic tape.

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Generation and Size Control of Particle Beams at Low Pressures Using Aerodynamic Lenses (저압상태에서 공기역학적 렌즈를 이용한 입자 빔의 생성 및 크기 제어)

  • Bae, Gwi-Nam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.10
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    • pp.1320-1326
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    • 1999
  • Since it is not possible to generate spatially uniform particle distribution at low pressures in which in-situ particle monitors(ISPMs) are normally operated, it is of interest to investigate the response of an ISPM to particle beams at low pressures. The purpose of this study is to develop technique that can control the size of particle beams. In this study, particle beams were generated at low pressures by using identical aerodynamic lenses, and their shape and size were visualized by collecting uniform sized methylene blue aerosol particles on a filter media. It was found that the size of particle beams depends on the number of lens, the distance between lenses, and the downstream distance from the final lens. The size of particle beams decreases with increasing distance between lenses, and increases with increasing downstream distance from the final lens. The experimental results obtained in this work will be used to investigate performance of an ISPM at low pressures.

Development of volume reduction method of cesium contaminated soil with magnetic separation

  • Yukumatsu, Kazuki;Nomura, Naoki;Mishima, Fumihito;Akiyama, Yoko;Nishijima, Shigehiro
    • Progress in Superconductivity and Cryogenics
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    • v.18 no.1
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    • pp.10-13
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    • 2016
  • In this study, we developed a new volume reduction technique for cesium contaminated soil by magnetic separation. Cs in soil is mainly adsorbed on clay which is the smallest particle constituent in the soil, especially on paramagnetic 2:1 type clay minerals which strongly adsorb and fix Cs. Thus selective separation of 2:1 type clay with a superconducting magnet could enable to reduce the volume of Cs contaminated soil. The 2:1 type clay particles exist in various particle sizes in the soil, which leads that magnetic force and Cs adsorption quantity depend on their particle size. Accordingly, we examined magnetic separation conditions for efficient separation of 2:1 type clay considering their particle size distribution. First, the separation rate of 2:1 type clay for each particle size was calculated by particle trajectory simulation, because magnetic separation rate largely depends on the objective size. According to the calculation, 73 and 89 % of 2:1 type clay could be separated at 2 and 7 T, respectively. Moreover we calculated dose reduction rate on the basis of the result of particle trajectory simulation. It was indicated that 17 and 51 % of dose reduction would be possible at 2 and 7 T, respectively. The difference of dose reduction rate at 2 T and 7 T was found to be separated a fine particle. It was shown that magnetic separation considering particle size distribution would contribute to the volume reduction of contaminated soil.

Effect of Reaction Factors on the Fabrication of Nano-Sized Indium Oxide Powder by Spray Pyrolysis Process (분무열분해공정에 의한 인듐 산화물 나노 분말 제조에 미치는 반응인자들의 영향)

  • Yu Jae-Keun
    • Journal of Korean Powder Metallurgy Institute
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    • v.11 no.6
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    • pp.493-502
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    • 2004
  • In this study, nano-sized indium oxide powder with the average particle size below 100 nm is fab-ricated from the indium chloride solution by the spray pyrolysis process. The effects of the reaction temperature, the concentration of raw material solution and the inlet speed of solution on the properties of powder were studied. As the reaction temperature increased from 850 to $1000^{\circ}C$, the average particle size of produced powder increased from 30 to 100 nm, and microstructure became more solid, the particle size distribution was more irregular, the intensity of a XRD peak increased and specific surface area decreased. As the indium concentration of the raw material solution increased from 40 to 350 g/l, the average particle size of the powder gradually increased from 20 to 60 nm, yet the particle size distribution appeared more irregular, the intensity of a XRD peak increased and spe-cific surface area decreased. As the inlet speed of solution increased from 2 to 5 cc/min., the average particle size of the powder decreased and the particle size distribution became more homogeneous. In case of the inlet speed of 10 cc/min, the average particle size was larger and the particle size distribution was much irregular compared with the inlet speed of 5 cc/min. As the inlet speed of solution was 50 cc/min, the average particle size was smaller and microstructure of the powder was less solid compared with the inlet speed of 10 cc/min. The intensity of a XRD peak and the variation of specific area of the powder had the same tendency with the variation of the average par-ticle size.

