• Title, Summary, Keyword: Kinetic Model

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Pyrolysis kinetic analysis of poly(methyl methacrylate) using evolved gas analysis-mass spectrometry

  • Han, Tae Uk;Kim, Young-Min;Watanabe, Atsushi;Teramae, Norio;Park, Young-Kwon;Kim, Seungdo
    • Korean Journal of Chemical Engineering
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    • v.34 no.4
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    • pp.1214-1221
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    • 2017
  • The results of evolved gas analysis-mass spectrometry (EGA-MS) analysis were used for the kinetic analysis of poly-methyl methacrylate (PMMA) pyrolysis for the first time. Various kinetic methods, such as model-free, integral master-plots, and model-fitting methods, have been applied to derive the kinetic parameters (activation energy, pre-exponential factor and reaction model). The PMMA pyrolysis reaction mechanism was suggested to occur via a single step unzipping reaction producing methyl methacrylate (MMA) as the main pyrolyzate from the kinetic analysis results and mass spectrum obtained from the EGA-MS measurements. The kinetic parameters derived from model-free method combined with the integral master-plots method were comparable to those obtained from the peak property method (PPM). The theoretical curve derived from the kinetic results by the PPM was also well matched with the experimental thermal conversion curve using the EGA-MS measurements.

Evaluation of Two Kinetic Models on the Inactivation of Major Foodborne Pathogens by Aqueous Chlorine Dioxide Treatment (이산화염소수 처리에 의한 주요 식중독균의 불활성화에 관한 두 kinetic models의 비교)

  • Lee, Ji-Hye;Song, Hyeon-Jeong;Song, Kyung-Bin
    • Korean Journal of Food Preservation
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    • v.18 no.3
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    • pp.423-428
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    • 2011
  • Inactivation kinetic data of Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Salmonella Typhimurium, and Salmonella Enteritidis via treatment with aqueous chlorine dioxide treatment at a specific concentration were evaluated using the first-order kinetic and Weibull models. The Weibull model showed a better fit with the kinetic data than the first-order kinetic model. The survival curves after the aqueous chlorine dioxide treatment showed $t_R$ values(time required to reduce microbial populations by 90%) of 2.49 min for E. coli O157:H7 at 5 ppm, 1.47 min for L. monocytogenes at 5 ppm, 0.94 min for S. aureus at 5 ppm, 0.87 min for S. Typhimurium at 1 ppm, and 0.08 min for S. Enteritidis at 1 ppm, according to the Weibull model.

Kinetic Modiling of Cyclodextrin forming Reactionin a Heterogeneous Enzyme Reaction System using Swollen Extrusion Starch (팽윤 Extrusion 전분을 기질로 한 불균일상 효소 반응계에서 Cyclodextrin 생성반응의 수치적 해석)

  • 조명진;박동찬;이용현
    • Microbiology and Biotechnology Letters
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    • v.23 no.4
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    • pp.425-431
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    • 1995
  • A kinetic model of the cyclodextrin formation in a heterogeneous enzyme reaction system using swollen extrusion starch as substrate was derived emphasing the structural features of extrusion starch. The degree of gelatinization, the ratio of accessible and inaccessible portion of extrusion starch, adsorption of CGTase on swollen starch, the structural transformation during reaction, and product inhibition caused by produced CDs were considered in deriving kinetic model. Various kinetic constants were also evaluated. The derived kinetic equation was numerically simulated, which result showed that the derived kinetic equations can be used to predict the experimental data reasonably well under the various experimental conditions. Kinetic model can be utilized for the optimization of enzyme reactor and the process development for CD production from swollen extrusion starch.

