WCDMA 기지국 모뎀의 구현을 위한 상위 레벨 설계 및 통합 성능 평가

도주현,이영용,정성현,최형진,Do Joo-Hyun,Lee Young-Yong,Chung Sung-Hyun,Choi Hyung-Jin 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.1a

본 논문에서는 다년간에 걸쳐 진행되었던 WCDMA(UMTS) 기지국 모뎀 개발을 위한 상위 레벨 설계 및 설계에 적용된 기저대역 동기 알고리즘에 대한 분석과 고정 소수점 설계를 통한 성능 평가 결과를 제시하였다. 설계 대상 시스템이 기지국임을 고려하여 모뎀을 구성하는 각 동기 모듈은 빠른 추적 성능보다 안정적인 성능을 보장할 수 있도록 설계되었으며, 구현을 위한 고정 소수점 설계시 각 모듈의 내부 연산에 대한 최적의 비트설정을 통하여 복잡도를 최소화하였다. 본 논문에서는 먼저 모뎀 설계를 위하여 개발된 각 기저대역 동기 모듈에 대한 분석을 수행하였으며, 이후 구현을 위하여 고정 소수점 설계된 모뎀과 부호화/다중화를 포함하는 심볼 레벨 프로세싱(Symbol Level Processing; SLP)파의 링크 성능을 제시하였다. 성능 평가는 3GPP TS 25.104(Release 5)에 제시된 12.2kbps, 64kbps, 144kbps, 384kbps의 전송 속도에 대하여 참조 무선 채널 환경을 기반으로 수행되었으며, 규격에 제시된 최소 요구 성능과의 비교를 통하여 약 2dB 이상의 성능 여유(margin)를 갖는 매우 안정적인 동작을 보임을 증명하였다. 본 논문에서 제시된 WCDMA 기지국 모뎀은 기지국 모뎀 칩으로 성공적으로 구현되었다. In this paper, we propose a high level design architecture of WCDMA(UMTS) base station modem and synchronization algorithms applied to the proposed architecture. Also analysis of each synchronization algorithm and performance evaluation of fixed point designed modem are shown. Since the target system is base station modem, each synchronization algorithm is designed for its stable operation. To minimize implementation complexity, optimum fixed point design for best operation of synchronization algorithms is performed. We performed symbol level link simulation with fixed point designed modem simulator for data rate of 12.2kbps, 64kbps, 144kbps, and 384kbps. We compared performance results to the minimum requirements specified in 3GPP TS 25.104(Release 5). Extensive computer simulation shows that the proposed modem architecture has stable operation and outperform the minimum requirement by 2 dB. The proposed modem architecture has been applied in the implementation of WCDMA reverse link receiver modem chip successfully.

NES Trajectories: From Untrained Language Teachers to Professional Academics

도주현 팬코리아영어교육학회 2017 영어교육연구 Vol.29 No.2

There is a growing literature on the professional identity development of two kinds of TESOLteachers: 1) non-native speaker novice teachers of English; and 2) native speaker teachers ofEnglish who are novices at the time of study. However, few studies of established native speakerTESOL professionals who began teaching English abroad with no preparation or academicbackground in the field exist. By examining the life story of five well-establishedteacher-scholars in TESOL with a special focus on their experience as novice/untrained EFLteachers abroad, the research aimed to enrich our understanding of the potentialities of noviceESL/EFL teachers. The findings revealed that each of the participants learned somethingsignificant from their experience abroad at the beginning of their careers. The participantsevaluated their experience as novice teachers abroad very highly, placing it in several cases atthe center of their subsequent careers. In addition, the participants attributed great importance totheir attempts to understand the host country’s language and culture. The professional life storiesof such individuals can have a positive/inspirational effect on individuals currently entering thefield, and provide useful knowledge regarding career development in TESOL.

Two Children’s Language Practices in the EFL Classroom: A Language Socialization Perspective

도주현 언어과학회 2019 언어과학연구 Vol.0 No.89

The study explores how students' variable experience with English learning beyond the classroom influences language learning in primary EFL classrooms as parents’ sociocultural values and attitudes toward English, investment in English education inside and outside of school, and economic status interplay with EFL learners’ language experience. To understand how children are educated in the EFL classroom in relation to macro-micro linkages (Garrett 2008), language socialization allows this study to make a contribution to the current literature on primary EFL studies. The participants have had rich language learning experience beyond the school setting. The gap between the advanced learner and the beginner exists even in a relatively equal socioeconomic setting. The local educational context reveals that the macro level does not meet the educational needs at the micro level no matter how much teachers try to provide learning opportunities at the appropriate levels.

