Synthesis of Polyimide having Spiropyran Group And Optoelectrical Properties

DeokGi Hong,YoungJun Gwak,JiHun Seo,Seong Woo Lee 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

백색 LED를 위한 광적응형 형광체층 형성

김덕기(DeokGi Kim),강소라(KANG SORA),이광철(Kwang-Cheol Lee) 한국소성가공학회 2014 금형가공 심포지엄 Vol.2014 No.8

The emission-adaptive phosphor layer was fabricated by self-exposure method to realize the pc-white LED. The effect of phosphor layer forming parameters such as phosphor content and exposure time on the phosphor layer shape and LED characteristics was investigated. Through the fabrication process of phosphor layer, two types of phosphor layer shape were fabricated by phosphor layer forming parameters. In the case of low exposure intensity and/or short exposure time with high phosphor content, the conformal coating shape phosphor layer which is imitative of the irradiance pattern of an LED chip was formed, whereas in the long exposure time with low phosphor content, the light distribution proportional shape phosphor layer which reflects the near-filed pattern of an LED chip was formed. As a result of analysis of LED characteristics, as phosphor content and exposure time respectively decreased CCT increased. In the case of luminous efficacy as exposure time decreased luminous efficacy increased irrespective of phosphor content due to the photon scattering loss of phosphor particles in the thick phosphor layer. Also as exposure time increased the thickness of phosphor layer increased. It was concluded that the optimum condition for high luminous efficacy white LED is shorter exposure time for thin phosphor coating layer under adequate phosphor content.

Resistance Characteristics of Thin Films and Contacts in CMOS under Cryogenic Temperature and High Magnetic Field Environment

Dongha Shim,Deokgi Kim 대한전자공학회 2024 Journal of semiconductor technology and science Vol.24 No.2

This paper investigates the resistance characteristics of thin film and contact structures in a 90-nm CMOS process under cryogenic temperature and high magnetic field environment for the first time. The temperature dependences of the test structures were measured at the ambient temperatures of 300 K, 150 K, 77 K and 4.2 K, respectively. To understand the magnetic field dependence of the test structures at the temperatures, measurements were also performed under the magnetic fields of 0 T, 2 T, 4 T and 6 T, respectively. The sheet resistances and the contact resistances are analyzed along with the magnetoresistances under the various conditions. All test structures showed a decreasing sheet resistance or contact resistance as the temperature decreases. The sheet resistance of a thin films with a lower value drops faster as the temperature decreases. The metal thin film and the metal-to-n+ contact showed the maximum resistance change of 89.5% and 35%, respectively, over the temperature range. Meanwhile, negligible magnetoresistances are observed except the metal thin film, which shows a higher magnetoresistance under a lower temperature and higher magnetic field. The maximum magnetore-sistance of the metal thin film is measured to be 10.4% for the horizontal magnetic field of 6 T at 4.2 K.

A Corpus Analysis on Korean Pre-serviceEFL Teachers’ Morphology in Use

Han Suk Bae,Deokgi Min 한국초등영어교육학회 2021 초등영어교육 Vol.27 No.1

The present study established a pre-service Korean EFL teacher corpus (KTC) and investigated the teachers’ actual knowledge of using morphologically complex words, in comparison with native English speaker corpora (i.e., the English teacher corpus and the Corpus of Contemporary American English; ETC and COCA). The AntConc word list analysis results showed that morphologically complex words were more often encountered in the KTC than the ETC and the COCA. Also, specific terms related to education or instruction were more utilized in the teacher corpora (KTC and ETC) than general corpus (COCA). Filter analysis in Excel program provided that the ten most frequent suffixes were -ly, -ion, -ic, -er, -al, -ment, -ive, -ity, -ation, and -ous in order, which was similar to the list of native English speaker corpora (i.e., the Brown Corpus and the Open American National Corpus). However, the use of suffixes (e.g., -ly) in the KTC was less diverse and accurate than the native English speaker corpora. Advanced leveled irregular suffixes (e.g., -ic and -ive) were more often utilized in the KTC, instead of using frequent and regular suffixes (e.g., -y). Based on the results of this study, implications for teacher training and future research ideas were discussed.

모둠 중심 의사소통 활동에서 교육용 로봇 활용이 상호작용 양상에 미치는 영향

이승민(Lee, Seungmin),민덕기(Min, Deokgi),심규남(Shim, Gyunam) 한국영어교과교육학회 2013 영어교과교육 Vol.12 No.2

In terms of elementary English teaching and learning, educational robots can provide a powerful methodology for involving students in an emotional and interactive learning experience with language used for genuine communicative purposes. This study attempted to examine some effects of using an educational robot on interactional aspects in group-based communicative activities in elementary English classes. The subjects of this study were 24 students in the fifth and sixth grades. The educational robot was specially developed for elementary English teaching and learning. It was used in three types of group-based communicative activities: a map completion activity, a survey activity, and a role-play. The results of this study show that educational robots can have some positive effects on students’ interactional aspects such as the quantity of interaction and meaning negotiation. Through this research, it is believed that educational robots can bring opportunities for elementary school students to work together in a cooperative context and help students raise English communicative competence.

