• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.257-262
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• 1996

The first purpose of this study investigates the influence of stiffening on the acoustic response of stiffened plates, which are often employed in steel structures. And the radiation efficiency is measured by average mean square velocity and sound intensity of stiffened plates. The second, it determines influence of mass, damp and stiffeness due to the partial adhesive visco-elastic material to reduce radiated sound power.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.293-295
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• 2004

In this research, we suggest the effective technique that the thickness of slab isn't increased, and considering proper shock absorbing material and supporting point, we make the floating floor which has multi-supporting system floating floor. As the result, it is effective in reduction of heavy weight system as well as one of light weight

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.928-931
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• 2003

In this research, we suggest the effective technique that the thickness of slab isn't increased, and considering proper shock absorbing material and supporting point, we make the floating floor which has multi-supporting system floating nut. As the result, it is effective in reduction of heavy weight system as well as one of light weight

• Journal of KSNVE
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• v.10 no.4
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• pp.629-635
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• 2000

Wheel /rail interaction has been known as a major source of railway noise. In this paper, a low noise wheel structure is developed and its effect on noise reduction is investigated. The developed low noise wheel employees a rubber material inserted into a steel rim or mounted on the wheel surface. Since the low noise wheel has low stiffness and high damping ratio compared to a solid wheel, the measurement results show that it reduces the rolling and squeal noise. It turns out that the proposed wheel could reduce interior noise level by 4∼5dB(A) and vehicle vibration level by 7∼10 dB. Although the proposed structure seems to be promising in noise reduction of railway vehicles, the low noise wheel is to be verified in endurance and cost effect.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.651-655
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• 2004

This paper studies the designing method and application for grommets, rubber material used to absorb vibration on the air conditioner compressor. The existing grommet with hardness 40 degrees, EPDM, has the high transmissibility on the compressor that causes additional structure born sound. The problem for EPDM is transformation over long time usage possibly due to its design in which stress is concentrated on a certain position. In order to resolve it, silicon material was previously used with the same design in some models. The vibration performance did improve, but the cost became high. Below are the major developments regarding improvements in compressor rubber material, vibration performance and durability through design change, and new grommet to attain cost reduction. 1 The optimum grommet design for stress even distribution through FEM methods. 2. Comparison for grommet material and design for improved transmissibility. 3. Assess for grommets durability and product applications.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.10 s.115
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• pp.1036-1043
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• 2006

Damping materials for reducing heavy-weight floor impact noise in reinforced concrete structures were tested in apartment buildings. The effect of damping materials and an impact isolator were compared with an on-site experiment conducted in a high-rise apartment building. The loss factor of damping material analyzed more than 2 times than rubber to $1.5{\sim}2.3$, could know that Damping layer has excellent attenuation performance in side of vibration reduction. The results showed that the resonance frequency increased but vibration acceleration level decreased when the damping materials were used. The heavy-weight impact sound levels of the structure decreased substantially at 63 Hz, whereas the sound levels of the structure with the impact isolator increased.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1573-1581
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• 1996

This paper present as experimental demonstratio of DSP and a sensory actuator that is used to actively control sound transmission/radiation through a vibrating plate. A plane acoustic wave incident on a clamped, thin circular plate was used as a noise source, and a sensory actuator bounded to the plate was used to control and sense vibration of the plate. The sound transmission reduction problem was tranformed as a structural vibration control problem that actively control the structural vibration modes coupled to acoustic modes. The results show that the first structural vibration mode is controlled with a reduction of 78 percent in the displacement and velocity of the plate. This corresponds to a 13dB reduction in the acoustic response. These experimental results indicate that a sensory actuator bounded to the plate can be employed to attenuate the sound transmitted to radiated from the plate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.304-308
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• 2006

The focus of this study is modeling technique for a bellows in vehicle exhaust system. Bellows was developed using tile finite element model by replacing with the equivalent beam. The equivalent beam model were studied in detail. Non-structural node in the cross section of original model is given to expressing their motion. Equivalent mass matrix and stiffness matrix calculated using Guyan reduction method. Material Properties of beam was obtained from the direct comparison between equivalent model and that of Timoshenko beam model. The calculated natural frequencies and mode shape are compared with the reference results and coincided well. The results were compared with the confirmed results, which were in good agreement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1150-1155
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• 2001

Vehicle Manufacturers use asphalt deadener sheets for their passenger cars to reduce noise and vibration from engine and road surface. Since their shapes are limited to a few variations, it is very difficult to reduce unnecessary weight by changing the shape of the deadeners. There is also damping performance limit in the asphalt sheets. Therefore, a high damping material should be implemented into the vehicle noise and vibration reduction activities to overcome the disadvantage of asphalt sheets. In this study, measurement of the damping loss factor and sound transmission loss were made to compare the properties and vehicle test and analysis was followed to evaluate the NVH performance of each deadener type in the vehicle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1242-1248
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• 2001

In this paper, the process of development of resilient sleepers, which improves the train safety, passenger comport and reduces the noise and vibration, is presented. To determine the required material properties of elastic pad, static and dynamic simulations are performed and is applied in manufacturing. Lateral resistance and durability characteristics of the resilient sleepers are experimentally investigated. From the experiment results, it is investigated that the displacement is less for sleeper with elastic pad than that in ordinary PC form. However, the lateral resistance is investigated little less -for sleeper with elastic pad than ordinary PC form. These results indicate that the elastic pad can reduce possibility of rail-corrugations and thus resulting in the reduction of maintenance costs.