• Proceedings of the KSR Conference
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• 2011.05a
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• pp.580-584
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• 2011

Sound power is one of the most significant factors to predict and assess noise from sound source. However, many researchers developed indirect methods to calculate the sound power with noise level because it is impossible to measure sound power directly while a train is running. In this paper, we proposes a method to estimate separately each sound power for rolling noise and propulsive noise with the noise emitted from rolling stocks and verifies the validity of the estimation method using other sound power estimation formula.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1138-1141
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• 2002

In this study, the ISO 15186-1 “Measurement of sound insulation in buildings and of building elements using sound intensity - Part 1 : Laboratory conditions” was reviewed in order to make it as a new Korean Industrial Standard. Several main contents are discussed.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1243-1246
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• 1998

Three-dimensional(3-D) sound is a technique for generating or recreating sounds so they are perceived as emanating from locations in a three-dimensional space. Three dimensional sound has the potential of increasing the feeling of realism in music or movie soundtracks. Three-dimensional sound effects depend on psychoacoustic spectral and phase cues being presented in a reproduced signal. In this paper we propose an effective algorithm for the sound image expansion in television system using stereo image enhancement techniques. Compared to the other techniques of three-dimensional sound, the proposed algorithm use only two speakers to enhance the sound image expansion, while maintaining the original sound characteristics.

• Fibers and Polymers
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• v.6 no.3
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• pp.269-276
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• 2005

In this study, cross-cultural comparison of sound sensation for Korean traditional silk fabrics between Korea and America was performed and prediction models for sound sensation by objective measurements including sound parameters such as level pressure of total sound (LPT), Zwicker's psychoacoustic characteristics, and mechanical properties by Kawabata Evaluation System were established for each nation to explore the objective parameters explaining sound sensation of the Korean traditional silk. As results, Koreans felt the silk fabric sounds soft and smooth while Americans were revealed as perceiving them hard and rough. Both Koreans and Americans were pleasant with sounds of Gongdan and Newttong and especially Newttong was preferred more by Americans in terms of sound sensation. In prediction models, some of subjective sensation were found as being related mainly with mechanical properties of traditional silk fabrics such as surface and compressional characteristics.

• Journal of KSNVE
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• v.7 no.6
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• pp.919-929
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• 1997

Induction motors are used in many areas to transform electrical energy to mechanical energy. In the design of an induction motor, not only energy efficiency but also noise becomes an important factor. To effectively address the noise problem, it will be convenient if one can see where and how noise is generated and propagated. In this study sound radiation by an induction motor is visualized using cylindrical acoustic holography. To minimize the bias error by window effect Minimum Error Window(MEW) is used. Its performance is verified by numerical simulations. Based on these theoretical understanding, sound pressure measurement with an induction motor are performed. Not only sound radiation are visualized but sound pressure level and sound power level are also estimated. Results show that the main source is located at nearly bottom part of the motor and the total sound pressure level is 49dB, which satisfies the guideline value suggested by the KS C 4202.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.595-598
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• 2005

The impact sound of the golf club is one of the major factors to purchase it. Sound qualify evaluation techniques are mostly developed for harmonic sounds. Sound quality metrics for the impact sound is proposed in this study. Jury test, one of the typical subjective evaluation scheme, is carried out for evaluating the sound quality of 11 different golf drivers. Above subjective classification results are assumed to be the right answers. Conventional objective evaluation methods such as Zwicker loudness sensory pleasantness are calculated. Wavelet analysis and instantaneous loudness are applied in order to evaluate the transient sounds, which shows better correlation with the results from those by jury test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.152-157
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• 2008

Enclosure is widely used for the sound insulation in a ship. But it is very difficult to estimate the sound insertion loss for the enclosure because the sound field between the enclosure and the machine is so complex. Therefore, it is usually estimated experimentally. In this research, sound insertion loss of the enclosure is estimated by theory assuming that the sound field in the enclosure is reverberation field. And the results from the theory are compared to those from the experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.498-501
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• 2006

When an object or objects, rigid or flexible, presents in incident sound field, the sound wave is scattered. This, we call, is scattered sound field. It, of course, depends on the amplitude and the direction of the incident sound field as well as the geometry and the surface impedance of the scatterer(object). This paper addresses the way to measure scattered sound field by using arbitrary incident sound wave. This means that the method can decompose the scattered field from measured sound field with respect to any magnitudes and directions of incident plane-waves.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2426-2436
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• 1993

Vibration characteristics of a tire play an important role to judge a ride conformability and sound quality for a passenger car. In this study, the experimental investigation for the sound radiation of a radial tire has been examined. Based on the sound intensity techniques, the sound pressure field and the sound radiation are measured. It turns out that air pressure in tire, tread patterns, and aspect ratio of the tire govern the sound radiation characteristics. Then a numerical analysis for the tire element is conducted. During analysis, the tire element is modelled as an elastic ring. The comparison shows that the numerical output correlates to the experimental data.

• Interaction and multiscale mechanics
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• v.3 no.4
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• pp.373-387
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• 2010

This study is intended to assess low frequency sound radiated from a viaduct under normal traffic. The bridge comprises steel box girders and wide cantilever decks on which vehicles pass. The low frequency sound and the acceleration response of the bridge under normal traffic are measured to investigate how bridge vibrations affect the low frequency sound observed near the bridge. Observations demonstrate that strong relationships exist between frequency characteristic of bridge's acceleration response and the sound pressure level of low frequency sound. A noteworthy point is that the dynamic feature of the sound pressure level is mostly affected by dynamic feature of the span locating near the observation point.