• Title/Summary/Keyword: 단일 입자

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Ultrathin Window EPMA를 이용한 제주도 고산과 한라산 1100 고지에서의 입자상 물질 특성 분석

  • ;;;;R. Van Grieken
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • pp.325-327
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    • 2000
  • 본 연구에서는 한반도의 청정지역인 제주도 고산과 한라산 1100 고지에서의 입자상 물질을 분석하였다. 입자상 물질을 분석하는 방법 중에 EPMA(Electron Probe X-ray Microanalysis)를 이용한 단일 입자 분석법(Single Particle Analysis)은 개개 입자의 형상과 크기 그리고 화학 조성에 대한 정보를 동시에 제공하기 때문에 개개 입자의 생성, 이동, 반응성, 소멸 그리고 환경에의 영향에 대한 자세한 정보를 얻을 수 있다. (중략)

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Ultrathin Window EPMA를 이용한 서울에서의 입자상 물질 분석

  • ;;;R. Van Grieken
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • pp.335-336
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    • 2000
  • 도시 대기는 복잡한 성분을 가진 입자상 물질로 이루어져 있는데, 검댕 입자나 비산재(fly ash)등과 같이 일차오염물질과 복잡한 대기 화학반응에 의해 생성되는 이차오염물질이 혼재하고 있기 때문이다. 도시 대기 중의 입자상 물질은 대부분 황산염, 질산염, 암모늄염 입자상 물질과 유기 입자들로 구성되어 있는데, 탄소 입자는 도시의 미세 입자 중 거의 반 정도를 차지한다. (Ro et. el., 2000) 본 연구에서는 서울 대기에서의 입자상 물질에 대한 분석을 EPMA(Electron Probe X-ray Microanalysis)를 이용한 단일 입자 분석법(Single Particle Analysis)을 가지고 행하였다. (중략)

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Electrochemical Behaviors of the Surface-Treated Nickel Hydroxide Powder and Electrolyte Additive LiGH for Ni-MH Batteries (니켈수소전지용 수산화니켈 입자의 표면처리와 전해액 첨가제 LiOH의 전기화학적 거동)

  • Kim, Ho-Sung;Oh, Ik-Hyun
    • Journal of the Korean Electrochemical Society
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    • v.11 no.2
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    • pp.115-119
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    • 2008
  • Single particle of nickel hydroxide and the surface-treated one with cobalt element were performed to review the effect of LiOH additive in alkaline electrolyte for Ni-MH batteries using microelectrode test system. As a result of cyclic voltammetry, the electrochemical behaviors such as the oxidation/reduction and oxygen evolution reaction are clearly observed for a single particle of nickel hydroxide, respectively. Furthermore, the reduction current peak of nickel hydroxide added with LiOH in electrolyte was very low and broad compared with the normal nickel hydroxide without an additive LiOH, which had a bad effect to the crystallization structure of nickel hydroxide. However, it was found that capacity and cycle properties of the nickel hydroxide treated with cobalt greatly increased by the addition of LiOH.

Direct-current Dielectrophoretic Motions of a Single Particle due to Interactions with a Nearby Nonconducting Wall (비전도성 벽과의 상호작용에 따른 단일 입자의 직류 유전영동 운동)

  • Kang, Sangmo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.5
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    • pp.425-433
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    • 2015
  • In this paper, we have numerically investigated two-dimensional dielectrophoretic (DEP) motions of a single particle suspended freely in a viscous fluid, interacting with a nearby nonconducting planar wall, under an externally applied uniform direct-current electric field. Particularly, we solve the Maxwell equation with a large sharp jump in the electric conductivity at the particle-fluid interface and then integrate the Maxwell stress tensor to compute the DEP force on the particle. Results show that, under an electric field parallel to the wall, one particle is always repelled to move far away from the wall and the motion depends strongly on the particle-wall spacing and the particle conductivity. The motion strength vanishes when the particle is as conductive as the fluid and increases as the conductivity deviates further from that of the fluid.

Kinetic Parameter Analysis of Hydrogen Diffusion Reaction for Hydrogen Storage Alloy of Fuel Cell System (연료전지의 수소저장용 합금에 대한 수소확산반응의 속도론적 해석)

  • Kim, Ho-Sung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.2
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    • pp.45-49
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    • 2006
  • Electrochemical hydrogenation/dehydrogenation properties were studied for a single particle of a Mm-based(Mm : minh metal) hydrogen storage alloy($MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3}$) for fuel cell and Ni-MH batteries. A carbon fiber microelectrode was manipulated to make electrical contact with an alloy particle, and the potential-step experiment was carried out to determine the apparent chemical diffusion coefficient of hydrogen atom($D_{app}$) in the alloy. Since the alloy particle we used here was a dense, conductive sphere, the spherical diffusion model was employed for data analysis. $D_{app}$ was found to vary the order between $10^{-9}\;and\;10^{-10}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process. Compared with the conventional composite film electrodes, the single particle measurements using the microelectrode gave more detailed, true information about the hydrogen storage alloy.

