• The Journal of the Korea Contents Association
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• v.15 no.2
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• pp.542-551
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• 2015

The purpose of this study is to examine how Korean college students perceive and produce American English vowels /i, ɪ, eɪ, ${\varepsilon}$, ${\ae}$, ${\alpha}$, ɔ, oʊ, ʊ, u, ʌ/ embedded in CVC words, and further to examine the relationship between perception and production of the target vowels. Forty-two participants who are English major/double major were divided into 2 groups under different conditions: the control group took only theoretical lessons about English phonetics and the experimental group took 4-week phonetic training lessons in addition to the theoretical ones. The result of the pretest revealed that the two groups showed strong correlations between perception and production. However in the post-test, both of the two groups had no correlation between the two elements. The two groups showed changes in the correct percentage in the post-test and this had the influence on the correlations between perception and production. The control group showed the fluctuation in perception, whereas the experimental group showed improvement in production, and these changes in the post-test had an influence on the correlations between perception and production. Based on this analysis, pedagogical implications were discussed and limitations of the study were also described.

• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.527-534
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• 2014

Motivated by the fact that English grapheme is realized as 5 different English vowels [ɑ, eɪ, æ, ɔ, ə], the present study aims to investigate how Korean students perceive and produce English grapheme in words. To this end, 31 university students participated in the perception and production tests on 28 English words containing grapheme . Overall, the participants performed better on production than perception both in the pretest and posttest. Also, the accuracy of perception and production was improved in the posttest. While the accuracy rates of [ɑ] and [eɪ] were among highest in the perception test, those of [ɑ] and [ɔ] were in the production test. By contrast, the accuracy of unstressed [ə] was worst both in perception and production. As for the training effect, [eɪ] and [æ] showed significant improvement both in perception and production. In addition, the perception and the production of [ɔ] were improved at the .051-4 significance level. However, the accuracies of [ɑ] improved significantly neither in perception nor in production. In the case of [ə], the production ability was improved significantly whereas the perception ability was not. The prominent error patterns of were the replacement of the target vowels with [æ], [ɑ], or [eɪ]. The influence of orthography was attested through the persistent occurrence of [ɑ]. Finally, pedagogical implications were discussed.

• The Journal of the Korea Contents Association
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• v.21 no.5
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• pp.285-294
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• 2021

Motivated by the mixed results in the previous studies on the relationship between speech production and perception, the current study aims to investigate the relationship between production and perception in depth through a case study on how Korean EFL university students produce and perceive American English vowels. To this end, 19 Korean students at a university located in the Seoul-metropolitan area participated in the production and perception tests on American English vowels to elucidate the precedence relationship and the correlation between production and perception. Results showed that precedence of neither perception nor production was found in the overall result. However, either precedence of perception or production was found for the vowels [ɛ], [α], [ɔ], [u], which implies that the precedence relationship between production and perception varies depending on individual vowels. As for the correlation between production and perception, no correlation was attested between production and perception, suggesting that production and perception skills are not closely linked for these participants. Given that mastering language requires to coordinate two distinct production and perception skills and that L2 learners' preception and production skills become more closely connected as the learners' L2 experience and proficiency increases, no correlation between production and perception attested by the current EFL students implies that the correlation between production and perception varies during the course of foreign language/L2 acquisition in such a way that production and perception skills become increasingly related. Implications of the findings were further discussed and pedagogical suggestions were provided.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.495-503
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• 2013

The purpose of this study was to investigate how Korean speakers produce English vowels. Twenty one Korean learners produced the vowels [i, ɪ, eɪ, ɛ, æ, ɑ, ʌ, ɔ, oʊ, ʊ, u] in bVt or pVt forms of real words. Acoustic measurements were conducted for the vowel formant frequencies (F1, F2) and duration. Results showed that Korean learners tended to produce the vowel duration longer than native English speakers. Also, the front vowels produced by Korean participants tended to be produced at the more frontal part of the tongue. In addition, Korean participants distinguished the tense and lax pairs not through quality(F1, F2) but through vowel duration. This is different from the native English speakers in that they differentiate tense and lax pairs by quality(F1, F2) as well as vowel duration. Based on these results, pedagogical implications are discussed.

• Journal of the Korean Applied Science and Technology
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• v.39 no.2
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• pp.368-376
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• 2022

Spontaneous ignition occurs in industrial sites or anywhere in our lives, and is a phenomenon in which a substance ignites itself without an ignition source in the atmosphere. As the rate of chemical reaction increases, the heat generated increases, and the risk of spontaneous ignition increases. In this study, safe raw materials used for food and cosmetics were mixed to prepare coal spontaneous ignition prevention agents specifically among various spontaneous ignition phenomena. The effect of suppressing spontaneous combustion of coal was confirmed through lab and field tests with low-calorie, low-grade coal from Indonesia. As a result of the outdoor field test, the ignition prevention agent manufactured in this study compared with the control group(Fire after 90 days) showed excellent ignition inhibitors for more than 120 days. In addition, CO concentration control was confirmed by comparing the concentration of carbon monoxide for 50 days at the indoor coal yard. It was confirmed that the results were better than the comparative group coal and the existing anti-firing method. In addition, the possibility of coal fire prevention agents for indoor coal farms will be applied from 2024 was confirmed by studying the environment and safety of workers' working environments through official test such as soil and water quality test, MSDS of coal fire prevention agents in consideration of working workers, water quality, and eye irritation tests.

