• Journal of Animal Environmental Science
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• v.14 no.1
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• pp.53-60
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• 2008

This study was carried out to measure and analyze the vibration levels and modes produced by a hopper type feeder used at laying hen farms, to prevent the vibration resonance and to reduce the vibration of the hopper type feeder (6-tier). The most vibration in a layer house were produced by hopper type feeder as shown the previous study. According to the measurement results, the ratio of transmissibility was as high as 100-638% for natural frequency of 170 Hz or less. And vibration simulations were taken by the results of vibration mode analysis and the weakest points to vibrations were determined accordingly. Then measurement and analysis were taken for those points. The quantities of vibration were 4.6354-4.9118 g($g=9.81^m/s^2$) by axis. In this study, it was found that hopper type feeder generated vibration as much as to influence the ratio of laying eggs of layer. And by the analysis of vibration on the weakest points, design methods and equipment were suggested for isolating/reducing of vibration by each axis.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.5
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• pp.259-264
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• 2000

In this paper, the characteristics of piezoelectric transformer is studied for driving CCFL(Cold Cathode Fluorescent Lamp). In order to investigate the effects of geometrical dimensions, λvibration-mode type piezoelectric transformers with different sizes in the length(l), width$(\omega)$ and thickness(t) are made of ceramics with PZT-PMWS compositions. The increases in temperature and aging effect are also measured in the transformer of PT-3 sample under the condition of operation continuously for 10 hrs. As the results of dimensional effects, the output power and voltage step-up ratio are largely affected by the ratio of length to thickness(l/t) rather than that of length to $width(l/\omega)$. The output power and step-up ratio are increased with increasing l/t. On case of PT-3, the output voltages are 510[Vrms] at 36[Vrms] in input voltage, $100[k\Omega]$ in load resistance. Temperature increases and variation of output voltages are $10[^{\circ}C]$ and less than 5[%], respectively.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2559-2562
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• 2009

The lattice vibration and crystal structure of alkaline earth metal-substituted $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$ (A = Ca, Sr, and Ba) have been investigated with micro-Raman spectroscopy. The present $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$ materials show not only several weak Raman peaks corresponding to the vibrations of $O_{Cu}$ and $O_{Ru}$ but also strong characteristic phonon lines related to $O_{Sr}$ vibration mode. A comparison between the frequency of $O_{Sr}$ vibration and the bond distances of (Ru$O_{Sr}$) and (Cu‒$O_{Sr}$) in the present ruthenocuprates reveals that the vibration energy of $O_{Sr}$ is mainly dependent on the bond distance of (Ru‒$O_{Sr}$). The peak splitting of the $O_{Sr}$ phonon lines was observed for the unsubstituted $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$, suggesting the existence of two different (Ru‒$O_{Sr}$) bond distances. Such a peak splitting caused by the appearance of low-energy shoulder reflects the presence of internal charge transfer pathway from the $RuO_2$ plane to the superconductive $CuO_2$ one. After the substitution of Sr with Ca or Ba, the low-energy shoulder peak of $O_{Sr}$ vibration becomes suppressed, underscoring the depression of internal charge transfer between the $RuO_2$ and $CuO_2$ planes. The weakened role of $RuO_2$ layer as charge reservoir in the $RuSr_{1.9}A_{0.1}GdCu_{2}O_{8}$8 (A = Ca, Ba) would be responsible for the depression of $T_c$ upon the Ca/Ba substitution.

• Earthquakes and Structures
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• v.21 no.5
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• pp.551-562
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• 2021

In this study, the generalized intensity measure (IM) named I_Npg is analyzed. The recently proposed proxy of the spectral shape named N_pg is the base of this intensity measure, which is similar to the traditional N_p based on the spectral shape in terms of pseudo-acceleration; however, in this case the new generalized intensity measure can be defined through other types of spectral shapes such as those obtained with velocity, displacement, input energy, inelastic parameters and so on. It is shown that this IM is able to increase the efficiency in the prediction of nonlinear behavior of structures subjected to earthquake ground motions. For this work, the efficiency of two particular cases (based on acceleration and velocity) of the generalized I_Npg to predict the peak floor acceleration demands on steel frames under 30 earthquake ground motions with respect to the traditional spectral acceleration at first mode of vibration Sa(T₁) is compared. Additionally, a 3D reinforced concrete building and an irregular steel frame is used as a basis for comparison. It is concluded that the use of velocity and acceleration spectral shape increase the efficiency to predict peak floor accelerations in comparison with the traditional and most used around the world spectral acceleration at first mode of vibration.

• Structural Engineering and Mechanics
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• v.9 no.1
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• pp.17-35
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• 2000

Dynamic response of a three span continuous bridge has been determined by full scale experiments on the bridge. In the experiments, a heavy vehicle was driven across the bridge at different speeds and along different lanes of travel and the strains were recorded at different locations. The bridge was made of reinforced concrete and was asymmetric in plan and in elevation. Frequencies and modes of vibration excited by the vehicle were determined. The dependence of the dynamic amplification on bridge location and vehicle speed was investigated and dynamic amplifications up to 1.5 were recorded, which was higher than values predicted by bridge design codes. It was evident that when this asymmetric bridge was loaded by an asymmetric forcing function, higher modes, which are lateral and/or torsional in nature, were excited. Dynamic modulus of elasticity and the support stiffness influenced the natural frequencies of the bridge, which in turn influenced the dynamic amplifications. Larger than anticipated dynamic amplification factors and the excitation of lateral and/or torsional modes should be of interest and concern to bridge engineers.

