• 대한전자공학회논문지
• /
• 제22권2호
• /
• pp.13-17
• /
• 1985

음성신호의 기본주파수를 구하는 새로운 방법인 area comparison method를 제안 하였다. 음성신호는 생성모델에 의한 한 pitch 구간에서 첫 봉우리의 면적이 강조 된다. 이 논문은 이러한 성질을 이용하여 pitch period를 구하는 것으로 기존의 방법에 비해 많은 장점을 갖는다. 시간 영역에서 취급하고 알고리즘이 간단하기 때문에 고속이다. 또한 sample의 개개가 아닌 면적을 적용하므로 impulse 성 잡음이나, 전처리 filtering이 필요없게 된다.

• 한국기계연구소 소보
• /
• 통권15호
• /
• pp.57-66
• /
• 1985

Fibers with a high degree of axial preferred orientation can be obtained from mesophase pitch. Prior to cabonization, the pitch fibers must be rendered in fusible so that their orientation is preserved. The stabilization of the pitch fibers was heated at temperature between $250^{circ}C$ and $300^{circ}C$ and a treatment time 5 to 80minutes. Oxidized fibers heated $1800^{circ}C$without stretching. Pitch based carbon fiber have a young's modulus as high as 304GN/$m^2$. The structure of the pitch cased carbon fiber is determining factor for the mechanical properties of the produced fibers. The structure depending on the pitch precursor as well as on the oxidation time.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집B
• /
• pp.314-320
• /
• 2000

In this study, the wet surface heat transfer coefficients and friction factors of PF heat exchangers are presented. Two sample with different fin pitch(1.25mm, 1.5mm) were tested. Tests were conducted in a open loop wind tunnel. The wet surface heat transfer coefficient was reduced following the procedure given in ARI 410-81. Results showed that the heat transfer coefficients of the heat exchanger with 1.5mm fin pitch were approximately the same as those with 1.25mm fin pitch, except at low reynolds number(Re<100), where the heat transfer coefficients of 1.5mm fin pitch were slighly higher than those with 1.25mm fin pitch. The friction factors of the 1.25mm fin pitch, however was 120 % to 160 % higher than those of the 1.5mm fin pitch. The wet surface heat transfer coefficients were lower than those of the dry surface. The wet surface friction factors, however, were higher than those of the dry surface.

• 대한후두음성언어의학회지
• /
• 제9권2호
• /
• pp.152-155
• /
• 1998

Laryngeal framework surgery to improve change the voice is a challenging development in phoniatric surgery. Basically two categories can be distinguished : (1) attempted medialization of the vocal fold, as for the treatment of paralytic dysphonias (2) adjustment of the vocal fold's tension of transsexuals or mutational dysphonia. Vocal pitch can be elevated by various surgical technique 1) cricothyroid approximation 2) A-P expansion of the thyroid ala 3) longitudinal incision in the cords 4) intrachondral injection of the steroid, and 5) evaporation of the cords by $CO_2$ laser. We have experienced a case of pitch elevation procedure after transsexual operation. After transsexual operation, he had received anterior commissure laryngoplasty modified from Le Jeune with no change in voice pitch(Fo=110Hz). 8 monthes later, he had received cricothyroid approximation resulting in pitch elevation(Fo=160Hz).

• 한국정밀공학회지
• /
• 제15권1호
• /
• pp.69-77
• /
• 1998

Linear displacement accuracy is one of the most important factors that determine machine tool accuracy The laser interferometer has been usually recommended for the measurement of linear displacement accuracy. In this paper, microcomputer aided measurement and compensation system has been developed for the pitch error in a CNC machine tool. For accurate pitch error calculation. the analysis code for the pitch error has been also implemented according to the international standards (ISO). The PC based automatic compensation system for the pitch error is also implemented. A new algorithm for calculating optimum value for pitch error compensation is proposed, minimizing the deviation at each target points. The development system has been applied to a practical CNC maching center and the performance has been demonstrated.

