• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.144-149
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• 2012

The transfer matrix method is used to determine the dynamic characteristics(natural frequencies and mode shapes) by rotational speed of wind turbine blade. The problems treated on this study is coupled flapwise bending and chordwise bending of pre-twisted nonuniform wind turbine blade. The orthogonality relations that exist between the vibrational modes is derived and the algorithm for determination of the natural vibrational characteristics is suggested.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1761-1764
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• 2008

The adsorption structure and binding of maleimide (MI) and succinimide (SI) on silver nanocolloidal surfaces have been comparatively investigated by means of pH-varied surface-enhanced Raman scattering (SERS). The two molecules appeared not to adsorb onto Ag surfaces at pH values below 5. The appearance of a ring ν (CH) band at ~3100 $cm^{-1}$ denoted the standing geometry of MI’s aromatic ring on Ag. The absence or weakness of in-plane vibrational modes of MI and SI also supported a perpendicular orientation of MI and SI on Ag from the electromagnetic selection rule. Density functional theory (DFT) calculations were employed to examine the vibrational frequencies of MI’s and SI’s neutral and anionic states.

• 대한화학회지
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• 제29권3호
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• pp.205-212
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• 1985

2,2'-bipyridyl crown ether에 관한 allosteric 효과를 분자진동연구방법을 사용하여 연구하였는데, 방법으로는 mass-weighted-cartesian 좌표방법을 사용하였다. Crown ether의 pore opening 운동에 관여하는 모드로는 235, 234, 188 그리고 178cm$^{-1}$에 해당되는 파수가 얻어졌고, biphenyl축을 통한 회전운동이 crown ether에 영향을 미치는 rotational vibration 운동은 168, 104 그리고 67cm$^{-1}$에서 파수가 얻어졌다. 특히 178cm$^{-1}$의 모드는 allosteric효과를 가장 많이 포함한 것으로 생각되어 진다.

• 한국재료학회지
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• 제6권6호
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• pp.555-560
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• 1996

The vibrational behavior and the molecular dynamics of the high Tc superconductor Ba0.6K0.4BiO3 have been studied experimentally and by atomistic computer simulation methods. For Ba0.6K0.4BiO3, the vibrational spectrum is dominated by oxygen ion modes from 150cm-1 to 820cm-1 including infrared absorption bands at 330, 480, 640 and 830cm-1including infrared absorption bands at 330, 480, 640 and 830cm-1at room temperature. Band assignments are discussed in relation to those bands predicted by simulations, and the infrared and Raman measurements reported in the literature.

• Bulletin of the Korean Chemical Society
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• 제24권8호
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• pp.1097-1101
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• 2003

The cubic and quartic anharmonic force field of malonaldehyde is calculated using density functional theory at the B3LYP/6-31G(d,p) level, and used to simulate coherent infrared vibrational spectra. 12 normal modes are included in the simulation, and the Arnoldi method is employed for the diagonalization of the Hamiltonian. The calculated three pulse infrared signals in the k1 + k2 - k3 direction show signatures of the intramolecular hydrogen bond couplings between the C=O stretch, H-O-C bend and O-H stretch vibrations.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.230-233
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• 1995

Using Polyimide Langmuir-Blodgett(LB) films as a tunneling barrier, Current -Voltage(I-V) characteristics and inelastic electron tunneling spectroscoupy(IETS) of the junctions incorporating 1-layer orgainc monolayer were invesgated. Several peaks originating in vibrational modes of constituted molecules of 1-layer monolayers were clearly observed in the IET spectra.

• 한국소음진동공학회논문집
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• 제14권10호
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• pp.1041-1047
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• 2004

This paper deals with the dynamic stability and vibration of a discontinuous cantilevered Pipe conveying fluid. The present model consists of two segments with different cross-sections. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. The critical flow velocities and stability maps of the pipe are obtained by changing ratios of second area moment of inertia and mass ratios. Finally, the vibrational modes associated with flutter are shown graphically.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.15-15
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• 2002

Homogeneous and crack-free potassium lithium niobate (K₃Li/sub 2-x/Nb/sub 5+x/O/sub 15/, 0＜x＜0.5, KLN) single crystals were successfully grown by the Czochralski technique. The KLN single crystals of several different compositions were employed for the investigation of the lattice vibration spectra using infrared Raman spectroscopy. The characteristic Raman spectra of the [NbO/sub 6/]/sup 7-/ octahedral ions were strikingly influenced by the Li ion content. The symmetric stretch vibrational modes V₁, V₂ are broadened, and the symmetric bend vibration mode V/sub 5/ is broadened and even split into three peaks with increasing the Li content, supporting that the bend vibration modes of the [NbO/sub 6/]/sup 7-/ octahedrons are obviously perturbed by Li ions in the C site. Enhanced Raman peak intensities after the post annealing at 900℃ and for 24 h evidenced that a residual stress in as-grown crystals was negligible and only a defect concentration might be reduced.

• Smart Structures and Systems
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• 제20권2호
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• pp.115-126
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• 2017

The modal identification of large civil structures such as bridges under the ambient vibrational conditions has been widely investigated during the past decade. Many operational modal analysis methods have been proposed and successfully used for identifying the dynamic characteristics of the constructed bridges in service. However, there is very limited research available on reliable criteria for the robustness of these identified modal parameters of the bridge structures. In this study, two time-domain operational modal analysis methods, the data-driven stochastic subspace identification (SSI-DATA) method and the covariance-driven stochastic subspace identification (SSI-COV) method, are employed to identify the modal parameters from field recorded ambient acceleration data. On the basis of the SSI-DATA method, the modal contribution indexes of all identified modes to the measured acceleration data are computed by using the Kalman filter, and their applicability to evaluate the robustness of identified modes is also investigated. Here, the benchmark problem, developed by Hong Kong Polytechnic University with field acceleration measurements under different excitation conditions of a cable-stayed bridge, is adopted to show the effectiveness of the proposed method. The results from the benchmark study show that the robustness of identified modes can be judged by using their modal contributions to the measured vibration data. A critical value of modal contribution index of 2% for a reliable identifiability of modal parameters is roughly suggested for the benchmark problem.

• 대한기계학회논문집A
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• 제40권1호
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• pp.97-102
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• 2016

회전 기계에서 회전에 따른 진동은 성능 저하 및 고장의 직접적 원인이 되어, 진동을 예측하고 저감 방안을 수립하는 것이 매우 중요하지만, 회전 기계의 조립이나 설치 과정에서 발생하는 불평형의 변화나 지지 구조물의 진동 모드는 예측이 어려워 그 영향을 사전에 평가하기 어렵다. 본 논문에서는 자기베어링에 의해 지지된 터보 압축기의 전달함수를 시스템 식별과정을 통해 구하고 이를 활용하여 압축기의 불평형 응답을 예측한다. 식별된 전달함수는 회전체의 진동 모드와 지지 구조물의 진동 모드를 함께 포함하고 있어, 불평형 응답에 대한 지지 구조물의 영향을 실질적으로 평가할 수 있다. 저속 운전에 의해 불평형을 추정하고 정격 속도까지의 불평형 응답을 시험 결과와 비교하여 예측의 적절성과 문제점을 파악하였다.