• Title, Summary, Keyword: kinetics

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Kinetics and Catalytic Activity of Carbon-Nickel Nanocomposites in the Reduction of 4-Nitrophenol

  • Li, Jiulong;Ko, Jeong Won;Ko, Weon Bae
    • Elastomers and Composites
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    • v.50 no.3
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    • pp.217-222
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    • 2015
  • Carbon-nickel nanocomposites were prepared by the reaction of fullerene ($C_{60}$) and nickel hydroxide in an electric furnace at $700^{\circ}C$ for 2 h. The hybrid carbon-nickel nanocomposites were characterized by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. The kinetics and catalytic activity of the carbon-nickel nanocomposites in the reduction of 4-nitrophenol were confirmed by UV-vis spectroscopy.

Non-thermal effects of microwaves and kinetics on the transesterification of soybean oil

  • Hsiao, Ming-Chien;Liao, Pei-Hung;Chang, Li-Wen
    • Advances in environmental research
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    • v.1 no.3
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    • pp.191-199
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    • 2012
  • A kinetic study of the transesterification of soybean oil was conducted using microwaves under various temperatures, power densities, and reaction times. Results show that power density affects the kinetics and yield. The biodiesel yield increased with increasing microwave power density. The non-thermal effects of microwave irradiation on transesterification reactions were evaluated at a constant reaction temperature ($65^{\circ}C$) and power density (0.204 $Wg^{-1}$). Microwave irradiation was found to increase the reaction rates by 3.52-7.06 fold.

Adomian Decomposition Method for Point Reactor Kinetics Problems

  • Cho, Young-Chul;Cho, Nam-Zin
    • Nuclear Engineering and Technology
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    • v.28 no.5
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    • pp.452-457
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    • 1996
  • A system, such as a reactor point kinetics equation, can be solved with Adomian Decomposition Method (ADM) which uses the notion that all solutions and operators can be expressed as an infinite sum of those basis states, like Adomian polynomials. In this work, ADM is applied to point reactor kinetics equations for step reactivity insertion, ramp input of reactivity, and nonlinear feedback cases without linearization approximation. The results of ADM are more accurate and faster than those of other existing methods, even though we use comparatively large time step sizes.

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Curing Kinetics of Amine Terminated Polyetherimide/Epoxy Resin Blends and Its Application on the High Toughness Composites (Amine terminated polyetherimide/Epoxy 블렌드의 경화공정과 고강인성 복합재료에의 응용)

  • 김민영;김성호;이광기;김원호;안병현
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.49-52
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    • 2001
  • The investigation of cure kinetics, morphology, and fracture toughness studies on epoxy resin/amine terminated PEI/Anhydride system were performed by differential scanning calorimetry and scanning electron microscopy. Modified autocatalystic kinetics model was applied by isothermal scan test. The fracture toughness for the neat epoxy resin was 2.15 MPa m0.5 and the fracture toughness was improved 45% as neat epoxy resin system. The generation of secondary phase of AT-PEI was observed and its size was grown up by increasing contents of PEI.

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The Sigmoid Kinetics of Mass-action and Photosynthesis based on Influx and Efflux in a Plant Bio-system (유출입의 원리에 의한 물질대사와 광합성능에 관한 동력학적 연구)

  • 장남기
    • The Korean Journal of Ecology
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    • v.1 no.1
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    • pp.3-10
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    • 1977
  • The sigmoiod kinetics of mass-action in a biosystem have been studied by theoretical bases on the carrier hypothesis of influx and efflux of substrates. The sigmoid kinetic equations of assimilation and dissimilation rates indicate that each trophicfactor and each bio-factor behave according to the sigmoid kinetic equation and the bell shape case, and all of them are multiplicative. The general sigmoid kinetics of mass-action is given by the equation (30) which is determined by the total of the equation (28) of the assimilation rate and the equation (29) of the dissimilation rate. The sigmoid kinetic model of photosynthesis has been derived from the general equation of the sigmoid kinetics of mass-action.

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Analysis of the Pultrusion Process of Thermosetting Composites Containing Volatiles (휘발물질이 존재하는 열경화성수지 복합재료의 Pultrusion 공정 해석)

  • 김대환;이우일;김병선
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.527-536
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    • 1995
  • Analysis of pultrusion process for the thermosetting composites containing volatiles was performed. Degree of cure, amount of volatile evolved and pulling force were calculated for the processing variables such as die temperature and pulling speed. Cure kinetics was modeled from the data obtained by DSC(Differential Scanning Calorimeter). The volatile evolution kinetics was modeled from the data by DSC as well as TGA(Thermo Gravimetric Analyzer). The cure kinetics and volatile evolution kinetics models were incorporated into the energy equation. The resulting governing equation was solved using finite element method. Pulling force was calculated through the analysis of pressure developed inside the pultrusion die. Experiments were performed and the data were compared with the calculated results. Good agreements were observed.

