• Journal of KSNVE
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• v.9 no.1
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• pp.174-183
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• 1999

An analytical model for the lateral vibration of beams with a bonded lap joint and partial layered dampers has been proposed in this paper. Both shear and normal forces acting along the interface between the elastic and viscoelastic layers were considered in the vibration analysis. Analytical results were compared with those obtained by a finite element method. Effects of the size and location of layers in partial dampers on system loss factor($\eta_s$) and resonant frequency($\omega_r$) were studied. which showed that partial dampers adhered to the site exhibiting the maximum amplitude of vibration were most influential in the increase of $\eta_s$ and the decrease of $\omega_r$. Specific system loss factor( $\eta_s$ divided by total mass of system) was also evaluated in the analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.974-978
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• 2006

To improve the riding comfort and to increase the speed of high-speed railway, it needs active suspension system for railway more and more. In Korea, Korean Train Express (KTX) was opened to commercial traffic 2years ago. Korea High-speed Railway (HSR 350x) is being developed and succeeded 350km/h test run. With the increase of the speed, the vibration control of the high-speed railway becomes important to meet high ride quality. In this paper, we suggest the install of lateral damper to HSR 350x. The result shows better ride quality.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.94-99
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• 2000

When operating NC lathe, gear box which is equipped with gear train and spindle sometimes generates loud noise and excessive vibrations. In order to identify their causes, In this study, torsional and lateral vibration characteristics including critical speeds of the gear train-spindle system are first analyzed by using torsional and lateral vibration models of the gear train and shafts. Natural frequencies and modes of the gear box structure are also analyzed by impulse hammer test. Furthermore, measured vibration and noise signals are analyzed and compared with theoretical analysis results. At last it is concluded that the cause of the excessive mise and vibration is the resonance between gear meshing frequency including its side bands, shaft bending and torsional vibration frequencies, and the natural frequencies of th gear box structure. Consequently the noise and vibration levels are greatly reduced by avoiding resonance between them through the redesign of the gear module.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.3-10
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• 2002

Recently, arches are used structurally because of their high in-plane stiffness and strength, which result from their ability to transmit most of the applied loading by axial forces actions, so that the bending actions are reduced. On the other hand, the resistances of arches to (out-of-plane,) flexural-torsional behavior depend on the rigidities EI/sub y/, for lateral bending, GJ for Uniform torsion, and EI/sub w/ for warping torsion which are related to axial stress for flexural-torsional behavior. The resistance of an arch to out-of-plane behavior may be reduced by its in-plane curvature, and so it may require significant lateral bracing. Thus. it is supposed that In-plane preloading which cause an axial stress, have an effect on out-of-plane free vibration behavior of arches. Because axial stresses caused increase or decrease out-of-plane stiffness. But study about this substance is insufficient. In this thesis, We will study an effect of preloading on lateral free vibration of arches, using finite element method based on Kang and Yoo's curved beam theory (about curved beam element have 7 degree of freedom including warping) with FORTRAN programming.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.131-136
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• 2008

The transducer for multi-directionally movable ultrasonic motor having lambda shaped vibrators has been proposed and designed. The two branches cross at a right angle with each other at the tip. FEM analyses of lambda shaped transducer were carried out to find vibration modes for ultrasonic motor. The lambda shaped transducer has one symmetric mode and two anti-symmetric modes. The symmetric mode generates the normal direction motion of the tip. The lateral and vertical direction motion of the tip are excited by two anti-symmetric modes. The normal and lateral direction motions made an lateral elliptic trajectory. And the normal and vertical direction motions made an vertical elliptic trajectory normal to previous one. The transducer with 1 mm in thickness and 25 mm in length has been fabricated and evaluated. The resonance frequencies of the transducer was 32 kHz and 103 kHz. The tangential and vertical vibration displacement of the transducer having the lateral elliptic trajectory were $1.5{\mu}m\;and\;1.1{\mu}m$, respectively at the driving voltage of 100 Vpp and frequency of 32 kHz and 103 kHz. And the tangential and vertical vibration displacement of the transducer having the vertical elliptic trajectory were $0.4{\mu}m\;and\;0.2{\mu}m$, respectively at the same driving condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.583-588
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• 2002

As environmental problem in course of construction has been a matter of interest, noise and vibration in the process of piling are considered as a serious problem. For this reason, the use of SIP method inserting pile as soon as boring and cement grouting is rapidly increasing for preventing vibration and noise. But a resonable bearing capacity formula for SIP method does not exit and even the standard specification for domestic condition isn't formed, though the lateral friction between cement paste and the ground does an important role and boring depth largely influences to the design bearing capacity, applying the SIP method . Therefore, the lateral friction was analyzed after the direct shear test worked with the lateral face of SIP and the soil.

