• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.234-236
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• 1994

We fabricated Au/PI/Pb and Au/PI/1-layer Arachidic acid/Pb structures in order to electron transport properties through the junctions. It was found that 9-layer PI LB films function as a good tunneling barrier from the I-V properties. And several peaks originating in the vibrational modes of the constituent molecules of 1-layer arachidicacid LB films were clearly observed in $d^2V/dI^2-V$ curves.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.703-706
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• 2000

The acoustic characteristics radiated from the acoustic transducer with metal-piezoceramic laminated circular plate were simulated. The Vibrational modes of metal-piezoceramic laminated circular plates were calculated by using the finite element method. After meshing the inside closed boundary of the acoustic transducer, the pressure gradients and the isotaric lines were calculated for the various frequencies. It has been observed that the characteristics of the sound pressure calculated for the various frequencies. Also, the directivity patterns and the sound pressure radiated from the acoustic transducer were calculated by 2-dimensional analysis.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.204-212
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• 1999

In this paper, the vibrational motion of a flexible beam clamped on a translating base and carrying a moving mass is investigated. The equations of motion which describe the total dynamics of the beam-mass-cart system are derived and the coupled dynamic equations are solved by unconstrained modal analysis. In modal analysis, the exact normal mode solutions corresponding to the eigenfrequencies for the position of the moving mass and the ratios of the mass of the flexible beam, the moving mass and the base cart are used. Proper transformations of the time solutions between the normal modes for a position and those for the next position of the moving mass are also adopted. Numerical simulations are carried out to obtain the open-loop responses of the system in tracking the pre-designed path of the moving mass.

• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.460-463
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• 1990

The normal and fluorinated high-Tc superconducting materials, $YBa_2Cu_3O_{7-x}F_y$with $0.25{\leq}x{\leq}0.55\;and\;0.00{\leq}y{\leq}0.30$, were synthesized to investigate the dopping effect of fluorine atom on the superconductivity of Y123 and studied by X-ray diffraction analysis and electron probe microanalysis, resistivity and thermopower measurements, and polarized micro-Raman spectroscopy. The reproducible micro-Raman spectra were recorded and analyzed. The coherent assignments could be suggested for the spectra of normal and fluorinated samples. The fluorine atoms introduced were found to be substituted for oxygen in pyramidal Cu-O units rather than in Cu-O chains. The unit cell parameters were decreased upon the substitution of oxygen by fluorine atom. From the decreasing cell parameters and Tc, the increasing thermopower, and the possible assignments of the vibrational modes, it could be suggested that the dopping of fluorine atom localizes the superconducting electrons in Y123.

• Bulletin of the Korean Chemical Society
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• v.17 no.5
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• pp.461-463
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• 1996

The laser-induced fluorescence excitation spectrum of 7-amino-4-(trifluoromethyl)coumarin in a supersonic jet has been recorded in the 340-352 nm region. The electronic band origin was observed at 28622.8 cm-1. Vibrational assignments for the three fundamental low-frequency modes and eight combination bands have been made for the S1 electronic excited state. The out-of-plane vibrations of this molecule have been characterized from the low-frequency assignments of the spectrum. The periodic potential energy function for the CF3 torsion, which satisfactorily fits the observed data, were also determined to be V(Φ)=95X(1-cos3Φ)-32X(1-cos6Φ) where Φ is the torsional angle. The relatively low torsional barrier of 99 cm-1 in S1 state could be explained by the small steric interactions between the functional groups attached to a bicyclic ring.

• Bulletin of the Korean Chemical Society
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• v.15 no.3
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• pp.241-245
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• 1994

A method has been developed to estimate the kinetic energy release originating from the reverse critical energy in unimolecular ion dissociation. Contribution from the excess energy was estimated by RRKM theory, the statistical adiabatic model and the modified phase space calculation. This was subtracted from the experimental kinetic energy release distribution (KERD) via deconvolution. The present method has been applied to the KERDs in $H_2$, loss from $C_6H_6^+$ and HF loss from ${CH_2CF_2}^+$. In the present formalism, not only the energy in the reaction coordinate but also the energy in some transitional vibrational degrees of freedom at the transition state is thought to contribute to the experimental kinetic energy release. Details of the methods for treating the transitional modes are found not to be critical to the final outcome. For a reaction with small excess energy and large reverse critical energy. KERD is shown to be mainly governed by the reverse critical energy.

