• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.797-806
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• 2008

In a double-passage cascade apparatus, only two blades are installed in order to increase the accuracy of experimental result by applying bigger blade than the size of multi-blades on the same apparatus. However, this causes difficulties to make correct periodic condition. In this study, sidewalls are designed to meet periodic condition without removing the operating fluid or adjusting tail boards. Surface Mach number on the blade surface is applied to a responsible variable, and 12 design variables which are related with sidewall profile control are selected. A gradient-based optimization is adopted for wall design and CFX-11 is used for the internal flow computation. The computed result shows that it could obtain the same flow structure by modifying only the sidewalls of the double-passage cascade apparatus.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.77-83
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• 2004

In this paper, the Classification of Energy Labeling has been proposed. Energy parameters of input signal which are extracted from each phoneme are labelled. And groups of labelling according to detected energies of input signals are detected. Next. DTW processes in a selected group of labeling. This leads to DTW processing faster than a previous algorithm. In this Method, because an accurate detection of parameters is necessary on the assumption in steps of a detection of speeching duration and a detection of energy parameters, variable windows which are decided by pitch period are used. A pitch period is detected firstly : next window scale is decided between 200 frames and 300 frames. The proposed method makes it possible to cancel an influence of windows and reduces the computational complexity by $25\%$.

• Korean Journal of Optics and Photonics
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• v.9 no.1
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• pp.9-14
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• 1998

We present a simple method of determining the absolute order of moire fringes formed by the moire shadow topography with a criss-crossed grating. Two experimental methods in this topography are proposed and demonstrated; one is to change the ratio of x and y pitches in a criss-crossed grating after fixing the position of a light source and a camera, and the other is to change the position of a light source and a camera after fixing the ratio of x and y pitches in a criss-crossed grating.

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.54-57
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• 1992

음성합성에 있어서 음의 자연성을 합성시키는 문제는 크게 두가지로 나누어진다. 첫째는 합성음을 원음에 가깝게 구현하려는 합성방법 자체의 문제로, 언어 합성이 가지고 있는 일반적인 문제이다. 또 다른 문제는 운율에 관한 것으로 낱말 또는 문장 내에서의 운율에 따라 합성음의 자연성이 좌우된다. 이러한 운율에 따라 합성음의 자연성이 좌우된다. 이러한 운율의 조절에는 지속시간, 피치, 그리고 음의 세기 등이 이용된다. 켑스트럼을 이용하여 분석합성을 하는 경우, pole-zero 모델로 스펙트럼 포락을 근사하므로 원음에 충실하고, 필터계수와 구동정보를 분리하여 분석, 합성하므로 인위적인 운율의 조절이 용이하여 음성합성이 가지는 위의 두가지 문제를 해결하는데 적합하다고 판단된다. 본 연구에서는 켑스트럼을 이용하여 분석합성 시스템을 구성하였다. 음성 합성 과정에서, 운율 조절 파라미터중의 하나인 피치 주기의 변경에 따라 스펙트럼 포락의 왜곡에 대해 살펴보고, 왜곡을 최소화하는 방안을 제안한다.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2447-2450
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• 2003

화자인식은 음성의 특성을 이용해서 화자의 신원을 확인하는 기술이다. 이러한 기술은 등록된 화자집단 중 화자를 식별하는 화자식별(speaker Identification)과 지금 발성한 화자만을 비교하여 확인하는 화자확인(speaker verification)이 있다. 이러한 화자인식은 음성에 내재되어 있는 화자정보를 추출하여 개인을 확인하는 기술로 전화망을 통한 서비스가 확산되어 가고 있는 현대사회에 가장 효과적인 기술 중 하나이다. 또한 PDA를 이용한 증건거래 시스템 등 현대사회에서는 실시간으로 화자인식이 이루어져야 한다. 본 논문에서는 이와 같이 실시간 화자인식을 위한 처리시간 단축에 관하여 연구하였다. 처리시간 단축을 위하여 우선 피치주기 단위로 음성 파형을 분해한 다음 분해된 피치 단위에 윈도우 함수를 곱해서 단구간 신호의 열로 만들고 분해된 단위를 조절하는 PSOLA 합성방식을 이용하여 인식 시스템의 전처리단을 재구성하였다. 이와 같은 방식으로 제안한 인식시스템의 처리시간, 인식률을 기존의 화자인식 시스템과 비교하였다.

• The Journal of the Acoustical Society of Korea
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• v.12 no.2
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• pp.14-27
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• 1993

본 논문은 매 40ms 정도의 음성파형으로부터 추출된 6내지 9ms 정도의 1피치주기 파형을 합성단위로 사용하여 합성시킨 시간영역에서의합성방식을 한국어 문어 변환 시스템내에서의 음성합성기에 적용시킨 연구결과이다. 시험 결과, 4가지 유형의 한국어 음절 합성이 가능하고, 장단강약과 같은 운율요소의 제어가 용이하고, 또한 합성 알고리즘이 간단하여 실시간 처리가 가능하였으나, 문장 단위의 음성을 합성하기 위하여는 문장내에서의 다양한 피치 패턴에 대한 연구와 이의 효율적인 제어에 관한 연구가 이루어져야 할 것이다. 합성음에 대한 평가방법으로는 원음과 합성음에 대한 시간영역에서의 파형비교, 주파수 영역에서의 스펙트럼 포락선 유사성 비교 및 합성음에 대한 청취도 실험을 행하였다.

• Polymer(Korea)
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• v.30 no.5
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• pp.422-425
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• 2006

Due to their periodic helical structure, cholesteric liquid crystals (CLC) have a unique ability to selectively reflect visible light. CLC films reflecting a broad wavelength band were prepared by inducing a pitch gradient in CLC layers through a diffusion of small molecules and through a thermal mixing of cyclic siloxane CLC molecules with different pitch lengths. Various pitch gradients in the CLC cell were observed using UV/Vis spectrometer and SEM technique.

• The Journal of the Acoustical Society of Korea
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• v.14 no.1E
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• pp.22-29
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• 1995

Code excited Linear Prediction(CELP) vocoder exhibits good performance at data rates below 4.8 kbps. The major drawback of CELP type coders is their large amount of computation. In this paper, we propose a new pitch searching method that preseves the quality of the CELP vodocer reducing computational complexity. The basic idea is that pregrasps preliminary pitches about signal and performs pitch search only about the preliminary pitches. Applying the proposed method to the CELP vocoder, we can reduce complexity about 90% in th pitch search.

• 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.

• The Journal of the Acoustical Society of Korea
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• v.13 no.6
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• pp.91-97
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• 1994

In speech processing, the waveform codings are concerned with simply preserving the waveform of signal through a redundancy reduction process. In the case of speech synthesis, the waveform codings with high quality are mainly used to the synthesis by analysis. Because the parameters of this coding are not classified as both excitation and vocal tract, it is difficult to apply the waveform coding to the synthesis by rule. Thus, in order to apply the waveform coding to synthesis by rule, it is necessary to alter the pitches. In this paper, we proposed a new pitch alteration method that can change the pitch period in waveform coding by dividing the speech signals into the vocal tract and excitation parameters. This method is a time-frequency domain method preserving the phase component of the waveform in time domain and the magnitude component in frequency domain. Thus, it is possible that the waveform coding is carried out the synthesis by rule in speech processing. In case of using the algorithm, we can obtain spectrum distortion with $2.94\%$. That is, the spectrum distortion is decreased more $5.06\%$ than that of the pitch alteration method in time domain.