(The) effect of multi-word unit instruction on the development of L2 Oral fluency and multi-word unit use

정나라 Hankuk University of Foreign Studies. Department o 2015 국내석사

The Effect of Multi-word Unit Instruction on the Development of L2 Oral Fluency and Multi-word Unit Use This study investigated the effect of the instruction of multi-word unit on L2 oral fluency and whether the repertoire of multi-word units in free production is expanded and developed into more productive patterns. While it has been found that proficient language users exploit many automatized chunks of language, which overcomes cognitive limits in spontaneous productions, few attempts have been made to explore the role of multi-word unit in developing L2 oral fluency. Moreover, the developmental issues of multi-word unit in second language learners have been neglected. This study involved two adult EFL learners. The instruction of multi-word units consisted of noticing, automatization, memorization, which is based on the previous study’s teaching principles. Learners’ production data were collected for 5 times along 6-month period as semi-structured speeches prompted by three open questions. The transcripts of speech data were analyzed for assessing speech rate and mean-length of runs (MLR) and developmental pathways of multi-word units through trace-back methodology. Interviews were employed to consider self-perceived fluency and any perspective changes, which serves as a qualitative approach to oral fluency. To complement the qualitative aspect, observation and teaching journals were performed to scrutinize learners’ change. Findings showed that learning multi-word units positively affected oral fluency while its improvement in speech rate and MLR is moderate because of poor participation. The analysis of transcripts extracted various multi-word units, demonstrating learners’ multi-word unit use and the impact of instructing multi-word unit. Regarding the developmental pathway of multi-word units, as multi-word units were repetitively practiced and proceduralized, the use of some multi-word units happened to be combined with other multi-word units and get longer. In the interviews, learners witnessed the significance of multi-word units in language use and the necessity of procedural knowledge in fluent speech. In short, this study consolidated the assumption that the use of multi-word unit can facilitate fluent productions and explored the development of multi-word units in second language learners. 제 2언어 학습자의 다단어 단위의 학습이 말하기 유창성 발달과 다단어 단위 사용의 발달에 미치는 영향에 관한 사례연구 본 연구는 다단어 단위의 교수 및 학습이 영어 제 2언어 학습자의 말하기 유창성에 미치는 영향과 자주 사용되는 다단어 단위의 레파토리가 확장되는 동시에 더 생산적인 형태로 발달하는가 연구하였다. 많은 숙련된 언어사용자들은 다양한 자동화된 덩어리의 표현들을 사용함으로 즉흥적인 발화 과정에서 인지적인 용량 한계를 극복할 수 있다고 밝혀진 가운데, 제 2언어의 말하기 유창성의 발달에 있어서 다단어 단위의 역할을 밝히는 연구는 많이 이뤄지지 않고 있다. 게다가 제 2언어 학습자들의 경우 다단어 단위의 발달과정에 대한 연구가 미흡하다. 따라서 이에 대한 사례연구로써, 본 연구는 2명의 EFL 상황에서의 성인 영어학습자를 통해 이를 알아보고자 했다. 다단어 단위의 교수 및 학습은 선행연구를 바탕으로 다단어 단위에 대한 인지도를 높이는 전략과 자동화 과정, 그리고 암기라는 요소들로 구성되었다. 연구참여자들의 발화 자료들은 6개월의 기간 동안 5번 수집되었고 매 번 세 가지의 자유로운 의견을 표출하는 질문을 통해 이뤄졌다. 연구참여자의 본인의 유창성에 대한 주관적인 평가와 연구참여를 통한 관점의 변화를 조사하기 위해 인터뷰도 사용되었다. 연구의 질적인 부분을 보완하기 위해 교수자의 관찰과 교수일지를 자료수집의 도구로 사용하였다. 자료의 분석을 위해 참여자들의 발화내용은 전사되었고 말하기 속도와 평균 발화 길이라는 기준에 따라 유창성을 분석하였다. 또한 다단어 단위의 발달경로를 살펴보기 위해 역추적 방법론을 사용하였다. 분석 결과를 통해 발견된 것은 비록 저조한 수업참여로 인해 향상도가 다소 미미했지만 다단어 단위의 학습이 유창성에 긍정적으로 영향을 끼치는 것으로 나타났다. 전사된 학습자들의 발화내용을 분석하면서 다양한 다단어 단위가 추출되었고 그 과정에서 학습자들의 다단어 사용의 실제와 다단어 단위 수업의 효과를 살펴볼 수 있었다. 또한 다단어 단위의 발달경로에 대한 조사는 다단어 단위들이 종종 다른 다단어 단위들과 조합되어 길어지는 것을 관찰하였다. 인터뷰를 통해 발견된 것은 참여자들이 다단어 단위 중요성을 인식하게 되었고 이를 정형어구처럼 유창하게 사용하기 위한 자동화 과정에 대한 인식을 새롭게 했다는 것이다. 결론적으로, 본 연구는 다단어 단위의 사용이 유창한 발화를 촉진시킨다는 주장에 대한 근거를 제공하였고 제 2언어 학습자의 환경에서 다단어 단위의 학습과 교수에 대한 고찰이 이뤄졌다.

