• Phonetics and Speech Sciences
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• v.6 no.3
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• pp.81-89
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• 2014

Korean English learners tend to have difficulty perceiving and producing English vowels. The purpose of this study is to examine a link between perceived and produced vowel spaces of Korean learners of English. Sixteen Korean male and female participants perceived two sets of English synthetic vowels on a computer monitor and rated their naturalness. The same participants produced English vowels in a carrier sentence with high and low pitch variation in a clear speaking mode. The author compared the perceived and produced vowel spaces in terms of the pitch and gender variables. Results showed that the perceived vowel spaces were not significantly different in either variables. Korean learners perceived the vowels similarly. They did not differentiate the tense-lax vowel pairs nor the low vowels. Secondly, the produced vowel spaces of the male and female groups showed a 25% difference which may have come from their physiological differences in the vocal tract length. Thirdly, the comparison of the perceived and produced vowel spaces revealed that although the vowel space patterns of the Korean male and female learners appeared similar, which may lead to a relative link between perception and production, statistical differences existed in some vowels because of the acoustical properties of the synthetic vowels, which may lead to an independent link. The author concluded that any comparison between the perceived and produced vowel space of nonnative speakers should be made cautiously. Further studies would be desirable to examine how Koreans would perceive different sets of synthetic vowels.

• Phonetics and Speech Sciences
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• v.6 no.3
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• pp.13-21
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• 2014

Late talkers are young children who are delayed in their expressive language skills despite normal nonverbal cognitive ability, adequate hearing and typical personality development. The purpose of this study is to investigate the sentence interpretation strategies used by Korean-speaking late talkers and age-matched normal children. Nine late talkers and nine normal children matched by age at 30-35months were participated in this study. 27 simple noun-noun-verb(NNV) sentences were generated by factorial combination of case-marker [nominal case-marker on the first noun and accusative on the second (C1), accusative on the first noun and nominative on the second (C2), and no case markers on both nouns (C0)], and animacy of the nouns [animate-inanimate(AI), inanimate-animate(IA), animate-animate(AA)]. All the children were asked to "act out" their interpretation of the given sentence. For each type of sentences the percentage of choices of the first noun as the agent was calculated. The results of group (2) ${\times}$ animacy(3) ${\times}$ case-marker(3) mixed ANOVA showed a significant main effect for 'animacy', 'case marker' and 'group(2) ${\times}$ case-marker (3)'. The late talkers relied on semantic (animacy) cues in their interpretation of the sentences, while the normal peers utilized both animacy and grammatical morpheme (case-marker) cues. The results indicated that the late-talkers' comprehension skills were also delayed.

• Phonetics and Speech Sciences
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• v.9 no.3
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• pp.57-65
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• 2017

The current study explored how Korean-speaking children processed the multiple acoustic cues (VOT and f0) for the stop laryngeal contrast (/t'/, /t/, and /$t^h$/) and examined whether individual perceptual strategies could be related to a general cognitive ability performing executive functions (EF). 15 children (aged from 7 to 8) participated in the speech perception task identifying the three Korean laryngeal stops (3AFC) on listening to the auditory stimuli of C-/a/ with synthetically varying VOT and f0. They completed a series of EF tasks to measure working memory, inhibition, and cognitive shifting ability. The findings showed that children used the two cues in a highly correlated manner. While children utilized VOT consistently for the three laryngeal categories, their use of f0 was either reduced or enhanced depending on the phonetic categories. Importantly, the children's processing strategies of a f0 suppression for a tense-aspirated contrast were meaningfully associated with children's better cognitive abilities such as working memory, inhibition, and attentional shifting. As a preliminary experimental investigation, the current research demonstrated that listeners with inefficient processing strategies were poor at the EF skills, suggesting that cognitive skills might be responsible for developmental variations of processing sub-phonemic information for the linguistic contrast.

• Phonetics and Speech Sciences
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• v.9 no.4
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• pp.19-25
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• 2017

The current study focused on the production of geminate nasal consonants across different word boundary types in Korean as a function of speech style to investigate whether temporal properties are preserved across varying speaking rates. Assimilated geminates in Korean, known as true geminates, are produced with distinctively longer consonant duration compared to singletons. Despite a large body of literature for geminates across different languages, geminates in Korean have been relatively less investigated with respect to the durational patterns in relative terms and temporal variabilities. In this study, singletons, word-internal geminates and word-boundary (fake) geminates produced by ten native Seoul Korean speakers were compared in terms of absolute consonant closure duration, preceding vowel duration, the relative ratios (consonant-to-preceding vowel duration) as well as the temporal variabilities in speech production. The results showed that word-internal geminates were produced with longer consonant duration and greater temporal variabilities than singletons and word-boundary geminates in absolute duration, indicating relatively greater flexibility in timing. However, only word-internal geminates were produced with distinctively longer consonant duration with significantly lower variability in relative duration regardless of speech styles. The results provide some insight into the representation of temporal information in the production of Korean geminate consonants.