• The Journal of the Acoustical Society of Korea
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• v.39 no.1
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• pp.64-68
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• 2020

In a conventional speech recognition system using Gaussian Mixture Model-Hidden Markov Model (GMM-HMM), the cepstral feature normalization method based on pole filtering was effective in improving the performance of recognition of short utterances in noisy environments. In this paper, the usefulness of this method for the state-of-the-art speech recognition system using Deep Neural Network (DNN) is examined. Experimental results on AURORA 2 DB show that the cepstral mean and variance normalization based on pole filtering improves the recognition performance of very short utterances compared to that without pole filtering, especially when there is a large mismatch between the training and test conditions.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.04a
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• pp.325-329
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• 2011

Fire has developed from the inter-action of heat at the early state and it is very difficult to estimate the magnitude of the fire. Cone Calorimeter can obtain the important material properties from the exposed part of it. It can be contained that ignition, loss of mass, heat release rate, smoke generation, and gas analysis. The purpose of this study is emphasize on the properties of structural steels in terms of physical, mechanical and that will be important way to build the databases of fire safety.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.67-70
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• 1998

본 논문에서는 단어독립 음성인식 시스템을 위한 음성인식 거절(rejection)기능에 대해 기술한다. 음성인식 거절 기능은 음성인식기를 제작할 때 정해놓은 인식대상 단어 이외의 단어가 입력되었을 때 그 단어가 인식할 수 없는 단어임을 알려주는 기능이다. 본 연구에서는 단어독립 음성인식 시스템에 적용될 수 있는 발화 검증 방식에 의해 음성인식 거절 기능을 구현하였다. 특히 유사도를 결정함에 있어서 산술평균, 기하평균, 조화평균을 사용하고 각각을 비교하여, 기하 평균을 사용하는 방식이 우수한 성능을 보임을 알 수 있었다. 음성의 신뢰도(confidence score)를 정규화하기 위해서 Sigmoid 함수를 사용하는데 이 함수의 가중치(weight) 상수의 변화에 대해 인식률을 비교함으로써 가장 적절한 가중치 상수값을 결정하였다. 음성인식 테스트 결과에서는 신뢰도 임계치 값을 구하고 이 값을 사용하여 인식률을 계산하였으며, 거절의 오류까지 포함된 음성인식률은 약 76%였다. 이 연구결과는 현재 한국통신에서 시험 서비스 중인 음성인식 증권정보 안내 시스템에 적용될 예정이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1649-1652
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• 2012

본 연구에서는 사용자의 성격패턴을 사용자의 대화음성 정보만으로 자동 분류할 수 있는 방법과 이를 기반으로 사용자의 성격 맞춤형 학습전략을 적용하는 애플리케이션을 개발하는 것을 목적으로 하였다. 음성대화 속의 발화된 말의 빠르기(speech rate)나 말소리의 크기, 기본주파수(fundamental frequency)의 값과 그들의 변화패턴, 그리고 묵음구간의 여러 가지 통계적 정보 같은 비언어적 단서를 활용하여 성격패턴을 최고 86.3% 까지 정확하게 인식해 낼 수 있었다. 또한 성격 별 영어단어 학습방법을 개발하여 사전 및 사후테스트를 기반으로 실험한 결과 약 24% 성적 향상을 보였다. 이 연구를 통해 확보되는 원천기술은 각종 에듀테인먼트 콘텐츠에는 물론 로봇과의 대화시스템, 치료나 재활을 위한 기능성 콘텐츠 등에 유용하게 사용될 것이다.

• The Journal of the Acoustical Society of Korea
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• v.18 no.3
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• pp.3-9
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• 1999

This paper presents the study on the rejection capability based on anti-phone modeling for vocabulary independent speech recognition system. The rejection system detects and rejects out-of-vocabulary words which were not included in candidate words which are defined while the speech recognizer is made. The rejection system can be classified into two categories by their implementation methods, keyword spotting method and utterance verification method. The keyword spotting method uses an extra filler model as a candidate word as well as keyword models. The utterance verification method uses the anti-models for each phoneme for the calculation of confidence score after it has constructed the anti-models for all phonemes. We implemented an utterance verification algorithm which can be used for vocabulary independent speech recognizer. We also compared three kinds of means for the calculation of confidence score, and found out that the geometric mean had shown the best result. For the normalization of confidence score, usually Sigmoid function is used. On using it, we compared the effect of the weight constant for Sigmoid function and determined the optimal value. And we compared the effects of the size of cohort set, the results showed that the larger set gave the better results. And finally we found out optimal confidence score threshold value. In case of using the threshold value, the overall recognition rate including rejection errors was about 76%. This results are going to be adapted for stock information system based on speech recognizer which is currently provided as an experimental service by Korea Telecom.