Effects of Implicit and explicit learning on the acquisition of implicit and explicit knowledge of collocations from different proficiency levels

Ha, Joo Yeon Hankuk University of Foreign Studies. Department o 2015 국내석사

암시적, 명시적 학습 환경이 수준별 학습자의 암시적, 명시적 연어 지식 습득에 미치는 영향 본 연구에는 세가지 목적이 있다. 첫째, 암시적, 명시적 학습 환경이 암시적, 명시적 연어 지식 습득에 즉각적인 영향을 끼치는가를 살펴본다. 둘째, 암시적, 명시적 학습 환경이 장기적인 암시적, 명시적 연어 지식 습득에 차이를 일으키는가를 연구한다. 셋째, 암시적, 명시적인 환경에서 학습한 학습자의 수준이 높고 낮음이 암시적, 명시적 연어 지식 습득에 영향을 끼치는가를 알아본다. 이를 위해 고등학교 2학년 72명의 학생들이 각각 36명씩 암시적, 명시적 학습 환경에서 연어를 공부하고, 공부한 날과 같은날 친 시험 결과와 3주 후에 유사한 형태로 같은 연어를 시험 친 결과를 비교했다. 각 집단의 36명은 중간고사 점수를 기준으로 다시 상, 하 수준의 학생으로 나뉘어 졌다. 목표연어는 2013년에 시행된 고2 전국연합모의고사에서 쓰여진 기출 연어 150개 중, 사전시험을 통해 선택된 모든 학생들이 모르는 13개의 연어이다. 이 연어를 바탕으로 영어를 모국어로 사용하는 화자가 100~150자 정도의 텍스트를 만들었다. 암시적 학습환경의 학생들은 목표연어가 3개 이상 (3개에서 5개 사이) 쓰여진 텍스트를 교사의 명시적 지적 없이 읽고, 명시적 학습 환경 학생들은 암기 종이에 목표 연어를 반복해서 쓰며 외우고 교사의 명시적인 설명을 들었다.두 그룹 모두에게 전체적인 텍스트 이해 정도를 알 수 있는 이해도 확인 문제가 주어졌다. 모든 학습이 끝난 후, 학생들은 4가지 다른 종류의 시험을 쳤다. 이 시험은 Ellis (2005)가 고안한 것이다. 암시적 지식 측정을 위해 모방 말하기 시험 (Oral imitation test)와 제한된 시간내 타당성 판단 테스트 (Timed Plausibility Judgment Test; PJT)가 사용되었고, 명시적 지식 측정은 무제한 시간의 타당성 판단테스트 (Untimed PJT)와 오류 고치기 시험 (error correction test)으로 이루어졌다. 명시적 지식 습득의 과정에 대해 더 많은 정보를 얻기 위해, 타당성 판단 정도 테스트 (PJT certainty)와 문장해석 (L1 translation) 능력도 함께 평가 되었다. 실험 결과 다음과 같은 결론을 얻을 수 있었다. 첫째, 학습후 즉각적으로 시험을 쳤을 때는, 명시적 학습자들의 암시적, 명시적 연어지식이 전반적으로 더 높았다. 둘째, 일정시간 (3주) 후에 다시 시험을 쳤을 때는, 암시적 학습자들의 점수가 증가함을 알 수 있었다. 셋째, 학습자의 수준을 나누었을 때, 상위 학습자 들의 위의 관찰된 결과와 유사한 결과를 보였으나, 하위 학습자들은 명시적인 학습자들의 점수가 더 높았다. 이는 학습자의 수준에 따라 학습 환경이 조성 될 필요가 있다는 것을 시사한다. Effects of Implicit and Explicit Learning on the Acquisition of Implicit and Explicit Knowledge of Collocations from Different Proficiency Levels The current study was conducted with three aims. First, it investigates whether implicit and explicit learning conditions lead to the different results of immediate acquisition of implicit and explicit collocational knowledge. Second, it studies whether there are differences between immediate and long-term acquisition of implicit and explicit collocational knowledge from implicit and explicit learning conditions. Third, it researches how learners’ proficiency levels lead to different gaining of implicit and explicit collocational knowledge from implicit and explicit learning. To investigate the above research questions, 72 participants were divided into implicit and explicit learning conditions, and their gain scores were compared in both immediate and delayed tests. In each learning group, students were divided into upper and