• Smart Structures and Systems
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• v.19 no.4
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• pp.393-402
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• 2017

Many vibration-based global damage detection methods attempt to extract modal parameters from vibration signals as the main structural features to detect damage. The local flexibility method is one promising method that requires only the first few fundamental modes to detect not only the location but also the extent of damage. Generally, the mode shapes in the lateral degree of freedom are extracted from lateral vibration signals and then used to detect damage for a beam structure. In this study, a new approach which employs the mode shapes in the rotary degree of freedom obtained from the macro-strain vibration signals to detect damage of a beam structure is proposed. In order to facilitate the application of mode shapes in the rotary degree of freedom for beam structures, the local flexibility method is modified and utilized. The proposed rotary approach is verified by numerical and experimental studies of simply supported beams. The results illustrate potential feasibility of the proposed new idea. Compared to the method that uses lateral measurements, the proposed rotary approach seems more robust to noise in the numerical cases considered. The sensor configuration could also be more flexible and customized for a beam structure. Primarily, the proposed approach seems more sensitive to damage when the damage is close to the supports of simply supported beams.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.143-152
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• 2010

Development and verification of whole vibration test system was requested for developing a geostationary satellite. This satellite is enlarged significantly compared with fore-satellite in KARI. For vertical vibration test, new vertical vibration system was developed. For lateral vibration test, thermal equilibrium test was performed because of difference of thermal characteristics between test adapter and slip table. And lateral vibration system performance for overturning moment was verified by analysis and test. As the number of acquisition channels was increased, new shaker control and data acquisition system was installed. In this paper, verification process and techniques to improve test stability are introduced for the whole vibration test system.

• Wind and Structures
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• v.11 no.2
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• pp.153-178
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• 2008

Based on the empirical formulas for power spectra of generalized modal forces and local fluctuating wind forces in across-wind and torsional directions, the wind-induced lateral-torsional coupled response analysis of a representative rectangular tall building was conducted by setting various parameters such as eccentricities in centers of mass and/or rigidity and considering different torsional to lateral stiffness ratios. The eccentricity effects on the lateral-torsional coupled responses of the tall building were studied comprehensively by structural dynamic analysis. Extensive computational results indicated that the torsional responses at the geometric center of the building may be significantly affected by the eccentricities in the centers of mass and/or rigidity. Covariance responses were found to be in the same order of magnitude as the along-wind or across-wind responses in many eccentricity cases, suggesting that the lateral-torsional coupled effects on the overall wind-induced responses can not be neglected for such situations. The calculated results also demonstrated that the torsional motion contributed significantly to the total responses of rectangular tall buildings with mass and/or rigidity eccentricities. It was shown through this study that the framework presented in this paper provides a useful tool to evaluate the wind-induced lateral-torsional coupled responses of rectangular buildings, which will enable structural engineers in the preliminary design stages to assess the serviceability of tall buildings, potential structural vibration problems and the need for a detailed wind tunnel test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.17-23
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• 2013

In a subway vehicle, a lateral damper is used for compensating the lateral stiffness deterioration due to the air-spring as a secondary suspension. This lateral damper can reduce the lateral vibration of the carbody. When the damping force of the lateral damper is lowered, the running stability and ride quality of the subway vehicles worsens and the lateral motion of the carbody is increased. In this study, the lateral displacement variation of the carbody according to the damping force of the lateral damper was analyzed by multi-body dynamics to solve the abnormal impact problem during vehicle operation. Furthermore, the noise and vibration due to abnormal impact were considered. An adequate damping coefficient of the lateral damper for the subway vehicle treated in this paper was suggested for preventing abnormal impact.