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대기중 안정한 MAPbI3에서의 Photo Seebeck 효과
김유성,박병남 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.2
With increasing interest in energy harvesting using heat as a next-generation eco-friendly energysource, organic-inorganic perovskite materials have emerged as promising materials for thermoelectricdevices. In particular, the photo-Seebeck effect of halide perovskite materials has attracted attention due totheir wide optical absorption spectrum and large diffusion length, depending on their composition. MAPbI3,a representative organic perovskite component, has been reported to have a Seebeck coefficient of onlyhundreds of μV/K. In this manuscript, we report a photo-Seebeck effect for bulk MAPbI3 perovskite in whichthe magnitude of the Seebeck coefficient significantly increased by 700 μV/K under illumination with a greenlaser diode. An air-stable perovskite pellet was synthesized using the alcohol substitution synthesis method,and both the Seebeck coefficient and the photocurrent increased in air, proving that enhanced Seebeckcoefficient is associated with the formation of excitons in MAPbI3. X-ray diffraction analysis found that theremnant PbI2 led to n-type electronic transport characterized by a negative Seebeck coefficient. Photo-inducedelectron transfer from MAPbI3 to the PbI2-rich phase under illumination led to dedoping of electrons, to forman MAPbI3 pellet. The significant enhancement in the Seebeck coefficient was found to depend on thecomposition of the remnant PbI2, which alters the majority carrier type in the bulk MAPbI3.
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김유성,이준호,김기철 대한건축학회지회연합회 2021 대한건축학회연합논문집 Vol.23 No.2
Most of the domestic apartment are reinforced concrete shear wall structures that high stiffness and low ductility, so most of the damping system that apply slit dampers to lintel beams are applied. The slit damper has a damping effect in a single direction, and the energy dissipation capacity due to flexural deformation is somewhat inferior. In this study, In order to complement the existing slit damper, a slit damper combined with a steel cable was proposed, and the seismic performance was analyzed and damping effect was verified through structural performance experiments. As a result of the incremental loading test, the strength, energy dissipation, and equivalent damping ratio of the cable-slit damper specimen increased compared to the steel cable damper specimens. And specimen applied in the shear-direction showed higher damping performance than specimen applied in the roll-direction, but the roll direction also showed similar damping performance to the shear direction. The proposed lintel-type cable-slit damper has increased ductility compared to the cable damper, and the damping performance increased in the out-of-plane direction compared to the conventional lintel-type slit damper according to the roll direction damping effect of the cable damper.
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Miniatures as Mediatized Futurity, City in the Air 008
김유성 한국영상문화학회 2024 영상문화 Vol.- No.44
The transformative possibilities of the futures were exhibited through the miniatures and their movements in postwar Japan, around the time of Osaka Expo ‘70. In 1969, Komatsu Sakyō, a renowned Japanese Sci-Fi writer, published City in the Air 008 (j. Kūchū toshi 008), a serialized science fiction for children and adolescents, which showcased Komatsu’s imaginative exploration of futures, rooted in events that occurred in Japan and across the world in the late 1960s, tying technological advancements and architectural designs for future cities. Shortly thereafter, this work was adapted into an animated version using marionettes, which was then aired on NHK from 1969 to 1970, just before Expo ‘70. This essay will look into the ways that the miniatures, animated world of City in the Air 008, revealed certain ambivalent feelings about unknown futures, interestingly echoing Komatsu’s thoughts on models (j. mokei) as a historically significant concept, and embodying both positive and apocalyptic elements in the futuristic, technological environment of the late 1960s.
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김유성,노경희 한국외국어대학교 외국어교육연구소 2023 외국어교육연구 Vol.37 No.1
The goal of this study is two-fold. The first is to examine the self-directed learning activities in the elementary English textbooks in terms of cognitive, motivational, and behavioral aspects, and by activity types (learning goals, diagnostic learning, learning resources, self-reflection, supplementary activities, review, self-evaluation) in order to identify some problems, if any. The second is to suggest ways to improve those learning activities in the direction of developing learners' self-directed competence. To achieve this goal, the criteria were developed for the analysis of self-directed learning activities, and the five types of English textbooks for the 5th and 6th grades were analyzed based on the criteria. The results showed that cognitive and behavioral strategies were generally well reflected except for creativity, but motivational strategies, which are the most important factor in self-directed learning, were hardly reflected. The analysis by activity types revealed that learning goals, review, and self-assessment were reflected to some degree, but diagnosis learning, various learning resources, self-reflection, and supplementary activities needed considerable improvement. This study suggests diversification of learning resources and learning methods, detailing of learning activity types, and elaboration of teaching activities to foster learners’ self-directed competence. 본 연구의 목적은 초등영어 교과서의 자기 주도적 학습 활동의 영역별(인지적, 동기적, 행동적 영역) 양상과 활동별(학습 목표, 진단 학습, 학습 자원, 자기반성, 보충활동, 복습, 자기평가) 양상을 분석함으로써 문제점을 파악하고, 나아가 자기 주도적 학습 활동의 개선 방안을 제시하는데 있다. 이를 위해 문헌 연구를 바탕으로 자기 주도적학습 활동의 영역별 분석 기준과 활동별 기준을 설정하였고, 이 기준에 의거하여 초등 5·6학년 영어 교과서 5종을분석하였다. 영역별 분석 결과, 창의성 항목을 제외한 인지적 전략과 행동적 전략은 대체적으로 잘 반영되어 있으나, 자기 주도적 학습에 가장 중요한 요인인 동기적 전략은 거의 반영되어 있지 않았다. 활동별 분석 결과, 학습목표와 복습, 자기 평가는 잘 반영되어 있으나, 진단 학습, 다양한 학습자원, 그리고 자기반성과 보충활동은 보완이 필요함을 확인하였다. 따라서 이를 개선하기 위한 방안으로 학습자원 및 학습방법의 다양화, 학습활동 유형의상세화, 그리고 교수활동의 정교화가 필요함을 주장한다.
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