• Journal of the Korean earth science society
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• v.23 no.8
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• pp.707-721
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• 2002

Seafloor acoustic image data using the side scan sonar system were gathered on the Sindu-ri offshore near the Taean peninsula, middle western Korea. The relationship between the back-scattering acoustic intensity and the sea-bottom sediment properties was studied. And these two data sets were compared and interpreted with the water depth, respectively. Most of sediment properties were correlated well to the acoustic intensity, however the distribution patterns of the sea-bottom sediment and the seafloor acoustic image were not similar to each other except the rocky bottom area. The water depth was not only influential on the distribution pattern of seafloor acoustic image but also showed a linear relation with the sediment properties distribution.

• The Journal of the Acoustical Society of Korea
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• v.23 no.5
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• pp.340-352
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• 2004

Acoustic streaming induced by the microscopic longitudinal ultrasonic vibration at 28.5 ㎑ is visualized between the quiescent glass plate and ultrasonic vibrator by particle imaging velocimetry(PIV) using laser. To investigate the augmentation of air flow velocity of acoustic streaming. the velocity variations of air streaming between the stationary plate and ultrasonic vibrator are measured in real-time. It is experimentally investigated that the magnitude of the acoustic streaming dependent upon the gap between the ultrasonic vibrator and stationary p1ate results in the variations of the average velocity fields as a outcome of the bulk air flow caused by the ultrasonic vibration. In addition. maximum acoustic streaming velocity exists at resonant gap. 18mm that is one of the resonant gaps (H=18, 24, 30, 36㎜) at which resonance occurs. The variation of the local maximum turbulent intensity with axial direction appear to reveal the value of 8%∼70% dependent upon the gap between the quiescent glass plate and ultrasonic vibrator. Shearstress is also maximized at the center region of the vibrator and the vorticity is also maximum and minimum in the neighborhood of the center of the vibrator at which the local maximum turbulent intensity and shear stress exist.

• Proceedings of the Acoustical Society of Korea Conference
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• 1985.10a
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• pp.37-42
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• 1985

The errors caused by developmental finite difference approximations in the two microphone acoustic intensity measurement technique are considered in this paper. The frequencies and pressure responses obtained experimentally, are presented for both face to face (FF) and side by side(SS) microphone configurations. The implications of these results by the use of such a cofiguration for two microphone sound intensity measurement are discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.117-123
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• 1998

We investigated the effect of mechanical backside damage in Czochralski grown silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductivity decay method, photo-acoustic displacement method, X-ray section topography, and wet oxidation/preferential etching methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the photo-acoustic displacement values increased proportionally, and it was at Grade 1: Grade 2:Grade 3 = 1:19.6:41 that the normalized relative quantization ratio of excess photo-acoustic displacement in damaged wafer was calculated, which are normalized to the excess PAD from sample Grade 1.

• The Journal of the Acoustical Society of Korea
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• v.16 no.2E
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• pp.3-13
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• 1997

The Jing is a traditional Korean percussion instrument which plays a major role in Korean folk music. The distingishing feature of this instrument is its unique, long lasting low tone timbre. In this paper, we investigated the vibro-acoustic characteristics of the Jing. Our attention was focused mainly on findings out the physical variables that determine its unique sound. By understanding the way in which the Jing is manufactured, we were able to realize that the unique manufacturing and especially the tuning process by expert craftsman is responsible for the peculiar timbre the Jing produces. The experimental methods implemented to analyzer the Jing were planar acoustic holography and direct measurements by accelerometers. The results from the holographic method and the direct measurements were in good agreement. It turned out that unlike most percussion instruments which have inharmonic partials, the Jing has harmonic partials which are responsible for its unique low-tone timbre. From the holographic representations of the modes, it is clear that the antinodes are located in the center of the Jing which is coincident with the typical striking location. In addition, intensity maps were constructed so that the specific acoustic energy flow can be visualized. It was also interesting to see the the circulation of energy intensity which corresponds to the rotating mode of the Jing.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1983.10a
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• pp.44-47
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• 1983

Through intensity modulation induced by micro bending of an optical fiber, a sensor detects the pressure and frequency of acoustic wave has been implemented. Axial slots on the cylinder suface with a period of 5.5 mm induce efficient microbending of the fiber, and a rubber sleeve covering the fiber enhances the fiber. Compared with a conventional hydrophone, it has a low minimum detectable pressure and can detect acoustic wave in 100Hz - 2KHz range.

