• 말소리와 음성과학
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• 제2권1호
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• pp.13-21
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• 2010

The purpose of this study was to examine the prosody characteristics of sentence-level utterances which contain homographs with context cues in patients with neurogenic communication disorders. Homographs which may be affected by prosody, especially tonic length features, were used to investigate this matter. The characteristics of tone, duration, pitch, and pitch peak were analyzed to examine the characteristics of prosody in patients with lesions in the left or right hemisphere and normal controls. The whole process was recorded using Praat 4.3.14 and for statistical analyses, three-way ANOVA and multiple comparative analyses, Chi-Square tests, and a one-way ANOVA were carried out using SPSS 12.0 for Windows. The conclusions of this study are as follows. First, the length of syllables and vowels in homographs in Korean was different depending on the meaning and was not significant between groups. Second, it was found that patients with lesions in the right hemisphere had significant difference on pitch. Third, it was found that frequency of pitch peak and tone in 'short' tone syllables were different between groups. The conclusion of this study found that the prosody of homographs between groups absolutely was not differentiated. Accordingly, more detailed studies of acoustic parameters and other parameters which the prosody characteristic between groups could be found are needed in the future.

• Korean Chemical Engineering Research
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• 제45권6호
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• pp.604-610
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• 2007

납사타르피치의 연소 및 수증기 가스화의 반응특성을 알아보기 위하여 납사타르피치를 탄소원으로 사용하여 열중량분석을 수행하였다. 반응의 활성화에너지, 반응차수, 빈도인자 등을 구하기 위하여 Friedman 방법과 Ozawa-Flynn-Wall 방법이 사용되었다. Friedman 방법을 사용하여 반응전환에 따른 연소의 활성화에너지를 구하였는데, 0.2~0.6 정도의 전환이 일어났을 때는 활성화에너지가 41.6~68.1 kJ/g-mol이었다. 0.9~1.0 정도의 전환이 일어났을 때는 183.1~191.2kJ/g-mol이었다. 그리고 수증기 가스화에 대해서는, 0.2~0.6 반응전환에서 활성화에너지는 31.9~44.9 kJ/g-mol이었다. 0.8~0.95 전환에서는 70.6~87.8 kJ/g-mol이었다. 이러한 결과로 미루어보아 반응은 탈휘발화와 연소 또는 가스화 반응의 두 단계로 진행되는 것을 알 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.658-664
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• 2002

Unsteady flow characteristics and associated blade tonal noise of a cross-flow fan are predicted by a computational method. The incompressible Navier-Stokes equations are time-accurately solved for obtaining the pressure fluctuations between the rotating blades and the stabilizer, and sound pressure is predicted using Curie's equation. The computed fan performance is favorably compared with experimental data, and also indicates that the performance is not significantly altered by the random pitch effect at ${\phi}>0.4$. In the present study, the narrow-band noise characteristics of three impellers with a uniform and two random Pitch (type-A and-B) blades are compared by the SPL (Sound Pressure Level) spectra, and their frequency modulation characteristics of the BPF (Blade Passing Frequency) noise are also discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.144-147
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• 2005

The tire is considered as one of the Important noise sources having an influence on vehicle's performance. The Pattern noise of a tire is the transmission sound of airborne noise. On smooth asphalt road, Pattern noise is amplified with the velocity. In recent, the study on the reduction of Pattern noise is energetically processed. Pattern noise is strongly related with pitch sequence. To reduce the pattern noise, tire's designer has to randomize the sequence of pitch. The FFT is a traditional method to evaluate the level of the randomization of the pitch sequence, but gives no information on time-varying, instantaneous frequency. In the study, we found that Time-Frequency transform is a useful method to non-stationary signal such as tire noise.

• 한국소음진동공학회논문집
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• 제16권6호
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• pp.627-633
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• 2006

The tire is considered as one of the important noise sources having an influence on vehicle's performance. The Pattern noise of a tire is the transmission sound of airborne noise. On smooth asphalt road, Pattern noise is amplified with the velocity. In recent, the study on the reduction of Pattern noise is energetically processed. Pattern noise is strongly related with pitch sequence. To reduce the pattern noise, tire's designer has to randomize the sequence of pitch. The FFT is a traditional method to evaluate the level of the randomization of the pitch sequence, but gives no information on time-varying, instantaneous frequency. In the study, we found that Time-Frequency transform is a useful method to non-stationary signal such as tire noise.