lower proficiency levels, based on their final exam. The target collocations were selected from Korean Nationwide Achievement Test for second year high school students, and students were pretested to choose unknown collocations. The materials were written by a native speaker of English using the selected collocations. For the implicit learning group, the target collocations were exposed more than 3 times (3 to 5 times) in the texts without teachers’ explicit explanations. For the explicit learning group, memorization sheets were provided before covering the materials. Students were given opportunities to memorize target collocations, and the teacher gave explicit explanations of each target. For both learning groups, comprehension questions were used to follow up to check learners’ overall understanding of the texts. After treatments in each learning group, 4 different instruments designed by Ellis (2005) were implemented to see how well they acquired implicit and explicit knowledge. Oral imitation test and timed plausibility judgment test (PJT) were used for measuring implicit knowledge, and untimed plausibility judgment test (PJT) and error correction test were used for explicit knowledge. Also, to obtain more information on the learners’ acquisition of explicit knowledge, PJT certainty and L1 translation were asked, as well. The immediate test was implemented on the same day of the treatment, and the delayed test was conducted 3 weeks after the immediate test. The findings of this study were as follows: first, when it comes to immediate acquisition, it seems that explicit learners were better than implicit learners in both implicit and explicit collocational knowledge. Second, when considering long-term retention of implicit and explicit collocational knowledge, it can be possible to draw a conclusion that implicit learners are better than explicit learners in remembering both implicit and explicit collocational knowledge in the long-term. Both results lead to the possibilities that there seem to be interface between implicit and explicit knowledge, because learners gained both implicit and explicit knowledge, regardless of the learning conditions. Third, upper learners showed similar results to the ones mentioned above, but explicit lower learners did better in both immediate and delayed tests compared to implicit lower learners. This leads to the implication that learners’ proficiency might be the important consideration before the implementation of implicit and explicit learning conditions for the acquisition of implicit and explicit lexical knowledge.

