• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.331-338
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• 2000

In this paper, a non-linear finite element formulation for the spatial cable-net structures is simulated and using this formulation, the characteristics of structural behaviors for the elastic catenary cable are examined In the simulating procedure for the elastic catenary cable, nodal forces and tangential stiffness matrices are derived using catenary parameters of the exact solutions by a governing differential equation of catenary cable, cable self-weights and unstressed cable length. Dynamic Relaxation Method that considers kinetic damping is used for the structure analysis and Newton Raphson Method is used to verify the accuracy of solutions. In the analysis of two dimensional cable, the results obtain from the elastic catenary elements are shown more accurate than does of truss elements and in the case of spatial cable-net structures, Dynamic Relaxation Method is more stable to be converged than Newton Raphson Method.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.45-50
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• 2004

$Cu^{II}$-complexes of N-salicylideneaniline and its derivatives were not light sensitive in most solvents such as acetonitrile. A photo-decomposition occurred upon irradiation in halocarbon solvents such as $CHCl_3$. It has been suggested that such photoreactivity is attributed to the reactivity of charge-transfer to solvent (CTTS) excited state attained upon irradiation. A mechanism has been proposed to account for the results obtained. The complexes have been thermally analysed in nitrogen and static air using thermogravimetry (TG) and derivative thermogravimetry (DTG). The thermal degradation of the complexes proceeds in two or three stages. The kinetic parameters obtained from the Coats-Redfern and Horowitz-Metzger equations show the kinetic compensation effect.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.712-715
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• 1996

Kinetic studies are carried out on the reactions of N-methyl-N-phenylcarbamoyl chlorides with benzylamines in acetonitrile. The selectivity parameters, ρX (=-0.6~-0.8), ρY (=1.0-1.1), and ρXY (=-0.14), suggest that the reaction proceeds by an SN2 mechanism. Kinetic isotope effects, kH/kD, involving deuterated nucleophiles (XC6H4CH2ND2) are all inverse type (<1.0), and the trends of changes in the magnitude are consistent with those expected for the observed negative sign of ρXY(=∂ρX/∂σY = ∂ρY/∂σX < 0). The relatively low activation enthalpies also support the proposed mechanism.

• Bulletin of the Korean Chemical Society
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• v.21 no.4
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• pp.379-382
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• 2000

The temperature dependence of the kinetic parameters of the aspartase-catalyzed reaction has been examined in the direction of deamination. The pK1values at 37$^{\circ}C$, 25$^{\circ}C$, 16$^{\circ}C$ and 7$^{\circ}C$ were 6.2 $\pm$ 0.1, 6.3 $\pm$ 0.1, $6.7{\pm}0.3$ and 6.9 $\pm$ 0.3, respectively. On the other hand, the pK2 values at 37$^{\circ}C$,25$^{\circ}C$, 16$^{\circ}C$ and 7$^{\circ}C$ were 8.1 $\pm0.2$, 8.3 $\pm$ 0.2, 8.2 $\pm$ 0.3 and 8.0 $\pm$ 0.2,respectively. The enthalpy of ionization, DHion, calculated from the slope of pK1, are 6.0 $\pm$ 0.3 kcal/mol. These results validate the prediction that aspartase requires a histidine residue for a general base, and a cysteine (or having a carboxyl functional group) for a general acid.

• Journal of the Semiconductor & Display Technology
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• v.16 no.2
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• pp.19-26
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• 2017

The cure properties of ethoxysilyl bisphenol A type epoxy resin (Ethoxysilyl-DGEBA) systems with different hardeners were investigated, comparing with DGEBA and Diallyl-DGEBA epoxy resin systems. The cure kinetics of these systems were analyzed by differential scanning calorimetry with an isothermal approach, and the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. The Ethoxysilyl-DGEBA epoxy resin system showed lower cure conversion rates than DGEBA and Diallyl-DGEBA epoxy resin systems. The conversion rates of these epoxy resin systems with DDM hardener are lower than those with HF-1M hardener. It can be considered that the optimum hardener for Ethoxysilyl-DGEBA epoxy resin system is Phenol Novolac type. These lower cure conversion rates in the Ethoxysilyl-DGEBA epoxy resin systems could be explained by the retardation of reaction molecule movements according to the formation of organic-inorganic hybrid network structure by epoxy and ethoxysilyl group in Ethoxysilyl- DGEBA epoxy resin system.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.143-152
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• 2018

