• Journal of Biosystems Engineering
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• v.23 no.1
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• pp.57-66
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• 1998

This study was conducted to investigate the relationships between parameters affecting internal quality of watermelon and its acoustic characteristics. The measuring and analyzing system was established to study the acoustic characteristics of watermelon. Algorithms for analyzing sound signals were developed. Sound signals which was detected with the microphone were filtered, and their spectrum was computed by means of the Fast Fourier Transform. As watermelon changed from the unripe stage to ripe, acoustic waves in time domain became complicated, and several components appeared in frequency domain. The correlationship was investigated between some parameters affecting internal quality of the watermelon and several peak frequencies. Results indicated that weight, density and sugar content had high correlations with several frequencies(the first peak frequency, the second peak frequency, and the third peak frequency). And the sugar content and the volume of the watermelon were highly correlated with the third peak frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.333.1-333
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• 2002

This paper suggests the noise reduction method of the engine cooling fan. It was estimated the fannoise contribution at the engine room and identified the noise source at the rotating fan by sound intensity method, first. And it has been developed the program for predicting the noise spectrum of axial flow fan. The radiated acoustic pressure is expressed the discrete frequency noise peaks at BPF and its harmonics and the line spectrum at the broad band by the noise generation mechanisms. In this paper it is shown that the comparison of the measuted and calculaed noise spectra of fn for the validation of the noise predictiong program. And this paper presents the characteristics of a fan noise due to modify the design parameters. Accordingly, it was obtained the design parameter values for noise reduction of fan.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.217-223
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• 2013

This paper proposes a spatial audio reproduction system based on audio fingerprinting that combines the audio fingerprinting and the spatial audio processing. In the proposed system, a salient audio peak pair fingerprint based on modulation spectrum improves the accuracy of the audio fingerprinting system in real noisy environments and spatial audio information as metadata gives a listener a sensation of being listening to the sound in the space, where the sound is actually recorded.

• International Journal of Railway
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• v.6 no.3
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• pp.125-130
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• 2013

Most of the test methods used for determining the acoustic performance of the noise barriers in Korean standards address the sound-proof panels but refer to noise barriers as a whole system or their in-situ performances less. Many new types of trains with different operating speeds have been developed and produced, and civil appeals against railway noise are becoming quite extensive. Considering these latest changes of circumstances, it is necessary to investigate the current standards and specifications pertaining to railway noise barriers. In this paper, criteria for the measurements and evaluations of noise barriers and sound-proof panels are examined and experimental studies are introduced. In order to suggest more efficient methods for reasonable evaluations of the noise barriers, frequency spectrums of the noise source, the power of the actual railway vehicles, are investigated and introduced.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.181-182
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• 2007

Wireless home theater and speaker system was designed. That has 20W output per channel, 0.1% THD (Total Harmonic Distortion) and automatic algorithm avoiding noise. The 3D stereophonic sound was realized through the wireless 5.1channel speaker system designed. That could be secured 0.4% improvement effect of THD compared with wire speaker systems. Specially in transfer sound with wireless, Frequency Hopping Spread Spectrum was superior than Direct Sequence Spread Spectrum in household electric appliances and wireless internet environment that radiated noise similar with ISM Band using 2.4GHz.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1217-1220
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• 1987

We have developed a Ultra Sound Pulsed Doppler System with two-dimensional M-mode image and Spectrum analyzer. The image of the M-mode is composed of time and depth axes. The Spectrum analyzer shows the spectrum of Doppler signal which represents the velocity component of time dependent blood-flow behavior. The spectrogram using Spectrum analyzer is composed of frequency and amplitude axes. The outputs of the system are audio signals, velocity curves, velocity profiles, M-mode images and spectrogram.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.1
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• pp.78-82
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• 2019

This paper addressed the spectrum of ultrasonic waves produced by arc and/or coronal discharge inside the switchboard. Portable ultrasound sensors are useful for detecting discharge phenomena, such as coronal means in electrical systems. However, a typical handheld ultrasound detector has a disadvantage of determining the type of problem by listening to the sound characteristics and predicting the results, as a result of the determination of whether a discharge is present. Therefore, a new method of analysis is required to distinguish ultrasonic characteristics. In this paper, we published an ultrasound analysis case study to visualize the sound of ultrasonic waves measured with ultrasonic sensors. From the results of the experiment, it was possible to detect coronal discharge and serial arc discharge without interference by the ultrasonic detection system.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.33 no.2
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• pp.64-76
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• 2022

Praat is a useful analysis tool for linguists, engineers, doctors, speech-language pathologits, music majors, and natural scientists. Basic parameters including duration, pitch, energy and perturbation parameters such as jitter and shimmer can be easily measured and manipulated in the sound editor. When a more in-depth analysis is needed, it is recommended to understand the advanced menus of the object window and learn how to use them. Among the object window menus, vowel formant analysis, spectrum analysis, and cepstrum analysis can be cited as useful ones in the clinical field. The spectrum object can be usefully used for voice quality measurement and diagnosis of patients with voice disorders by showing the energy distribution according to frequency axis (domain). A cepstrum object is useful for speech analysis when periodicity of the sound object is not measurable. The low to high ratio obtained from the spectral object and the CPPs measured from the cepstrum object have attracted many researchers, and it has been proven that the CPPs measured in Praat are relatively excellent.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.707-708
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• 2012

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.15 no.2
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• pp.122-127
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• 2004

Background and Objectives : Many studies have described and analyzed singer's formant and it has been shown that the epilaryngeal tube in the human airway is responsible for vocal ring, or the singer's formant. A similar phenomenon produced by trained singers in their speech led some authors to examine the speaker's ring. This study was designed to analyze the speaking voice of the singers and speaker's ring. Baterials and Methods : Ten tenors, fifteen baritones, fifteen sopranos and ten mezzo sopranos attending the music college, department of vocal music were chosen for this study. Fifteen male and fifteen female untrained normal speakers were chosen for control group. Each subject was asked to produce a sample of a sustained spoken vowel /ah/ sound for at least five seconds and read sentence 'Kaeul'. The sound data was analyzed using the Fast Fourier Transform(FFT) - based power spectrum, Long term average(LTA) power spectrum using the FFT algorithm of the Computerized Speech Lab(CSL, Kay elemetrics, Model 4300B, USA). Statistical analysis was performed using the Mann-Whitney test of the Statistical Package for Social Sciences(SPSS). Results : For LTA Power spectrum of/ah/ sound, a significant increase was seen in the 2,500-3,500Hz region(p<0.01) in four trained singer group compared with untrained speaker group, and a significant increase in the 9,000-10,000Hz region(p<0.01) in soparano group. Similarly, in sentence 'Kaeul', there was a significant increase in energy in the tenor, baritone, mezzo soprano group compared with the untrained speaker group in the 2,500-3,500Hz region(p<0.01), and a significant increase in all frequency region(p<0.01) in the soprano group. Conclusions : The LTA power spectrum suggests that trained singers group show more energy concentration in the 'singer's formant' region in the speaking voice, and authors believe this region to be the 'speaker's ring'. Further research is needed on the effect of singing training on the resonance of the speaking voice.