The Relationship Between the Corpus-based Learning and Phrasal Verb Acquisition

Kim, Jee Eun HANKUK UNIVERSITY OF FOREIGN STUDIES. DEPARTMENT O 2015 국내석사

The Relationship Between the Corpus-based Learning and Phrasal Verb Acquisition Phrasal verbs are one of the grammatical patterns that are present in English. They are one of the several areas of vocabulary and grammar which is quite difficult for the EFL learners to master. Although it is a source of confusion and frustration to the EFL learners, phrasal verbs are commonly used to those who speak English as their mother tongue. In order to approach one step closer in mastering English, phrasal verbs must be acquired. However, most of the Korean students learn vocabulary and grammar through cramming method of teaching, and by memorizing the terms rather than analyzing them. They are also used to memorizing one-word verbs and therefore translate the terms incorrectly by just focusing on the verb or on the particle that follows. Educators need to find ways to teach phrasal verbs through the authentic texts and give chance for the students to analyze the definition of words through contexts that are given to them. This research study focuses on teaching phrasal verbs effectively to students who are at beginner's level by conducting a corpus-based method of teaching in class. It also attempts to find out whether the corpus-based instructions help students improve learning and understanding English phrasal verbs. With a number of 30 Korean adult EFL learners who are at a beginner's level as respondents used in the study, a total of 7 weeks of study was made. Using ten phrasal verbs: (1) put off, (2) get over, (3) get back, (4) try on, (5) get through, (6) heat up, (7) give up, (8) put away, (9) look up, and (10) turn on, found and used on their conversation book, pre-test, corpus-based teaching materials, and post-test were made. Using the scores from the pre-test and the post-test, statistical treatment has been analyzed. Through this research, the scores from the post-test increased when compared to the scores from the pre-test. The result showed that there is a significant difference between the acquisition of phrasal verbs before learning phrasal verbs with corpus-based instruction, and the acquisition of phrasal verbs after studying and analyzing the phrasal verbs with corpus-based instruction and materials in class when taught to the EFL learners who are at a beginner's level. The respondents replied that they experienced difficulty in understanding phrasal verbs through corpus-based materials because they are used to cramming method or memorization. Though it was challenging, the students find it helpful when learning and mastering English. 구동사 (phrasal verb)는 영어 문법에 나오는 패턴 중 하나이다. EFL 영어 학습자들이 배우기 어려워하는 어휘와 문법 중 하나이다. EFL 학습자들에겐 혼란과 불만을 주지만, 영어를 모국어로 사용하는 사용자들에게 있어선 구동사는 아주 흔히 쓰이고 있다. 영어를 습득을 향해 한발자국 다가가기 위해선 구동사를 습득 할 필요성이 있다. 하지만 대부분의 한국 학생들은 어휘나 문법을 스스로 분석하여 배우지 않고, 암기를 통해 배우고 있다. 그들은 1어 동사를 외우는 데 익숙해 져 있기 때문에 구동사를 해석 할 때 동사와 전치사를 따로 해석함으로 인해 정확하지 정의를 내려 버리게 된다. 그렇기에 교육자들은 구동사를 실제적 텍스트 (authentic text)를 통해 학생들이 단어의 뜻을 스스로 정의를 내리는 연습을 할 수 있도록 여러 교육 방법을 찾아 봐야 한다. 이 논문은 코퍼스를 기반한 학습(corpus-based learning)을 통해 초급 영어 단계에 있는 학생들에게 효과적으로 구동사를 가르치는 방법에 초점을 두고 있다. 코퍼스를 기반한 학습 도구들이 학생들이 구동사를 습득하는 데 도움을 주는 지 알아보려고 한다. 30 명의 한국 성인EFL 학생들을 대상으로 6 주 동안 연구가 진행이 되었다. 회화교재에서 발견된 10개의 구동사: (1) put off, (2) get over, (3) get back, (4) try on, (5) get through, (6) heat up, (7) give up, (8) put away, (9) look up, 그리고 (10) turn on 을 사용하여 사전 검사 (pre-test), 코퍼스 기반 학습지와 시험들, 그리고 사후 시험 (post-test)이 만들어 졌다. 사전 검사와 사후 시험에서 나온 점수들을 가지고 통계적 처리가 이루어 졌다. 이 연구를 통해 사후 시험에 나온 점수가 사전 검사에 나온 점수들과 비교 했을 때 더 높아진 것으로 발견 되었다. 그렇기에 이 결과를 통해 코퍼스 기반 학습을 통해 초급 EFL 학생들이 구동사를 배우기 전과 코퍼스 기반 학습을 통해 구동사를 배운 후에 유의미적인 차이가 있었다는 것이 발견 되었다. 학생들은 암기로 어휘를 외우는 방식에 익숙해 져 있기 때문에 코퍼스를 기반한 학습을 통해 구동사를 배우는 방식이 많이 어렵다고 대답 하였다. 비록 어려울지라도, 코퍼스를 기반한 구동사 학습이 영어를 배우는 데 도움이 된다고 답하였다.

