• Journal of the Korean Ceramic Society
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• v.34 no.10
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• pp.1021-1026
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• 1997

RuO2 thin film has reasonably good conductivity and stiffness and it is thought to substitute for the cantilever beam made up of Pt and Si3N4 double layers in microactuators. Therefore, anisotopic Si etching was performed using RuO2 thin film as a mask layer in 25 wt. % TMAH water solution. In the etching temperature ranging from 6$0^{\circ}C$ to 75$^{\circ}C$, the etch rates of all the crystallographic directions increased linearly as the etching temperature increased. The etch rate ratio(selectivity) of [111]/[100] which varied from 0.08 to 0.14, was not sensitive to temperature. The activation energies for [110] direction, [100] direction and [111] direction were 0.50, 0.66 and 1.04eV, respectively. RuO2 cantilever beam with a clean surface was formed at the etching temperatures of 6$0^{\circ}C$ and $65^{\circ}C$. But the damages due to formation of pin holes on RuO2 surface were observed beyond 7$0^{\circ}C$. The tensile stress of RuO2 thin films caused the cantilever bending upward. As a result, it was demonstrated that the formation of conducting oxide RuO2 cantilever beam which can replace the role of an electrode and supporting layer could be possible by TMAH solution.

• Korean Journal of Materials Research
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• v.18 no.6
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• pp.302-306
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• 2008

Polycrystalline germanium (Ge) thin films were grown by metal organic chemical vapor deposition (MOCVD) using tetra-allyl germanium [$Ge(allyl)_4$], and germane ($GeH_4$) as precursors. Ge thin films were grown on a $TiN(50nm)/SiO_2/Si$ substrate by varying the growth conditions of the reactive gas ($H_2$), temperature ($300-700^{\circ}C$) and pressure (1-760Torr). $H_2$ gas helps to remove carbon from Ge film for a $Ge(allyl)_4$ precursor but not for a $GeH_4$ precursor. $Ge(allyl)_4$ exhibits island growth (VW mode) characteristics under conditions of 760Torr at $400-700^{\circ}C$, whereas $GeH_4$ shows a layer growth pattern (FM mode) under conditions of 5Torr at $400-700^{\circ}C$. The activation energies of the two precursors under optimized deposition conditions were 13.4 KJ/mol and 31.0 KJ/mol, respectively.

• Elastomers and Composites
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• v.48 no.2
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• pp.161-166
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• 2013

Thermal degradation behavior of chlorine cure-site ACM and carboxylic cure-site ACM rubbers was studied by non-isothermal TGA thermal analysis. Carboxylic cure-site ACM rubber exhibited comparatively more thermally stable than chlorine cure-site ACM, showing higher peak temperature, at which maximum reaction rate occurred. Activation energies from Kissinger method were calculated as 118.6 kJ/mol for the chlorine cure-site ACM and 105.5 kJ/mol for the carboxylic cure-site ACM, showing similar values from Flynn-Wall-Ozawa analysis over the conversion range of 0.1~0.2. From the analysis of the reaction order change, both samples seemed thermally decomposed through the multiple reaction mechanism as is the common rubber materials.

• Membrane Journal
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• v.6 no.4
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• pp.227-235
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• 1996

poly(acrylic acid)(PAA)-poly(vinyl alcohol)(PVA) membranes have been prepared by crosslinking reaction between the carboxylic acid groups of PAA and the hydroxylic groups of PVA. In the measurements of the swelling and preferential sorption of the membranes, sorption behaviors of the membranes in pure water, pure acetic acid and a mixture of them have been investigated, respectively. From the measurements of the preferential sorption in 90wt% acetic acid of aqueous mixture, the sorption of water component was found to be more enhanced at high PAA content in the membrane than that of acetic acid component due to the interaction of water with acetic acid. The sorption behavior and the degree of crosslinking influenced competitively the permeation behavior of permeants. Permeation behavior of perrecants through the membranes was analyzed by using permeation activation energies which had been obtained from the Arrhenius plots of fluxes.

