• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2008.04a
• /
• pp.561-566
• /
• 2008

Recently, because of development of the high speed train technology, the vibration loads by train is significantly increased ever than before. This buried gas pipelines are exposed to both repeated impact loads, and, moreover, they have been influencing by vibration loads than pipeline which is not located under vehicle loads. The vibration characteristic of pipeline is examined by dynamic analysis, and variable is only train speed. Since an effect of magnitude of vibration loads is more critical than cover depth, as increasing the train speed, the vibration speed of buried pipelines is also increased. The slope of vibration velocity is changed by attenuation of wave, at train speed, 300 km/h. From the analysis results, the vibration velocity of pipelines is satisfied with the vibration velocity criteria which are established by Korea Gas Corporation. The results present operation condition of pipelines under rail loads has fully sound integrity based on KOGAS specification.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.1 s.106
• /
• pp.19-26
• /
• 2006

The test blasts were carried out by detonating some single blastholes at two upper sites of the underground storage cavern for the crude oil. One was performed at the entrance site of the construction tunnel and the other at the middle area of the underground storage cavern. Based on the blast-induced nitration measured by the test blasts, we suggested the propagation equations of blasting vibration that were capable of estimating the peak particle velocity. In addition, in order to assess the stability of the adjacent ground storage tank, we did the frequency analysis and the response spectrum analysis with the particle velocity-time history and the particle acceleration-time history that were measured by the test blast carried out on the entrance site of the construction tunnel. In result, it was predicted that the displacement on the highest part of the tank shell was less than the allowable displacement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.824-829
• /
• 2002

Since many reciprocating and rotating components are attached to jet loom structure. it is exposed to a more vibration and moise problems than the other textile machinery. Thus the design of the jet loom frame is very important to characterize the dynamic response. In this study, a finite element model of jet loom main frame was developed to investigate the dynamic characteristics of jet loom. Two different finite element models of different main frames were constructed and these models were validated by the experimental results. Dynamic characteristics such natural frequencies and mode shapes were in good agreement between the finite element analysis and experimental results within 10% error range. It is expected that the result from this study can be used as the basic information of jet loom dynamic analysis and be extended for further analysis of forced response case.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.10
• /
• pp.905-913
• /
• 2017

In this work, a method of size optimization is proposed to maximize the natural frequency of a rod that consists of a hidden shape in one part and an exposed shape in the other. The frequency response function of a rod composed of two parts is predicted by using the frequency response functions of each of the parts instead of the shapes of the parts. The mass and stiffness matrices of the rod are obtained by using the mass and stiffness matrices of the equivalent vibration systems, which are obtained by applying the experimental modal analysis method to the frequency response functions of the parts. Through several numerical examples, the frequency response function obtained by using the proposed method is compared with that of a rod to validate the prediction method based on equivalent vibration systems. A size optimization problem is formulated for maximizing the first natural frequency of a combined rod, which is replaced with an equivalent vibration system, and a rod structure is optimized by using an optimization algorithm.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.5
• /
• pp.390-398
• /
• 2014

Heavy-weight floor impact noise is directly related to the impact source and floor vibration property. Dynamic properties of the standard floating floor that is used in Korea was investigated using accelerance, acceleration energy spectral density(ESD), and structural modal test. In the standard floating floor, natural frequency was decreased by the finishing mortar mass and the damping ratio was increased. Bang-machine force spectrum acting on the concrete slab can be calculated using inverse system analysis. Impact force acting on concrete slab is changed by interaction of finishing mortar and resilient material. The amplitude of the bang-machine force spectrum was amplified in low frequency range(below 100 Hz), and over 100 Hz was decreased. Changed force spectrum influence to the response of structure vibration, so the heavy-weight floor impact noise level was changed.