Exploration of Form-Focused Instruction of Pronunciation

Jeon, Jae Seung HANKUK UNIVERSITY OF FOREIGN STUDIES. DEPARTMENT 2014 국내석사

Exploration of Form-Focused Instruction of Pronunciation: A Case Study of Korean Middle School Learners The purpose of this study is to explore form-focused instruction of pronunciation according to the SLA paradigm pursuing the balance of form and meaning. 4 research questions are addressed in this study. First, how does participants’ pronunciation develop based on focus on phonological form? Second, how does their fluency develop? Also, how do their fluency and accuracy interface? Third, what attitudes and perspectives do they have on form-focused instruction of phonological forms? Fourth, what difficulties and problems do they report in speaking without breakdowns? In order to answer those questions, this case study included 2 middle school seniors and provided 14-week form-focused instruction of pronunciation. For the elicitation of data, interviews, stimulated recall, diaries and public spoken performances were recorded and transcribed, and then qualitatively analyzed. The first finding of this study is that form-focused instruction of pronunciation resulted in the development of the participants’ phonological forms, and the increase of their intelligibility ensued from it. However, when they explicitly monitored new phonological forms they had learned and reached their attentional overload, they deteriorated in unautomatized forms without their attentional care. As a result, their intelligibility was not guaranteed. Furthermore, one important finding is that the deterioration phenomenon was obvious only in the performances of the participant with lower pre-existing proficiency. It is implied that learning amount and speed should be adjusted through differentiated classes according to pre-existing proficiency levels of learners. The second finding is that fluency was contingent on the implicit processing of forms. The participant with higher pre-existing proficiency had already familiarized herself with many forms before the current instruction, and therefore the number of new forms and learning speed did not generate her attentional overload. As a result, she steadily increased in fluency. However, her counterpart with lower pre-existing proficiency had to experience attentional overload due to the excessive number of new forms needing her explicit monitoring and the learning speed over her pace. She deteriorated in fluency producing more breakdowns. The third finding is that they reported positive attitudes and perspectives on form-focused instruction of pronunciation. They noted that it raised their awareness of forms, learning speed, and listening ability. Also, they reported that they did not have difficulty understanding almost all the phonological forms through the rather short 10-minute instruction of pronunciation stemming from focus on form. The last finding is that they reported that they had difficulty speaking without breakdowns due to the excessive amount of information to monitor in real time, the lack of articulatory motor skill, and fears for errors. They suggested as a solution repetitious training through the habituation of daily English use. The role of instructional intervention appears to be manifest for the development of pronunciation and intelligibility. Form-focused instruction of pronunciation shows it can serve as a rational methodological approach for achieving the balance of form and meaning. For more effectual education, however, study courses should be customized to meet the different needs of individuals and encourage their habituation of English use for automatization.