The process parameters of ethyl violet from aqueous solution by activated carbon adsorption were carried out as a function of pH, temperature, contact time, initial concentration and temperature. The adsorption equilibrium data can be described well by the Langmuir and Freundlich isotherm models. Base on Langmuir constant ($R_L=0.0343{\sim}0.0523$) and Freundlich constant (1/n=0.1633~0.1974), This process could be employed as effective treatment for adsorption of ethyl violet. The kinetic experimental results showed that the adsorption process can be well described with the pseudo second order model. Based on the positive enthalpy (6.505 kJ/mol), the adsorption of ethyl violet onto granular activated carbon is endothermic. The negative Gibbs free energy (-1.169~-1.681 kJ/mol) obtained indicates that the adsorption process is spontaneous and physisorption.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.38-38
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• 2002

Kinetic indentation technique was studied and a method to evaluate wear and fatigue behaviors of irradiated small specimen was suggested. The method is based on both the proportion of elastic and plastic deformation and values obtained by micro-hardness test. The parameters obtained from the diagram of load-indentation depth-time are required to evaluates wear and fatigue properties. Considering the irradiated test specimen, it is one of possible and useful methods to estimate the irradiated wear and fatigue behaviors of the small size specimen. This article briefly describes the status of irradiated material study in domestic research reactor.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.7
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• pp.55-63
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• 2006

Bacterial transport models were evaluated in this study to determine the suitable model at describing bacterial transport in saturated column experiments. Four models used in the evaluation were: advective-dispersive equation (ADE) + equilibrium sorption/retardation (ER) + kinetic reversible sorption (KR) (Model I), ADE + two-site sorption (Model 2), ADE + ER + kinetic irreversible sorption (KI) (Model 3), ADE + KR + KI (Model 4). Firstly, analyses were performed with the first experimental data, showing that Model 4 is appropriate for describing bacterial transport. Even if Model 1 and 2 fit well to the observed data, they have a defect of not including the irreversible sorption, which is directly related to mass loss of bacteria. Model 3 can not properly describe the tailing observed in the data. However, further analysis with the second data indicates that Model 4 can not describe retardation of bacteria, even if the sorption-related parameters are varied. Therefore, Model 4 is modified by incorporating retardation factor into the model, resulting in the improved fitting to the data. It indicates that the transport model, into which retardation, kinetic reversible sorption, and kinetic irreversible sorption are incorporated, is suitable at describing bacterial transport in saturated column experiments. It is expected that the selected transport model could be applied to properly analyze the bacterial transport in saturated porous media.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.486-491
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• 2014

In this paper, the adsorption behavior and kinetic characteristics of cibacron brilliant red 3B-A from aqueous solution using granular activated carbon were investigated. The effect of various parameters such as adsorbent dose, pH, initial concentration, contact time and temperature on the adsorption system were studied. Base on the estimated Langmuir constant ($R_L$) and Freundlich constant (1/n), This process could be employed as effective treatment method. From the Temkin constant (B) and Dubinin-Radushkevich constant (E), This adsorption process is physical adsorption. From kinetic experiments, the adsorption process followed the pseudo second order model with good correlation. Base on the Gibbs free energy and enthalpy, the adsorption of cibacron brilliant red 3B-A onto granular activated carbon was physisorption and endothermic in nature.

• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.226-232
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• 2014

In this study, we investigated kinetic model for the acid-catalyzed xylan hydrolysis at temperature $120{\sim}150^{\circ}C$. Also, we analyzed the kinetic parameters for xylose production and furfural decomposition. The hydrolysis of xylan and the degradation of xylose were promoted by high reaction temperature and acid concentration. The optimal hydrolysis condition for the highest reaction rate constants ($k_1$) was different depending on the acid catalysts. Among sulfuric, oxalic and maleic acid, the xylan reaction rate constants ($k_1$) to xylose had the highest value of $0.0241min^{-1}$ when 100 mM sulfuric acid was used at $120^{\circ}C$. However, sulfuric acid induced more xylose degradation compared to oxalic and maleic acid hydrolysis. The activation energy for xylan degradation was the highest when sulfuric acid was used.