• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1251-1254
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• 1998

본 논문에서는 최근들어 널리 연구되고 있는 다해상도 신호해석 방법인 웨이브렛 변환, 웨이브렛 패킷, 그리고 코사인 패킷 알고리듬을 음성개선에 이용하여 각각의 성능을 비교하였으며, 또한 이를 기존의 스펙트럼차감법의 성능과 비교 분석 하였다. 성능비교의 척도로는 SNR과 ㅋ스트랄 거리를 이용하였다. 실험결과 SNR면에서는 코사인 패킷이 가장 좋은 결과를 보였다. 그리고 ㅋ스트랄 거리의 경우 코사인 패킷과 웨이브렛 패켓이 훨씬 나은 결과를 보였으며 주관적인 청취결과 역시 코사인 패킷이 가장 좋은 결과를 보였고, 기존의 스펙트럼 차감법은 musical noise의 영향으로 인해 상대적으로 다른 방식에 비해 합성음의 음질이 많이 떨어짐을 확인할 수 있었다.

• The Journal of the Acoustical Society of Korea
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• v.23 no.1
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• pp.61-74
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• 2004

In this paper, a contort- and speaker-dependent cepstrum extraction method and a channel normalization method for minimizing the loss of speaker characteristics in the cepstrum were proposed for a robust speaker recognition system over the channel. The proposed extraction method creates a cepstrum based on the pitch synchronous analysis using the inherent pitch of the speaker. Therefore, the cepstrum called the 〃pitch synchronous cepstrum〃 (PSC) represents the impulse response of the vocal tract more accurately in voiced speech. And the PSC can compensate for channel distortion because the pitch is more robust in a channel environment than the spectrum of speech. And the proposed channel normalization method, the 〃formant-broadened pitch synchronous CMS〃 (FBPSCMS), applies the Formant-Broadened CMS to the PSC and improves the accuracy of the intraframe processing. We compared the text-independent closed-set speaker identification on 56 females and 112 males using TIMIT and NTIMIT database, respectively. The results show that pitch synchronous km improves the error reduction rate by up to 7.7% in comparison with conventional short-time cepstrum and the error rates of the FBPSCMS are more stable and lower than those of pole-filtered CMS.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.605-611
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• 2011

In this study, based on previous studies, the thrust generated by using flapping tandem wings is examined. We studied on the relationship between the parameters for characterizing oscillatory tandem wings (namely, the Strouhal number and Reynolds number) for thrust generation in micro flow regime. At each Reynolds number, Strouhal number, heaving amplitude, distance between tandem wings, and phase difference are varied and the flapping motions of tandem mode are calculated to find the optimum conditions for generating thrust. As a result, comparing with a single flapping mode, we found that the minimum Strouhal number for generating thrust is shifted down up to approximately 25% when the tandem flapping mode is applied.