• The KIPS Transactions:PartB
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• v.11B no.2
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• pp.241-246
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• 2004

In this paper, we propose VCCV units as a processing unit of language model and compare them with clauses and morphemes of existing processing units. Clauses and morphemes have many vocabulary and high perplexity. But VCCV units have low perplexity because of the small lexicon and the limited vocabulary. The construction of language models needs an issue of the smoothing. The smoothing technique used to better estimate probabilities when there is an insufficient data to estimate probabilities accurately. This paper made a language model of morphemes, clauses and VCCV units and calculated their perplexity. The perplexity of VCCV units is lower than morphemes and clauses units. We constructed the N-grams of VCCV units with low perplexity and tested the language model using Katz, absolute, modified Kneser-Ney smoothing and so on. In the experiment results, the modified Kneser-Ney smoothing is tested proper smoothing technique for VCCV units.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.160-166
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• 2002

In this paper, we implement a new vocabulary-independent speech recognition system that uses CV, VCCV, VC recognition unit. Since these recognition units are extracted in the trowel region of syllable, the segmentation is easy and robust. And in the case of not existing VCCV unit, the units are replaced by combining VC and CV semi-syllable model. Clustering of vowel group and applying combination rule to the substitution model in the case of not existing of VCCV model lead to 5.2% recognition performance improvement from 90.4% (Model A) to 95.6% (Model C) in the first candidate. The recognition results that is 98.8% recognition rate in the second candidate confirm the effectiveness of the proposed method.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2419-2422
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• 2003

To improve performance of sentence speech recognition systems, we need to consider perplexity of language model and the number of words of dictionary for increasing vocabulary size. In this paper, we propose a language model of VCCV units for sentence speech recognition. For this, we choose VCCV units as a processing units of language model and compare it with clauses and morphemes. Clauses and morphemes have many vocabulary and high perplexity. But VCCV units have small lexicon size and limited vocabulary. An advantage of VCCV units is low perplexity. This paper made language model using bigram about given text. We calculated perplexity of each language processing unit. The perplexity of VCCV units is lower than morpheme and clause.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.836-839
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• 2003

In this paper, we implement a language model by a bigram and evaluate proper smoothing technique for unit of low perplexity. Word, morpheme, clause units are widely used as a language processing unit of the language model. We propose VCCV units which have more small vocabulary than morpheme and clauses units. We compare the VCCV units with the clause and the morpheme units using the perplexity. The most common metric for evaluating a language model is the probability that the model assigns the derivative measures of perplexity. Smoothing used to estimate probabilities when there are insufficient data to estimate probabilities accurately. In this paper, we constructed the N-grams of the VCCV units with low perplexity and tested the language model using Katz, Witten-Bell, absolute, modified Kneser-Ney smoothing and so on. In the experiment results, the modified Kneser-Ney smoothing is tested proper smoothing technique for VCCV units.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.25-28
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• 2001

본 논문에서는 조음 효과에 대처할 수 있는 반음절, 반음절 + 반음절 단위 HMM과 모음열 정보를 적용하여 연속 숫자 음성인식을 구현하였다. 모음열 정보를 적용하여 기준모델을 모음이 포함된 HMM단위로만 구성한 시스템과 모든 기준모델과 비교하는 시스템과 성능을 비교하였다. 인식실험결과 인식률의 향상으로 제안된 방법이 효율적임을 확인하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.103-106
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• 2000

무제한 인식 시스템을 구현하기 위해서는 적절한 인식단위, 훈련 데이터 베이스의 확보, 인식단위의 분할, 인식 알고리즘과 같은 문제점을 모두 해결하여야 한다. 따라서 본 논문에서는 무제한 음성인식 시스템의 인식의 기본 단위로 모음의 안정구간을 검출하여 분할하는 CV(Consonant-Vowel), VC(Vowel-Consonant), VC CV(Vowel-Consonant-Consonant-Vowel)단위와 분할 파라미터를 제안하고, 분할 실험을 통해 그 유효성을 확인하고자 한다.

• The KIPS Transactions:PartA
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• v.10A no.1
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• pp.1-6
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• 2003

In this paper, we present a new Korean connected digit recognition based on vowel string and number of syllables. There are two steps to reduce digit candidates. The first one is to determine the number and interval of digit. Once the number and interval of digit are determined, the second is to recognize the vowel string in the digit string. The digit candidates according to vowel string are recognized based on CV (consonant vowel), VCCV and VC unit HMM. The proposed method can cope effectively with the coarticulation effects and recognize the connected digit speech very well.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2240-2243
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• 2003

In this paper. we present a new speech recognition system using DSP chip. DSP chip used TMS320c6711 of TI. We designed hardware system including acoustic model, word list and code book in flash memory. The word candidates are recognized based on CV, VCCV, and VC units HMM. This system can be applied to various electric ＆ electronic devices: home automation, robotics etc.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.46-49
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• 2003

The use of confidence measures for word/utterance verification has become art essential component of any speech input application. Confidence measures have applications to a number of problems such as rejection of incorrect hypotheses, speaker adaptation, or adaptive modification of the hypothesis score during search in continuous speech recognition. In this paper, we present a new utterance verification method using vowel string. Using subword HMMs of VCCV unit, we create anti-models which include vowel string in hypothesis words. The experiment results show that the utterance verification rate of the proposed method is about 79.5%.

• Phonetics and Speech Sciences
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• v.5 no.4
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• pp.145-155
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• 2013

This study investigated the articulatory characteristics of Korean singleton and geminate sonorants in the word-medial position, effects of the duration of the sonorant consonant and the preceding vowel on perception, and the difference between native Korean speakers and foreign learners of Korean in perceiving the singleton and geminate consonant contrast. The Korean sonorant consonants(/m, n, l/) are examined from the VCCV, VCV sequences through speech production and perception experiments. The results suggest that the duration of the sonorant consonant is the most important factor for native Korean speakers to recognize whether sonorants are overlapped, and the duration of preceding vowel and other factors affect the recognition of singleton/geminate consonant contrast if the duration is not obvious. A perception experiment showed Chinese Korean language learners did not clearly distinguish singleton consonants from geminate consonants. The results of this study provide basic data for recognition of singleton/geminate consonant contrast in word-medial of Korean language, and can be utilized for teaching Korean pronunciation as a foreign language.