• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.51-56
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• 1998

This paper presents modal contribution method to reduce vehicle vibration. Normal mode analysis is performed to obtain modal vector matrix. The proposed method uses this modal vector matrix to evaluate forced response of an active mode to the applied engine forces and the rotating force due to wheel unbalance mass. Comparing the responses, of the specific active mode with one another, it can be easily done to determine most contributed mode in the interesting frequency band. Then we can find dominant bushes by the strain energy distribution of the mode. Vibration response is decrease with modification of those bushes.

• Smart Structures and Systems
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• 제17권3호
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• pp.391-411
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• 2016

This study investigates the mode identifiability of a multi-span cable-stayed bridge in terms of a benchmark study using stabilization diagrams of a system model identified using stochastic subspace identification (SSI). Cumulative contribution ratios (CCRs) estimated from singular values of system models under different wind conditions were also considered. Observations revealed that wind speed might influence the mode identifiability of a specific mode of a cable-stayed bridge. Moreover the cumulative contribution ratio showed that the time histories monitored during strong winds, such as those of a typhoon, can be modeled with less system order than under weak winds. The blind data Acc 1 and Acc 2 were categorized as data obtained under a typhoon. Blind data Acc 3 and Acc 4 were categorized as data obtained under wind conditions of critical wind speeds around 7.5 m/s. Finally, blind data Acc 5 and Acc 6 were categorized as data measured under weak wind conditions.

• 한국소음진동공학회논문집
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• 제16권4호
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• pp.339-345
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• 2006

In this paper, a physically meaningful methodology which can assess the contribution of each vibration mode to various vibration response signals (displacement, velocity, acceleration) is developed. Based on these results, the problem of quantitative assessment of the relative importance of a structural system's vibrational modes is discussed. In addition, a direct method which ran assess the relative importance of each mode from uniformly sampled experimental data is also proposed.

• Steel and Composite Structures
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• 제46권2호
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• pp.221-236
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• 2023

In order to study the seismic response of the main plant of steel reinforced concrete (SRC) structure of the CAP1400 nuclear power plant under the influence of different high-mode vibration, the 1/7 model structure was manufactured and its dynamic characteristics was tested. Secondly, the finite element model of SRC frame-bent structure was established, the seismic response was analyzed by mode-superposition response spectrum method. Taking the combination result of the 500 vibration modes as the standard, the error of the base reactions, inter-story drift, bending moment and shear of different modes were calculated. Then, based on the results, the influence of high-mode vibration on the seismic response of the SRC frame-bent structure of the main plant was analyzed. The results show that when the 34 vibration modes were intercepted, the mass participation coefficient of the vertical and horizontal vibration mode was above 90%, which can meet the requirements of design code. There is a large error between the seismic response calculated by the 34 and 500 vibration modes, and the error decreases as the number of modes increases. When 60 modes were selected, the error can be reduced to about 1%. The error of the maximum bottom moment of the bottom column appeared in the position of the bent column. Finally, according to the characteristics of the seismic influence coefficient αj of each mode, the mode contribution coefficient γj•Xji was defined to reflect the contribution of each mode to the seismic action.

• 한국자동차공학회논문집
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• 제2권2호
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• pp.59-72
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• 1994

For a panel contribution of the passenger vehicle compartment, a model was created for acoustic analysis of the passenger vehicle compartment and through the acoustic normal modal analysis, frequencies and mode shapes of the resonance modes were calculated. Also, the contribution analysis of each panel was executed using acoustic reciprocal theorem, and through this analysis, normalized responses at the particular point indicate the relative contribution of each panel for generating noise and vibration

• 대한기계학회논문집
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• 제16권8호
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• pp.1458-1467
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• 1992

본 연구에서는 균질재에서의 결과를 토대로 이종재에서도 그 성질이 보존될 것으로 기대되기 때문에 계면균열에서의 CED의 기본적 성질을 검토한후, 각 모드 인자 의 분리법과 평가법을 CED를 통해 제시한다. 또 제시한 수법을 이용하여 우선 탄성 균열 모델에서 유한요소해석을 통해 CED 및 각 모드 인자의 평가 및 기초적 검토를 실시하여 그 유효성을 확인한다.