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Adsorption Characteristics and Kinetic Models of Ammonium Nitrogen using Biochar from Rice Hull in Sandy Loam Soil

  • Choi, Yong-Su;Kim, Sung-Chul;Shin, Joung-Du
    • Korean Journal of Soil Science and Fertilizer
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    • v.48 no.5
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    • pp.413-420
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    • 2015
  • Objective of this study was to investigate adsorption characteristics and kinetic models of $NH_4-N$ to biochar produced from rice hull in respective to mitigation of greenhouse gases. $NH_4-N$ concentration was analyzed by UV Spectrophotometer. For the experiment, the soil texture used in this study was sandy loam soil, and application rates of chemical fertilizer and pig compost were $420-200-370kgha^{-1}$ (N-P-K) and $5,500kgha^{-1}$ as recommended amount after soil test for corn cultivation. Biochar treatments were 0.2-5% to soil weight. Its adsorption characteristic was investigated with application of Langmuir isotherm, and pseudo-first order kinetic model and pseudo-second order kinetic model were used as kinetic models. Adsorption amount and removal rates of $NH_4-N$ were $39.3mg^{-1}$ and 28.0% in 0.2% biochar treatment, respectively. The sorption of $NH_4-N$ to biochar was fitted well by Langmiur model because it was observed that dimensionless constant ($R_L$) was 0.48. The maximum adsorption amount ($q_m$) and binding strength constant (b) were calculated as $4.1mgg^{-1}$ and $0.01Lmg^{-1}$ in Langmuir isotherm, respectively. The pseudo-second order kinetic model was more appropriate than pseudo-first order kinetic model for high correlation coefficient ($r^2$) of pseudo-second order kinetic model. Therefore, biochar produced from rice hull could reduce $N_2O$ by adsorbing $NH_4-N$ to biochar cooperated in sandy loam soil.

A Chemical Kinetic Model Including 54 Reactions for Modeling Air Nonequilibrium Inductively Coupled Plasmas

  • Yu, Minghao;Wang, Wei;Yao, Jiafeng;Zheng, Borui
    • Journal of the Korean Physical Society
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    • v.73 no.10
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    • pp.1519-1528
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    • 2018
  • The objective of the present study is the development of a comprehensive air chemical kinetic model that includes 11 species and 54 chemical reactions for the numerical investigation of air nonequilibrium inductively coupled plasmas. The two-dimensional, compressible Navier-Stokes equations coupled with the electromagnetic-field equations were employed to describe the fundamental characteristics of an inductive plasma. Dunn-Kangs 32 chemical-reaction model of air was reconstructed and used as a comparative model. The effects of the different chemical kinetic models on the flow field were analyzed and discussed at identical/different working pressures. The results theoretically indicate that no matter the working pressure is low or high, the use of the 54 chemical kinetic model presented in this study is a better choice for the numerical simulation of a nonequilibrium air ICP.

Study on the numerical models of turbulent dispersion of solid particles in a two-phase turbulent jet flow (이상난류제트 유동에서 고체입자 난류확산의 수치모델에 관한 연구)

  • 양선규;최영돈
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.1
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    • pp.1-18
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    • 1987
  • Prediction performances by Einstein's equation of diffusivity, Peskin's model, Three-Equation model, Four-Equation model and Algebraic Stress Model, have been compared by analyzing twophase (air-solid) turbulent jet flow. Turbulent kinetic energy equation of dispersed phase was solved to investigate effects of turbulent kinetic energy on turbulent diffusivity. Turbulent kinetic energy dissipation rate of particles has been considered by solving turbulent kinetic energy dissipation rate equation of dispesed phase and applying it to turbulent diffusivity of dispersed phase. Results show that turbulent diffusivity of dispersed phase can be expressed by turbulent kinetic energy ratio between phases and prediction of turbulent kinetic energy was improved by considering turbulent kinetic energy dissipation rate of dispersed phase for modelling turbulent diffusivity. This investigation also show that Algebraic Stress Model is the most promising method in analyzing gas-solid two phaes turbulent flow.