AI 펭톡 연계 초등영어 수업과 평가의 설계와 적용에 관한 연구

김민제(MinJe Kim),심규남(KyuNam Shim),민덕기(DeokGi Min) 한국영어평가학회 2023 영어평가 Vol.18 No.2

This study aims to incorporate spaced practice activities into an elementary English teaching model using AI Pengtalk, analyze its learning effects, and visualize learning experience data. For this purpose, a spaced practice using AI Pengtalk was conducted over five lessons with temporal intervals aimed at sixth-grade elementary students. Each lesson consisted of six periods, and during six periods, the spaced practice was conducted three times, with the intervals set at one day, three days, and eight days, progressively widening the temporal gaps from one day to four days for each session. The results show that positive effects were observed across all students regardless of their achievement levels, and it was particularly effective for students with lower achievement levels. It is also shown that data visualization using the AI Pengtalk’s assessment data can be effectively used for instructional guidance, such as determining the need for supplementary pronunciation teaching. Moreover, students positively perceived the learning facilitated by AI Pengtalk and acknowledged the usefulness of spaced practice. However, to obtain meaningful learning and assessment data, it is necessary to create optimized conditions that consider the environmental factors within the classroom to reduce the voice recognition errors of AI Pengtalk.

코퍼스 기반 현대 그림책 작가 Anthony Browne작품 어휘 분석

장우정(Jang, WooJeong),민덕기(Min, DeokGi) 한국초등영어교육학회 2013 초등영어교육 Vol.19 No.2

The purpose of this study was to compare and analyze a corpus of Anthony Browne’s picture books with other four corpora including elementary school English textbooks, children’s literature, fantasy movies for children, and CANCODE. In an effort to enhance the authenticity of English textbooks in terms of the selection and use of basic vocabulary, similarities and differences of vocabulary were evaluated and analyzed among the corpora. The following results were drawn: first, with reference to TTR analysis, the results show that Browne’s picture books are 14.07, which is the highest level among analyzed corpora due to the small size of the corpus and use of a variety of vocabulary derivatives. On the other hand, the TTR of elementary English textbooks is 10.90. Second, the vocabulary lists from the picture books, children’s literature, and CANCODE show a considerably high rate of accordance. Third, in connection with frequency of nouns, Browne’s picture books, children’s literature, and fantasy movies show a higher ratio of nouns ahead of lexical verbs. However, in the case of elementary English textbooks, they show the highest ratio of pronouns at 16.23%. Fourth, although the accordance rate of nouns among the corpora is very low, the frequency of two specific words, ‘time’ and ‘day’ is much higher. Fifth, the result of a comparison between the 391 vocabulary which appeared more than 8 times in Browne’s picture books and the required 800 vocabulary from the MOE recommended curriculum currently used matched by 55.2%, 216, despite the relatively small size of the corpus. Based on the above mentioned findings, the vocabulary utilized in elementary English textbooks needs to change to reflect the commonly used vocabulary in the corpora.

A Fully Integrated Dual-Mode CMOS Power Amplifier With an Autotransformer-Based Parallel Combining Transformer

Ahn, Hyunjin,Baek, Seungjun,Nam, Ilku,An, Deokgi,Lee, Jae Kyung,Jeong, Minsu,Kim, Bo-Eun,Choi, Jaehyouk,Lee, Ockgoo THE INSTITUTE OF ELECTRICAL ENGINEERS 2017 IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS Vol.27 No.9

<P>This letter presents a fully integrated dual-mode power amplifier (PA) with an autotransformer-based parallel combining transformer (ABPCT), fabricated with a standard 40-nm CMOS process. In comparison with a parallel combining transformer, the proposed ABPCT can offer high-efficiency performance in both high-power (HP) and low-power (LP) modes, and does so with a compact die area. With an 802.11g signal (64-QAM 54 Mbps) of 20-MHz channel bandwidth, the fully integrated dual-mode PA achieves 19.7 and 15.7 dBm average output powers with PAEs of 17.1% and 13%, in HP and LP modes, respectively, while satisfying a -25 dB error vector magnitude and spectral mask requirements. Operating the PA in the LP mode can save more than 40% of the current consumption at a 10-dBm average output power when compared with that in the HP mode.</P>

Unet-VGG16 모델을 활용한 순환골재 마이크로-CT 미세구조의 천연골재 분할

홍성욱,문덕기,김세윤,한동석,Sung-Wook Hong,Deokgi Mun,Se-Yun Kim,Tong-Seok Han 한국전산구조공학회 2024 한국전산구조공학회논문집 Vol.37 No.2

Segmentation of material phases through image analysis is essential for analyzing the microstructure of materials. Micro-CT images exhibit variations in grayscale values depending on the phases constituting the material. Phase segmentation is generally achieved by comparing the grayscale values in the images. In the case of waste concrete used as a recycled aggregate, it is challenging to distinguish between hydrated cement paste and natural aggregates, as these components exhibit similar grayscale values in micro-CT images. In this study, we propose a method for automatically separating the aggregates in concrete, in micro-CT images. Utilizing the Unet-VGG16 deep-learning network, we introduce a technique for segmenting the 2D aggregate images and stacking them to obtain 3D aggregate images. Image filtering is employed to separate aggregate particles from the selected 3D aggregate images. The performance of aggregate segmentation is validated through accuracy, precision, recall, and F1-score assessments.

멀티스케일 기법을 활용한 혼입 시멘트풀의 인장강도 평가

김세윤(Kim, Se-Yun),음동휘(Eum, Donghwi),문덕기(Mun, Deokgi),한동석(Han, Tong-Seok) 대한토목학회 2023 대한토목학회 학술대회 Vol.2023 No.10