• 말소리와 음성과학
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• 제16권2호
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• pp.37-47
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• 2024

본 연구는 대중가요 관련학과에서 보컬을 전공하고 있거나 입시를 준비하는 전공하는 남성 27명을 대상으로 자신의 성종과 음역을 제대로 파악하고 있는지를 살펴보기 위해 주관적으로 평가한 성종과 음향학적으로 평가한 성종 간에 차이가 있는지를 비교하였고, 성종 간 기본주파수(fundamental frequqency, F0)와 평균발화기본주파수 간의 차이도 비교하였다. 또한, 이들이 모음에 따라 고음역에서 산출할 수 있는 정도가 다를 수 있으므로 극모음인 /a/, /i/, /u/ 모음 간 음역의 차이와 성종별로 구분하여 모음 간 음역의 차이가 있는지를 살펴보았으며, 모음별로 성종 간에 음역의 차이가 있는지도 비교하였다. 연구 결과, 대중가요 보컬을 전공하거나 입시를 준비하는 남성의 절반 이상이 본인의 성종을 정확하게 파악하지 못하고 있으며, 모음 간에 최대기본주파수와 주파수범위는 통계적으로 유의한 차이를 보여 모음의 종류에 따라 산출할 수 있는 음역의 차이가 있음을 알 수 있었다. 특히 모음 /a/>/u/>/i/ 순으로 음역이 감소하였다. 이는 모음 /a/가 다른 모음에 비해 고음역에서 조음하기에 용이하지만, 모음 /u/와 /i/는 고모음으로 혀의 위치가 상승함으로써 구강 면적이 좁아지고 후두의 상승이 동반되기 때문에 음역이 감소하고 고음에서 발성하기에 어려움이 초래된다는 것을 알 수 있다.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.46-57
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• 1995

The aim of the present study is to provide fundamental informations for the development of magneticfluid actuator. To achieve the aim, oscillation characteristics of the magneticfluid plug are investigated by experiment for the various length and position of the magneticfluid plug and the frequency of magnetic field. The oscillation characteristics are obtained. Amplitude, natural frequency, phase shift and damping ratio, are compared with theoretical values. From the study, the following conclusive remarks can be made. The experimental equation for the magnetic field is obtained. The critical magneticfluid length exists and its value is about 70mm. The range of the damping ratio and fluid loss coefficient obtained by experiment are 0.1~0.2 and 30~100, respectively. Comparison between experimental and theoretical results of oscillation characteristics shows good agreement in the high frequency range. Meanwhile, in the low frequency range, there appears little discrepancies(5% in the frequency and amplitude and 10% in phase difference and damping ratio) with each other.

• 한국조명전기설비학회지:조명전기설비
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• 제6권6호
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• pp.32-41
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• 1992

In this paper, an advanced Pulse Width Modulation Inverter strategy for driving a variable-speed induction motor is introduced. A switching pattern making use of the near-proportionality of voltage and frequency in AC machines operating with constant flux was computed. At low magnitudes and ow frequencies of the fundamental, many more harmonics are eliminated than at high magnitudes and frequencies. In order to keep the inverter switching frequency constant over the output frequency range, the chopping frequency is diminished as the frequency of the fundamental increases. Using these modulation strategy, the harmonics components of PWM inverter are efficiently eliminated.

• 말소리와 음성과학
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• 제4권1호
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• pp.111-118
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• 2012