• Bulletin of the Korean Chemical Society
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• v.11 no.4
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• pp.343-347
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• 1990

A thermal decomposition of the tert-butoxy radical has been studied in the gas phase over the pressure range of 1-200 torr at $413_{\circ}K$ using di-tert-butyl peroxide + trimethylsilane mixtures. The relative rate constants were obtained by studying the competitive reactions between tert-butoxy radical decomposition 4(t-BuO·→ CH_3COCH_3 + CH_3·)$ and hydrogen abstraction reaction from trimethylsilane $(t-BuO·+ HSi(CH_3)_3 → t-BuOH + Si(CH_3)_3)·).$ The conventional RRKM calculations were carried out to compare the observed fall-off behavior of the decomposition rate constant $({\kappa}_d)$ with the theoretical predictions using reasonable values of input parameters. In all cases the calculated half-rate pressure $(P_{1/2})$ were significantly higher than those observed. The failure of RRKM to reproduce the fall-off behavior led us to suggest that not all of vibrational modes contribute to excitation (leading to decomposition) on the same time scale.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.345-351
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• 1999

The structures, the energetics, and the spectra of K+(H2O)3 have been studied at HF and MP2 levels with the basis set of triple-zeta plus two sets of polarization functions (TZ2P) for water molecules. Two structures considered are 3+0 (D3), and 2+1 (C2v). The 2+1 (C2v) has two hydrogen bonds between the primary hydration and the secondary hydration shell water molecules. They have similar binding energy and enthalpy. The most stable conformation of K+(H2O)3 is entropy driven as shown in Na+(H2O)5 and in Na+(H2O)6 cases. The 3+0 (D3) conformation is the most stable at 298 K and at 1 atm, based on Gibbs free energy changes (ΔGr). The thermal contributions to the enthalpy and the Gibbs free energy are corrected for the low frequency modes. The corrected ΔGr is in good agreement with the experimental value. Vibrational frequencies of two conformations are revealed as their characteristics.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.163-169
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• 1993

A flexible manipulator can move in the high speed even with the small driving torque. The dymanic equations of flexible manipulator which include 2 vibrational modes are derived using the clamped-free boundary condition. Simulation results of the 6th order model are well matched with experimental results. The hub angle of the flexible mainpulator can be controlled without vibration of the beam by the feedback of both hub angle and strain. The overshoot of the hub angle in the step response is reduced without sacrificing the rise time using the cycloidal function instead of the step function as the referenmce input.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.625-629
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• 2011

A quantitative analysis of the decreasing rate of the monomer and increasing rate of the polymerization was made by monitoring radiation level increments using Raman spectroscopy within the therapeutic radiation range for a normoxic polymethacrylic acid gel dosimeter. The gel dosimeter was synthesized by stirring materials such as gelatin, distilled water, methacrylic acid, hydroquinone and tetrakis phosphonium chloride at $50^{\circ}C$, and the synthesized gel was contained in a 10- mm diameter and 32-mm high vial to conduct measurement. 24 hours after gel synthesis, it was irradiated from 0 Gy to 20 Gy by 2 Gy using a Co-60 radiotherapy unit. With use of the Cryo FE-SEM, structural changes in the 0 Gy and 10 Gy gel dosimeters were investigated. The Raman spectra were acquired using 532-nm laser as the excitation source. In accordance with fitting the changes in C-COOH stretching (801 $cm^{-1}$), C=C stretching (1639 $cm^{-1}$) and vinyl $CH_2$ stretching (3114 $cm^{-1}$) vibrational modes for monomer and $CH_2$ bending vibrational mode (1451 $cm^{-1}$) for polymer, sensitive parameter S for each mode was calculated. The values of S for monomer bands and polymer band were ranged in $6.0{\pm}2.6$ Gy and $7.2{\pm}2.3$ Gy, respectively, which shows a relatively good conformity of the decreasing rate of monomer and the increasing rate of polymerization within the range of error.