Effect of Particle Size Distribution on the Sensitivity of Combustion Instability for Solid Rocket Motors (입자 크기 분포도를 고려한 고체로켓 모터의 연소 불안정 민감도 예측)

  • Joo, Seongmin;Kim, Junseong;Moon, Heejang;Ohm, Wonsuk;Lee, Dohyung
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.5
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    • pp.37-45
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    • 2015
  • Prediction of combustion instability within a solid-propellant rocket motor has been conducted with the classical acoustic analysis. The effect of particle size distribution on the instability has been analyzed by comparing the log-normal distribution to the fixed mono-sized particle followed by a survey of motor length scale effect between the baseline model and small scale model. Particle damping effect was more efficient for the small scale motor which has a relatively high unstable mode frequencies. It was also revealed that the prediction results by considering the particle size distribution show an overall attenuation of fluctuating pressure amplitude with respect to the mono-sized case.

Combustion Modeling of Nano/Micro Aluminum Particle Mixture (나노-마이크로 알루미늄 혼합 입자의 공기와의 연소 모델링)

  • Yoon, Shi-Kyung;Shin, Jun-Su;Sung, Hong-Gye
    • Journal of the Korean Society of Propulsion Engineers
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    • v.15 no.6
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    • pp.15-25
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    • 2011
  • One dimensional combustion modeling of aluminum combustion behavior is proposed. Combustion model is assumed that region consists as follows ; preheat, reaction, post reaction region. Flame speed as a function of particle size, equivalence ratio for unitary particles and fraction ratio of micro to nano particle size for binary particles were investigated for lean burn condition at 1 atm. Results were compared with experimental data. For unitary particles, flame speed increase as particle size decreases, but opposite trend with equivalence ratio. For binary particles, flame speed increases proportionally as nano particle fraction increases. For flame structure, separated or overlapping flames are observed, depending on the fraction of nano sized particles.

A study on grinding characteristics of CBN single abrasive grain (CBN 단입자의 연삭특성에 관한 연구)

  • 팽현진;손명환
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.6
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    • pp.1533-1541
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    • 1990
  • Cubic boron nitride (CBN) is known the second hardest material followed diamond and was provided industry as an abrasive grain in the late 1960's. Since the introduction of CBN, a large amount of research has been carried out to determine the best application condition for grinding operation. Despite the advantages in its characteristics, CBN has not yet gained full acceptance as more excellent abrasive grain than traditional one. The reason for this state is that the surface roughness ground by CBN is worse than by traditional one and dressing and truing is very difficult. This led user's resistance to the use of CBN as an abrasive grain. Present study is to investigate the cause of lower surface roughness ground by CBN single crystal abrasive grain comparing with traditional one.

Analysis of Characterization on Ancient Ink Stick (고대 먹의 특성 분석)

  • Nam, Tae-Gwang;Shin, Soo-Jeong;Park, Won-Kyu;Kim, Byung-Ro
    • Journal of Conservation Science
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    • v.28 no.2
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    • pp.165-173
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    • 2012
  • In this work, scientific and systematic analysis was conducted for finding out the methods and techniques of ancient ink stick making. Analysis the ancient ink stick on ancient documents and wooden writing as letter or painting, we concluded as followings. From the analysis of ancient wood by dendrochronology, wood was cut at 1899, which provided the information on the year of ink stick's made on writing on ancient wood. Single particle size for soot of ancient ink stick was 107 nm for ink on the roof-filling timber in Sinsunwonjeon of Changdeok Palace, compared to 38 to 86 nm on the letter on ancient 12 paper document. Aggregate particle size was 370 nm for ink on the roof-filling timber in Sinsunwonjeon of Changdeok Palace, but 206 to 318 nm for aggregate particle size on 12 paper documents. There was similar pattern between single particle size and aggregate particle size of soot, which might provide the information of raw material for ancient ink. From infra-red and Raman spectroscopic analysis of sheet of writing on paper or wood, there was severe interference from background material (paper or wood). From Raman spectroscopic analysis of ancient ink carefully separated from ancient wood, spectrum pattern was closer to ink stick made by the soot from pine burning.