• Structural Engineering and Mechanics
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• v.15 no.1
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• pp.115-134
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• 2003

The Ting Kau Bridge in Hong Kong is a cable-stayed bridge comprising two main spans and two side spans. The bridge deck is supported by three towers, an end pier and an abutment. Each of the three towers consists of a single reinforced concrete mast which reduces its section in steps, and it is strengthened by transverse cables and struts in the transverse vertical plane. The bridge deck is supported by four inclined planes of cables emanating from anchorages at the tower tops. In view of the threat from typhoons, the dynamic behaviour of long-span cable-supported bridges in the region is always an important consideration in their design. This paper is devoted to the ambient vibration measurements of the bridge for evaluation of dynamic characteristics including the natural frequencies and mode shapes. It also describes the modelling of the bridge. A few finite element models are developed and calibrated to match with the field data and the results of subsequent structural health monitoring of the bridge.

• Structural Engineering and Mechanics
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• v.34 no.6
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• pp.719-738
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• 2010

The aim of this paper concerns with the nonlinear analysis of cable-stayed bridges including the vibration effect of cable stays. Two models for the cable stay system are built up in the study. One is the OECS (one element cable system) model in which one single element per cable stay is used and the other is MECS (multi-elements cable system) model, where multi-elements per cable stay are used. A finite element computation procedure has been set up for the nonlinear analysis of such kind of structures. For shape finding of the cable-stayed bridge with MECS model, an efficient computation procedure is presented by using the two-loop iteration method (equilibrium iteration and shape iteration) with help of the catenary function method to discretize each single cable stay. After the convergent initial shape of the bridge is found, further analysis can then be performed. The structural behaviors of cable-stayed bridges influenced by the cable lateral motion will be examined here detailedly, such as the static deflection, the natural frequencies and modes, and the dynamic responses induced by seismic loading. The results show that the MECS model offers the real shape of cable stays in the initial shape, and all the natural frequencies and modes of the bridge including global modes and local modes. The global mode of the bridge consists of coupled girder, tower and cable stays motion and is a coupled mode, while the local mode exhibits only the motion of cable stays and is uncoupled with girder and tower. The OECS model can only offers global mode of tower and girder without any motion of cable stays, because each cable stay is represented by a single straight cable (or truss) element. In the nonlinear seismic analysis, only the MECS model can offer the lateral displacement response of cable stays and the axial force variation in cable stays. The responses of towers and girders of the bridge determined by both OECS- and MECS-models have no great difference.

• Structural Engineering and Mechanics
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• v.64 no.4
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• pp.473-485
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• 2017

An isolated building, composed of superstructure and isolation system which have very different damping properties, is typically non-classical damping system. This results in inapplicability of traditional response spectrum method for isolated buildings. A multidimensional response spectrum method based on complex mode superposition is herein introduced, which properly takes into account the non-classical damping feature in the structure and a new method is developed to estimate velocity spectra from the commonly used displacement or pseudo-acceleration spectra based on random vibration theory. The error of forced decoupling method, an approximated approach, is discussed in the viewpoint of energy transfer. From the base-isolated benchmark model, as a numerical example, application of the procedure is illustrated companying with comparison study of time-history method, forced decoupling method and the proposed method. The results show that the proposed method is valid, while forced decoupling approach can't reflect the characteristics of isolated buildings and may lead to insecurity of structures.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.2
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• pp.132-151
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• 1993

The proposed method in this paper. termed the substructural reanalysis technique, utilizes the computational merits of the component mode synthesis technique and of reanalysis technique for the design sensitivities of the dynamic characteristics of substructurally combined structure. It is shown that the dynamic characteristics of the entire structure can be obtained by synthesizing the substructural eigensolution and the characteristics of the eigensolution for the design variables of the modifiable substructure. In this paper , the characteristics of the eigenvalue problems obtained by this proposed method are compared to exact eigensolution in terms of accuracy and computational efficiency. and the advantage of this proposed method as compared to the direct application of the whole structure and experimental results is demonstrated through examples of numerical calculation for the dynamic characteristics (natural frequencies and mode shapes) of a flexible vibration of thin cylinderical shell with branch shell under 2-end fixed positions, boundary condition. Thin cylinderical shell of overall length 1280mm, external diameter 360mm, thickness 3mm with branch shell is made of mild steel. The load condition for dynamic response in this paper is impulsive load of which magnitude is 10kgf, which have short duration of 0.1 sec. and time interval applied to calculate. $\Delta$T is 1.0$\times$10 super(-4) seconds.

• Structural Engineering and Mechanics
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• v.11 no.1
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• pp.71-87
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• 2001

A frequency domain response analysis is presented for building frames passively controlled by viscoelastic dampers, under harmonic ground excitation. Three different models are used to represent the linear dynamic force-deformation characteristics of viscoelastic dampers namely, Kelvin model, Linear hysteretic model and Maxwell model. The frequency domain solution is obtained by (i) an iterative pseudo-force method, which uses undamped mode shapes and frequencies of the system, (ii) an approximate modal strain energy method, which uses an equivalent modal damping of the system in each mode of vibration, and (iii) an exact method which uses complex frequency response function of the system. The responses obtained by three different methods are compared for different combinations of viscoelastic dampers giving rise to both classically and non-classically damped cases. In addition, the effect of the modelling of viscoelastic dampers on the response is investigated for a certain frequency range of interest. The results of the study are useful in appropriate modelling of viscoelastic dampers and in understanding the implication of using modal analysis procedure for building frames which are passively controlled by viscoelastic dampers against base excitation.