• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.19-22
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• 2004

A numerical system to extract effective elastic properties of polycrystalline thin-films for MEMS devices is already developed. In this system, the statistical model based on lattice system is used for modeling the microstructure evolution simulation and the key kinetics parameters of given micrograph, grain distributions and deposition process can be extracted by inverse method proposed in the system. In this work, the effective elastic properties of polysilicon, $BaTiO_3\;and\;ZrTiO_4$ are extracted using this system and by employing the fraction of the potential site($f_P$) as a kinetics parameter for the microstructure evolution, the statistical tendency of these materials is studied.

• 환경위생공학
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• 제15권4호
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• pp.44-51
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• 2000

The reactivity of a range of volatile organic compounds with differing functional groups observed over 0.5% $Pt/{\gamma}-Al_2O_3$ catalyst. In general, the reactivity pattern observed was alcohols > aromatics > ketones > cycloalkane > alkanes. The deep conversion was increased as reaction temperature was increased. A correlation was found between the reactivity of the individual and the strength of the weakest C-Hbond in structure. The conversion of volatile organic compounds increases in order methanol > benzene > cyclohexane > MEK > n-hexane. That is the effect of differences in total dissociation energy. An apparent zeroth-order kinetics with respect to inlet concentration have been observed. A simple multicomponent model based on two-stage redox model made reasonably good predictions of conversion over the range of parameters studied. thus, the catalytic process was suggested as the new VOCs control technology.

• 한국재료학회지
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• 제4권5호
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• pp.574-580
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• 1994

본연구는 DSC (dynamic run)의 Barrett method Integral mdthod DGEBA/MDA/MN(malononitrile) DSC DSC pre exponential factor, kinetic parameter 들을 구할 수 있었다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.49-56
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• 1999

A material was formulated with Phenol novolac and HEXA only. The cure kinetics and thermal characteristics of phenol novolac with various HEXA contents were peformed by differential scanning calorimetry and thermal gravimetric analysis. All kinetic parameters of the curing reaction including the reaction order, activation energy, and rate constant were calculated and reported. The results indicate that the curing reaction goes through an autocatalytic kinetic mechanism. The friction and wear characteristics of this material were determined using friction material testing machine. The friction coefficient of phenol novolac with various HEXA contents was determined using the PV(pressure & velocity) factor. The most stable and highest friction coefficient with a various pressure and velocity condition was found at HEXA 10 wt.% material. The specific wear rate per unit sliding distance with a various HEXA contents was reported.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3391-3398
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• 2013

The carboxylated multiwall carbon nanotubes (MWCNT-COOH) and functionalized with isatin derivative (MWCNT-isatin) have been used as efficient adsorbents for the removal of lead (Pb) from aqueous solutions. The influence of variables including pH, concentration of the lead, amount of adsorbents and contact time was investigated by the batch method. The adsorption of the lead ions from aqueous solution by modified MWCNTs was studied kinetically using different kinetic models. The kinetic data were fitted with pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The sorption process with MWCNT-COOH and MWCNT-isatin was well described by pseudo-second-order and pseudo-first-order kinetics, respectively which it was agreed well with the experimental data. Also, it involved the particle-diffusion mechanism. The values of regression coefficient of various adsorption isotherm models like Langmuir, Freundlich and Tempkin to obtain the characteristic parameters of each model have been carried out. The Langmuir isotherm was found to best represent the measured sorption data for both adsorbent.

• 대한화학회지
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• 제16권2호
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• pp.84-92
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• 1972

A mechanism for the ring formation of nickel phthalocyanine (Ni-Pc) has been proposed based on chemical kinetics. The effect of the catalyst on the rate was examined, and ammonium molybdate has been found to be the most effective. The reaction order of the ring formation was determined to be of the 1st order over all, with only the concentration of urea affecting the rate of the ring formation. All the results including thermodynamic parameters support a conclusion that the rate-determining step seems to be the enolization of the urea-catalyst transition complex, followed by fast decomposition of the tautomeric enolized urea into ammonia and isocyanic acid. These intermediates then reacted with the phthalic anhydride to form imino and diimino-phthalimide, which condense to form nickel phthalocyanine in the presence of the nickel cation.

• 대한화학회지
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• 제57권2호
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• pp.210-215
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• 2013

Kinetics of oxidation of indole by peroxomonosulphate (PMS) in aqueous acetonitrile medium has been investigated. The reaction follows a total second order, first order each with respect to [Indole] and [PMS]. The rate of the reaction was not affected by added [$H^+$]. Variation of ionic strength (${\mu}$) had no influence on the rate. Increase of percentage of acetonitrile decreased the rate. Absen ce of any polymerization indicated a nonradical pathway. Activation and thermodynamic parameters have bee n computed. A suitable kinetic scheme based on these observations is proposed. The reactivity of PMS towards Indole was found to be higher than that with peroxodisulphate.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.70-71
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• 2006

Growth behavior and kinetics of grains in a liquid matrix has been studied by computer simulation for various physical and processing conditions. The kinetics of growing and dissolving grains were considered to follow those of single crystals in a matrix. Depending on the shape of crystals, rounded or faceted, different kinetic equations were adopted for growing grains and an identical equation for dissolving grains. Effects of such critical parameters as step free energy, temperature, and liquid volume fraction were evaluated.

• Bulletin of the Korean Chemical Society
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• 제18권11호
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• pp.1199-1203
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• 1997

The investigation of cure kinetics of biphenyl epoxy (4,4-diglycidyloxy-3,3,5,5-tetramethyl biphenyl)-xylok resin system with four different catalysts was performed by differential scanning calorimeter using an isothermal approach. All kinetic parameters of the curing reaction including the reaction order, activation energy and rate constant were calculated and reported. The results indicate that the curing reaction of the formulations using triphenylphosphine (TPP) and 1-benzyl-2-methylimidazole (1B2MI) as a catalyst proceeds through a first order kinetic mechanism, whereas that of the formulations using diazabicyloundecene (DBU) and tetraphenyl phosphonium tetraphenyl borate (TPP-TPB) proceeds by an autocatalytic kinetic mechanism. To describe the cure reaction in the latter stage, we have used the semiempirical relationship proposed by Chern and Poehlein. By combining an nth order kinetic model or an autocatalytic model with a diffusion factor, it is possible to predict the cure kinetics of each catalytic system over the whole range of conversion.

• Bulletin of the Korean Chemical Society
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• 제20권12호
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• pp.1418-1420
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• 1999

Kinetics and mechanism of the aminolysis of Z-thiophenyl acetates with X-benzylamines are investigated in acetonitrile at 45.0 ℃. The magnitudes of Bronsted coefficients β$_x$ (=1.3~-1.6) and β$_z$ (= -2.1~-2.4) are all large and cross-interaction constant ρxz is relatively large and positive (0.90). These trends are consistent with the rate-limiting breakdown of a tetrahedral intermediate, $T^±$. The proposed mechanism is also supported by adherence of the rate data to the reactivity-selectivity principle (RSP). The kinetic isotope effects, $k_H/k_D$, are greater than unity (1.3-1.4) suggesting a possibility of hydrogen-bonded four-centered transition state. The activation parameters, ΔH$^≠$ and ΔS$^≠$, are consistent with this transition-state structure.