• 수산해양기술연구
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• 제37권4호
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• pp.313-320
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• 2001

In the presence of incident waves with different frequencies, there are second order sum and difference frequency wane exciting forces due to the nonlinearty of the incident waves. Although the magnitudes of these nonlinear forces are small, they act at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency wane loads occurring close to the natural frequencies of TLPs often give greater contributions to high and low frequency resonant responses. The components of the second order forces which depend on first order quantities have been evaluated using the three dimensional source distribution method. The numerical results of time domain motion analysis for the nonlinear wave exciting forces in regular waves are compared with the numerical ones of frequency domain analysis. The results of comparison confirmed the validity of the proposed approach.

• 한국안전학회지
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• 제12권2호
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• pp.37-44
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• 1997

Composite materials have various complicated characteristics depending on the ply materials, ply orientations, ply stacking sequences and boundary conditions. Therefore, it is difficult to analyze composite materials. For efficient use of composite materials in engineering applications, the dynamic behavior such as natural frequencies and nodal patterns should be identified. This study presents FEM results for the free vibration of symmetrically and antisymmetrically laminated composite and hybrid composite rectangular plates. The natural frequencies of laminated composite rectangular plates having the various boundary conditions (completely clamped, 2-edge clamped, cantilevered) are experimentally obtained. In order to demonstrate the validity of the experiment, FEM analysis using ANSYS was performed and natural frequencies experimentally obtained is compared with that calculated by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.414-419
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• 1997

The free vibration analysis of cantilever CFRP and GFRP composite rectangular plates with point supports at the free edge and interior position is performed. The natural frequencies and mode shapes of plates are experimentally determined by impact testing using an impact hammer. To compare and verify these experimental results, the finite element analysis is also carried out and the non-dimensional frequency parameters are compared with FE analysis results. The effects of the number and location of the point support on the frequencies are examined. In the experimental results, it is found that a significant increase in frequencies occurs when the point supports are added on certain parts of plates.

• Advances in nano research
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• 제15권5호
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• pp.411-422
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• 2023

In the present study, the axial vibration of the nanorods is investigated in the framework of the doublet mechanics theory. The equations of motion and boundary conditions of nanorods are derived by applying the Hamilton principle. A finite element method is developed to obtain the vibration frequencies of nanorods for different boundary conditions. A two-noded higher order rod finite element is used to solve the vibration problem. The natural frequencies of nanorods obtained with the present finite element analysis are validated by comparing the results of classical doublet mechanics and nonlocal strain gradient theories. The effects of rod length, mode number and boundary conditions on the axial vibration frequencies of nanorods are examined in detail. Mode shapes of the nanorods are presented for the different boundary conditions. It is shown that the doublet mechanics model can be used for the dynamic analysis of nanotubes, and the presented finite element formulation can be used for mechanical problems of rods with unavailable analytical solutions. These new results can also be used as references for the future studies.

• 한국지진공학회논문집
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• 제2권4호
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• pp.191-197
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• 1998

This paper described the dynamic characteristics of 20-story apartment buildings from the results of full-scale measurements and analysis. The natural frequencies and mode shapes are quantified by measuring and analyzing ambient vibrations of the structure and compared with the results from dynamic analysis. Comparison with computed mode shapes and frequencies shows good agreement with the experimental results. It proved that it is important to estimate coupling beam and soil parameters through a comparison of the measured results with calculated results.

• 한국자동차공학회논문집
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• 제5권4호
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• pp.152-159
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• 1997

This paper presents a vibration analysis method of crank shaft of six cylinder internal combustion engine. For simple analysis journal, pin and arm parts were assumed to have uniform section. Transfer Matrix Method was used, considering branched part and coordinate transformation part. Natural frequencies, modeshapes and transfer functions of crank shaft were investigated based upon the Euler beam theory: It was shown that the calculated natural frequencies, modeshapes agree well with the existing paper results.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 가을 학술발표회 논문집
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• pp.131-137
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• 1996

To perform condition monitoring of P.C. Box girder bridge under ambient traffic, dynamic characteristics were identified using the results of load test an analysis. It was found that natural frequencies obtained from the measured acceleration data for the forced vibration part and free vibration part were nearly identical. Thus it can be concluded that dynamic parameters are properly determined under ambient traffic condition. Finite element model for analysis was calibrated using measured frequencies. Change of dynamic characteristics were predicted through analysis of the established finite element model with anticipated change.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.66-68
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• 2014

The paper deals with the vibration characteristics of the stack transducers made of piezoelectric discs with different radius. Natural frequencies of the stack transducers were evaluated by finite-element analysis. The natural frequencies of the analysis results were compared with those of each piezoelectric disc, and their relations were investigated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.205-210
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• 1997

The analysis of the free vibrations of a circular cylindrical shell with a logitudinal, interior rectangular plate is performed. The natural frequencies and the mode shapes of the combined shells are experimentally obtained by impact testing using an impact hammer and an accelerometer. The effects of the position of the plate on the frequencies and mode shapes of the combined system are examined. The experimental results are compared with a finite element analysis and show good agreement.

• Journal of the Korean Data and Information Science Society
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• 제9권2호
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• pp.119-138
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• 1998

The case of proportional cell frequencies for the two-way cross-classification with interaction is considered. Several types of hypotheses for the general unbalanced data that are commonly used in the literature are shown, and they are written out for this particular case. A reparameterized form of the cell means model is defined to establish the reparameterized model, and orthogonal property of the model is shown using the augmented matrix and the numerator sums of squares are computed. Different ways of producing the same analysis of variance tables are shown in both orthogonal and nonorthogonal situations.