• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.359-367
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• 2008

The maximum sound pressure level in a ship is restricted by the international standard such as MIL-Std. 740-1 in order to protect hearing ability for the crew on a ship. Especially, the noise of a fan system is restricted by the maximum level of the sound power according to the military specification such as MIL-F-1900A. In this paper, the reduction of tonal noise for the fan-motor system on a ship is described related to the electrical as well as structural problems. For the electrical problems, the difference of the magnetic flux caused by the variation of the air-gap is described related to the bad concentricity of the motor housing and the shaft-bearing. And for the structural problem, the resonance of the fan motor system is described.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.116-121
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• 2013

Panaroma Sun roof's sun shade motor elicits two major sounds when operating: the tonal sound and the white noises. Generally, the sound related to the sharpness contributes the most to the quality of motors' tonal sound. The primary purpose of this study was to set the loudness of the motor's objective tonal sound utilizing the masking effect by its white noises. To conduct this study, the sound made by the operating sun shade motor was categorized into two different subsets of masker and test tone to examine the masking threshold. Also, the shifts of masking threshold were observed with the varying masker loudness.