• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1994.06a
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• pp.139-142
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• 1994

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2725-2736
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• 1998

In this paper. we present a new pitch determination method for speech analysis. namely VFF(Variable Forgetting Factor) based. by using the WRLS-VFF-VT(Weighted Recursive Least Square-Variable Forgetting Factor-Variable Threshold) algorithm. A proposed method uses VFF to identify the glottal closure points which correspond to the instants of the main excitation pulses for voiced speech. The modified EGG

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.124-130
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• 2005

This paper presents the simulation modeling and analysis of variable wind speed turbine system(VWTS) using Psim program In the simulation, using the Vestas V47 VWTS located in Hangwon wind farm in Jeju-Do as a model, wind model, blade model, pitch control model and grided connected generator are modeled. The VWTS is controlled by the optimal pitch angle for maximum output power under the rated wind speed and for the rated output power over the rated wind speed. To verify the effectiveness of proposed method, simulation results are compared with the actual data from the model system According to the comparison of these results, this method shows excellent performance. So it is very useful for understanding and applications of wind power control system.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.73-76
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• 2002

본 논문에서는 8kbps의 전송율을 가진 ITU G.729 보코더와 PSOLA(Pitch Synchronized Overlap -Add) 알고리즘을 적용하여 전송율을 6kbps와 4kbp까지 낮출 수 있는 가변 전송율 보코더를 구현하였다. 제안한 방법은 4kbps일 경우에 G.729의 부호화전에 PSOLA를 적용하여 피치의 주기를 반으로 줄여 부호화한다. 이렇게 부호화된 데이터는 G.729의 복호화를 거치고 다시 PSOLA를 통해 음성의 피치 주기를 2배로 늘려주어 원음성을 합성하게된다. 기존의 Bkbp의 전송율을 갖는 G.729는 음성의 크기가 반으로 줄어 부호화되므로 전송율이 4kpb로 줄어들게 된다. 실험의 평가는 MOS 테스트를 통해 수행되었으며 4kbp에서 MOS값이 3.37정도로 측정되었다. 또한 처리해야할 음성의 길이가 줄어들게 되므로 계산시간도 줄어들게 된다.

• The Journal of the Acoustical Society of Korea
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• v.13 no.5
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• pp.77-82
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• 1994

In speech signal processing, it is very important to detect the pitch exactly. Although various methods for detecting the pitch of speech signals have been developed, it is difficult to exactly extract the pitch for wide range of speakers and various utterances. Thus we propose a new pitch detection algorithm which takes advantage of the G-peak extraction. It is a method to detect the pitch period of the voiced signals by finding MZCI (maximum zero-crossing interval) of the G-peak which is defined as cut-off bandwidth rate of LPF (low pass filter). This algorithm performs robustly with a gross error rate of 3.63% even in 0 dB SNR environement. The gross error rate for clean speech is only 0.18%. Also it is able to process all courses with high speed.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.83-88
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• 2012

The pitch searching is a very important process in a vocoder. Generally, the method of pitch searching method is used by highlighting the periodicity, where a correlation is identified with the signal by changing the interval of two pulses. When the correlation value is highest, the pitch can be found by the pulse interval because it is the repetition interval with most striking period. There are many methods to solve this problem and search the pitch by dividing a frame into many subframes, but there is too much calculation to solve. A method in this paper is suggested to vary the number of subframes by predicting the amplitude change rate in a frame. If this method is applied, the general pitch searching performance will be improved because the accuracy may be enhanced without affecting the sound quality in the synthesized signal after parameter transmission; and the pitch searching time may be reduced.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.135-140
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• 2022

Most machines are made of several types of . In particular, the shaft system of the ship consists of the brass of the propeller blade and the stainless steel of the shaft. When dissimilar the electrolyte solution of seawater, a voltaic cell and a shaft electromotive force is generated. This electromotive force causes electrical corrosion of the bearing and shaft supporting the shaft system. prevent this corrosion, a shaft grounding system is installed in ships. As for the experimental method, various information acquired by designing a program to periodically measure the electromotive force of the controllable pitchpropeller) system using an A/D converter of NI. This study analyzed the generation and characteristics of accumulator electromotive force for CPP and considered the installation location of the grounding system to remove the accumulator electromotive force.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.52-60
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• 2019

The control circuit of the CPP applied to FFX Batch-I and LST-II may be capable of generating a backward pitch even when the grounding phenomenon occurs in the other system. The purpose of this study was to improve the CPP control circuit to maintain the pitch even in the event of grounding. Since the CPP control circuit changes the propeller angle with the voltage difference input, it has a design structure that can be vulnerable if the input voltage fluctuates instantaneously. In order to solve the above problem, a terminating resistor is applied to the end of the control wire and a signal converter is applied between the control wires, as a way to improve the CPP control circuit design. In order to verify that there is no problem in improving the CPP control circuit design, the CPP pitch change control was tested in the actual sailing commissioning with LST-II. Since the command pitch value and the feedback pitch value are very similar to each other, it is confirmed that the CPP control circuit is suitable for the control signal transmission because there is no problem in transmitting the control signal.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.27-34
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• 2011

A numerical analysis was peformed for the supersonic aircraft with variable pitch thrust vector nozzle. Based on the requirement of the mixed turbofan engine of the supersonic aircraft, two dimensional thrust vector nozzle with variable pitch angle was designed. To investigate the effect of the thrust vectoring nozzle, the numerical analysis was conducted by using Fluent under the several pitch deflection angle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.170-176
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• 2010

A numerical analysis was peformed for the supersonic aircraft with variable pitch thrust vector nozzle. Based on the requirement of the mixed turbofan engine of the supersonic aircraft, two dimensional thrust vector nozzle with variable pitch angle was designed. To investigate the effect of the thrust vectoring nozzle, the numerical analysis was conducted by using Fluent under the several pitch deflection angle.