• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.327.2-327
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• 2002

In this paper, the transmitted noise reduction of smart panels of which passive piezoelectric shunt damping is used, is experimentally studied. Shunt damping experiments are based on the measured electrical impedance model. A passive shunt circuit composed of inductor, and load resistor is devised to dissipate the maximum energy into the joule heat energy For multi mode shunt damping, the shunt circuit is redesigned by adding a blocking circuit. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.332-335
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• 2014

Applying damping sheets or dampers (dynamic or mass) can reduce noise from vibrating structure as well as vibration. However, this approach requires increases of weight and cost. If one can reduce structural noise by only modifying the structural shape, which would be the best practice. It is natural that the noise characteristics change when the structure is modified, but the recent experiment on the sunroof frame showed that the modification of the frame beads results in change of the structural damping, so that the corresponding noise can be reduced. In this context, the reason why the structural damping and the related noise upon an impact excitation is changed is theoretically investigated. The change of dynamic and damping characteristics of the strip panels when their shapes are modified is experimentally found and it is shown that such behaviours can be predicted by computer simulation. Some experimental specimen, mainly strip-type panels, are examined for the numerical verification, and especially damping ratios are investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.317-322
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• 2002

A solution procedure of vibration and radiated noise of the plate covered with damping material has been studied. To predict the vibration level and the radiated noise level of the plate covered with damping material, FEM and BEM have been utilized, respectively. A property of damping material has been measured by using a composite beam. Two different kinds of measuring procedure for the composite beam have been introduced by comparing its characteristics. The numerical prediction of vibration level of the Plate covered with damping material has been proved with experimental data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.155-162
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• 2009

Because the tonal sound of the underwater noise in a naval vessel can be identified from the sub-marine of the enemy, it should be reduced sufficiently. This kind of the noise usually comes from the structure-borne noise of the onboard machine and transfers to the sea through the hull of the ship. The vibration at the high frequency can be reduced sufficiently with damping material. In this paper, the damping coefficient of the steel plate with damping sheet is evaluated by experiment. Using these evaluated properties, the numerical analysis is performed in order to evaluate how much vibration of the generator can be reduced applying damping sheet on the encloser and base of it.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1329-1337
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• 2009

Because the tonal sound of the underwater noise in a naval vessel can be identified from the sub-marine of the enemy, it should be reduced sufficiently. This kind of the noise usually comes from the structure-borne noise of the onboard machine and transfers to the sea through the hull of the ship. The vibration at the high frequency can be reduced sufficiently with damping material. In this paper, the damping coefficient of the steel plate with damping sheet is evaluated by experiment. Using these evaluated properties, the numerical analysis is performed in order to evaluate how much vibration of the generator can be reduced applying damping sheet on the encloser and base of it.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1149-1152
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• 2007

Many kind of damping materials are generally used on concrete slab in apartment building to reduce floor impact noise level. Lately, multi-layered damping material that is consist of several materials are used to improve the effect of floor impact noise insulation. In this study, dynamic stiffness of multi-layered damping material that is consist of common materials such as expanded polystyrene(EPS), expended polyethylene(EPE), ethylene vinyl acetate(EVA) and polyester was investigated. It was found that dynamic stiffness of multi-layered damping material could be estimated if know value of each layer that compose whole structure. And it was found that dynamic stiffness of whole structure did not change even if change order that build layer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1463-1466
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• 2007

Visco-elastic damping material for reducing heavy-weight floor impact noise and vibration in reinforced concrete structures was tested according to its thickness in the damping layer. The effect of damping material was compared with 20, 15, 10 and 5mm thickness. The wave propagation characteristics was measured for suggestion of an efficient method to reduce the floor impact noise. The method was proposed using the flexural wave propagation characteristics. The result showed that reduction of the thickness of damping layer made a slight difference; the natural frequency moved to higher frequency and the amplitude increased at low frequencies with 5mm thickness of damping material.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.461-464
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• 2004

The reduction effect of floor impact noise depends on the various factors such as stiffness and thickness of the concrete slab, finishing If ceiling materials and the composition method. Among the rest it is well known that floating floor system is more effective. Standard floating floor(SFF) type-2 consisted of 50mm lightweight aerated concrete(LAC) and 20mm damping material has been widely used. But LAC construction problem on dry damping material occurred and the reduction effect of floor impact noise has bare minimum qualifications. Thus the aim of this study is to develop 40mm composite damping material(Soundzero Plus) for SFF type-5 which substitute LAC and damping material. 'Soundzero Plus' is satisfied with quality requirement for damping material for SFF. The heat transition rate, $0.45W/m^2{\cdot}K$ is more effective 55% about than the regulation. The test results of floor impact noise by using 'Soundzero Plus' are showed good improvement about 12dB (tested by tapping machine) and 4dB (tested by bang machine) between before and after.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.1072-1076
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• 2004

In automotive industry, all passenger vehicles are treated with damping materials to reduce structure borne noise. The effectiveness of damping treatments depends upon design parameters such as choice of damping materials. locations and size of the treatment. Generally, the CAE method uses modal strain-energy information of the bare structural panels to identify flexible regions, which in turn facilitates optimization of damping treatments with respect to location and size. This paper proposes a design of the damping material with a CAE(Computer Aided Engineering) methodology based on finite element analysis and DOE(Design Of Experiments) to optimize damping treatments.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.2
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• pp.115-122
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• 2012

Sound packages and damping materials have been widely applied on the floor to decrease the interior noise of a vehicle. Based on the previous researches on the low-noise vehicles, weight optimization through minimization of damping material usage is required while decreasing mid and high frequency range noise by application of sound packages. This paper describes the analysis process of robust design of vehicle body structure before applying damping materials and focuses on the analysis and test process of the location optimization at the stage of damping material application. A vibration experiment for the analysis of floor panel velocity with respect to the excitation of suspension attachment parts at the underfloor of a vehicle is performed. And through the improvement correlation between FEA and TEST, a design guide to optimize damping materials application in the early design stage is proposed. A research on vibration damping steel sheets and liquid acoustic spray on deadener(LASD) is performed to minimize manufacturing time and to minimize the space for pre-existing asphalt damping materials. As results of this study, panel stiffness is achieved through curved surface panel and bead optimization. And test baseline of optimum design is suggested through damping material optimization. And finally, through re-establishing the analysis process for vibration reduction of vehicle floors and lightweight design of damping materials, it is possible to design damping materials efficiently in the preceding stage of design.