A Study on the Characteristics of Water Quality According to Particle Size Distribution of Sediments (하상퇴적물의 입도분포에 따른 수질특성에 관한 연구)

  • Park, Sung-Jin;Kim, Hwan-Gi
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.1
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    • pp.97-105
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    • 2009
  • Analysis was done on the particle size distribution of sediments flown into Saemangeum from the Mankyung and Dongjin River. The organic pollutants and heavy metal existing in the sediments were analyzed, which was further used to study the properties of pollution in the sediments according to the particle size distribution. Conclusions shown below were made from these analyses. The particle size distribution showed a big difference between the upriver areas of Mankyung and Dongjin River. Particles under $75{\mu}m$ showed to be around 85% at Dongjin River, while it showed to be around 70% at Mankyung River. This kind of distribution in particle size concluded in greatly affecting the contamination density of the sediments. From the analysis done on the soil type of sediments, deposition in Mankyung River categorized into Silty loam and Sandy loam, where Silty loam covered most of area and deposition in Dongjin River categorized into Sand, Loamy sand, Silty loam, Sandy loam. Considering the weight ratio, the density of contamination of the sediments by particle size at Dongjin and Mankyung River has been analyzed to show that organic pollutants and heavy metals occupy more than 70% of the whole contamination in the range under the particle size of $75{\mu}m$.

Model for simulating the effects of particle size distribution on the hydration process of cement

  • Chen, Changjiu;An, Xuehui
    • Computers and Concrete
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    • v.9 no.3
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    • pp.179-193
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    • 2012
  • The hydration of cement contributes to the performance characteristics of concrete, such as strength and durability. In order to improve the utilization efficiency of cement and its early properties, the particle size distribution (PSD) of cement varies considerably, and the effects of the particle size distribution of cement on the hydration process should be considered. In order to evaluate effects of PSD separately, experiments testing the isothermal heat generated during the hydration of cements with different particle size distributions but the same chemical composition have been carried out. The measurable hydration depth for cement hydration was proposed and deduced based on the experimental results, and a PSD hydration model was developed in this paper for simulating the effects of particle size distribution on the hydration process of cement. First, a reference hydration rate was derived from the isothermal heat generated by the hydration of ordinary Portland cement. Then, the model was extended to take into account the effect of water-to-cement ratio, hereinafter which was referred to as PSD hydration model. Finally, the PSD hydration model was applied to simulate experiments measuring the isothermal heat generated by the hydration of cement with different particle size distributions at different water-to-cement ratios. This showed that the PSD hydration model had simulated the effects of particle size distribution and water-to-cement ratio on the hydration process of cement with satisfactory accuracy.

Effect of NCO Index on the Particle Size of Polycarbonate Diol-based Polyurethane Dispersion

  • Kim, Dong-Eun;Kang, Seung-Oh;Lee, Sang-Ho
    • Elastomers and Composites
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    • v.55 no.1
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    • pp.20-25
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    • 2020
  • The effect of the isocyanate index (NCO index) on the particle size and particle size distribution of a waterborne polyurethane dispersion (WPUD) with polycarbonate-diol was determined. The WPUDs were prepared using a conventional acetone process with polycarbonate-polyol (Mn = 2028), 4,4'-methylenebis(cyclohexyl isocyanate) (H12MDI), 2,2-bis(hydroxymethyl) propionic acid (DMPA), and dibutyltin dilaurate catalyst. At NCO index values below 1.5, the number average particle diameter of the WPUDs significantly increased with the NCO index, whereas the particle diameter slightly varied at higher NCO indexes. The dependency of the WPUD viscosity on the NCO index exhibited similar behavior to that of the particle size. The relative values of the full width at half maximum of the WPUD particle distribution curves at various NCO indexes were not influenced by the NCO index.

Effects of Particle Size of Dry Water on Fire Extinguishing Performance (드라이워터의 입자크기가 소화성능에 미치는 영향)

  • Lee, Eungwoo;Choi, Youngbo
    • Journal of the Korean Society of Safety
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    • v.34 no.3
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    • pp.28-35
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    • 2019
  • Dry water is a core-shell structured powder which comprises a very fine water core covered with hydrophobic silica particles. Recently, the dry water has attracted attention as a new type of fire extinguishing agents. However, characteristics of the dry water as a fire extinguishing agent have not been revealed until now. To our best knowledge, this is the first work to uncover effects of particle size of the dry water on the fire extinguishing performance. Pristine dry water, which has heterogeneous particle size distribution, was carefully separated by sieving method into three fractions which were a small size (ca. $110{\mu}m$) fraction, a medium size (ca. $220{\mu}m$) fraction and a large size (ca. $400{\mu}m$) fraction. Microscopic observations confirmed the effective separation of dry water's particle size. In extinguishing tests of wood cribs fire, the medium size dry water showed most excellent fire extinguishing performance, as compared to other dry waters having small (ca. $110{\mu}m$) and large (ca. $400{\mu}m$) particle size. The good performance of the medium size (ca. $220{\mu}m$) dry water may be attributed to the balance between cooling effect of the water core and smothering effect of the silica particles. It is also revealed that small size dry water has poor flowability than large size dry water.