• Earthquakes and Structures
• /
• v.2 no.4
• /
• pp.337-356
• /
• 2011

In this paper, cable-stayed bridges with single pylon and two equal side spans, with variations in geometry and span ranging from 120 m to 240 m have been studied. 3D models of the bridges considered in this study have been analysed using ANSYS. As the first step towards a detailed seismic analysis, free vibration response of different geometries is studied for their mode shapes and frequencies. Typical pattern of free vibration responses in different frequencies with change in geometry is observed. Further, three different seismic loading histories are chosen with various characteristics to find the structural response of different geometries under seismic loading. Effect of variation in pylon shape, cable arrangement with variation in span is found to have typical characteristics with different structural response under seismic loading. From the study, it is observed that the structural response is very much dependent on the geometry of the cable-stayed bridge and the characteristics of the seismic loading as well. Further, structural responses obtained from the study would help the design engineers to take decisions on geometric shapes of the bridges to be constructed in seismic prone zones.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.498-498
• /
• 2001

Seismic qualification of the Main Control Boards for nuclear power plants has been performed with the guideline of AS ME Section III. US NRC Reg. Guide and IEEE 344 code. The analysis model of the Main Control Boards is consist of beam. shell and mass element by using the finite element method. and, at the same time. the excitation forces and other operating loads for each model are encompassed with respect to different loading conditions. As the fundamental frequencies of the structure are found to be less than 33Hz. which is the upper frequency limit of the seismic load, the response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the structural and functional integrity of the major components, modal analysis theory is adopted to derive the required response spectrum at the component locations. As all the combined stresses obtained from the above procedures are less than allowable stresses and no mechanical or electrical failures are found from the seismic testing, it concludes the Main Control Boards is dynamically qualified for seismic conditions. Although the authors had confirmed the structural and functional integrity of both Main Control Boards and all the component, in this paper only the seismic analysis of the Main Control Board is introduced.

• Journal of Theoretical and Applied Mechanics
• /
• v.3 no.1
• /
• pp.34-44
• /
• 2002

Theoretical analysis Is carried out to identify the modal coupling effect between some particular acoustic modes of a vehicle compartment cavity and vibration modes of body panels like side doors, roof or floor. A simplified panel-cavity coupled model is investigated on the coupled resonance frequencies, modes and frequency response characteristics. Through parametric study, It Is possible to explain how the acoustic response of a coupled system will be determined by the vibration and acoustic property of the individual panel and cavity system. Full coupled system shows some interesting features different from those of the semi-coupled system In frequency, mode and acoustic response.

• Structural Monitoring and Maintenance
• /
• v.7 no.2
• /
• pp.149-166
• /
• 2020

This paper presents the results of an experimental investigation on a vibration-based damage identification framework for a steel girder type and a truss bridge based on acceleration responses to operational loading. The method relies on sensor clustering-based time-series analysis of the operational acceleration response of the bridge to the passage of a moving vehicle. The results are presented in terms of Damage Features from each sensor, which are obtained by comparing the actual acceleration response from the sensors to the predicted response from the time-series model. The damage in the bridge is detected by observing the change in damage features of the bridge as structural changes occur in the bridge. The relative severity of the damage can also be quantitatively assessed by observing the magnitude of the changes in the damage features. The experimental results show the potential usefulness of the proposed method for future applications on condition assessment of real-life bridge infrastructures.

• Nuclear Engineering and Technology
• /
• v.50 no.8
• /
• pp.1402-1411
• /
• 2018

Nuclear-related facilities can be detrimentally affected by ground vibrations due to the collapse of adjacent cooling towers in nuclear power plants. To reduce this hazard risk, a design-oriented acceleration response spectrum (ARS) was proposed to predict the dynamic responses of nuclear-related facilities subjected to ground vibrations. For this purpose, 20 computational cases were performed based on cooling tower-soil numerical models developed in previous studies. This resulted in about 2664 ground vibration records to build a basic database and five complementary databases with consideration of primary factors that influence ground vibrations. Afterwards, these databases were applied to generate the design-oriented ARS using a response spectrum analysis approach. The proposed design-oriented ARS covers a wide range of natural periods up to 6 s and consists of an ascending portion, a plateau, and two connected descending portions. Spectral parameters were formulated based on statistical analysis. The spectrum was verified by comparing the representative acceleration magnitudes obtained from the design-oriented ARS with those from computational cases using cooling tower-soil numerical models with reasonable consistency.