• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.1019-1029
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• 2014

In recent years, researchers have become increasingly interested in the creation and pedagogical use of English learner corpora. Many studies have shown that learner corpora can not only make a significant contribution to second language acquisition research but also contribute to the construction and evaluation of language tests by advancing our understanding of English learners. So far, however, little attention has been paid to the Korean EFL (English as a foreign language) learners' corpus. The Yonsei English Learner Corpus (YELC 2011) is a specialized, monolingual, and synchronic Korean EFL learner corpus that was developed by Yonsei University from 2011 to 2012. Over 3,000 Korean high school graduates (or equivalents) who were accepted by Yonsei University for their further studies participated in this project. It consists of 6,572 written texts (1,085,828 words) at nine different English proficiency levels. In this paper, we describe its compilation, and more specifically, how we have corpusized from a text archive to a corpus. After introducing the process of corpusization, we report arresting insights into the specific linguistic features that different proficiency levels of Korean learners of English have. This study also discusses the potential use of the YELC 2011 which is now freely available for research purposes.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1290-1293
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• 2013

본 논문은 문장 내에서 나타나는 어휘간의 관계를 통해 표현 수준을 자동으로 평가할 수 있는 시스템을 제안한다. 제안하는 방법은 영어에세이 코퍼스 내의 문장에서 발생하는 철자 및 문법의 오류와 함께 어휘와 문법 패턴에 따른 표현난이도를 평가할 수 있는 자질을 생성하고 다양한 기계학습기법을 사용하여 문장의 수준을 평가하고자 하였다. 또한 기존에 연구되어온 규칙기반의 문장 평가시스템을 구현하고 기계학습기법을 이용한 문장 평가시스템과 비교하였다. 이를 통해 철자 및 문법의 오류율뿐만 아니라 표현난이도를 평가할 수 있는 자질들이 유용함을 확인할 수 있었다. 영어작문 문장의 수준평가를 위해서 국내 학생들의 토플 에세이 코퍼스를 수집하여 2,000문장을 추출하였고, 4명의 전문평가자들을 통해 6단계로 평가하여 학습 및 테스트 세트를 구성하였다. 성능척도로는 정확률과 재현율을 사용하였으며, 제안하는 방법으로 67.3%의 정확률과 67.1%의 재현율을 보였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1298-1301
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• 2013

대화 시스템에서 올바른 대화를 진행하기 위해서는 화자의 대화 의도를 파악하는 것이 중요하다. 특히 영어를 교육하기 위한 영어 교육용 대화 시스템에서는 학습자의 대화 의도 파악 오류가 발생할 경우 영어 교육에 문제가 발생하기 때문에 학습자의 대화 의도를 더욱 정확하게 분석 및 파악하는 것이 중요하다. 대화 패턴이란 시스템 발화에 대응되는 사용자 발화의 규칙적인 연쇄라고 할 수 있다. 대화 패턴 기반 대화 의도 부착 방법은 1) 대화 코퍼스 구축 2) 대화 시나리오에 있는 발화를 대상으로 기본 명사구 청킹(Base NP Chunking)을 하고 중심어(Head Word), 토픽 추적(Topic Tracking)에 의한 대화 패턴을 자동으로 추출한 후, 3) 대화 패턴 수동 검수이다. 대화 패턴 기반 대화 의도 부착 방법은 기본 명사구에 대한 지식만 가지고 있으면 대량으로 구축할 수 있다는 장점이 있다. 99 개의 대화 시나리오를 학습코퍼스로 하고 1 개의 대화 시나리오에 대해 대화턴 성공률을 시물레이션 한 결과 63.64%가 나왔다.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.576-593
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• 2021

