• Proceedings of the KSR Conference
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• 1999.11a
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• pp.558-565
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• 1999

Rubber wheel-type AGT has two major kinds of bogie; one is the bogie type and the other and passenger loads. This paper deals with the statics analysis for two types of bogie frame subjected to combined external forces, as well as independent ones specified in UIC 515-4. Furthermore, the dynamics analysis is performed under vibrational loading conditions so as to compare dynamic characteristics, Numerical results by using commercial packages, Ⅰ-DEAS and NASTRAN show that maximum stresses do not exceed the yielding level of material used for both bogies. From an overall viewpoint of strength, the bogie type turns out to be superior to the steering type except the case of a lateral loading. It is also observed that the steering type shows a be stiffened. It is strongly anticipated that vibrational fatigue analysis should be carried out under realistic loading conditions closely matching to situations such as running surface and lateral clearances along the guideway.

• Journal of the Korean Chemical Society
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• v.52 no.3
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• pp.322-327
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• 2008

The geometrical structure, binding energy and vibrational frequencies of HOOCl-H2O cluster were investigated with MP2/6-311G(d,p) and MP2/6-311G(2d,2p) methods. The most stable conformer is skew HOOCl-H2O cluster and the binding energy was 46~48kJ/mol. The trans HOOCl-H2O cluster is less stable than skew form, but the binding energy is big enough to stablize the complex. The vibrational frequencies of skew and trans HOOCl-H2O cluster were calculated and compared with the spectrum of HOOCl.

• Advances in aircraft and spacecraft science
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• v.3 no.3
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• pp.317-330
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• 2016

Nowadays, the interest of aerospace and automotive industries on virtual testing of medium-frequency vibrational behavior of shallow shell structures is growing. The development of software capable of predicting the vibrational response in such frequency range is still an open question because classical methods (i.e., FEM, SEA) are not fully suitable for the medium-frequency bandwidth. In this context the Variational Theory of Complex Rays (VTCR) is taking place as an ad-hoc technique to address medium-frequency problems. It is a Trefftz method based on a weak variational formulation. It allows great flexibility because any shape function that satisfies the governing equations can be used. This work further develops such theory. In particular, orthotropic materials are introduced in the VTCR formulation for shallow shell structures. A significant numerical example is proposed to show the strategy.

• Journal of the Korean Wood Science and Technology
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• v.26 no.3
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• pp.16-25
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• 1998

This study was carried out to compare vibrational properties and adsorption among shellac, cashew finished plate and untreated plate of Sitka spruce(Picea sitchensis Carr). By the method of statistical regression modeling, the fundamental resonance frequency of finished plate was higher than that of untreated plate. The fundamental resonance frequency of cashew finished plate was higher than that of shellac finished plate. By the method of modal analysis, mode frequency ratio of cashew finished plate was higher than that of shellac finished plate. Amounts of adsorption of finished plate was lower than that of untreated plate, and amount of adsorption of cashew finished plate was lower than that of shellac finished plate. It was clarified that the vibrational properties and adsorption of finished plate were superior to those of untreated plate. The vibrational properties and adsorption of cashew finished plate was superior to those of shellac finished plate.

• Journal of KSNVE
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• v.9 no.3
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• pp.517-524
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• 1999

Mathematical formulas for multi-dimensional isolation analysis via vibrational power transmission can be derived in a rather simple form when the wave effects of the isolators are completely neglected. With increase of frequency range of interest, however, the wave effects play a very important role and hence cannot be neglected. The formulas get involved accordingly. In this study, a method of equivalent stiffness modeling of the isolators to include the wave effects is proposed in such a way that not only the complexity of the mathematical expressions but also that of experiments of necessity can be reduced. This method is illustratively applied to a two-dimensional vibration isolation system with nonrigid source and base structures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.229-234
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• 1997

