• 제목/요약/키워드: Sedimentation of particles

검색결과 151건 처리시간 0.022초

전통 안료 제법 규명을 위한 연표법 연구 (A Study on the Yeonpyo-beob for the Explanation of the Manufacturing Method of Traditional Pigments)

  • 강영석;정혜영
    • 보존과학회지
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    • 제35권6호
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    • pp.664-669
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    • 2019
  • 연표법은 대나무통과 아교수를 이용해 안료를 제조하는 방법이다. 연표법에 따른 안료의 제조과정을 과학적으로 규명하기 위해 1%, 5%, 10%의 아교수를 적용하여 안료를 제조하고, 아교수의 농도에 따른 안료제조 특성을 분석하였다. 안료제조 과정은 크게 정치단계와 건조단계로 나눌 수 있는데, 정치단계에서 비교적 큰 입자들의 침전이 이루어지고, 건조단계에서는 작은 입자들의 침전이 이루어진다. 건조단계에서 형성되는 층위의 경우 아교수의 농도에 상관없이 거의 유사한 형태를 보이지만, 정치단계에서 형성되는 안료 층위의 경우는 아교수의 농도가 낮은 경우에는 입자들이 혼재되고 층위형성이 어려운 반면 아교수 농도가 높아질수록 안료의 입도별 층위형성이 뚜렷하게 나타났다. 이와 같은 결과를 통해 아교수의 농도에 따른 점성도의 차이가 안료 입자의 침강속도에 영향을 미치며, 이로 인해 안료 층위의 형성 및 안료 제조에도 영향을 미친다는 것을 확인하였다. 결과적으로 고농도인 10% 아교수를 적용하여 입자의 침강속도를 감소시키는 것이 안료 층위의 형성 및 안료제조에 보다 적합한 것으로 판단된다.

침강 장-흐름 분획법을 이용한 CdS 양자점 입자의 특성 분석 (Characterization of CdS-quantum dot particles using sedimentation field-flow fractionation (SdFFF))

  • 최재영;김도균;정의창;권해두;이승호
    • 분석과학
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    • 제28권1호
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    • pp.33-39
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    • 2015
  • CdS 양자점 입자는 특정 파장의 빛을 방출하는 반도체 나노 결정으로 이러한 광학적 특성 때문에 질병 진단 시약, 광학기술, 미디어 산업 및 태양전지와 같은 다양한 분야에서 응용되는 물질이다. 방출하는 빛의 색은 입자의 크기에 의존하기 때문에 CdS 양자점 입자의 크기 및 크기분포를 정확하게 분석하는 것이 필요하다. 본 연구에서는 CdS 양자점 입자를 감마-선 조사법(${\gamma}$-ray irradiation method)을 이용하여 합성하고, 크기 및 크기 분포도를 결정하기 위하여 침강 장-흐름 분획법 (SdFFF)를 이용하였다. 침강 장-흐름 분획법을 이용한 CdS 양자점 입자의 정확한 분석을 위하여 분석조건의 최적화(유속, 외부장 세기, field-programming)에 대하여 조사되었다. 투과 전자 현미경(transmission electron microscopy, TEM)으로 확인된 단일 입자의 크기는 ~4 nm 였으며, 단일 입자의 응집으로 생성된 2차 입자 크기의 평균은 159 nm로 확인되었다. 첨가된 입자 안정제의 농도가 증가할수록 CdS 양자점 입자의 크기가 감소하는 경향성을 확인하였다. 침강 장-흐름 분획법, 투과 전자 현미경, 그리고 동적 광 산란법(dynamic light scattering, DLS)으로 결정된 CdS 양자점 크기는 각각 126, 159, 그리고 152 nm 였다. 본 연구의 결과로 침강 장-흐름 분획법은 비교적 넓은 크기분포를 갖는 다양한 종류의 무기입자의 크기 및 크기 분포도를 결정하는데 유용한 방법임을 확인하였다.

응집의 이론 (I) - 수리동역학과 입자간 작용력을 고려한 응집의 모델 - (Theory of Coagulation(I) Coagulation Theory Including Hydrodynamics and Interparticle Forces)

  • 한무영
    • 상하수도학회지
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    • 제9권3호
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    • pp.65-77
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    • 1995
  • The kinetics of flocculation of heterodisperse suspension like those in water treatment plants and natural water system are usually described by the Smoluchowski equation, which incorporates collision frequency functions for particle collisions by Brownian motion, fluid shear, and differential sedimentation. These collisionfrequeney functions have been based on a rectilinear view of collisions, i.e., one that ignores short-range forces and changes in fluid motion as particles approach one another. In this research, a curvilinear approach, i.e., one that accounts for hydrodynamic forces and particle interaction in the collision of two different size particles is developed. Collision efficiency factors of each mechanism can be calculated by trajectory analysis (fluid shear and differential sedimentation) or the solution of diffusion equation (Brownian motion). The results are presented as a set of corrections to the rectilinear collision frequency functions for each mechanism.