In this study, in order to investigate the factors that affect the percentage of correct answers and the degree of discrimination of the TOEIC test, a regression analysis was performed using corpus indicators that influence correct answer rate and the degree of discrimination for each part derived from the item analysis. The basic calculation word_length, consistency index LSA_overlap_adjacent_sentences, lexical diversity MTLD_VOCD, conjunction All_logical_causal_connectives_incidence, situational model casual_particles_causal_verbs_Ratio, syntactic complexity Left_embeddedness, and syntactic pattern density Infinitive_density were found to have negative effects. These factors that lower the correct answer rate can be utilized when setting learning goals. Vocabulary diversity index MTLD_VOCD, conjunction Additive_connectives_incidence, syntactic pattern density Infinitive_density, and lexical information person1_2_pronoun_incidence were found to have a positive effect. Factors influencing the increase in discrimination may provide important information for developing a learning program.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.27-40
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• 2020

In this paper, we investigate the correlation between the amount of English sentences that Korean English learners (L2ers) are exposed to and their sentence processing patterns by examining what Long Short-Term Memory (LSTM) language models (LMs) can learn about implicit syntactic relationship: that is, the filler-gap dependency. The filler-gap dependency refers to a relationship between a (wh-)filler, which is a wh-phrase like 'what' or 'who' overtly in clause-peripheral position, and its gap in clause-internal position, which is an invisible, empty syntactic position to be filled by the (wh-)filler for proper interpretation. Here to implement L2ers' English learning, we build LSTM LMs that in turn learn a subset of the known restrictions on the filler-gap dependency from English sentences in the L2 corpus that L2ers can potentially encounter in their English learning. Examining LSTM LMs' behaviors on controlled sentences designed with the filler-gap dependency, we show the characteristics of L2ers' sentence processing using the information-theoretic metric of surprisal that quantifies violations of the filler-gap dependency or wh-licensing interaction effects. Furthermore, comparing L2ers' LMs with native speakers' LM in light of processing the filler-gap dependency, we not only note that in their sentence processing both L2ers' LM and native speakers' LM can track abstract syntactic structures involved in the filler-gap dependency, but also show using linear mixed-effects regression models that there exist significant differences between them in processing such a dependency.

• Phonetics and Speech Sciences
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• v.15 no.4
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• pp.1-10
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• 2023

This study investigated the relative effectiveness of letter-based versus syllable-based measures of speech rate and articulation rate in predicting the articulation score, prosody fluency, and rating sum using "English speech data of Koreans for education" from AI Hub. We extracted and analyzed 900 utterances from the training data, including three balanced age groups (13, 19, and 26 years old). The study built three models that best predicted the pronunciation assessment scores using linear mixed-effects regression and compared the predicted scores with the actual scores from the validation data (n=180). The correlation coefficients between them were also calculated. The findings revealed that syllable-based measures of speech and articulation rates were more effective than letter-based measures in all three pronunciation assessment categories. The correlation coefficients between the predicted and actual scores ranged from .65 to .68, indicating the models' good predictive power. However, it remains inconclusive whether speech rate or articulation rate is more effective.

• Phonetics and Speech Sciences
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• v.12 no.3
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• pp.33-40
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• 2020

The purpose of this research was to find out the relation between Korean learners' English proficiency and the ratio of the length of the stressed vowel in a monosyllabic noun to that of the unstressed vowel in an article of the noun phrases (e.g., "a cup", "the bus", etcs.). Generally, the vowels in monosyllabic content words are phonetically more prominent than the ones in monosyllabic function words as the former have phrasal stress, making the vowels in content words longer in length, higher in pitch, and louder in amplitude. This study, based on the speech samples from Korean-Spoken English Corpus (K-SEC) and Rated Korean-Spoken English Corpus (Rated K-SEC), examined 879 English noun phrases, which are composed of an article and a monosyllabic noun, from sentences which are rated on 4 levels of proficiency. The lengths of the vowels in these 879 target NPs were measured and the ratio of the vowel lengths in nouns to those in articles was calculated. It turned out that the higher the proficiency level, the greater the mean ratio of the vowels in nouns to the vowels in articles, confirming the research's hypothesis. This research thus concluded that for the Korean English learners, the higher the English proficiency level, the better they could produce the stressed and unstressed vowels with more conspicuous length differences between them.