The purpose of this study was to characterize and determine variances of speaking fundamental frequency and vocal intensity depending on gender and three utterance conditions (spontaneous speech, reading, and counting). A total of 65 undergraduate students (32 male students, 33 female students) attending universities in Daegu, South Korea participated in this study. The subjects were all in their 20s. This study used KayPENTAX's Visi-Pitch IV (Model 3950) to measure the variances of speaking fundamental frequency (SFF0) and vocal intensity (VI). As a result, this study came to the following conclusions. First, it was found that both males and females showed no significant difference in SFF0 and vocal intensity among three utterance conditions. Second, this study sought to analyze differences in the variances of SFF0 between males and females. As a result, it was found that females showed significantly higher levels of four measured variances (SFF0 $SD^{**}$, SFF0 $range^{***}$, Min $SFF0^{***}$ and Max $SFF0^{***}$) than males on spontaneous speech. However, it was found that there was no significant difference between males and females in SFF0 range on reading or in SFF0 SD and SFF0 range on counting. It was found that there was no significant difference between males and females in the level of measured variances of vocal intensity depending on utterance conditions. Finally, this study made a comparison and analysis on differences in the variances of SFF0 and vocal intensity among utterance conditions. As a result, it was found that all the measured variances of SFF0 in males were most significantly reduced depending upon spontaneous speech which was followed by reading and counting respectively (SFF0 SD: p<.001, SFF0 range: p<.05, Max SFF0: p<.05). Females however, show no significant difference in the measured variances of SFF0 depending upon three utterance conditions. It was also found that the measured variances of vocal intensity in females were most significantly reduced depending on spontaneous speech that was followed by reading and counting (VI SD: p<.001, VI range: p<.001, Min VI: p<.01 Max VI: p<.05), while males showed no significant difference in the measured variances of vocal intensity depending on three utterance conditions. In sum, these findings suggest that variances of SFF0 in males are affected by three utterance conditions, while variances of vocal intensity in females are affected by three utterance conditions.

• 말소리와 음성과학
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• 제8권4호
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• pp.15-22
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• 2016

This study aims to examine whether the fundamental frequency (F0) varies depending on languages or distinguishes between L1 (first language) and L2 (second language) speech and whether the type of materials which vary in control of consonant voicing affects the use of F0-especially, mean F0. For this purpose, we compared productions of two languages produced by Korean L2 learners of English to those of Korean-English bilingual speakers. Twelve Korean L2 speakers of English and twelve Korean-English bilingual speakers participated in this study. The subjects read aloud 22 declarative sentences-balanced and unbalanced-once in English and once in Korean. Mean F0 of Korean was higher than that of English for both speaker groups, and the difference in the value of mean F0 between the Korean and English sentences was different depending on the type of materials that the participants read. With regard to F0 range, the L2 speakers had a larger F0 range in English than in Korean; however, the effect of language on F0 range was not statistically significant for the bilingual speakers. These results indicate that language-specific properties may affect the use of F0, in particular, mean F0.

• 말소리와 음성과학
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• 제1권4호
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• pp.187-193
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• 2009

For this study, the external laryngeal lengths of 9 females and 9 males with normal voices were measured together with their ages, heights, and weights, and after they read aloud sentences for 3 minutes, their habitual speaking fundamental frequencies, speaking low pitches, speaking high pitches, and vocal fold closed quotients were measured. The Spearman rank correlation analysis on these data showed a significant negative correlation between the external laryngeal length and the habitual speaking fundamental frequency for both females and males, a significant negative correlation between the external laryngeal length and the speaking high pitch for only males, a significant negative correlation between the external laryngeal length and the speaking low pitch for both females and males, and a significant positive correlation between the external laryngeal length and the vocal fold closed quotient for only males.

• 대한후두음성언어의학회지
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• 제18권1호
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• pp.56-61
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• 2007

Introduction: Actually classification of classic singers' voice depends on habitual judgment by voice teachers or voice trainer referring to vocal timbre, vocal range and vocal quality. Such judgments, however, may turn out to be incorrect because they are based on subjective opinions. Therefore, more objective methodology is required. Method: Foreign dissertations searched through Pub Med, along with foreign and domestic journals, were reviewed regard ing how singers' voice has been categorized. Results: Vocal range, vocal timbre, voice quality, fundamental frequency of habitual speaking, length of vocal tract, the length from cricoid cartilage to thyroid cartilage's thyroid notch and length of vocal fold, tone of passaggio as well as traditional approaches such as perceptual judgment used by professional singers have been used for categorize the voice classification. Conclusion: To optimize categorizing singers' voice, vocal range, vocal timbre, voice quality, fundamental frequency of habitual speaking, length of vocal tract, the length from cricoid cartilage to thyroid cartilage's thyroid notch and length of vocal fold, tone of passaggio may be totally recommended.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.1-6
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• 2001

