• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1380-1386
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• 2003

Speech recognition performance is degraded by the variation in vocal tract length among speakers. In this paper, we have used a vocal tract length normalization method wherein the frequency axis of the short-time spectrum associated with a speaker's speech is scaled to minimize the effects of speaker's vocal tract length on the speech recognition performance In order to normalize vocal tract length, we tried several frequency warping functions such as linear and piece-wise linear function. Variable interval piece-wise linear warping function is proposed to effectively model the variation of frequency axis scale due to the large variation of vocal tract length. Experimental results on TIDIGITS connected digits showed the dramatic reduction of word error rates from 2.15% to 0.53% by the proposed vocal tract normalization.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.5
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• pp.555-567
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• 2019

Speech recognition rate is lowered even in a noisy environment, and it is difficult for a person with a speech disability or an inconvenient language to use it in a social life. In addition to improving the inconvenience of using the language, 280 words were selected using the word selection method which was improved when the word was selected considering the pronunciation characteristics of the language impaired. The MEMS development device used in the experiment was made considering material, lead wire type, length and direction. We improved the speech recognition rate by using the developed word selection method and the MEMS device developed to improve the speech recognition rate due to incorrect pronunciation and severe noise. The new method of selecting words and the mems device were improved and the results were included.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.158-162
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• 2007

Anomia, word finding difficulty, is one of the most common feature in aphasia. Previous studies support that the process of picture naming consists of three stages, in the order of the object recognition, semantic, and phonological output stages. Anomic patients have many symptoms and it means that anomia can be sub-divided into several symptom groups. Our anomia assessment battery consists of several parts: (1) picture naming set, (2) picture-word matching task, (3) lexical decision task for mental lexicon damage, (4) naming task for phonological lexicon damage, and (5) semantic decision task. Pictures and words were selected on the basis of usage frequency, semantic category, and word length. We administered this anomia evaluation battery to many anomic aphasics and we subdivided patients into several groups. We hope that our anomia evaluation set is useful and helpful for evaluation anomic aphasics

• The KIPS Transactions:PartB
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• v.13B no.3 s.106
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• pp.337-344
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• 2006

In this paper, we describe the design and the implementation of word clustering system using a definition of an entry word in the dictionary, called a dictionary definition. Generally word clustering needs various features like words and the performance of a system for the word clustering depends on using some kinds of features. Dictionary definition describes the meaning of an entry in detail, but words in the dictionary definition are implicative or abstractive, and then its length is not long. The word clustering using only features extracted from the dictionary definition results in a lots of small-size clusters. In order to make large-size clusters and improve the performance, we need to transform the features into more general words with keeping the original meaning of the dictionary definition as intact as possible. In this paper, we propose two methods for extending the dictionary definition using ontology. One is to extend the dictionary definition to parent words on the ontology and the other is to extend the dictionary definition to some words in fixed depth from the root of the ontology. Through our experiments, we have observed that the proposed systems outperform that without extending features, and the latter's extending method overtakes the former's extending method in performance. We have also observed that verbs are very useful in extending features in the case of word clustering.

• Korean Journal of Cognitive Science
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• v.29 no.4
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• pp.193-220
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• 2018

Recent studies have demonstrated that word frequency, word length, neighborhood and word shape may have a role in visual word recognition. Shape information may affect word processing in different ways as Korean letter system works differently than that of English. The purpose of this study was to apply Gestalt's continuity principle to Korean alphabetic script(hangul), and to investigate the processing unit of hangul and to verify whether syllable shape affects word recognition in hangul. In experiment 1, three syllable words were utilized and two variables; 1) syllable types(horizontal syllable shape, e.g., "가". vertical syllable shape, e.g., "고") and 2) presenting direction (horizontal, vertical) were manipulated. Whereas "가" meets the criteria of Gestalt's continuity principle, "고" does not. Based on the result of lexical decision time, horizontal syllable shape type showed significant performance improvement, when compared to vertical syllable shape type, regardless of the presenting direction. In experiment 2, syllable types(horizontal syllable shape, vertical syllable shape) and the visual relationship between prime and target(identical, similar, different) were manipulated by using masked priming. There was a significant performance difference between the visual relationship of prime and target, and thus the effect of syllable shape was verified.

