• 대한음성학회:학술대회논문집
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• 대한음성학회 2004년도 춘계 학술대회 발표논문집
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• pp.215-218
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• 2004

The aim of this paper is to analyze the acoustic features for disguised voice. In this paper we examined the features such as pitch range, vowel formants(F1, F2, F3, F4). So the result of the analysis is as follows. : (1) Pitch range and average of pitch value is very important cue for speaker verification. (2) F3-F2 is also important cue for speaker verification (3) /a/ is more verified than other vowels.

• 음성과학
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• 제11권2호
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• pp.119-136
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• 2004

Ellipsis is the figure of speech characterized by the deliberate omission of words that are obviously understood, but that must be supplied to make a construction grammatically or semantically complete. The purpose of this study is to examine how ellipsis affects its adjacent elements acoustically and phonologically in English VP-ellipsis, sluicing and gapping. In the experiment, the realizations by English native speakers are set as the criteria for the observing point and are compared to Korean speakers' realizations. For the results, while English native speakers utilized various acoustic information such as word duration and pitch range and phonological information such as pith accent realization in order to intend the cues for decoding the missing constituent, Korean English learners relied on only duration information and could not use various information effectively.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.221-225
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• 2000

The effect of twisting on the microstructural evolution and critical current of BSCCO superconductor tape has been evaluated. Twisting pitches of the tapes are in the range of 8-70 mm and uniformly deformed. The critical current of twisted tape was dependent on the twist pitch. Specifically, it was observed that the critical current decreased with decreasing twist pitch, and only 50% of critical current was retained when the tape was twisted to a pitch of 8 mm. This reduction of the critical current may be related to the interface irregularity, smaller grain size, worse texture and the presence of cracks due to the induced strain during the twisting processing.

• Carbon letters
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• 제5권1호
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• pp.23-26
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• 2004

A study of partial carbonisation of green pitch fibres to temperatures in the range of 500-$1000^{\circ}C$ was carried out on three precursors - a neat pitch and two polymer modified pitches, with a view to find out a suitable temperature at which the fibres acquire considerably improved toughness or handleability (compared to that in the green stage) for their subsequent processing into carbon fibres. A partial carbonisation temperature of 500-$600^{\circ}C$ has been identified to result in a remarkable improvement in the toughness/handleability of the fibres in all the three cases. However, from techno-economical considerations, the neat pitch appears to provide the best precursor system for the production of pitch based carbon fibres.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.1104-1111
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• 1994

Code Excited Linear Prediction(CELP) as a speech coder exhibits good performance at data rates below 4.8 kbps. The major drawback to CELP type coders is their large amount of computation. In this paper, we propose a new pitch search method that preserves the quality of the CELP vocoder with reduced complexity. The basic idea is to restrict the pitch searching range by estimating the preliminary pitches. Applying the proposed method to the CELP vocoder, we can get approximately 87% complexity reduction in the pitch search.

• International Journal of Aeronautical and Space Sciences
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• 제13권3호
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• pp.317-322
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• 2012

The low speed aerodynamic characteristics for a modified sonic arc airfoil which is designed by using the nose shape function of sonic arc, the shape function of NACA four-digit wing sections, and Maple are experimentally investigated. The small rotor blades of a modified sonic arc and NACA0012 airfoil are precisely fabricated with a commercially available light aluminum(Al 6061-T6) and are spin tested over a low speed range (3000rpm-5000rpm). In a consuming power comparison, the consuming powers of NACA0012 are higher than that of modified sonic arcs at each pitch angle. The measured rotor thrust for each pitch angle is used to estimate the rotor thrust coefficient according to momentum theory in the hover state. The value of thrust coefficients for both two airfoils at each pitch angle show almost constant values over the low Mach number range. However, the rotor thrust coefficient of NACA0012 is higher than that of the modified sonic arc at each pitch angle. In conclusion, the aerodynamic performance of NACA0012 is better than that of modified sonic arcs in the low speed regime. This test model will provide a convenient platform for improving the aerodynamic performance of small scale airfoils and for performing design optimization studies.