• 음성과학
• /
• 제3권
• /
• pp.132-147
• /
• 1998

Previously developed methods for pitch modification have not been based on the voice source model. Therefore, the synthesized speech often sounds unnatural although it may be highly intelligible. The purpose of this paper is to analyze the alteration of a voice source signal with pitch period and to establish the pitch-modification rule based on the result of this analysis. We examine the alteration of the interval of closing phase, closed phase and open phase using the excitation waveform as the pitch increases. In comparison to the previous methods which performed directly on the speech signal, the pitch modification method based on a voice source model shows high intelligibility and naturalness. This study might benefit the application to the speaker identification and the voice color conversion. Therefore the proposed method will provide high quality synthetic speech.

• 음성과학
• /
• 제11권2호
• /
• pp.151-164
• /
• 2004

This study examined the use of intonation in children with single word sentences and investigated the communicative functions of pitch range and pitch direction. Two children aged 13months were observed in interaction with their mothers for 10 months. The vocalizations were coded separately for communicative function and for prosodic feature. Results show that level tones are used most frequently, and pitch range is higher for request than declaration or answer and lower for answer than request or declaration. And trends in prosodic contours were observed in request, declaration, and answer respectively. For one child, rising tones were frequently associated with request whereas rising-falling tone with declaration. For the other child, rising-level tones were more frequently associated with request whereas falling-level appeared more often in conjunction with declaration. These trends appeared more distinct in proportion as they grow in months. This result indicate that the way to express communicative functions transfer gradually from differentiating pitch range to diversify pitch direction.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 추계학술대회 논문집
• /
• pp.627-627
• /
• 2009

In this work, the activated carbons (ACs) with high porosity were synthesized from pitch by KOH chemical activation. The structure and surface properties of ACs were characterized by means of elemental analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy(XPS). And, the influence of the KOH-to-pitch ratio on the porosity of the ACs was investigated using the nitrogen adsorption isotherms at 77 K and a scanning electron microscopy (SEM). As a result, pitch could be successfully converted into ACs with well-developed micro and mesopores. The specific surface areas and pore volumes were increased with an increase of the KOH-to-pitch ratio. Furthermore, it was found that the addition of KOH led to the transformation of the micropores to the meso- and macropores. In the application to electric double layer capacitors (EDLC), the pitch-based ACs showed a higher capacitance per weight and per volume, and an excellent electrochemical stability in the high voltage region.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
• /
• pp.381-384
• /
• 2002

In speech signal processing, it Is very important to detect the pitch exactly in speech recognition, synthesis and analysis. but, it is very difficult to pitch detection from speech signal because of formant and transition amplitude affect. therefore, in this paper, we proposed a pitch detection using the spectrum flattening techniques. Spectrum flattening is to eliminate the formant and transition amplitude affect. In time domain, positive center clipping is process in order to emphasize pitch period with a glottal component of removed vocal tract characteristic. And rough formant envelope is computed through peak-fitting spectrum of original speech signal in frequency domain. As a results, well get the flattened harmonics waveform with the algebra difference between spectrum of original speech signal and smoothed formant envelope. After all, we obtain residual signal which is removed vocal tract element The performance was compared with LPC and Cepstrum, ACF 0wing to this algorithm, we have obtained the pitch information improved the accuracy of pitch detection and gross error rate is reduced in voice speech region and in transition region of changing the phoneme.

• Carbon letters
• /
• 제23권
• /
• pp.48-54
• /
• 2017

This research considers the effect of added mesophase pitch (MP) as an additive during the pitch synthesis reaction of pyrolyzed fuel oil (PFO). Two effects are generated by adding MP. One is an enhancement of thermal stability due to the high thermal property of the additive; the other is that the volatile compounds that were removed by vaporization of PFO during the thermal reaction can participate in the pitch synthesis reaction ($PFO{\rightarrow}pitch$) more efficiently. The effect differs according to the amount of the additive. When the amount of the additive is less than 7 wt%, the first effect is dominant, whereas the second effect is dominant when the additive amount exceeds 10 wt%.