• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.74-79
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• 2002

The piping verification tests were performed in order to verify the structural integrity during initial operation of the reactor coolant systems and the primary heat transportation systems of nuclear power plants by KEPRI in Korea. The tests were conducted at full operating temperature and pressure. The objective is to evaluate the possibility of excessive load generating on piping, piping supports, and reactor structures etc. in the steady normal operation and expected pump transient conditions. As a result, the measured vibrations have been shown acceptable level according to ASME/ANSI OMa-Standard, Part 3.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.605-610
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• 2002

Eigenvalues are taken as performance criteria for structural damping design using viscoelastic material. Given material properties, optimal distribution of damping material is sought based on eigenvalue sensitivity. For eigenanalysis of frequency dependent viscoelastic material treated structures, Golla-Mushes-McTavish (GHM) model is used and some dominant modes are chosen for consideration. To avoid the intensity of computation caused by increased problem size, an alternative approximate method is proposed which uses elastic modes and can be applied under small damping assumption. A cantilever beam treated with unconstrained viscoelastic layer is tested and optimal distribution of thickness of the layer is illustrated. Partial coverage configurations are compared with the one-sided full coverage case.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.233-237
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• 2014

In this paper, the finite element modeling of the RK4 rotor kit system (RK4) and then frequency analysis and transient analysis, and was compared with the actual experimental results. RK4 manufactured by General Electric for the purpose of education and research. It is composed of two shaft, Two shaft is connected using a flexible coupling, one disk is mounted. The analytical model is modeled by using the ANSYS finite element analysis program commercially available. Based on impact hammer test results, material properties and the stiffness of the bearing and coupling was tuned. Considering the operating conditions and the vibration response of the analytical model were compared with experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.876-879
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• 1996

The vibration of an attractive magnetic levitation(Maglev) vehicle transportation system is caused by the irregularity of the guideway track and the performance of the suspensions of the Maglev system. It is essential for us to give attention to the secondary suspension of the vehicle system as it determines the ride quality. In order to improve the ride quality and running stability, active secondary suspensions have been developed and applied to the vibration problems. This paper analyzes the performance of the active secondary suspension which is applied to an attractive magnetic levitation vehicle system running on a rough track. The dynamics of the suspension system and the optimal control problems are studied. According to the transient and frequency response analyses to the track disturbance, the ride quality of an attractive Maglev vehicle has been improved by applying the designed LQR active controller, and it has been confirmed that this improvement was also influenced by the configuration of the system.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.324-330
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• 2013

The dispersion of acoustic noise during the turn-on and turn-off switching of HEV(hybrid electric vehicle) relay was experimentally analyzed to identify the reason for the dispersion of noise level. An effective method was proposed to reduce the dispersion of noise level. First, a method to wrap the side of moving core with a tape was adopted to reduce the transverse vibration. It enabled the moving core to make a consistent motion and reduce the dispersion of noise level from switching operation of relay. Second, the dispersion of noise level from vibration transmission of parts such as the outer frame and yoke caulking part of relay were tested to find out main sources. From this result, it was identified that the yoke caulking part made inconsistent transient vibration and noise dispersion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.315.1-315
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• 2002

The piping verification tests were performed in order to verify the structural integrity during initial operation of the reactor coolant systems and the primary heat transportation systems of nuclear power plants by KEPRI in Korea. The tests were conducted at full operating temperature and pressure. The objective is to evaluate the possibility of excessive load generating on piping, piping supports, and reactor structures etc. in the steady normal operation and expected pump transient conditions. (omitted)

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.395-403
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• 2005

The dynamic characteristics of delaminated smart composite laminates are studied using animproved layerwise laminate theory. The theory is capable of capturing interlaminar shear stresses that are critical to delamination. The presence of discrete delamination is modeled through the use of Heaviside unit step functions. Stress free boundary conditions are enforced at all free surfaces. Continuity in displacement field and transverse shear stresses are enforced at each ply level. In modeling piezoelectric composite plates, a coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. Numerical analysis is conducted to investigate the effect of nonlinearity in the transient vibration of bimodular behavior caused by the contact impact of delaminated interfaces. Composite plates with delamination, subject to external loads and voltage history from surface bonded sensors, are investigated and the results are compared with corresponding experimental results and plates without delamination.

• Journal of KSNVE
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• v.9 no.1
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• pp.33-41
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• 1999

This paper presents a method of actively controlling the interior noise by a trim panel with hybrid feedforward-feedback control loop. The control technique is designed to minimize the vibration of panel whose motion is limited to that of a piston (out-of-plane motion). The hybrid controller consists of an adaptive feedforward controller in conjunction with a linear quadratic Gaussian (LQG) feedback controller. In order to maintain control performance of both persistent and transient disturbances, the feedback loop speeds up the adaptation rate of feedforward controller by improving damping capacity of secondary plant related with the adaptation rule. Numerical simulation and experimental result indicate that the hybrid controller is a more effective method for reducing the vibration of the panel (and therefore the interior noise) compared to using feedforward controller.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.310-317
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• 2006

Currently most practical vibration and structural problems in automotive suspensions require the use of the finite element method to obtain their structural responses. When the finite element model has a very large number of degrees of freedom the harmonic and dynamic analyses are computationally too expensive to repeat within a feasible design process time. To alleviate the computational difficulty, this paper presents a moment-matching based model order reduction (MOR) which reduces the number of degrees of freedom of the original finite element model and speeds up the necessary simulations with the reduced-size models. The moment-matching model reduction via the Arnoldi process is performed directly to ANSYS finite element models by software mor4ansys. Among automotive suspension components, a knuckle is taken as an example to demonstrate the advantages of this approach for vibration simulation. The frequency and transient dynamic responses by the MOR are compared with those by the mode superposition method.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.319-322
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• 2006

This paper deals with the HVDC system fault analysis and the sound noise analysis. In this paper, the reasons of the audible noise and vibration were analyzed, the fault waveform were analyzed using DTR (Digital Transient Recorder). Finally, using the fault current waveform and the vibration equation, the reason of crack of smoothing reactor support is estimated.