• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.925-933
• /
• 2006

Using the physics-based model for the vibration isolation system, the model uncertainties are described. With the model including parameter perturbations, the robust controller to meet the robust performance and stability is designed through $\mu$-synthesis by DK-iteration. The order of controller is reduced by virtue of Hankel norm approximation technique to allow the efficient implementation in the real-time experimental environment without any performance degradation. The performance of the reduced $\mu$-controller is accessed in comparison with the original one. The experiments validate the superiority of the proposed control scheme against the model uncertainties and its applicability with varying payload.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.12 s.117
• /
• pp.1262-1271
• /
• 2006

Using the physics-based model for the vibration isolation system, the model uncertainties are described. With the model including parameter perturbations, the robust controller to meet the robust performance and stability is designed through $\mu$-synthesis by DK-iteration. The order of controller is reduced by virtue of Hankel norm approximation technique to allow the efficient implementation in the real-time experimental environment without any performance degradation. The performance of the reduced $\mu$-controller is accessed in comparison with the original one. The experiments validate the superiority of the proposed control scheme against the model uncertainties and its applicability with varying payload.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.04a
• /
• pp.166-170
• /
• 2008

In this study, it proved that transfer path analysis is a proper technique to estimate the interior noise from comparing measured interior noise in case of 3 point supported engine mount system. And the simulation of the vibration isolation for active engine mount using FXLMS algorithm is performed. Also, it verified that reduction of estimated interior noise from transfer path analysis and simulation of the vibration isolation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.291-298
• /
• 2000

This paper describes a theoretical and experimental investigation into an active vibration isolation system in which four electromagnetic actuators are installed in parallel with each of four passive mounts placed between a piece of equipment and a vibrating base structure. Decentralised velocity feedback control is employed, where each actuator is operated independently by feeding back the absolute equipment velocity at the same location. Although one end of each actuator acts at the sensor positions on the equipment, the control system is not collocated because of the reactive forces acting on the flexible base structure, whose dynamics are strongly coupled with the mounted equipment. Isolation of low frequency vibration is considered where the equipment can be modelled as a rigid body and the mounts as lumped parameter springs and dampers. Control mechanisms are discussed, and some experimental and simulation results are reported.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1772-1777
• /
• 2000

The Combat Computer Consoles installed in surface ships should endure harsh environment such as vibration from engine or propeller and shock from underwater explosion. Generally, commercial isolation mounts are selected and used for anti-vibration and anti-shock design. In this research, the environment of the Combat Computer Console was analyzed first. Selected proper mount was modeled and computer simulation was performed to emulate the environment test. The real environment test was conducted with a manufactured Combat Computer Console. The test results were same as the simulation and satisfied the performance requirements. The computer simulation proved to be a useful design tool to predict the performance before the final environment test.

• Earthquakes and Structures
• /
• v.6 no.3
• /
• pp.281-300
• /
• 2014

This study proposes a scheme to design control parameters for a data center facility with a vibration controller on its top floor and a secondary isolation device with its own vibration controller designed to protect vibration-sensitive computer equipment. The aim is to reduce the effects of acceleration and drift from an earthquake on computer servers placed on the isolation device that must operate during a seismic event. A linear elastic model is constructed and the evaluation function of the linear quadratic Gaussian (LQG) control is formulated. The relationship between the control parameters and the responses is examined, and based on the observations, a control parameter design scheme is constructed to reduce the responses of both the building and the computer server effectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.933-939
• /
• 2001

A Satellite shipping container must afford the satellite a relatively benign thermal, vibration, and particle environment that is oblivious to the extreme temperatures, sand, dust, vibrations and shocks that can accompany the transportation. In this study, we have designed a vibration isolation system of a spacecraft container that will be used to transport a satellite called KOMPSAT (KOrea Multi-Purpose SATellite) -2 from KARI (Korea Aerospace Research Institute) Taejon to its launch site. To identify the dynamic characteristics of the system, a 1/3-scaled mockup of the container was developed. A large electro-magnetic shaker (Max. 240 KN) was used to excite the mockup, and vibration signals from 20 points were collected for modal tests. Numerical simulations through CATIA 3D Modeling were performed to identify the behavior of isolation springs. The results showed that a simplified model predicts the behavior in a reasonable accuracy. Moreover, the model guides us how to design a full-scaled satellite-shipping container.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.4
• /
• pp.436-442
• /
• 2016

This paper presents the torsional vibration isolation performance evaluation of a centrifugal pendulum absorbers (CPAs) that has a continuously varying resonance frequencies proportional to engine firing (excitation) order. CPAs are commonly used to suppress torsional vibrations in rotating machinery and internal combustion engines. In this study, they are employed on the current spring type torsional damper inside a torque converter of automotive vehicle. To evaluate the effectiveness of designed resonance tuning order, the torsional vibration transmissibility based on torque measurements with respect to different engine firing orders is experimentally measured with a lower-inertia dynamometer. The torsional vibration transmissibility with respect to different frequencies with engine order of 2 is also evaluated. It has been demonstrated that the significant vibration reduction over operational frequency range of interest can be achieved by attaching simple pendulums. Future research direction includes the study on theoretical analysis, improved design of pendulum etc.

• Earthquakes and Structures
• /
• v.15 no.4
• /
• pp.411-417
• /
• 2018

To solve the seismic response problem of a vertical floating roof tank with base isolation, the floating roof is assumed to experience homogeneous rigid circular plate vibration, where the wave height of the vibration is linearly distributed along the radius, starting from the theory of fluid velocity potential; the potential function of the liquid movement and the corresponding theoretical expression of the base shear, overturning the moment, are then established. According to the equivalent principle of the shear and moment, a simplified mechanical model of a base isolation tank with a swinging effect is established, along with a motion equation of a vertical storage tank isolation system that considers the swinging effect based on the energy principle. At the same time, taking a 150,000 m 3 large-scale storage tank as an example, a numerical analysis of the dampening effect was conducted using a vibration mode decomposition response spectrum method, and a comparative analysis with a simplified mechanical model with no swinging effect was applied.

• Journal of KSNVE
• /
• v.2 no.4
• /
• pp.273-280
• /
• 1992

The prediction of vibration response of floor is necessary in order to check whether the floor vibration level will satisfy the allowable vibration standard of precise machinery such as electronic microscopes in semiconductor manufacturing plant before the installation of various neighboring equipment facility. In conventional vibration isolation, we were mainly interested in minimization of vibration transmissibility and stabilization of vibration isolation system. But in order to predict vibration response of floor, it is necessary to know exciting force of equipment installed on the floor and the mobility of the floor. We measured the exciting force of the dropped mass assumed as equipment and the mobility of some practical building floor using large impact hammer. And from this we predicted the vibration response of floor on which the mass dropped. This predicted vibration response of floor is compared with measured vibration response. Through upper procedure, we examined the possibility of predicting vibration response of floor from the information of exciting force of equipment and the mobility of floor.