• 센서학회지
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• 제26권4호
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• pp.259-265
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• 2017

Magnetometer calibration must be performed before the use of three-axis magnetometers to ensure the accuracy of orientation estimation. Recently, one of the most popular calibration approaches is the ellipsoid fitting technique due to its high performance in calibration. To date, in fact, performances of the existing ellipsoid fitting methods have been evaluated with full range rotation data. However, in case of the calibration of magnetometers attached to vehicles, ships, and planes, it is very difficult to collect the full range rotation data since their allowable ranges in terms of roll and pitch are limited to small. This constraint may result in serious performance degradation of some ellipsoid fitting algorithms. Therefore, to be practical, this paper proposes a weighted least square-based magnetometer calibration method that is robust in roll-pitch limited conditions. Furthermore, the proposed method is a linear approach and thus is free from the well-known initial value issue in nonlinear approaches. Experimental results show the superiority of the proposed method to other ellipsoid-fitting calibration methods.

• 음성과학
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• 제9권2호
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• pp.109-132
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• 2002

The purpose of this study is to examine the focus realization of [Adjective+Noun] phrases which are used in English classroom situations. In order to examine this, two production and one perception experiments were designed. The noun phrases in the first two production experiments are divided into three patterns according to the location of focus. The difference between the two production experiments is that in the first experiment the focused words are contextually given in the classroom situation, but in the second experiment they are presented in written form. We compare the native English teachers' focus realization of noun phrases with that of Korean teachers from the point of view of intonational phonology. In the perception test, we examine how the uttered sentences are perceived by English native speakers and Korean native speakers. The results from the three experiments show that native English teachers' focus realization is quite consistent with informational structure. Also, there is a significant difference in pitch range of adjectives and nouns when the native speakers give pitch accents on the two content words, and the uttered sentences are mostly perceived as well as the speakers' intentions. As for Korean speakers, however, they usually focus only on the adjective or they focus on both the adjective and the noun, regardless of the relative informativeness of these words. From these findings, we can conclude that focus realization of Korean teachers is rather inconsistent with respect to informational structure when compared to that of native English teachers.

• Journal of Biosystems Engineering
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• 제9권2호
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• pp.27-36
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• 1984

This study was carried out to investigate the effects of the tilling depth, tilling travel speed and soil shear stress on the tilling load characteristics and power requirement for rotary tillers. The results obtained from the study are summarized as follows. 1. The average and maximum PTO torque increased as the tilling depth, tilling pitch and soil shear stress increased. A multiple linear regression equation to estimate the average PTO torque in terms of the above parameters was developed. 2. The ratios of maximum PTO torque to the average torque were in the range of 1.17 to 1.65 for the various tilling conditions tested. The variation in PTO torque increased greatly as the tilling pitch and soil shear stress increased, but decreased as the tilling depth increased. 3. Power requirement for the PTO shaft increased with the tilling depth, travel speed and soil shear stress, but decreased slightly as the tilling pitch increased. A multiple linear regression equation to estimate power requirement for the PTO shaft in terms of the above parameters was developed. 4. The specific power requirement for the rotary tiller was in the range of $0.008-0.015ps/cm^2$ for the various tilling conditons tested. The specific tilling capacity decreased as the tilling depth and soil shear stress increased, but increased with the tilling pitch. A multiple linear regression equation to estimate the specific tilling capacity in terms of the above parameters was developed.

• 말소리와 음성과학
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• 제11권2호
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• pp.15-21
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• 2019

Korean and English are both known to show on-focus pitch range expansion and post-focus pitch range compression (PFC). But it is not clear if this prosodic similarity would make it easy for Korean speakers to learn English focus prosody. In the present study, we conducted a production experiment using phone number strings to examine whether Korean learners of English produce a native-like focus prosody. Korean learners of English were classified into three groups (advanced, intermediate and low) according to their English proficiency and were compared to native speakers. Results show that intermediate and low groups of speakers did not increase duration, intensity, and pitch in the focus positions, nor did they compress those cues in the post-focus positions. Advanced speakers noticeably increased the acoustic cues in the focus positions to a similar extent as native speakers. However, their performance in post-focus positions was quite far from that of native speakers in terms of pitch and excursion size. These results thus demonstrate a lack of positive transfer of focus prosody from Korean to English in L2 learning, and learners may have to relearn it from scratch, which is consistent with a previous finding. More importantly, the results provide further support for the view proposed in other works that acoustic properties of PFC were not easily transferred from one language to another.