• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.822-825
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• 2005

In the case of aeroacoustic test in windtunnel, measurement accuracy is reduced by not only Doppler effects but also by the microphone self noise due to airflow and high turbulence in the wall boundary layer. Microphone array measurements can be easily utilized for the solutions of these problems. In this paper, geometrical optics approach and diagonal term elimination of cross spectral matrix was introduced to the de-dopplerization and self noise reduction methods for the microphone array measurement. For the validation, beamforming tests for sinusoidal point source were performed in the closed type test section of windtunnel, and their performances of beam width and sidelobe rejection were significantly improved.

• Journal of Auto-vehicle Safety Association
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• v.12 no.4
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• pp.70-77
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• 2020

In this study, we estimate the vehicle speed by analyzing the acoustic data recorded in a single microphone of a surveillance camera. The frequency analysis of the acoustic data corrects the Doppler effect, which is a characteristic of the moving sound source, and reflects the geometric relationship according to the location of the sound source and the microphone on the two-dimensional plane. The acoustic data is selected from the horn sound that is mainly observed in an urgent situation among various sound sources that may occur in a traffic accident, and the characteristics of the monotone source are considered. We verified the reliability of the proposed method by time domain acoustic analysis and actual vehicle evaluation. This method is effective and can be used for traffic accident analysis in the blind spot of the camera using a single microphone built into the existing surveillance camera.

• The Journal of the Korea Contents Association
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• v.17 no.1
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• pp.120-128
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• 2017

Acute flank pain from urolithiasis is the most common condition in people visiting emergency rooms. This study is to evaluate the usefulness of color Doppler in detecting ureteral stones in patients without hydronephrosis. We performed ultrasonography and retrospective analysis on 161 patients who were suspected of urinary stones through plain radiography of the kidney, ureter, and bladder examination or urine tests that showed positive signs of hematuria. In ultrasonography, a total of 154 (95.6%) cases from the 161 patients were diagnosed with ureteral stones. In color Doppler, ureteral stones with twinkling artifact (TA) in the absence of hydronephrosis was shown in 18 (85.7%) cases of the 21 patients(p<0.001). The use of color Doppler has a high diagnostic efficacy for the detection of indistinguishable stones, non-dilatational ureteral stones, and middle ureter stones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.90-98
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• 2002

To increase system capacity in WCDMA receiver, the coherent detection is an essential technology for recovering transmitted symbols correctly. For coherent detection, an accurate and fast channel estimation is required. In next generation mobile communication system, high frequency carriers are used, and high data rate services are provided for subscribers having high mobility. In this communication environment, however, the rapidly-changing doppler frequency degrades the quality of the transmitted signal a lot. In WCDMA system, the channel estimation is conducted using pilot channel and/or pilot symbols which are known to both transmitter and receiver. Some existing channel estimation algorithms utilize these information quite well, but the performance of channel estimation gets very poor in a complicated fading channel distorted by the doppler effect. In this paper, we propose a new channel estimation algorithm combining an early-late doppler compensator so that the doppler effect and the fading characteristics are compensated at the same time. By computer simulation, the proposed algorithm proved to be a much more efficient channel estimation method in the fast fading channel, even at reasonably low Eb/No.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.999-1001
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• 2015

CW Doppler radar is capable of giving the relative velocity of an object using the Doppler effect. When detecting more than an object, frequency domain analysis is needed using CW Doppler radar and FFT. Even though the number of objects and velocities can be obtained within the frequency domain, there is a disadvantage that it is difficult to assess information on approach or deviation of an object. When detecting more than an object using FFT, this study suggests an algorithm for efficiently assessing information about approach or deviation of objects within the frequency domain. The proposed algorithm divides sections into real and imaginary numbers in the frequency domain, and then determines deviation if the total sum of the amplitudes of each frequency is on the left side and approach if the total sum of the amplitudes is on the right side.

• 한국ITS학회:학술대회논문집
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• 2008.11a
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• pp.127-131
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• 2008

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1995.10a
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• pp.667-672
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• 1995

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.379-379
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• 2004

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.119-124
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• 1986

• The Magazine of the IEIE
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• v.44 no.7
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• pp.36-46
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• 2017