• Speech Sciences
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• v.6
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• pp.103-117
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• 1999

This paper suggests that the onset-coda asymmetry found in languages like Korean and others should be dealt with in terms of one acoustic feature rather than other articulatory features, claiming that the acoustic feature involved here is [noise], i.e., 'aperiodic waveform energy'. It determines the structural well-formedness of the languages in question whether a coda ends in [noise] or not, regardless of the intensity, the frequency, and the time duration of the [noise]. Fricatives, affricates, aspirated stops, tense stops, and released stops are all disallowed in the coda position due to the acoustic feature [noise] they, commonly end with if they were, posited in the coda. The proposal implies that the three seemingly separate prohibitions of consonants in the coda position -- i) no fricatives/affricates, ii) no aspirated/tense stops, and iii) no released stops -- are directly correlated with each other. Incorporation of the one acoustic feature [noise] in the feature theory enables us to see that the aspects of onset-coda asymmetry are derived from one single source: ban, of [noise] in the coda.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.19-26
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• 2011

Previous laboratory studies have shown that prosodic structures are encoded in the modulations of phonetic patterns of speech including suprasegmental as well as segmental features. Drawing on a prosodically annotated large-scale speech data from the Buckeye corpus of conversational speech of American English, the current study first evaluated the reliability of prosody annotation by a large number of ordinary listeners and later examined whether and how prosodic prominence influences the phonetic realization of multiple acoustic parameters in everyday conversational speech. The results showed that all the measures of acoustic parameters including pitch, loudness, duration, and spectral balance are increased when heard as prominent. These findings suggest that prosodic prominence enhances the phonetic characteristics of the acoustic parameters. The results also showed that the degree of phonetic enhancement vary depending on the types of the acoustic parameters. With respect to the formant structure, the findings from the present study more consistently support Sonority Expansion Hypothesis than Hyperarticulation Hypothesis, showing that the lexically stressed vowels are hyperarticulated only when hyperarticulation does not interfere with sonority expansion. Taken all into account, the present study showed that prosodic prominence modulates the phonetic realization of the acoustic parameters to the direction of the phonetic strengthening in everyday conversational speech and ordinary listeners are attentive to such phonetic variation associated with prosody in speech perception. However, the present study also showed that in everyday conversational speech there is no single dominant acoustic measure signaling prosodic prominence and listeners must attend to such small acoustic variation or integrate acoustic information from multiple acoustic parameters in prosody perception.

• Journal of Broadcast Engineering
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• v.17 no.3
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• pp.519-528
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• 2012

Voice activity detection (VAD) is generally conducted by extracting features from the acoustic signal and a decision rule. The performance of such VAD algorithms driven by the input acoustic signal highly depends on the acoustic noise. When video signals are available as well, the performance of VAD can be enhanced by using the visual information which is not affected by the acoustic noise. Previous visual VAD algorithms usually use single visual feature to detect the lip activity, such as active appearance models, optical flow or intensity variation. Based on the analysis of the weakness of each feature, we propose to combine intensity change measure and the optical flow in the mouth region, which can compensate for each other's weakness. In order to minimize the computational complexity, we develop simple measures that avoid statistical estimation or modeling. Specifically, the optical flow is the averaged motion vector of some grid regions and the intensity variation is detected by simple thresholding. To extract the mouth region, we propose a simple algorithm which first detects two eyes and uses the profile of intensity to detect the center of mouth. Experiments show that the proposed combination of two simple measures show higher detection rates for the given false positive rate than the methods that use a single feature.

• Journal of the Korean Society for information Management
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• v.29 no.4
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• pp.191-208
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• 2012

Two fundamental aspects of speech summary generation are the extraction of key speech content and the style of presentation of the extracted speech synopses. We first investigated whether acoustic features (speaking rate, pitch pattern, and intensity) are equally important and, if not, which one can be effectively modeled to compute the significance of segments for lecture summarization. As a result, we found that the intensity (that is, difference between max DB and min DB) is the most efficient factor for speech summarization. We evaluated the intensity-based method of using the difference between max-DB and min-DB by comparing it to the keyword-based method in terms of which method produces better speech summaries and of how similar weight values assigned to segments by two methods are. Then, we investigated the way to present speech summaries to the viewers. As such, for speech summarization, we suggested how to extract key segments from a speech video efficiently using acoustic features and then present the extracted segments to the viewers.