• 말소리와 음성과학
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• 제8권4호
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• pp.131-138
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• 2016

This study analyzes the characteristics of good impression using speech manipulation scripts and investigates the characteristics of preferred speech voice. Fourty male and female college students participated in this study. They have been exposed to the Gyeongsang dialect spoken by their friends and family for more than 15 years. Two sample voices(1 male and 1 female), considered as giving good impression, were subject to voice analysis. Two students were asked to read the sample paragraph of 'Walking' and their voice samples were analyzed through Praat. The collected speech data were manipulated into 4 different sets by changing pitch level, degree of loudness and speech rate. First, both men and women received good impression more from pitch-lowered sound than from the original one. Second, men tended to receive good impression more from slightly louder voice than from the natural-pitched one. Third, it was shown that men often felt more drowned to a voice at slightly faster speech rate than at the original speech rate. Overall, both male and female listeners favored lower pitch over the original pitch. Men tended to prefer louder voice sound while women preferred less loud one. Men received better impression at a lower speech rate but women at a faster speech rate.

• 말소리와 음성과학
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• 제8권4호
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• pp.23-29
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• 2016

The present study tested if individual speakers showing great sound change in segments (i.e., vowels and fricatives) also had innovative changing patterns in suprasegmental properties (i.e., lexical pitch accents) in Kyungsang Korean. The acoustic analysis at a group level first confirmed the presence of group level differences in distinguishing /ɨ-ʌ/ and /s-s'/ both of which had different phonemic distinction from Seoul Korean. Younger speakers had more innovative segmental change than older speakers, and even within the younger generation, female speakers produced more innovative phonetic variants than male speakers. Regarding the individual observation within the younger group, the younger speakers with large acoustic distinction in vowels and fricatives also showed acoustically less distinct accent patterns, indicating the innovative sound change pattern consistent across segment and suprasegmental properties. The group and individual observations suggested that linguistic innovators introduced new phonetic variants with consistent degree of changing pattern between segment and suprasegmental properties.

• 한국음향학회지
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• 제31권7호
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• pp.419-426
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• 2012

보코더 에서 의 피치 분석 과정은 매우 중요하다. 일반적으로 먼저 신호의 주기성을 강조한 후 피치를 검색하는 방법을 주로 사용한다. 프레임 내에서 두 개의 펄스 간격을 변화시켜가며 신호와의 상관관계를 구하는 것으로 상관관계 값이 가장 높을 때가 주기가 가장 두드러지는 반복 구간이므로 이때 의 펄스 간격을 피치 주기로 찾는다. 그러나 찾아진 주기가 반주기, 배주기 및 세배주기인 경우에는 이 간격을 피치 주기라 할 수 없어 이를 해결하기 위한 여러 가지방법들이 제안되어있다. 또한 프레임 내에서의 신호의 진폭이 일정하지 않고 갑자기 변하는 구간이 있는 경우 정확하지 않는 피치가 얻어진다. 이를 해결하기 위해 프레임을 여러 개의 서브프레임으로 다시 나누어 피치를 검색하는 방법을 사용하고 있는데 이 방법은 피치를 정확하게 검색할 수 있지만 계산 량이 많아진다. 본 논문에서는 위에 제시한 두 가지 문제점을 개선하기 위한 알고리즘을 제안한다. 첫째 반주기, 배주기 및 세배주기를 줄이기 위해 피치를 검색하기 전에 프레임 내의 전체 에너지변화 비율을 추정하여 신호의 에너지 레벨을 미리 보상해 준 후 피치를 검색하는 방법을 제안한다. 둘째, 이렇게 구한 에너지 비율로 프레임 내의 진폭 변화율을 예측하여 서브프레임 수를 가변시키는 방법을 제안한다. 이 방법들을 적용하면 합성 음질에는 영향을 주지 않는 상태에서 피치검색 시간을 단축할 수 있고, 피치 검색의 정확도를 높일 수 있어 전반적인 피치 검색에 관한 성능 개선이 된다.