Writing Conferences as Mediated Worlds: Forms of Talk in L2 Writing Conferences

도주현 언어과학회 2017 언어과학연구 Vol.0 No.80

The linguistic and contextual features of writing conferences have been studied in both L1 and L2 settings. Based on previous literature regarding writing conferences, this study analyzes L2 writing conference talk collected in an experimental tutorial in which the researcher was the tutor. The data was analyzed according to two types of discourse features: participation structures and contextualization cues. Findings suggest that revision talk in this study seems to have followed a basic IRE structure, although students on occasion initiated new topics, thus showing their own agency and less asymmetric power between tutor and students. In addition, revision talk made plentiful use of contextualization cues. The context of the writing conferences studied is also described in detail, as is the role of the author/tutor as academic mediator. This study may provide a preliminary description of a special and in some ways unique site for “learning the ropes” of academic writing.

Joining a book club: EFL literacy practice of a primary EFL learner

도주현 한국초등영어교육학회 2020 초등영어교육 Vol.26 No.4

At most public primary schools in Korea, students are placed in classrooms regardless of their English proficiency. Teachers have limited means of dealing with such variation despite many pedagogical suggestions. The study examined what reading in English as a foreign language can bring a Korean primary student beyond the regular EFL classroom experience in a school setting. To be specific, the study explored a primary EFL learner’s L2 reading practice through participant-observation along with interviews and audio-recordings of classes throughout a semester to understand the role of L2 reading in one student’s educational experience. In total, 30 hours of EFL classroom observation, eight hours of book club class observation, and two hours of interviews were analyzed. The study tries to understand the L2 reading practice in a local setting including meanings of L2 literacy practices and the role of teachers and parents. The study showed when teachers extend their vision beyond regular EFL classes and find room for level-differentiated learning opportunities, students can enjoy rich and meaningful learning environments. This study sheds light on how alternative EFL language practices may compensate for a lack of exposure to the target language in the local context.

What’s Still Missing?: How Co-teachers View Co-teaching Practices in Elementary EFL Classrooms in Korea

도주현(Juhyun Do) 한국영어교과교육학회 2020 영어교과교육 Vol.19 No.4

This study reports on co-teaching practice in elementary EFL classrooms, in which Korean English teachers (KETs) and native English-speaking teachers (NETs) co-teach in order to enact the national English education agenda. The two groups of teachers were surveyed on their attitudes toward and experience with co-teaching using standard survey research methods. KETs are generally satisfied with co-teaching practice in EFL classrooms. However, the results showed that KETs need to plan lessons with NETs for successful co-teaching. Also, heavy burden of managing NETs needs to be ameliorated in order to focus on effective co-teaching. Most NETs have educational qualifications but lack actual teaching experience. The results revealed that NETs need to have a better understanding of the educational contexts. To maximize the effectiveness of co-teaching EFL classes, well-planned curricula, development of English proficiency scales, better matching procedures, fuller understanding of co-teaching practices, and readiness to improve English education are needed among all parties. The findings of this study illuminate the larger issue of using NETs in English education not just in Korea, but across Asia.

다단 추적모드를 적용한 W-CDMA 기지국 모뎀용 고속 AFC 설계

도주현(Joo-Hyun Do),이영용(Young-Yong Lee),최형진(Hyung-Jin Choi),김철(Cheol Kim),안재민(Jae-Min Ahn),임민중(Min-Joong Rim) 한국통신학회 2001 한국통신학회 학술대회 및 강연회 Vol.2001 No.4