• Structural Engineering and Mechanics
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• 제72권4호
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• pp.421-432
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• 2019

In high-speed railway (HSR) system, the structure-borne noise inside viaduct at low frequency has been extensively investigated for its mitigation as a research hotspot owing to its harm to the nearby residents. This study proposed a novel acoustic optimization method for declining the structure-borne noise in viaduct-like structures by separating the acoustic contribution of each structural component in the measured acoustic field. The structural vibration and related acoustic sourcing, propagation, and radiation characteristics for the viaduct box girder under passing vehicle loading are studied by incorporating Finite Element Method (FEM) with Modal Acoustic Vector (MAV) analysis. Based on the Modal Acoustic Transfer Vector (MATV), the structural vibration mode that contributes maximum to the structure-borne noise shall be hereinafter filtered for the acoustic radiation. With vibration mode shapes, the locations of maximum amplitudes for being ribbed to mitigate the structure-borne noise are then obtained, and the structure-borne noise mitigation performance shall be eventually analyzed regarding to the ribbing conduction. The results demonstrate that the structural vibration and structure-borne noise of the viaduct box girder mainly occupy both in the range within 100 Hz, and the dominant frequency bands both are [31.5, 80] Hz. The peak frequency for the structure-borne noise of the viaduct box girder is mainly caused by $16^{th}$ and $62^{th}$ vibration modes; these two mode shapes mainly reflect the local vibration of the wing plate and top plate. By introducing web plate at the maximum amplitude of main mode shapes that contribute most to the acoustic modal contribution factors, the acoustic pressure peaks at the field-testing points are hereinafter obviously declined, this implies that the structure-borne noise mitigation performance is relatively promising for the viaduct.

• 대한기계학회논문집
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• 제16권1호
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• pp.13-21
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• 1992

본 연구에서는 구조-음향모드 연성계수를 이용하여 심각한 소음문제가 발생하 는 경우의 효과적인 소음저감 방안을 제시하고, 제작된 차실모델에 대한 소음저감 시 뮬레이션을 수행한 후 그 결과를 실험치와 비교함으로써 수립된 소음저감 방안의 신뢰 도와 유용성을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2917-2920
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• 2011

This study aim at demonstrating the environmental performance of freight transport of the rail and road mode through an indicator of embodied energy and $CO_2$ emissions. Using the concept of LCA, the scope of evaluation includes energy production, supply chain activity and operation. The results of embodied energy and $CO_2$ emissions are normalized by means of traffic volume. The results shown that embodied $CO_2$ emissions road mode is 607.07 $gCO_2-eq./tkm$ and 284.67 $gCO_2-eq./tkm$ for road and rail mode, respectively. This number reveals that road mode is 2.1 times larger than rail mode. The results also indicate that the main contribution of $CO_2$ emission from road mode is in the operation stage, which accounts for 70%; however, it is the construction and supply chain stage that accounts for over 50% of the emission of rail mode.

• Interaction and multiscale mechanics
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• 제4권2호
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• pp.123-137
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• 2011

We review a series of crack problems arising in the general deformations of a linearly elastic solid (Mode-I, Mode-II and Mode-III crack) and, perhaps more significantly, when the contribution of surface effects are taken into account. The surface mechanics are incorporated using the continuum based surface/interface model of Gurtin and Murdoch. We show that the deformations of an elastic solid containing a single crack can be decoupled into in-plane (Mode-I and Mode-II crack) and anti-plane (Mode-III crack) parts, even when the surface mechanics is introduced. In particular, it is shown that, in contrast to classical fracture mechanics (where surface effects are neglected), the incorporation of surface elasticity leads to the more accurate description of a finite stress at the crack tip. In addition, the corresponding stress fields exhibit strong dependency on the size of crack.