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Separation and Characterization of Dust and Ground Water Particulates Using Gravitational SPLITT Fractionation.

  • 이승호;박희영;이상근;용성권;음철훈
    • Bulletin of the Korean Chemical Society
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    • 제22권6호
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    • pp.616-622
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    • 2001
  • Split-flow thin (SPLITT) cell Fractionation(SF) is a technique that allows separation of particulates and macromolecules into two fractions. A gravitational SF(GSF) system is constructed and tested for its applicability for separation of dust and ground water particulates. When tested with polystyrene latex particles, experimental data were in good agreements with theory. The 9.8 and 21.4㎛ polystyrene particles were successuflly separated in a continuous mode, where the mixture is continuously fed into the GSF channel allowing separation in a large sacle. The GSF system is successfully applied to continuous separation of dust and ground water particels based on the sedimentation coefficient, which is closely related to the particle size. The separations were confirmed by microscopy and energy-dispersive X-ray (EDX) analysos.

새만금간척 퇴적과정에 관한 연구( I ) -새만금간척 시행 전을 중심으로- (A study of Sedimentation Processes of Saemangeum Reclamation( I ) - A study of Sedimentation Processes before Saemangeum Reclamation -)

  • 신문섭
    • 한국농공학회지
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    • 제44권4호
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    • pp.62-74
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    • 2002
  • The purpose of this study is to find the variation of sedimentation patterns before Saemangeum reclamation. Residual flow before Saemangeum reclamation was calculated diagnostically from the observed water temperature and salinity data in May 1992 by the Marine Development Institute of Kunsan National University and wind data which were obtained from spring 1969 through winter 1977 by the Gunsan Meteorological Observatory. Three dimensional movements of injected particles due to currents, turbulence and sinking velocity are tracked by the Euler-Lagrange method. Calculated sedimentation patterns of riverine materials are highly similar to the observed ones. When suspended sediments with the size of soil grain of 60 ${\mu}m$ are injected from the Mangyeong River, their dispersion range of sediment is about 25km for 24 hours after the injection, while about 35km for 72 hours after the injection. When suspended sediments with the size of soil grain of 200 ${\mu}m$ are injected, their dispersion range of sediment is about 18km for 24 hours after the injection, while about 21km for 72 hours after the injection.

Analysis and Estimation of Reservoir Sedimentation Using Remote Sensing and GIS

  • Sungmin Cho
    • International Journal of Internet, Broadcasting and Communication
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    • 제15권4호
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    • pp.199-204
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    • 2023
  • Periodic assessment of reservoir capacity is essential for better water resources management and planning for the future water use. Reservoirs and water storage structures raised on the rivers are subjected to sedimentation and he sedimentation is caused by deposition of eroded sediment particles carried by the streams. Knowledge of reservoir sedimentation is important to estimate avaliable storage capacity for optimum reservoir operation and scheduling water release. In recent years, remote sensing and GIS techniques have emerged as an important tool in carrying out reservoir capacity analysis and water management. The reduction in storage capacity as compared to the original capacity at the time of reservoir impounding is indicative of sediment deposition. In this study, the application of GIS and remote sensing techniques were applied to assess the sediment deposition, losses in the reservoir storage and the revised cumulative capacity. Satellite images covering Pyodongdong reservoir were analyzed using Erdas Imagine and ArcGIS softwares.Cumulative capacities at different levels were also calculated and we estimated that the revised live storage was 84.2Mft3 in 2021 and 64.3Mft3 in 2022 while the original capacity was 22.8 and 53.6Mft3 in 2021 and 2022.

Dispersion stability of ultra-fine $BaTiO_3$ suspensions in aqueous medium

  • Chun, M.P.;Chung, Y.B.;Ma, Y.J.;Cho, J.H.;Kim, B.I.
    • 한국결정성장학회지
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    • 제15권6호
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    • pp.239-243
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    • 2005
  • The effect of pH and particle size on the dispersion stability of ultra-fine $BaTiO_3$ suspensions in aqueous medium have been investigated by means of zeta potential, sediment experiments, and powder properties (particle analysis, specific surface area) etc. Zeta potential as a function of pH for two particles of different size increases from -75 to +10 mV with decreasing pH from 8.5 to 1.4. The curve of zeta potential for small particle (150 nm) has slow slope than that of large particle (900nm), giving IEP (isoelectric point) value of pH=1.6 for small particle and pH=1.9 for large particle respectively, which means that it is more difficult to control zeta potential with pH fur small particle than large particle. The dispersion stability of $BaTiO_3$ particles in aqueous medium was found to be strongly related with the agglomeration of colloidal suspensions with time through the sedimentation behaviors of colloidal particles with time and pH value.

