• Journal of IKEEE
• /
• v.27 no.4
• /
• pp.472-476
• /
• 2023

Fundamental frequency/pitch period are major characteristics of speech signals. They are used in many speech applications like speech coding, speech recognition, speaker identification, and so on. In this paper, some of inflection points are used to estimate the pitch which is the inverse of the fundamental frequency. The inflection points are defined as points where local maxima, local minima or the slope changes occur. The speech signal is preprocessed to remove unnecessary inflection points due to the high frequency components using a low pass filter. Only the inflection points from local maxima are used to get the pitch period. While the existing pitch estimation methods process speech signals in blockwise, the proposed method detects the inflection points in sample and produces the pitch period/fundamental frequency estimates along the time. Computer simulation shows the usefulness of the proposed method as a fundamental frequency estimator.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 1998.06a
• /
• pp.1073-1076
• /
• 1998

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.10a
• /
• pp.96-96
• /
• 2003

• Analytical Science and Technology
• /
• v.19 no.4
• /
• pp.301-308
• /
• 2006

Pitch-coated anatase $TiO_2$ typed was prepared by $CCl_4$ solvent mixing method with different mixing ratios. Since the carbon layers derived from pitch on the $TiO_2$ particles were porous, the pitch-coated $TiO_2$ sample series showed a good adsorptivity and photo decomposition activity. The BET surface area depends on the pitch contents, which was made by changing the mixing ratios of the pitch with the raw $TiO_2$. The SEM results present to the characterization of porous texture on the pitch-coated $TiO_2$ sample and pitch distributions on the surfaces for all the materials used. From XRD data, a weak and broad carbon peak of graphene with pristine anatase peaks were observed in the X-ray diffraction patterns for the pitch-coated $TiO_2$. The EDX spectra show the presence of C, O and S with strong Ti peaks. Most of these samples are richer in carbon and major Ti metal than any other elements. Finally, the excellent photocatalytic activity of pitchcoated $TiO_2$ with Uv/Vis spectra between absorbance and time could be attributed to the homogeneous coated pitch on the external surface by $CCl_4$ solvent method.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.24 no.4
• /
• pp.366-371
• /
• 2014

The neural network pitch controller using changing rate of generator speed has been suggested in this paper to regulate wind turbine power above the rated wind speed. The changing rate of generator speed is used in the suggested pitch controller as well as the difference between the rated and current generator speed. Matlab/simulink has been used for simulations and it has been shown that the suggested pitch controller regulates generator speed as the rated speed of 122.9[rad/s].

• Journal of the Korean Institute of Intelligent Systems
• /
• v.13 no.1
• /
• pp.45-50
• /
• 2003

Recently, robots technique has been developed remarkably. Emotion recognition is necessary to make an intimate robot. This paper shows the simulator and simulation result which recognize or classify emotions by learning pitch pattern. Also, because the pitch is not sufficient for recognizing emotion, we added acoustic elements. For that reason, we analyze the relation between emotion and acoustic elements. The simulator is composed of the DRNN(Dynamic Recurrent Neural Network), Feature extraction. DRNN is a learning algorithm for pitch pattern.

• The Journal of the Acoustical Society of Korea
• /
• v.15 no.2
• /
• pp.90-94
• /
• 1996

Code Excited Linear Prediction(CELP) vocoder exhibits good performance at data rates below 8 kbps. The major drawback of CELP type coders is a large amount of computation. In this paper, we propose a new pitch searching method that preserves the quality of the CELP vocoder reducing computational complexity. The basic idea is that grasps preliminary pitches using the first formant of speech signal and performs pitch search only about the preliminary pitches. As applying the proposed method to the CELP vocoder, we can reduce complexity by 64% in the pitch search.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.6
• /
• pp.487-497
• /
• 2011

Numerical analysis has been performed to investigate the rotor speed and pitch range variations when the airspeed is increased in autorotation. Transient Simulation Method(TSM) was used to obtain the steady states of autorotation. The rotor blade was analyzed by the two-dimensional compressible Navier-Stokes solver in order to adapt to the airspeed increase and the results were used in the transient simulation method. Meanwhile, the Pitt/Peters inflow theory was used to supply the induced velocity fields. For the prescribed torque equilibrium state, the combinations of velocity, shaft angle, and pitch angle were produced to investigate the rotor speeds and variable ranges. The rotor tip Mach number and rotor speed were correlated and the trim range of pitch angle was observed with respect to the shaft angle decrease.

• The Journal of the Acoustical Society of Korea
• /
• v.29 no.1
• /
• pp.41-47
• /
• 2010

The pitch alteration technique for voice conversion is classified in time domain, frequency domain and hybrid domain. The Hybrid domain method has a merit of clearness and natural-ness of pitch altered speech but has the major drawback of long processing time. In this paper, we proposed a new method that can reduce the processing time of pitch alteration in time-frequency hybrid domain. We omitted the bit-reversing process of FFT and IFFT in changing the processing domain. Therefore we can reduce the processing time by 86.26% to the conventional method with same quality.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.79-82
• /
• 2000

감정 표현 음성을 합성하기 위하여 본 연구에서는 감정 음성 데이터의 피치와 지속시간의 음절 유형별 및 어절 내 음절 위치에 따른 변화를 분석하였고, 스펙트럼 포락이 감정 변화에 어떤 영향을 미치는지를 분석하였다. 그 결과, 피치와 지속시간의 음절 유형별, 어절 내 음절 위치에 따른 변화와, 스펙트럼 포락 등도 감정 변화에 영향을 미치는 것으로 나타났다. 또한, 감정 음성의 음향학적 분석 결과를 적용하여 감정 음성을 합성하고 평가하기 위하여, 평상 음성의 음운 및 운율 파라미터 (피치, 에너지, 지속시간, 스펙트럼 포락)를 조절함으로써 감정 음성을 생성하는 감정 편집기를 구현하였다.