• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.18-25
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• 2008

• 연구논문집
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• s.29
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• pp.83-90
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• 1999

In naval ships, pump machineries are the major sources of airborne and structure-borne noise. Noise is critical issue in ships not only it causes annoyance to crews, but also it can increase the underwater radiated noise, which is crucial in anti-submarine warfare. In present study, it is discussed the reduction of structure-borne noise of pump machineries by showing several examples. The most typical and effective solution is to use double resilient mount system. However, in cases where double resilient system cannot be applied due to space and weight increase, rubber pad can be used to reduce the structure-borne noise. In principle, the concept of structure-borne noise reduction is the same as that of vibration isolation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.182-186
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• 2006

An efficient dynamic response analysis mettled of structures supported by resilient mounts is presented by using the structural synthesis method in frequency domain and time domain. As a numerical example, a mount-deck system is considered. Through numerical simulations, the validity of the presented method is verified by comparison of the results with those of the 'traditional' analysis method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.1
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• pp.62-80
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• 2013

This paper has been focused on developing a new hybrid mount for shipboard equipment used in naval surface ships and submarines. While the hybrid mount studied in our previous research was 100 kg-class series-type mount, the new hybrid mount has been designed as an inertia-type mount capable of supporting a static of 500 kg. The proposed mount consists of a commercial rubber resilient mount, a piezostack actuator and an inertial mass. The piezostack actuator connected with the inertial mass generates actively the control force. The performances of the proposed mount with a newly designed specific controller have been evaluated in accordance with US military specifications and compared with the passive mount. An isolation system consisting of four proposed mounts and auxiliary devices has been also tested. Through a series of experimental tests, it has been confirmed that the proposed mount provides better performance than the US Navy's standard passive mounts.

• The Journal of the Acoustical Society of Korea
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• v.26 no.2E
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• pp.50-55
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• 2007

SBN (Structure-Borne Noise) reduction in resiliently mounted machineries are predicted by using mass-spring model and wave model. In mass-spring model, mount is modeled as a spring, while in wave model, mount is considered as an equivalent elastic rod for taking account into longitudinal wave propagation. The predictions for SBN reduction through mounts are compared to the measurements for four different pumps. It is found that the mass-spring model is valid only in low frequency range below few hundred Hz, while for high frequency ranges longitudinal wave propagation in the mount must be considered to explain the measurements. It is also shown that impedance of the floor slightly affects low frequency behaviour in mass-spring and wave model below 50 Hz - 80 Hz, so that in engineering practice the effect of floor impedance may be neglected in computing mount performance.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.5
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• pp.488-495
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• 2007

In this paper, SBN (Structure-Borne Noise) reduction of resiliently mounted machinery and effect of the foundation impedance on mount performance is studied. SBN reduction through the mount is analyzed by using two theoretical models; mass-spring model and wave model, in which longitudinal wave propagation is included. It is found that floor impedance greatly affects SBN reduction through lower mount, while it is almost negligible to SBN reduction through upper mount. Comparisons between measurement and predictions shows that the mass-spring model is valid only in low frequency range below few hundred Hz, while for high frequency ranges longitudinal wave propagation in the mount must be considered.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.82-89
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• 1999

In this article, the performances of acoustic enclosure with double resilient mount system which was designed by ADD to reduce the radiated noise by main noise source of ships, was tested and evaluated. From test results, it was verified that the acoustic performances of acoustic enclosure satisfied the requirements; vibration isolation level at 1st stage mount system of 15 ㏈ and airborne noise reduction level of 20 ㏈ in broad band.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.57-61
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• 2001

In a main propulsion system of naval ship, DRME(Double Resilient Mounted Engine) is mostly adopted to ensure vibration isolation and shock resistance against underwater explosion weapon attack. In this paper, an analysis program for vibration and shock evaluation of DRME is presented. DRME is modelled as multi-rigid bodies with nonlinear mounts, and direct time integration method is introduced for shock analysis. The computed results are compared with those of foreign ones. Navy's proposed specifications are well satisfied with this program. This analysis program serves for the development of domestic DRME technology of naval ship.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.5
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• pp.462-467
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• 2009

Reduction of the structure-borne noise of the naval vessel is very important in order to reduce the underwater radiated noise of it. One of the important factors to reduce the structure-borne noise of the installed machine in a ship is the design of the foundation having sufficiently high mechanical impedance. In this paper, the mechanical impedance of the foundation for the fan-coil unit in a naval vessel is evaluated numerically according to variation of the thickness of the foundation. And also, the forced vibration analysis is conducted considering the dynamic property of the anti-vibration mount. Through the analysis results, it can be known that the dynamic property of the anti-vibration mount should be considered when the minimum level of the mechanical impedance of the foundation is set.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.124-127
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• 2006

In this paper, noise and vibration reduction of double-resiliently mounted pump-like machinery is studied. SBN(Structure-borne noise) reduction through upper and lower mount is analyzed by assuming that the system is modeled as a mass-spring system. In addition, the impedance of the floor is included in the prediction. The comparison of the SBN difference through upper mount show that the effect of impedance is negligible, while the measurement differs significantly from the prediction for high frequency range. It is found that the assumption of point mass-spring system leads to the disagreement between prediction and measurements.