• Phonetics and Speech Sciences
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• v.9 no.4
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• pp.35-41
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• 2017

The existence and the extent of vowel length difference before voiced/voiceless consonants in English and Korean are examined in three groups: (1) Korean-speaking Americans (group A), (2) immigrants who moved to the U.S. in their early teens (group I), and (3) Koreans who have been in the U.S. for less than 3 years (group K). 14 subjects were recorded reading 10 English and 10 Korean sentences. The results show that the three groups exhibit different patterns of the vowel length difference: Group A shows a very strong tendency of vowel lengthening before voiced consonants in both English and Korean, while Group I shows less degree of vowel lengthening, and Group K shows almost no tendency of vowel length difference in both languages. This strongly suggests that, (1) unlike English, Korean does not have the vowel length difference depending on the following consonants, and (2) the vowel lengthening effect observed in Korean (L2) speech in group A may be the result of transfer of the phonetic trait acquired in English (L1). It also implies that, in teaching pronunciation, some facts such as the vowel length difference cannot be expected to be acquired automatically for the learners of English, but have to be taught explicitly.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.8
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• pp.743-748
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• 2007

Recently, various types of camera mouse are developed using the image processing. The camera mouse showed limited performance compared to the traditional optical mouse in terms of the response time and the usability. These problems are caused by the mismatch between the size of the monitor and that of the active pixel area of the CMOS Image Sensor. To overcome these limitations, we designed a new input device that uses the face recognition as well as the speech recognition simultaneously. In the proposed system, the area of the monitor is partitioned into 'n' zones. The face recognition is performed using the web-camera, so that the mouse pointer follows the movement of the face of the user in a particular zone. The user can switch the zone by speaking the name of the zone. The multimodal mouse is analyzed using the Keystroke Level Model and the initial experiments was performed to evaluate the feasibility and the performance of the proposed system.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.373-376
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• 2008

Industrial Steam Turbine first stage shell pressure is related to throttle flow. Theoretically, first stage shell pressure could, therefore, be measured and used as an index of turbine throttle flow. However, accurate flow measurements show that this pressure is not a reliable index of the actual flow. Data analysis of steam turbinessubjected to ASME acceptance tests shows that the use of first stage shell pressure as an index of throttle flow produced errors as large as 9.6 %. The mean of the errors was +2.2% with a standard deviation of ${\pm}$2.8 %. Applications that require an accuratedetermination of turbine steam flow, such as turbine acceptance testing, should, therefore, not rely on this method. Therefore, First stage shell pressure measurement serves as a valid and economical indicator of turbine throttle flow in cases where a high degree of accuracy in throttle flow measurement is not required but repeatability is desired, such as for boiler control. Generally speaking, Steam turbine first stage shell pressure may also be a very useful monitor of turbine performance when used with certain other turbine measurements.

• Journal of Korea Multimedia Society
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• v.21 no.7
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• pp.745-754
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• 2018

Language is an essential tool for verbal and emotional communication among human beings, enabling them to engage in social interactions. Although a majority of hearing-impaired people can speak; however, they are unable to receive feedback on their pronunciation most of them can speak. However, they do not receive feedback on their pronunciation. This results in impaired communication owing to incorrect pronunciation, which causes difficulties in their social interactions. If hearing-impaired people could receive continuous feedback on their pronunciation and phonation through lip-reading training, they could communicate more effectively with people without hearing disabilities, anytime and anywhere, without the use of sign language. In this study, the mouth area is detected from videos of learners speaking monosyllabic words. The grayscale information of the detected mouth area is used to estimate a velocity vector using Optical Flow. This information is then quantified as feature values to classify vowels. Subsequently, a system is proposed that classifies monosyllables by algebraic computation of geometric feature values of lips using the characteristics of articulatory phonation. Additionally, the system provides feedback by evaluating the comparison between the information which is obtained from the sample categories and experimental results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.669-672
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• 2008

In this paper, we propose a constant-amplitude multi-rode trans-bi-orthogonal modulation scheme by introducing a simple constant-amplitude coding scheme with redundant bits and trans-code, which if a modified orthogonal modulation scheme. Generally speaking, the orthogonal modulation scheme is not appropriate for the high speed data transmission applications because of bad bandwidth efficiency. Therefore, we use the multi-rode trans-bi-orthogonal modulation with trans-code for high bandwidth efficiency. Moreover, redundant bits are used for constant-amplitude-coding. Finally, we compare the performance of the proposed scheme with the orthogonal modulation and constant-amplitude multi-code trans-orthogonal modulation by using the computer simulation.

• Journal of Korea Water Resources Association
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• v.33 no.1
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• pp.39-50
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• 2000

Generally speaking, a hydrodynamic model needs a friction coefficient (Manning coefficient or Chezy coefficient) and eddy viscosity. For numerical solution the coefficients are usually determined by recursive calculations. The eddy viscosity in numerical model plays physical diffusion in flow and also acts as numerical viscosity. Hence its value has influence on the stability of numerical solution and for these reasons a consistent evaluation procedure is needed. By using records of stage and discharge in the downstream reach of the Han river, I-D models (HEC-2 and NETWORK) and 2-D model (SMS), estimated values of Manning coefficient and an empirical equation for eddy viscosity are presented. The computed results are verified through the recorded flow elevation data.n data.