다단 추적 모드를 적용한 WCDMA 역방향 링크 수신기용 Normalized CP-AFC

都周鉉,최형진,李映鏞,金容晳 대한전자공학회 2002 電子工學會論文誌-TC (Telecommunications) Vol.39 No.8

In this paper, we propose a modified AFC algorithm which is suitable for the implementation of WCDMA reverse link receiver modem. To reduce the complexity, the modified CP-FDD algorithm named 'Normalized CP-FDD' is applied to the AFC loop. The proposed FDD algorithm overcomes the conventional CP-FDD's sensitivity to the variance of input signal amplitude and increases the linear range of S-curve. Therefore, offset frequency estimation using the proposed scheme can be more stable than the conventional method. Unlike IS-95, since pilot symbol in WCDMA is not transmitted continuously, we introduce a moving average filter at the FDD input to increase the number of cross-product. So, tracking speed and stability are improved. For more rapid frequency acquisition and tracking, we adopt a multi-stage tracking mode. Using NCO having ROM table structure, the frequency offset is compensated. We applied the proposed algorithm in the implementation of WCDMA base station modem successfully. 본 논문에서는 제 3 세대 이동 통신인 WCDMA 기지국 모뎀의 실제 구현에 적합하도록 변형된 AFC(Automatic Frequency Control) 루프를 제안한다. 제안된 AFC 루프에는 구현상의 복잡도 감소를 위하여 기존의 CP-FDD(Cross Product Frequency Difference Detector) 알고리즘을 변형한 Normalized CP-FDD 알고리즘을 적용하였다. 제안된 Normalized CP-FDD는 입력 신호 진폭 변화에 민감한 기존 CP-FDD 출력 특성을 보완하며, FDD의 출력(S-curve)의 선형화 구간을 증가시킴으로써 안정적인 주파수 오차에 대한 추정을 가능하게 한다. WCDMA에서는 IS-95 시스템과 다르게 파일롯 심볼이 연속적으로 전송되지 않으므로, FDD 입력단에 이동 평균 필터(Moving Average Filter)를 도입하여 교차 곱(Cross-product)의 수를 증가시킴으로써 잡음의 영향을 감소시키고 주파수 오차에 대한 추적 시간 성능과 안정성을 향상시켰다. 또한 다단 추적 모드를 적용함으로써 수신 신호의 주파수 오차의 크기에 대한 능동적인 보상이 가능하도록 하였으며, 루프 필터의 출력을 이용한 ROM table 도약 구조의 NCO (Numerical Controled Oscillator)를 적용하여 주파수 오차를 보상하였다. 본 논문에서 제안한 알고리즘은 WCDMA 기지국 모뎀 구현에서 성공적으로 적용되었다.

COVID-19가 가져온 초등영어 수업의 변화, 그리고 미래: 블렌디드 러닝 초등영어 수업 개선 연구

도주현 ( Do Juhyun ),신혜원 ( Shin Hye Won ) 한국멀티미디어언어교육학회 2020 멀티미디어 언어교육 Vol.23 No.4

This study explores teaching and learning in primary EFL classrooms in Korea as they have shifted to a blended learning experience and tries to ascertain how we should prepare for an ever-changing educational environment within school settings. In short, this case study examines how Covid-19 has changed primary EFL classrooms, what we have learned from these changes, and how we can be ready for bigger changes. A blended learning approach combines the benefits afforded by traditional and online learning components. Participants were 142 sixth-grade students (72 males, 70 females) in six different English classrooms. Our qualitative methodology included surveys of the students in the primary EFL classroom and of one English subject teacher’s experiences amid the Covid-19 pandemic. On the student survey, traditional face-to-face classrooms were favored over online learning environments. The teacher also had a more positive attitude regarding her responsibility for students’ learning in a conventional classroom. Through descriptions of both teacher and student experiences of a blended learning approach, this study sheds light on possible new directions for primary English education.

Two Children’s Language Practices in the EFL Classroom: A Language Socialization Perspective

Juhyun Do(도주현) 언어과학회 2019 언어과학연구 Vol.0 No.89

The study explores how students’ variable experience with English learning beyond the classroom influences language learning in primary EFL classrooms as parents’ sociocultural values and attitudes toward English, investment in English education inside and outside of school, and economic status interplay with EFL learners’ language experience. To understand how children are educated in the EFL classroom in relation to macro-micro linkages (Garrett 2008), language socialization allows this study to make a contribution to the current literature on primary EFL studies. The participants have had rich language learning experience beyond the school setting. The gap between the advanced learner and the beginner exists even in a relatively equal socioeconomic setting. The local educational context reveals that the macro level does not meet the educational needs at the micro level no matter how much teachers try to provide learning opportunities at the appropriate levels.