A Study on the Improvement of Dynamic Characteristics of Spindle-Work System in Lathe - Focused on the Bolt Juint between Headstock and Bed - (선반주축계의 동특성 향상에 관한 연구 -주축대와 베드의 보울트 결합을 중심으로-)

  • 신용호;박태원;홍동표;정인성
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.1
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    • pp.1-7
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    • 1988
  • Prediction performances by Einstein's equation of diffusivity, Peskin's model, Three-Equation model, Four-Equation model and Algebraic Stress Model, have been compared by analyzing twophase (air-solid) turbulent jet flow. Turbulent kinetic energy equation of dispersed phase was solved to investigate effects of turbulent kinetic energy on turbulent diffusivity. Turbulent kinetic energy dissipation rate of particles has been considered by solving turbulent kinetic energy dissipation rate equation of dispersed phase and applying it to turbulent diffusivity of dispersed phase. Results show that turbulent diffusivity of dispersed phase can be expressed by turbulent kinetic energy ratio between phases and prediction of turbulent kinetic energy was improved by considering turbulent kinetic energy dissipation rate of dispersed phase for modelling turbulent diffusivity. This investigation also show that Algebraic Stress Model is the most promising method in analyzing gas-solid two phases turbulent flow.

Field tolerance of pesticides in the strawberry and comparison of biological half-lives estimated from kinetic models (Kinetic models에 의한 딸기 중 농약의 생물학적 반감기 비교와 생산단계잔류허용기준 설정)

  • Park, Dong-Sik;Seong, Ki-Young;Choi, Kyu-Il;Hur, Jang-Hyun
    • The Korean Journal of Pesticide Science
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    • v.9 no.3
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    • pp.231-236
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    • 2005
  • This study was conducted to determine the amounts of pesticide residues after treatment of criterion dose with 4 pesticides(tolclofos-m, folpet, procymidone, and triflumizole) under cultivated period and to compare the biological half-life of pesticides with 6 kinetic models(first, zero and second order kinetics, power function, elovich and parabolic model) and to establish proposed field tolerance using biological half-lives. Recovery of 4 pesticides form strawberry was ranged from 85.1 to 105.5%. For all of 4 pesticides, dissipation rate was over 73% at 5 days after application. Among 6 kinetic models, first order kinetic model (FO) was best fit to describe the relationship between residual pattern of pesticides and time. Therefore, half-lives were calculated by FO for establishing the field tolerance. These results showed that half-life should be calculated by comparative best fit kinetic model and field tolerance can help to prevent unacceptable agricultural products from marketing. It is good for both consumers and farmers having safe agricultural products and financial benefits, respectively.

Kinetic Model on the Vacuum Deposition (眞空 蒸着에 관한 速度論的 모델)

  • Kim, Dae-Soo
    • Journal of the Korean institute of surface engineering
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    • v.19 no.2
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    • pp.51-58
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    • 1986
  • A theoretical model was proposed to predict the rate of particles impinging on the negatively biased substrate and the total kinetic energy per unit time. The model takes into an account of kinetic theory based on Maxwell statistics and elementary plasma theory, incorporated with Hertz-Knudsen's evaporation theory. It is found that as the bias potential increases the ion flux and kinetic energy increases to a value above which the effect of potential is insignificant.

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Understanding the Use of Coal Char Kinetic Models in commercial CFD Codes (상용 CFD 코드에서 사용되는 촤 반응속도 모델에 대한 이해)

  • Kim, Daehee;Choi, Sangmin
    • 한국연소학회:학술대회논문집
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    • pp.91-94
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    • 2013
  • Commercial computational fluid dynamics (CFD) codes traditionally rely on the computational efficiency of the simplified single-film apparent char kinetic model to predict char particle temperatures and char conversion rates in pulverized coal boilers. The aim of this study is to evaluate the reliability of the single-film apparent kinetic model and to suggest the importance of proper use of this model. For this, a parametric study was conducted with a consideration of main parameters such as Stefan flow, product species, particle evolution, and kinetic parameters.

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