• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.492-497
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• 2002

In this paper, Power Flow Analysis(PFA) method has been applied to the prediction of vibration energy density and intensity of coupled shell structures in the medium-to-high frequency ranges. To consider the wave transformation at joint between shell elements, power transmission and reflection coefficients are investigated for various joint angles, and here Donnell-Mushtari thin shell theory has been used. For validations computations are performed to analyze the response of coupled shells by changing the excitation frequency and damping loss factor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.544-549
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• 2011

Simplified formulae for axial and bending natural frequencies of bellows are developed using an equivalent thin-walled pipe model. The axial and bending stiffness of bellows is determined using lumped transfer matrix method. Accordingly, the Expansion Joint Manufacturers Association (EJMA) formula for axial and bending stiffness calculation is modified using two different equivalent radii. The results from the simplified formulae are verified by those from a experiment result and a finite element (FE) model and good agreement is shown between the each other.

• Wind and Structures
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• v.29 no.5
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• pp.361-369
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• 2019

The modal frequency responses of adhesive bonded T-joint structure have been analyzed numerically and verified with own experimental data. For this purpose, the damped free frequencies of the bonded joint have been computed using a three-dimensional finite element model via ANSYS parametric design language (APDL) code. The practical relevance of the joint structure analysis has been established by comparing the simulation data with the in-house experimental values. Additionally, the influences of various geometrical and material parameters on the damped free frequency responses of the joint structure have been investigated and final inferences discussed in details. It is observed that the natural frequency values increase for the higher aspect ratios of the joint structure. Also, the joint made up of Glass fiber/epoxy with quasi-isotropic fiber orientation indicates more resistance towards free vibration.

• Journal of Ship and Ocean Technology
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• v.6 no.2
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• pp.1-11
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• 2002

For the analysis of vibrational energy density and intensity of partitioned complex system structures in medium-to-high frequency ranges, A software based on the Power Flow Analysis(PFA) has been developed for the plate elements. The flexural, longitudinal and shear waves in plates are formulated and the joint element equations for multi-coupled plates are fully developed. Also, the wave transmission approach has been introduced to cover the energy transmission and reflection at the joint plate elements. To confirm the validity of the developed PFA software, the submarine-shaped complex structures are used for the analysis of vibration intensity and energy density.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.347.2-347
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• 2002

This paper presented a design and a Vibration control of a biped walking RGO(Robotic Gait Orthosis) and walking simulation by this system. The vibration evaluation of the Knee Joint Mechanism on the biped walking RGO(Robotic Galt Orthosis) was used to access by the 3-axis accelerometer with a low frequency vibration for the spinal cord injuries. It will be expect that the spinal cord injury patients are able to recover effectively by a biped walking RGO. (omitted)

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.12
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• pp.929-934
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• 2002

This paper considers the vibration Problem of vehicle driveline which consists of two propeller shafts and the center bearing. The excessive vibration occurs at the center bearing when the vehicle starts to run. Using the kinematic constraints at the universal joint between two propeller shafts, we developed an one d.o.f model which describes the radial motion of the center bearing. We found out that the vibration occurs at the specific vehicle speed corresponding to the natural frequency of the model. Comparing the simulation results with test results we also show that the vibration at low vehicle speed is caused primarily by the feint angle and secondarily by the mis-aligned yoke flange rather than by the unbalance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.36-40
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• 2008

This study is analyzed by the simulation of automotive steering system. The maximum equivalent stress of $2.2418{\times}109Pa$ and the maximum total displacement of 0.014929m are shown at the universal joint and its lower part respectively. As the minimum cycle of 34.047 is shown at the universal joint in case of fatigue analysis, it is possible to have greatest damage at this part. In case of natural frequency analysis at vibration, its frequency of 47 to 59Hz is occurred generally. The maximum total displacement of 0.5m is shown at handle on the natural frequency of 57 to 58Hz. And the displacement over 2m is shown at the lower part of universal joint on the natural frequency of 58 to 59Hz. As the basis of the simulation analysis of steering system, passenger's comfort of car body can be improved in the design of practical part and the design effect necessary to safe driving can be promoted.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.1-7
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• 2010

The paper proposes a multi-body dynamic simulation to numerically evaluate the generated axial force(G.A.F) and plunging resistant force(P.R.F) practically related to the shudder and idling vibration of an automobile. A numerical analysis of two plunging types of CV joints, tripod joint(TJ) and very low axial tripod joint(VTJ), is conducted using the commercial program DAFUL. User-defined subroutines of a friction model illustrating the contacted parts of the outboard and inboard joint are subsequently developed to overcome the numerical instability and improve the solution performance. The Coulomb friction effect is applied to describe the contact models of the lubricated parts in the rolling and sliding mechanisms. The numerical results, in accordance with the joint articulation angle variation, are validated with experimentation. The offset between spider and tulip housing is demonstrated to be the critical role in producing the 3rd order component of the axial force that potentially causes the noise and vibration in vehicle. The VTJ shows an excellent behavior for the shudder when compared with TJ. In addition, a flexible nonlinear contact analysis coupled with rigid multi-body dynamics is also performed to show the dynamic strength characteristics of the rollers, housing, and spider.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.1
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• pp.28-40
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• 2015

This paper aims to address the intelligent active vibration control problem of a flexible rectangular plate vibration involving parameter variation and external disturbance. An adaptive sliding mode (ASM) MIMO control strategy and smart piezoelectric materials are proposed as a solution, where the controller design can deal with problems of an external disturbance and parametric uncertainty in system. Compared with the current 'classical' control design, the proposed ASM MIMO control strategy design has two advantages. First, unlike existing classical control algorithms, where only low intelligence of the vibration control system is achieved, this paper shows that high intelligent of the vibration control system can be realized by the ASM MIMO control strategy and smart piezoelectric materials. Second, the system performance is improved due to two additional terms obtained in the active vibration control system. Detailed design principle and rigorous stability analysis are provided. Finally, experiments and simulations were used to verify the effectiveness of the proposed strategy using a hardware prototype based on NI instruments, a MATLAB/SIMULINK platform, and smart piezoelectric materials.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.861-865
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• 2001

Generally the noise and vibration characteristics of 4WD vehicle is closely related to the characteristics of driveline such as bending mode, torsional mode, unbalance and nonuniformity of propeller shaft. In this paper the 4WD vehicle which has body vibration problem in high speed driving condition was tested. The sources of the body vibration and its transfer path are investigated by experimental approach. According to the experimental assessment, the body vibration is caused by the nonuniformity of joint of propeller shaft. And this paper presents a kinematic model of a vehicle driveline for the optimization of a driveline characteristics. Finally the optimized result of the drive line has been verified through the experiment.