The Effects of Corpus Consultation of Formulaic Expressions on the Improvement of Automaticity in the Cognitive Process and L2 Writing Quality

Cho, Hye Young HANKUK UNIVERSITY OF FOREIGN STUDIES. DEPARTMENT O 2014 국내박사

Korean University Students’ Individual Differences in Learning Styles and Their Perspectives on ELT Materials Evaluation

이보경 HANKUK UNIVERSITY OF FOREIGN STUDIES. DEPARTMENT O 2014 국내박사

Korean University Students’ Individual Differences in Learning Styles and Their Perspectives on ELT Materials Evaluation The purposes of this study were to identify Korean university students’ self-reporting learning style preferences, to investigate their perspectives on ELT materials evaluation criteria, to explore the relationships between salient (major) learning styles and perspectives on ELT materials evaluation criteria, and to find relationships between major learning styles and their actual evaluation of ELT materials. Quantitative data were gained through 521 subjects’ responses to a learning style survey, a questionnaire of evaluation checklist, and 40 subjects’ responses to a feedback survey on post-use evaluation of instructional materials for a class. Additionally, qualitative data were collected from retrospective interviews and written self-reports. The findings, in terms of perceptual learning styles, indicated that the most salient preference of Korean learners for an auditory learning style followed by visual and individual learning styles was captured while tactile, kinesthetic, and group learning styles were less favored. Additionally, a majority of the learners tended to maintain or reinforce their preferences throughout the research period. With regard to learners’ perspectives on ELT materials evaluation criteria, the subjects had a commonality of the high and low importance of the criteria, while different perspectives were also found depending on their backgrounds such as gender, year, major, academic membership, and English proficiency. It was found that the learners could be qualified evaluators of their own coursebooks or self-access materials because they had generally systematic and consistent perspectives on the evaluation. The findings above-mentioned and the result of the learners’ actual evaluation of ELT materials show that Korean university students’ major learning styles were likely to affect their views of materials evaluation. That is, learners with multiple major learning styles and with tactile or kinesthetic learning styles tended to have higher level of expectation concerning materials evaluation than those with one or no major learning style. Also, Korean university students tended to be significantly concerned with the criteria relevant to their major learning styles. In terms of actual evaluation of ELT materials used in class, auditory materials were considered most interesting and useful by auditory-oriented learners. Visual materials and audiovisual materials received the most positive feedback from tactile- and kinesthetic-oriented learners. Also, individual-oriented learners tended to prefer individual activities and group-oriented learners showed group activity preferences in all the materials of auditory, visual, and audiovisual. The major implications of the present study are as follows. First, teachers can utilize information about their students’ perspectives on ELT materials evaluation relative to learning styles to facilitate materials selection or adaptation and to develop teaching methods with consideration of individual learners’ preferences. Second, materials developers can refer to the target learners’ perspectives on materials evaluation for newly developed materials or revised editions so that they can best fit the target learners’ expectations. It is also possible for them to enable the learners to choose different options on the type of language materials or activities depending on learning styles. Finally, Korean university students themselves can take advantage of knowledge of their learning styles and experience of ELT materials evaluation to take greater responsibility for their own English learning and to become more intelligent users of ELT materials.

(An) Analysis on digital divide structure and pattern across Asia Pacific countries based on multivariate statistical methods