Reaction Characteristics and Kinetics for Treatment of Wastewater Containing Phenol (Phenol 함유 폐수의 처리를 위한 반응 특성과 속도론)

  • Kang, Sun-Tae;Kim, Jeong-Mog
    • Journal of Korean Society of Water and Wastewater
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    • v.11 no.3
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    • pp.124-130
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    • 1997
  • Wastewater containing phenol was treated using Pseudomonas sp. B3 in continuous reactor, reaction characteristics and kinetics according to variation of volumetric loading rate in continuous reactor were studied. The removal efficiencies of phenol were more than 99% at the whole range of experiment, and those of COD were 97% at the volumetric loading rate, $0.96kg/m^3{\cdot}d$ and 88% at $3.0kg/m^3{\cdot}d$, respectively. Kinetics constants of $q_m$, $K_s$, Y and $K_d$ were obtained 0.901 l/d, 0.620mg/l, 0.659 and 0.219 l/d, respectively. As compared with to constants of standard activated sludge process, these constants were remarkably different because of toxicity and inhibition of phenol to microbes. And also, kinetics constants of oxygen utilization, a, and b, were shown 0.384 kg $O_2/kg$ phenol and 0.029 l/d.

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Oxidation Kinetics of Carbon Fibers

  • Roh, Jae-Seung
    • Carbon letters
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    • v.6 no.1
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    • pp.1-5
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    • 2005
  • Isotropic pitch based carbon fibers were exposed to isothermal oxidation in carbon dioxide gas to study the activation kinetics under the temperature of 800~$1100^{\circ}C$. The kinetic equation $f=1-{\exp}(-at^b)$ was introduced and the constant b was obtained in the range of 0.92~1.25. It was shown that the activated carbon fiber shows the highly specific surface area (SSA) when the constant b comes close to 1. The activation kinetics were evaluated by the reaction-controlling regime (RCR) according to changes of the apparent activation energy with changes of the conversion. It was observed that the activation energies increase from 47.6 to 51.2 kcal/mole with the conversion increasing from 0.2 to 0.8. It was found that the pores of the activated carbon fiber under the chemical reaction were developed well through the fiber.

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The effect of chemical kinetics of slurry components on Cu CMP (화학반응속도가 Cu CMP에 미치는 영향)

  • Jung, Won-Duck;Chang, One-Moon;Park, Sung-Min;Jeong, Hae-Do
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.372-373
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    • 2006
  • Chemical kinetics affects Cu CMP results (removal rate, Non uniformity etc.) Because Cu is removed by chemical action. Key factors in chemical kinetics are process temperature and concentration of slurry components. In this study, Hydrogen peroxide and citric acid were selected as a oxidant and a complexing agent and Slurry were made by mixing this components. In order to study effects of Chemical Kinetics, X-ray photoelectron spectroscopy (XPS) were performed on Cu sample after etching test as concentration of citric acid and slurry temperature. Finally Cu CMP was performed as same conditions.

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In-situ Structure Modification of W powder Skeleton and related Cu Infiltration Kinetics in W-Cu (W-Cu 계에서 W 분말골격의 in-situ 구조 변화와 Cu의 용침 kinetics)

  • 이재성
    • Journal of Korean Powder Metallurgy Institute
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    • v.6 no.1
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    • pp.36-41
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    • 1999
  • The present work has attempted to investigate the dependence of Cu infiltration kinetics on in-situ structure modification of W powder skeleton in W-Cu system. In-situ structure modification of W skeleton by addition of 0.3wt%Ni-P eutectic alloy was designed to proceed during heat-up of the W compact for Cu infiltration process. It was found that the Ni-P added W skeleton underwent remarkable stucture change only during heating-up. its structure was composed of large necks of W particles above 0.5 in the ratio of neck to particle size and smooth pore channels. The infiltration experiment showed that the infiltration kinetics for the W-Ni-P followed well the linear relationship of h vs. $t^{1/2}$ the rate constant K of which was in good agreement with the theoretical value. On the other hand, in case of the pure W skeleton a lower K value by 20% than the theoretical one was obatined. Such discrepancy is discussed in terms of skeleton structure induced infiltration mechanics.

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