The dynamic behavior of underground structures is complex due to the effects of vibrational characteristics of the structure and the rock. In this study, dynamic displacement responses at the structure surface by the elastic stress waves are considered as the vibrational characteristics, and evaluated by the form of the frequency spectrum. The variation of the vibrational characteristic is simulated by numerical analysis at the case of the structure has internal defections. The results reveals the possibility of the experimental detection of void existence and size. Furthermore, the verification of the dynamic response can be used for rating the stability of a tunnel.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.194-201
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• 2001

The dynamic characteristic of the building using preflex composite beams is a low natural frequency due to long span. Therefore, both vibrational acceleration and the characteristic of natural frequency damage to people using the building, This study estimates a vibrational acceleration based on walking and natural frequency in five kinds of building. Recently, using methods of evaluating a serviceability are based on JIA, AISC, Eurocode, CSA, DIN and ISO. ed. The result of this study is content with foreign regulations and serviceability. However, considering of these results, the method of evaluating serviceability should be developed in the future.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3771-3776
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• 2010

The dynamics of the $CN^-$-ligated ferric cytochrome c (CytcCN) in $D_2O$ at 283 K following Q-band photoexcitation at 575 nm was observed using femtosecond time-resolved vibrational spectroscopy. The equilibrium vibrational spectrum of the CN stretching mode of CytcCN shows two overlapping bands: one main band (82%) at $2122\;cm^{-1}$ with $23\;cm^{-1}$ full width at half maximum (fwhm) and the other band (18%) at $2116\;cm^{-1}$ with $7\;cm^{-1}$ fwhm. The time-resolved spectra show bleaching of the CN fundamental mode of CytcCN and two absorption features at lower energies. The bleach signal and both absorption features are all formed within the time resolution of the experiment (< 200 fs) and decay with a life time of 1.9 ps. One transient absorption feature, appearing immediately red to the bleach signal, results from the thermal excitation of low-frequency modes of the heme that anharmonically couple to the CN fundamental mode, thereby shifting the CN mode to lower energies. The shift of the CN mode decays with a lifetime of 2 ps, equivalent to the time scale for vibrational cooling of the low-frequency heme modes. The other transient absorption feature, which is 3.3 times weaker than the bleach signal and shifted $27\;cm^{-1}$ toward lower energies, is attributed to the CN mode in an electronically excited state where the CN bond is weakened with a lowered extinction coefficient. These observations suggest that photoexcited CytcCN mainly undergoes ultrafast radiationless relaxation, causing photo-deligation of $CN^-$ from CytcCN highly inefficient. As also observed in $CN^-$-ligated myoglobin, inefficient ligand photodissociation might be a general property of $CN^-$-ligated ferric hemes.

• The Journal of the Acoustical Society of Korea
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• v.18 no.7
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• pp.39-44
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• 1999

An analysis of the frequency parameters and vibrational modes is described for a rectangular plate. Double Fourier sine series is used as a modal displacement functions of a rectangular plate and applied to the free vibration analysis of a rectangular plate under various boundary conditions. The frequency parameters obtained by the double Fourier sine series method are compared with those obtained by the theory of finite element method and Ritz method. Frequency parameters are presented for the various aspect ratios for plate. The first four modal shapes for the rectangular plate under various boundary conditions are accurately described.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.4
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• pp.43-51
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• 2001

An experimental modal analysis is the process to identify structure's dynamic characteristics such as resonant frequencies, damping values and mode shapes. An experimental model was made of stainless steel in the shape of a circular cylindrical shell and installed on the test bed with jigs. For investigating vibrational characteristics of the continuous circular cylindrical shell with intermediate supports, modal testing is performed by using impact hammer, accelerometer and 8-channel FFT analyzer. The frequency response function(FRF) measurements are also made on the experimental model within the frequency range from 0 to 4kHz. Modal parameters are identified from resonant peaks in the FRF's and animated deformation patterns associated with each of the resonances are shown on a computer screen. The experimental results are compared with analytical and FEA results.