Majid Mushtaq Hankuk University of Foreign Studies Department of 2018 국내석사

Seeing ICT as a catalyst for economic growth, many governments have come up with ways to induce the development of ICT in their strategic plans. Yet, the boom of internet technologies has also resulted in disparities in digital access between certain regions and countries, presenting a threat to leaving these countries behind in the race to global competitiveness. Various attempts have been made to define and analyze the digital divide in various regions of the world, yet until now, there hasn’t been any sort of work done measuring the digital divide structure and pattern on a large scale in the Asia Pacific region. The purpose of this research is to analyze the structure, pattern and dynamics of the digital divide in the Asia-Pacific area. We tackled the measurement of digital divide among 31 countries of this region by means of multivariate statistical methods. Our analysis of digital divide structure and dynamics was focused on 3 objectives. First, we used factor analysis in order to determine a small number of factors that summarize the set of economic, demographic, social and digital development related indicators. Second, we clustered countries using their ICT-related indicators and determined which group of countries can be classified as digital laggards and which ones are digital leaders. Third, we observed short term digital divide evolution by drawing the path movements of these countries between the year 2011 and 2016 which helped us to analyze the evolution of each country by answering the question that whether or not, a country has experience digital improvement in these 5 years. With the help of these multivariate statistical methods, we found out that the digital gap exists in this region and is much wider than the digital gap across the European Union countries. Moreover, of 10 variables in consideration, 2 latent factors were found, namely digital diffusion and cost, and digital infrastructure. On the other hand, cluster analysis grouped these Asia Pacific countries into 5 different clusters sharing similar digital profiles in each cluster. Short term digital evolution shows that countries have been improving in their digital development scores, yet the digital gap is huge between certain clusters. We have also suggested some recommendations for policy makers in these countries to help them narrow the digital gap between their countries and ‘digital leaders’. 전 세계 대부분의 국가들은 경제 성장의 촉매로서 정보통신기술의 개발과 활용을 위한 다양한 관련 정책들을 경제에 적용하였다. 그러나 인터넷 기술의 폭발적인 발전에도 불구하고 특정 지역이나 국가들 간 다양한 형태의 불균형이 발생하였으며, 이는 특정 국가들의 경제 성장이나 산업 경쟁력에서의 차이를 야기하는 결과로 이어 졌다. 따라서 국제 지역간 혹은 국가간 정보 격차에 대한 원인과 구조 그리고 동태적 변화와 해소를 위한 정책 개발에 다양한 연구가 수행되었다. 그러나 아시아, 태평양 지역을 대상으로 한 정보 격차의 구조와 패턴 그리고 정책 연구는 매우 미진한 상황이다. 이에 본 연구는 아시아, 태평양 지역의 정보 격차의 구조, 패턴 그리고 동태적 특성을 분석하여 역내 국가간 정보격차를 해소하기 위한 정책적 대안을 모색하는 것을 목적으로 한다. 아시아, 태평양 지역 31개 국가들을 대상으로 다변량 통계 방법론을 적용하여 정보 격차를 측정하여, 그 구조와 동태적 특성을 분석한다. 구체적으로 우선, 경제적, 인구학적, 사회적 그리고 정보통신기술 관련 다양한 지표들을 대상으로 요인 분석을 수행, 두 개의 요인을 추출하고, 이를 바탕으로 역내 국가간 정보격차의 핵심 원인을 고착한다. 두 번째로는 이러한 두 개의 핵심 요인을 기반으로 31개국에서 정보격차가 유사한 집단들을 구분하는 군집분석을 수행하여 역내 정보격차 구조의 특성을 분석한다. 특히, 요인분석 이전의 다양한 지표를 대상으로 군집분석을 수행하여, 2 요인 기반 군집분석과 비교하여 정보격차 구조의 특성을 고찰한다. 마지막으로 2011년과 2016년의 정보 격차의 구조를 비교하여 정보 격차 해소 과정에 효과를 보이는 국가들의 특성을 파악한다. 이러한 다자간 통계방법론을 통해 이 지역에서 정보 격차가 다양한 형태로 존재한다는 것과 기존 유럽연합국가들을 수행한 연구 결과와 비교하여 격차의 정도가 보다 심각하는 것을 파악하였다. 특히, 요인분석을 통하여 아시아, 태평양 지역의 정보 격차의 핵심 요인으로 디지털 확산 비용과 디지털 인프라를 파악하였다. 또한, 이러한 요인에 근거하여 31개 국가들의 정보격차 구조를 5개의 군집으로 식별할 수 있었으며, 하위 군집과 상위 군집간 정보 격차의 차이가 매우 크다는 사실을 확인하였다. 또한, 동태적 분석에서 하위 군집의 국가들의 정보격차가 개선되는 방향으로 이루어지고 있으나, 여전히 상위 및 하위 군집간 정보 격차는 지속되고 있다. 이러한 연구 결과를 바탕으로 상위 국가군과의 격차를 해소하기 위한 다양한 정책적 방안을 제시하였다. 본 연구결과와 정책적 제언은 향후 아시아, 태평양 지역의 정보 격차의 해소를 위한 좋은 참고 자료로 활용 가능하며, 특히 역내 정보격차의 동태적 변화를 추적하여 정책 실행의 효과 분석의 방법론적 기반으로 활용할 수 있을 것으로 기대된다. 그러나, 현재 정보통신기술의 발전 속도가 매우 빠르고, 또한 다양한 산업과의 융합 발전이 가시화되고 있는 상황에서 기술적, 경제적, 환경적 그리고 수요 변화 요인들을 고려한 보다 확장된 분석 모델이 필요할 것으로 보인다.