• 방송공학회논문지
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• 제9권1호
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• pp.2-7
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• 2004

본 논문에서는 내용 기반 음악 정보 검색에 MPEG-7에 정의된 오디오 서술자를 적용하는 방법을 제안한다. 특히 Pitch 정보와 timbral 특징들은 음색 구분을 용이하게 할 수 있어 음악 검색뿐만 아니라 음악 장르 분류 또는 QBH(Query By Humming)에 이용 될 수 있다. 이러한 방법을 통하여 오디오 신호의 대표적인 특성을 표현 할 수 있는 특징벡터를 구성 할 수 있다면 추후에 멀티모달 시스템을 이용한 검색 알고리즘에도 오디오 특징으로 이용 될 수 있을 것이다. 본 논문에서는 방송 시스템에 적용하기 위해 영화나 드라마의 배경음악에 해당하는 O.S.T 앨범으로 검색 범위를 제한하였다. 즉, 사용자가 임의로 검색을 요청한 시점에서 비디오 컨텐츠로부터 추출한 임의의 오디오 클립만을 이용하여 그 컨텐츠 전체의 O.S.T 앨범 내에서 음악을 검색할 수 있도록 하였다. 오디오 특징 백터를 구성하기 위해 필요한 MPEG-7 오디오 서술자의 조합 방법을 제안하고 distance 또는 ratio 계산 방식을 통해 성능 향상을 추구하였다. 또한 reference 음악의 템플릿 구성 방식의 변화를 통해 성능 향상을 추구하였다. Classifier로 k-NN 방식을 사용하여 성능평가를 수행한 결과 timbral spectral feature 보다는 pitch 정보를 이용한 특징이 우수한 성능을 보였고 vector distance 방식으로는 특징들의 비율을 이용한 IFCR(Intra-Feature Component Ratio) 방식이 ED(Euclidean Distance) 방식보다 우수한 성능을 보였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.367-373
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• 2008

Spinning detonations propagating in a circular tube were numerically investigated with a one-step irreversible reaction model governed by Arrhenius kinetics. Activation energy is used as parameter as 10, 20, 27 and 35, and the specific heat ratio and the heat release are fixed as 1.2 and 50. The time evolution of the simulation results was utilized to reveal the propagation mechanism of single-headed spinning detonation. The track angle of soot record on the tube wall was numerically reproduced with various levels of activation energy, and the simulated unique angle was the same as that of the previous reports. The maximum pressure histories of the shock front on the tube wall showed stable pitch at Ea=10, periodical unstable pitch at Ea=20 and 27 and unstable pitch consisting of stable, periodical unstable and weak modes at Ea=35, respectively. In the weak mode, there is no Mach leg on the shock front, where the pressure level is much lower than the other modes. The shock front shapes and the pressure profiles on the tube wall clarified the mechanisms of these stable and unstable modes. In the stable pitch at Ea=10, the maximum pressure history on the tube wall remained nearly constant, and the steady single Mach leg on the shock front rotated at a constant speed. The high and low frequency pressure oscillations appeared in the periodical unstable pitch at Ea=20 and 27 of the maximum pressure history. The high frequency was one cycle of a self-induced oscillation by generation and decay in complex Mach interaction due to the variation in intensity of the transverse wave behind the shock front. Eventually, sequential high frequency oscillations formed the low frequency behavior because the frequency behavior was not always the same for each cycle. In unstable pitch at Ea=35, there are stable, periodical unstable and weak modes in one cycle of the low frequency oscillation in the maximum pressure history, and the pressure amplitude of low frequency was much larger than the others. The pressure peak appeared after weak mode, and the stable, periodical unstable and weak modes were sequentially observed with pressure decay. A series of simulations of spinning detonations clarified that the unsteady mechanism behind the shock front depending on the activation energy.