In this article, the fundamental concept, characteristics and application potentials of coreless printed-circuit-board (PCB) transformers are described. Coreless PCB transformers do not have the limitations associated with magnetic cores, such as the frequency limitation, magnetic saturation and core losses. In addition, they eliminate the manual winding process and its associated problems, including labor cost, reliability problems and difficulties in ensuring transformer quality in the manufacturing process. The parameters of the printed windings can be precisely controlled in modern PCB technology. Because of the drastic reduction in the vertical dimension, coreless PCB transformers can achieve high power density and are suitable for applications in which stringent height requirements for the circuits have to be met. A transformer's power density of $24W/cm^2$ has been reported in a power conversion application. When used in an isolation amplifier application, coreless PCB transformers tested so far enable the amplifier to achieve a remarkable linear frequency range of 1MHz, which is almost eight times higher than the frequency range of 120kHz in existing Integrated-Circuit products. PCB materials offer extremely high isolation voltage, typically from 15kV to 40kV, which is higher than many other isolation means such as optocouplers. It is envisaged that coreless PCB transformers can replace traditional core-based transformers in some industrial applications. Their application potentials deserve more attention and exploration.

• 말소리와 음성과학
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• 제16권1호
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• pp.11-16
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• 2024

The fundamental frequency (f0), representing an acoustic measure of vocal fold vibration, serves as an indicator of the speaker's emotional state and language-specific pattern in daily conversations. This study aimed to examine the f0 distribution in an English corpus of spontaneous speech, establishing normative data for American speakers. The corpus involved 40 participants engaging in free discussions on daily activities and personal viewpoints. Using Praat, f0 values were collected filtering outliers after removing nonspeech sounds and interviewer voices. Statistical analyses were performed with R. Results indicated a median f0 value of 145 Hz for all the speakers. The f0 values for all speakers exhibited a right-skewed, pointy distribution within a frequency range of 216 Hz from 75 Hz to 339 Hz. The female f0 range was wider than that of males, with a median of 113 Hz for males and 181 Hz for females. This spontaneous speech corpus provides valuable insights for linguists into f0 variation among individuals or groups in a language. Further research is encouraged to develop analytical and statistical measures for establishing reliable f0 standards for the general population.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1656-1663
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• 2016

A capacitive wireless power transfer (C-WPT) system uses an electric field to transmit power through a physical isolation barrier which forms a pair of ac link capacitors between the metal plates. However, the physical dimension and low dielectric constant of the interface medium severely limit the effective link capacitance to a level comparable to the main switch output capacitance of the transmitting circuit, which thus narrows the soft-switching range in the light load condition. Moreover, by fundamental limit analysis, it can be proved that such a low link capacitance increases operating frequency and capacitor voltage stress in the full load condition. In order to handle these problems, this paper investigates optimal design of double matching transformer networks for C-WPT. Using mathematical analysis with fundamental harmonic approximation, a design guideline is presented to avoid unnecessarily high frequency operation, to suppress the voltage stress on the link capacitors, and to achieve wide ZVS range even with low link capacitance. Simulation and hardware implementation are performed on a 5-W prototype system equipped with a 256-pF link capacitance and a 200-pF switch output capacitance. Results show that the proposed scheme ensures zero-voltage-switching from full load to 10% load, and the switching frequency and the link capacitor voltage stress are kept below 250 kHz and 452 V, respectively, in the full load condition.