• Phonetics and Speech Sciences
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• v.4 no.1
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• pp.3-11
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• 2012

The aim of this paper is to examine the phonetic realizations of English unstressed vowels produced by advanced Korean learners (KLs) of English compared with English native speakers (NSs) focusing on the comparative study of English words and English loanwords. The result shows that KLs are usually not native-like in producing the English unstressed vowel /ə/ and loanword orthography affects the way the KLs produce /?/. The vowel quality of the unstressed vowels produced by the KLs is different from that of the NSs. In duration and pitch, KLs show significantly less difference between the stressed and unstressed vowels than do the NSs. The KLs usually have a high pitch in the stressed and the last syllable while the NSs usually produce peak F0 in the stressed syllable. When the KLs have a similar vowel quality with that of the NSs, they produce a shorter duration of the unstressed vowels. However, there is no correlation between the realization of the pitch and the vowel quality in KLs speech.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.2
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• pp.274-279
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• 1987

In this paper, we describe a new algorithm for extracting nasal sound in continuous speech. We obtain pitches by using Area Comparison Method and extract nasal sound by comparing the area of G-peak and the area of side peak in one pitch interval. By using this method, the process can be speeded up. Therefore realtime processing is possible with a general microprocessor.

• The Journal of the Acoustical Society of Korea
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• v.31 no.7
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• pp.419-426
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• 2012

The pitch searching is a vital process in a vocoder. Generally, the method of pitch searching is employed after highlighting the periodicity, where a correlation is identified with the signal by changing the interval of two pulses. When the correlation value reaches the peak, the pitch can be found by the pulse interval because it is the repetition interval with most striking period. However if the identified period happens to be one of half period, double period or triple period, this cannot be considered as the pitch period. Many methods were suggested to solve this problem. An inaccurate pitch could be obtained as well, when there is an interval where signal amplitude is not constant but varies abruptly in the frame. To solve this matter, searching the pitch by dividing a frame into various subframes is adopted, but too much calculation has to be followed while it leads the correct value. This paper suggests an algorithm to resolve these two problems. First, to search the pitch after advance correction of the signal energy level with an estimated overall energy change ratio in the frame before pitch search to reduce half period, double period and triple period is suggested. Second, to vary the number of subframes by predicting the amplitude change rate in the frame by the energy ratio obtained by the above-mentioned method is advised. If these two methods are applied, the pitch searching time can be reduced and the general pitch searching performance can be improved without affecting the sound quality in the synthesized signal.

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

• Phonetics and Speech Sciences
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• v.4 no.3
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• pp.43-49
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• 2012

This paper describes the categorical effects of pitch accent contrasts in a mimicry task. It focuses, specifically, on examining how fundamental frequency (f0) variation reflects phonological contrasts from speakers of two distinct varieties of Korean (i.e., North Kyungsang and South Cholla). The results showed that, in a mimicry task using synthetic speech continua, there was a categorical effect in f0 peak timing for North Kyungsang speakers, but the timing of f0 peaks and valleys in the responses of South Cholla speakers was more variable, presenting a gradient or non-categorical effect. Evidence of categorical effects was represented as the shift of f0 peak times along an acoustic continuum for North Kyungsang speakers. The range for the shift of f0 valley times was much narrower, compared to that of f0 peak times. The degree of a shift near the middle of the continuum showed variability across individual mimicry responses. However, the categorical structure in mimicry responses regarding the clustering of f0 peak points was more significant for North Kyungsang speakers than for South Cholla speakers. Additionally, the finding of the current study implies that the location of f0 peak times depends on individuals' imitative (or cognitive) abilities.

• The korean journal of orthodontics
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• v.36 no.4
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• pp.275-283
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• 2006

Objective: Small orthodontic mini-implants are useful as anchorage. However they have some weaknesses such as loosening. This study was carried out to analyze the mechanical effects of the dual pitch and diameter on the insertion and removal torque of mini-implants. Methods: The threads of mini-implants were mono and dual pitch. The diameters of mini-implants were 1.4 mm and 1.6 mm. Four groups were tested (mono 1.4 mm, mono 1.6 mm, dual 1.4 mm and dual 1.6 mm). All were inserted and removed on polyurethane foam with the torques being measured. Results: The maximum torque of the dual pitch groups was higher than the mono pitch groups during removal but lower during insertion. The maximum torque of the 1.6 mm diameter groups was higher than the 1.4 mm diameter groups during insertion and removal. The dual pitch 1.4 mm group showed the lowest insertion torque but had similar or superior levels of removal torque to that of the mono pitch 1.6 mm group. Conclusions: The dual pitch especially showed a continuous high removal torque after the peak. Despite the small diameter, the dual pitch might improve the initial mechanical stability.