Development of mass spectrometric methods for accurate citrulline quantification and selective detection of citrullinated peptide by reactive DESI MS

신은비 Hankuk University of Foreign Studies. Department o 2016 국내석사

Development of Mass Spectrometric Methods for Accurate Citrulline Quantification and Selective Detection of Citrullinated Peptide by Reactive DESI MS Arginine residues in a protein can be enzymatically deiminated to citrulline residues, and this post-translational modification of proteins, called citrullination, has been known to be associated with autoimmune diseases such as rheumatoid arthritis. Since citrullination of an arginine residue causes a mass shift of only 1 Da, isotopic distribution patterns of citrullinated and its control (non-citrullinated) peptides overlap each other, and the resulting isotopic pattern is skewed with respect to that of the control peptide. Recently, Deforce and coworkers utilized the citrullination-induced skewed isotopic patterns for estimating the extent of citrullination (J. Proteome Res. 2012, 11, 5245). However, electrospray ionization (ESI), which Deforce and coworkers employed, is not fully suitable for this type of quantification because the number of potential charge sites on a citrullinated peptide is less than that on its control peptide and this leads to different ion abundances for a given charge state. In this study, we employed matrix-assisted laser desorption/ionization (MALDI) instead of ESI for quantification of citrullination because the preference for singly charged ion formation by MALDI may overcome the aforementioned issue. Our results show that the isotopic patterns generated by MALDI time-of-flight (TOF) mass spectrometry (MS) reflect the citrullination contents better than those generated by ESI linear ion trap (LIT) MS. Development of Mass Spectrometric Methods for Accurate Citrulline Quantification and Selective Detection of Citrullinated Peptide by Reactive DESI MS Citrullination is one of the post-translational modifications on arginine side chains which results in conversion of arginine into citrulline through deimination. Since citrullination is accompanied by only 1 Da increase in mass, citrullinated peptide peaks are hard to be distinguished from deimidated peptide peaks or the isotope peaks from the control peptides. Therefore covalent labeling techniques on citrulline residues were usually employed to investigate citrullinated sites by MS. Recently, reactive desorption electrospray ionization (DESI) mass spectrometry (MS) was introduced in order to detect the sample which is hard to be ionized. The reagent was added the DESI solvent that leads to in situ derivatization of the analytes during the ionization process. Here, we attempted to use the phenylglyoxal (PG) as the derivatization reagent for the determination of the citrullination site in a citrullinated peptide by reactive DESI MS. 정확한 시트룰린화 정량과 감도 높은 시트룰린 분석을 위한 질량분석법 개발 본 논문은 post-translational modification 의 일종인 시트룰린화의 정도를 보다 정확하게 정량할 수 있는 MALDI 기반의 질량분석법 개발과 시트룰린화를 선택적으로 검출할 수 있는 reactive desorption electrospray ionization (DESI) 질량분석법에 관한 논문이다. 동위원소분포를 이용한 시트룰린화 정량에 있어서 MALDI와 ESI 질량분석법을 비교 분석하였으며, 보다 빠르고 감도 높게 시트룰린을 분석하기 위하여 Phenylglyoxal(PG)를 이용한 in situ reactive DESI MS법을 개발하였다.