• Journal of the Korean Chemical Society
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• v.24 no.3
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• pp.201-208
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• 1980

The CNDO/2 MO method has been used to study gas phase reactions of protonated acetaldehyde with alcohols and protonated acetic acid with alcohols respectively by optimizing state geometries. Results showed that the former is predicted to proceed by alkyl-O cleavage and the latter by acyl-O cleavage. It has also been found using eigenvector properties of reactants that the former should be a charge controlled while the latter an orbital controlled reaction. According to the calculated activation energies assuming the transition states proposed by Caserio et al., the predicted reactivity order for alcohols agreed with the experiments for the latter but the order predicted was the reverse of the experimental one for the former.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.33-37
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• 1992

Information about $^{14}N$ relaxation rates is obtained for thioacetamide (TA) in acetone from a detailed line-shape analysis of the $^1H$ resonance signal of $NH_2$ group. The effect of pressure and of temperature were investigated, and activation energies for molecular reorientation are given. And also $^1H$ relaxation rates of $NH_2$ group of TA as a function of pressure and temperature are obtained. These results are discussed with the results for the $^{14}N$ relaxation of amine group.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.581-586
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• 2014

The most stable adsorption structures and their corresponding energies of 4-pyridone, 4-hydroxypyridine, 2-pyridone and 2-hydroxypyridine have been investigated by Density Functional Theory (DFT) calculation and high-resolution photoemission spectroscopy (HRPES). We confirmed that between the two reaction centers of 4- and 2-pyridone, only O atom of carbonyl functional group can act as a Lewis base while both the two reaction centers of 4- and 2-hydroxypyridine (tautomers of 4- and 2-pyridone) can successfully function as a Lewis base. On the other hand, owing to their molecular structures, there is a remarkable difference between the adsorption structures of 4- and 2-hydroxypyridine. Through the analysis of the N 1s and O 1s core level spectra obtained using HRPES, we also could corroborate that two different adducts coexist on the surface at room temperature due to their activation energy investigating the coverage dependent variation of bonding configurations when these molecules are adsorbed on the Ge(100) surface.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.126-130
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• 1998

Aluminum sulfate, $AI_{2}(SO_4)_3\cdot18H_2O$ was prepared by adding of kaolin-dissolved sulphuric acid into ethanol and its thermal decomposition behavior was discussed. As-synthesized high purity precipitate particles were platelike shapes of $2\mu\textrm{m}$ size. With increasing drop rate of leach liquor into ethanol, the crystallite sizes of the precipitate decreased. The apparent activation energies for dehydration and sulfate decomposition of the precipitate were $11.9Kcal mol^{-1}$ and $48.2kcal mol^{-1}$ respectively.

• Korean journal of food and cookery science
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• v.7 no.3
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• pp.1-6
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• 1991

Potato starches are obtained from Irish Cobbler (the dry type), Shepody and superior (the intermediate type) and Dejima (the moist type). Rheological properties of heat-gelatinized potato starch paste were studied to elucidate difference of various potato starches. Heat-gelatinized 3 to 7% potato starch paste showed pseudo plasticity in yield stress. As starch paste concentration increased, the values of consistency index was increased. Relationship between logarithmic consistency index and concentration of potato starch paste was linear at 5% starch concentration. Concentration dependence of consistency index and yield stress of Shepody was highest. As measuring temperature increased, the value of consistency index was decreased. Irish Cobbler starch paste at $50^{\circ}C$, Shepody, Superior and Dejima starch paste at $60^{\circ}C$ showed linear relationships with different slopes. The activation energies of Shepody starch paste was 3.97㎉l/㏖.

• Elastomers and Composites
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• v.46 no.3
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• pp.245-250
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• 2011

The self diffusions and hole volumes of amorphous region of poly(acrylonitrile)-poly(vinyl chloride) fibers were investigated by experiments of stress relaxation. The experiments of stress relaxation were carried out using the tensile tester with the solvent chamber. The flow parameters of filament fibers were obtained by applying the experimental stress relaxation curves to the theoretical equation of stress relaxation. From the flow parameters, the hole volumes, self diffusions, viscosities and thermodynamic parameters of solid polymers were calculated. It was observed that the flow parameters of these samples are directly related to the hole volumes, self diffusions and flow activation energies of flow segments.