• Speech Sciences
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• v.13 no.2
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• pp.107-120
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• 2006

The main purpose of this study is to investigate whether Korean learners can use the vowel duration cue to distinguish voicing contrasts in word-final consonants in English. Given that the Korean group's performance on the auditory task was much better than their performance on the identification task or on the production task, we conclude that the AX discrimination task makes contact with a different layer of perception. In particular, the AX discrimination task can be done at the auditory or phonetic level, where differences in vowel length are still encoded in the representation. In contrast, the identification and production tasks are probing the mental representation of vowel length and voicing. It was also founded that Korean speakers stored neither vowel length nor voicing in memorized representations and did not internalize the lengthening of the preceding vowel as a rule to differentiate the voicing contrasts of final consonants, even though they were able to detect the acoustic differences in vowel duration provided that they were tested in an appropriate task.

• Speech Sciences
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• v.2
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• pp.135-147
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• 1997

This thesis describes pronunciation differences of vowel lengths between Koreans and Americans speaking English words and sentences. This study also analizes the reasons for these differences with the help of acoustic instruments. Sixteen sentences and eight words were selected as the experimental material. The informants for this study were 9 males; 3 Americans and 6 Koreans, who were asked to pronounce the test words and sentences five times. In this study, the acoustical analysis to measure duration was done through computer digital techniques. According to the results of the experiment, duration of 8 English vowels pronounced between Koreans and Americans shows very different features. When Koreans pronounce English vowels, the duration of the stressed vowel in the sentence-final position is much shorter than in other positions, such as in the sentence-initial and in word position. On the contrary, when Americans pronounce English vowels, the duration of the stressed vowel in the sentence-final position is much longer than in other positions. If the correlation between length and stress were to be studied in a more detailed manner, it would give fundamental help to the study of relation between stress and length.

• Bulletin of the Korean Mathematical Society
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• v.61 no.3
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• pp.585-595
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• 2024

We show that a pseudo-Anosov map constructed as a product of the large power of Dehn twists of two filling curves always has a geodesic axis on the curve graph of the surface. We also obtain estimates of the stable translation length of a pseudo-Anosov map, when two filling curves are replaced by multicurves. Three main applications of our theorem are the following: (a) determining which word realizes the minimal translation length on the curve graph within a specific class of words, (b) giving a new class of pseudo-Anosov maps optimizing the ratio of stable translation lengths on the curve graph to that on Teichmüller space, (c) giving a partial answer of how much power is needed for Dehn twists to generate right-angled Artin subgroup of the mapping class group.

• Korean Journal of Cognitive Science
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• v.24 no.1
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• pp.25-47
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• 2013

We conducted a psycholinguistic experiment in which participants orally produced sentences using a subject, a dative object, an accusative object, and a verb, provided just before the production. Results of the experiment are twofold: (i) Korean speakers basically produce the dative object earlier than the accusative one if the lengths of the objects are identical. (ii) If there is a length difference between the two objects, though, the longer one strongly tends to be placed before the shorter one, overriding the preference for 'dative-accusative' order. This 'long before short' preference which is generally observed in head-final languages appears to reflect the underlying tendency of the processing mechanism to put the heads of arguments and the predicate as closely as possible, thereby minimizing the cost for the processing of verb-argument structure.

• Speech Sciences
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• v.9 no.3
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• pp.223-235
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• 2002

Unlike Seoul dialect, in the Busan dialect, /ㅅ/ and /ㅆ/ are phonemically non-distinctive and realization of tensing is non-productive, on the other hand, that of voicing is productive. In order to discover causes of such characteristics in Busan dialect, this paper firstly compared acoustic characteristics of Seoul dialect with those of Busan dialect on fricative /ㅅ/ and /ㅆ/. The result showed that Busan dialect has much shorter length of friction and aspiration intervals of word initial and word-medial position than Seoul dialect. I expect that these results are important keys to discover causes of the following characteristics of Busan-dialect - non-distinction, non-productivity of tensing, and productivity of voicing - on Fricative /ㅅ/ and /ㅆ/.