• Speech Sciences
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• v.1
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• pp.137-152
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• 1997

The objectives of this paper are to see how the declination is realized in the different positions/lengths of the utterance, to see if the $F_0$ value throughout the utterance changes in a predictable way, and if so, to find out the best quantitative model which fits the declination. The experiment results are as follows. First, the peak value over the utterance can be affected by the position of the peak and length of the utterance. Second, the choice of quantitative models is dependent on the different list lengths. Third, in everyone's speech, there is a baseline (the lowest $F_0$ value a speaker can use), and the $F_0$ will not fall below the baseline. Forth, the peak $F_0$ of the last word in each list shows little variation in pitch value (target $F_0$) while the number of words in the list affects the starting $F_0$ values.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.68-75
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• 2007

The pitch and orthogonality of two-dimensional (2D) gratings have been measured by using a metrological atomic force microscope (MAFM) and measurement uncertainty has been analyzed. Gratings are typical standard artifacts for the calibration of precision microscopes. Since the magnification and orthogonality in two perpendicular axes of microscopes can be calibrated simultaneously using 2D gratings, it is important to certify the pitch and orthogonality of 2D gratings accurately for nano-metrology using precision microscopes. In the measurement of 2D gratings, the MAFM can be used effectively for its nanometric resolution and uncertainty, but a new measurement scheme was required to overcome some limitations of current MAFM such as nonnegligible thermal drift and slow scan speed. Two kinds of 2D gratings, each with the nominal pitch of 300 nm and 1000 nm, were measured using line scans for the pitch measurement of each direction. The expanded uncertainties (k = 2) of measured pitch values were less than 0.2 nm and 0.4 nm for each specimen, and those of measured orthogonality were less than 0.09 degree and 0.05 degree respectively. The experimental results measured using the MAFM and optical diffractometer were coincident with each other within the expanded uncertainty of the MAFM. As a future work, we also proposed another scheme for the measurements of 2D gratings to increase the accuracy of calculated peak positions.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1423-1428
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• 2006

In this study, we have prepared pitch binded AC (activated carbon)/$AC/TiO_2$ composites photocatalysts through carbon tetrachloride solvent method. The developed samples were characterized with surface properties, structural crystallinity between AC and $AC/TiO_2$, elemental identification and photocatalytic activity. The results of the textural surface properties demonstrate that there are slight increases in the BET surface area and adsorbed volume from adsorption isotherm of composite samples with increasing of the amount of AC. The SEM results present to the characterization of porous texture on the pitch/AC/$AC/TiO_2$ composites and homogenous compositions in the particle for all the materials used. From XRD data, a weak and broad carbon peak of graphene remained rutile peaks kept with anatase structure were observed in the X-ray diffraction patterns for the pitch/AC/$AC/TiO_2$ composites. 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 the pitch/AC/$AC/TiO_2$ composites between relative concentration ($c/c_o$) of MB and UV irradiation time could be attributed to the both effects between photocatalysis of the supported $AC/TiO_2$ and adsorptivity of the two kinds of carbons.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.803-808
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• 2006

This paper was a study about noise reduction through flow stabilization in duel using experimental method and numerical analysis at the same time. To determine the fan's type three kinds of fans(axial fan, centrifugal fan, and axial fan with centrifugal type) was examined to investigate the suitability for duct. As a result, under the equal number of rotation 2000 RPM, performance of an axial fan with centrifugal type was the most superior by 55dBA at 4.3CMM among other fans. After this, analyzed the results of the numerical analysis to find out the optimum design of pitch angle such as $0^{\circ},\;10^{\circ},\;15^{\circ}\;and\;20^{\circ}$. The intensity of turbulence was low when pitch angle was $15^{\circ}$ and air volume became peak by 5.08 CMM. It was observed that axis component of velocity increased gradually when pitch angle increased from $0^{\circ}\;to\;20^{\circ}$. Finally, designed the shapes of D/S(Down Stream) in duct that agreed inlet angle($\delta$) of stationary blades with pitch angle($\beta$) of axial fan with centrifugal type and derived flow to duct medial, and changed the shape of motor-mount to reduce occurance of unstable vortex in tip of impeller, and embodied noise reduction and improvement of air flow rate through flow stabilization.