이온화세기, 제타전위, 입자크기에 따른 속도차 침전에서의 입자간 충돌특성에 관한 연구 (A Study of Collision Characteristics in differential sedimentation according to variation of Ionic Strength, Zeta Potential and Particle Size)

  • 한무영;독고석;박중현
    • 상하수도학회지
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    • 제12권1호
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    • pp.81-87
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    • 1998
  • The possibility of collision of two particles slowly settling one after another in water can be described using the collision efficiency factor in differential sedimentation (${\alpha}_{DS}$). ${\alpha}_{DS}$ was found to be a function of several parameters particle size, particle size ratio, Hamaker constant, density of liquid and particle, gravity acceleration. Previous researches were limited to the case when there is no electric repulsion assuming that the suspension is destabilized. In this paper, ${\alpha}_{DS}$ is calculated for the stabilized condition. The relative trajectory of two particles are calculated including hydrodynamics, attraction and repulsion forces. Ionic strength and surface potential significantly affect the collision possibility of two settling particles. Depending on the surface potential and ionic strength, ${\alpha}_{DS}$ value is divided into three regions; stable, unstable and transition zone. ${\alpha}_{DS}$ increases as the ionic strength increases, and as the surface charge decreases. This result can be used to model both destabilized and stabilized suspension incorporating the collision efficiency factors of the other coagulant mechanisms such as fluid shear and Browian motion.

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습식 분급으로 입도 조절된 서브 마이크론 크기의 Si 음극활물질의 전기화학적 특성 분석 (Electrochemical Properties of Sub-micron Size Si Anode Materials Distributed by Wet Sedimentation Method)

  • 서진성;김현수;나병기
    • Korean Chemical Engineering Research
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    • 제61권1호
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    • pp.39-44
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    • 2023
  • 본 연구에서는 습식 분극을 통하여 Si 다결정의 입자 크기를 조절을 하였으며, 입자 크기에 따른 Si 음극활물질의 용량 및 수명 특성 변화를 관찰하였다. 진동밀로 분쇄한 Si 입자를 습식법으로 분급한 시료의 입도를 분석한 결과 Si의 불균일한 입자 분포가 균일하게 조절이 되었다. Si를 24시간 분급한 시료의 d50이 0.50 ㎛로 감소하였다. 전기화학적 특성 분석 결과, 입자 크기의 감소로 인하여 전극 내의 저항을 나타내는 Rct 값이 현저하게 줄어들었다.분급하지 않은 Si 시료는 첫 사이클에서 2,869 mAh/g의 방전용량을 나타내었고, 100 사이클 후에는 85.7 mAh/g으로 방전용량이 감소하였다. Si를 24시간 분급한 시료의 경우에 초기에는 3,394 mAh/g의 용량을 보였으며, 100사이클 후에는 1,726 mAh/g의 용량을 유지하였다. 결과적으로 Si 입자의 크기가 감소할수록 방전용량이 증가하였으며, 사이클 수명도 증가하였다.

Characterization of Fly Ash by Field-Flow Fractionation Combined with SPLITT Fractionation and Compositional Analysis by ICP-OES

  • Kang, Dong Young;Eum, Chul Hun;Lee, Seungho
    • Bulletin of the Korean Chemical Society
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    • 제35권1호
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    • pp.69-75
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    • 2014
  • Accurate analysis of fly ash particles is not trivial because of complex nature in physical and chemical properties. SPLITT fractionation (SF) was employed to fractionate the fly ash particles into subpopulations in large quantities. Then the SF-fractions were analyzed by the steric mode of sedimentation field-flow fractionation (Sd/StFFF) for size analysis. The SF-fractions were also analyzed by ICP-OES. The results showed that the fly ash is mainly composed of Fe, Ca, Mg and Mn. No particular trends were observed between the particle size and the concentrations of Fe, Ca, Mg, while Mn, Cu and Zn were in higher concentrations in smaller particles. Sample preparation procedures were established, where the fly ash particles were sieved to remove large contaminants, and then washed with acetone to remove organics on the surface of particles. The sample preparation and analysis methods developed in this study could be applied to other environmental particles.