• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.798-804
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• 2014

We present calculations for diglycine - $(H_2O)_n$ (n = 0-3) to examine the effects of microsolvating water on the relative stability of the zwitterionic vs. canonical forms of the dipeptide. We calculate the structures, energies and Gibbs free energies of the conformers at wB97XD/6-311++G** and MP2/aug-cc-pvdz levels of theory level of theory. We predict that microsolvation by up to three water molecules does not give thermodynamic stability of the zwitterion relative to the canonical forms. Our calculations also suggest that zwitterionic diglycine - $(H_2O)_3$ is not stable kinetically in low temperature gas phase environment.

• 한국수소및신에너지학회논문집
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• 제11권3호
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• pp.127-136
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• 2000

Molecular dynamics simulations have been carried out to investigate the scattering and penetration properties of hydrogen ions with the normal incident angle to Ni (100) surface. The initial kinetic energies of hydrogen ions range from 100 to 1,600 eV. The simulation results are used to assess the applicabilities of theoretical predictions based on the binary collision approximation, and, in the high kinetic regime, theoretical results for scattering energies were shown to he a good agreement with molecular simulations. The angle dependencies on both scattering and penetration distributions were found in the longitudinal direction, but not in the azimuthal direction except for the high kinetic energy of 1,600 eV.

• Carbon letters
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• 제9권2호
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• pp.121-126
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• 2008

High modulus pitch based carbon fibers (HM) were exposed to isothermal oxidation using tube furnace in carbon dioxide gas to study the oxidation 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 1.02~1.42. The oxidation kinetics were evaluated by the reaction-controlling regime (RCR) depending upon the apparent activation energies with the conversion increasing from 0.2 to 0.8. The activation energies decrease from 24.7 to 21.0 kcal/mole with the conversion increasing from 0.2 to 0.8, respectively. According to the RCR, the reaction was limited by more diffusion controlling regime for the HM fibers with the conversion increasing. Therefore, it seems that the oxidation which is under the diffusion controlling regime takes place continuously from the skin to the core of the fiber.

• Preventive Nutrition and Food Science
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• 제12권2호
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• pp.115-118
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• 2007

Tocopherols are important lipid-phase antioxidants that are subject to heat degradation. Therefore, kinetic analyses for oxidative degradation of tocopherols as a function of temperatures and times were performed. Alpha-, gamma- and delta-tocopherols dissolved in glycerol were heated at 100${\sim}$250$^{\circ}C$ for 5～60 min. Oxidized tocopherols were analyzed by HPLC using a reversed phase ${\mu}$-Bondapak C$_{18}$-column with two kinds of elution solvent systems in a gradient mode. The degradation kinetics for tocopherols followed a first-order kinetic model. The rate of tocopherol degradation was dependent on heating temperatures. The degradation rate constants for ${\gamma}$- and ${\delta}$-tocopherols were higher than those for ${\alpha}$-tocopherol. The experimental activation energies of ${\alpha}$-, ${\gamma}$- and ${\delta}$- tocopherols were 2.51, 6.05 and 5.34 kcal/mole, respectively. The experimental activation energies for the oxidative degradation of ${\gamma}$- and ${\delta}$-tocopherols were higher than that of ${\alpha}$-tocopherol.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.123-123
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• 2010

The hydrophobic coating for multi-walled nanotubes was treated with toluene and trimethylchlorosilane glow discharge plasma under low pressure, and the hydrophobic surface of the treated MWCNT was investigates. In order to investigate the effects of -CH components from the toluene and TMCS glow plasma, we conducted on the total surface free energies of the MWCNT powder, which was calculated by measuring the contact angle between the cushion of MWCNT powder and the probe liquids. The total surface free energies were determined by Owens-Wendt equation and drastically decreased.

• 한국전기전자재료학회논문지
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• 제29권11호
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• pp.720-724
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• 2016

Transparent n-type metal-oxide semiconductor of $MoO_x$ was applied on a p-type Si substrate for high-performing heterojunction photodetector. The formation of $MoO_x$ on Si spontaneously established a rectifying current flow with a high rectification ratio of 1,252.3%. Under light illumination condition, n-type $MoO_x$/p-type Si heterojunction device provided significantly fast responses (rise time : 61.28 ms, fall time : 66.26 ms). This transparent metal-oxide layer ($MoO_x$) would provide a functional route for various photoelectric devices, including photodetectors and solar cells.

• 천문학회지
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• 제29권spc1호
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• pp.99-102
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• 1996

I discuss implications of gamma-ray emission from blazars based on electron acceleration by shock waves in a relativistic jet. The number spectrum of electrons turns out to be a broken power law; while at low energies the power law index has a universal value of 2, at high energies it steepens to an index of 3 because of strong radiative cooling. This spectrum can basically reproduce the observed spectral break between X-rays and gamma-rays. I show that energetics of relativistic jets can be well explained by this model. I estimate physical quantities of the relativistic jets by comparing the prediction with observations. The results show that the jets are particle dominated and are comprised of electron-positron pairs. A connection between gamma-ray emission and radiation drag is also discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1240-1247
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• 2003

Water jet nozzle for LCD has been used as a wet cleaning process in many industries. It is necessary for the nozzle to consider cleaning effect and flux. In this paper, we applied the bubble dynamic theory(Rayleight-Plesset equation) to improve the cleaning efficiency. Generally, Rayleigh-Plesset equations for cavitation bubbles are used in analyzing computer simulation for caviting flows. Burst of bubbles causes potential energies and we can use these energies to remove organic and inorganic compounds on the LCD. Therefore, it is necessary to analyze the bubble generations and axiomatic design by computational fluid dynamics(CFD). By comparing the weight matrix of neural networks to the design matrix of axiomatic design, we propose methods to verify designs objectively. The optimal solution could be deduced by the regression analysis using the design parameters.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2007년도 한국음성과학회 공동학술대회 발표논문집
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• pp.123-126
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• 2007

This paper suggests a method to improve the performance of the pathological/normal voice classification. The effectiveness of the mel frequency-based filter bank energies using the fisher discriminant ratio (FDR) is analyzed. And mel frequency cepstrum coefficients (MFCCs) and the feature vectors through the linear discriminant analysis (LDA) transformation of the filter bank energies (FBE) are implemented. This paper shows that the FBE LDA-based GMM is more distinct method for the pathological/normal voice classification than the MFCC-based GMM.

• Coupled systems mechanics
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• 제6권3호
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• pp.369-376
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• 2017

Intermolecular interaction energies and conformer geometries of the hydrogen bonded acrylamide dimers have been studied by using the second-order Møller-Plesset (MP2) perturbation theory and the density functional theory (DFT) with 17 density functionals. Dunning's correlation consistent basis sets (up to aug-cc-pVTZ) have been used to study the basis set effects. The DFT calculated interaction energies are compared to the reference energy data calculated by the MP2 method and the coupled cluster method at the complete basis set (CCSD(T)/CBS) limit in order to determine the relative performance of the studied density functionals. Overall, dispersion-energy-corrected density functionals outperform uncorrected ones. The ${\omega}B97XD$ density functional is particularly effective in terms of both accuracy and computational cost in estimating the reference energy values using small basis sets and is highly recommended for similar calculations for larger systems.