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고온 진동 센서용 BiFeO3-BaTiO3 압전세라믹의 나노 BaTiO3 모분말 도입에 따른 화학적 불균일성 및 압전 특성 연구
박규현,이경자,이민구 한국소음진동공학회 2022 한국소음진동공학회 논문집 Vol.32 No.6
1mol% MnO2-doped 0.7BiFeO3-0.3BaTiO3 (BFO-BTO) piezoceramics were synthesized through a conventional solid-state method, using nano-sized BaTiO3 raw powders. In the application of the nano-BaTiO3 raw powders, the phase structure, chemical heterogeneity, microstructure, ferroelectric, and piezoelectric properties significantly changed, compared to the application of conventional micron-sized BaCO3 and TiO2 raw powders. The sintered BFO-BTO piezoceramics showed a reduced chemical heterogeneity and strong ferroelectric nature, whereas the counterparts using the conventional micron-sized raw powders typically exhibited a core-shell structure with a high degree of chemical heterogeneity, causing a relaxor characteristic. In addition, the piezoceramics sintered using the nano-sized BaTiO3 exhibited greater piezoelectric, ferroelectric and insulating properties, compared to those of ceramics sintered using the conventional micron-sized raw powders. The property enhancements of the BFO-BTO piezoceramics were attributed to the effects of reduced chemical heterogeneity, large grain size, low leakage current and the formation of appropriate morphotropic phase boundary. Finally, the achieved high TC of 519.1°C and excellent thermal aging resistance of d33 up to 480°C indicate great potential for use in high-temperature environments.
피에르 레비의 ‘집단지성’ 개념을 중심으로 본 디지털 시대의 신학적 전망
박규현 한국프랑스학회 2009 한국프랑스학논집 Vol.68 No.-
Dans notre étude, nous avons essayé d'étudier une sorte de perspective théologique de Pierre Lévy. Avec la notion d'intelligence collective, il veut examiner dans le temps digital une perspective anthropologique et théologique. D'abord, Lévy porte une vision positive sur la communication qui se produit dans le labyrinthe d'un cyberspace en devenir. La forme et le contenu du cyberspace sont encore indéterminés et ils se rapportent à la communication des individus. Lévy pense que cette nouvelle dimension de la communication devrait nous permettre de mutualiser nos connaissances et de nous les signaler réciproquement. C'est là qu'il définit la notion d'intelligence collective. Elle se caractérise par une intelligence partout distribuée, sans cesse valorisée, coordonnée et mobilisée en temps réel. Les individus qui l'animent sont à la fois singuliers, multiples, nomades. Lévy propose de concevoir l'ouverture d'espaces où pourront se déployer l'intelligence et l'imagination collective. Pour mettre en perspective son propos, il part de certaines conceptions théologiques médiévales sur l'intelligence collective. Par exemple, la théologie d'inspiration fârâbienne s'intéresse moins aux pouvoirs ou à la puissance de Dieu qu'à son énigmatique manière de penser, à sa contemplation éternelle de soi. Par analogie, cette théologie aura quelque chose à nous apprendre sur l'intellectuel collectif et la façon dont il se pense en pensant son monde. Limplication réciproque du monde et de la pensée est un thème essentiel pour la notion d'intelligence collective chez Pierre Lévy. Il conserve le shéma fârâbien, mais en inversant ses principaux termes. La divinité éternelle de la spéculation théologique se métamorphose en possibilité souhaitable à l'horizon du devenir humain. Ainsi, le monde angélique ou céleste devient la région des mondes virtuels par lesquels des êtres se constituent en intellectuels collectifs. Finalement, Lévy imagine le retour de ‘l'arbre mystique’ qui était à la fois vie et connaissance en affirmant que tout le savoir dans l'humanité où se produit l'intelligence collective.
박규현 한국디자인문화학회 1999 한국디자인문화학회지 Vol.5 No.2
Maker`s usual concern for textile machine has consisted not in it`s external cover design but in it`s engineering and technical development, without any added value from the cover design. But I think the concern with the external cover design of the textile machines has grown in recent years. Korean makers, getting out of underdeveloped state of enterprise management, are now trying to create a new design for the textile machines. But it is a serious problem that minor enterprises have no designers in their system because they cannot hire some talented designers owing to the high wages. The title "a Study on the Development of Warping Machine Design" is about it`s external cover design which was outsourced to me from one of the small enterprises in Sungseu factory town of Taegu city. In it`s research and development I compared the present condition of textile machines most Korean small enterprises produce with most advanced countries`s. But it was very hard to find some good precedents about the cover design of warping machine in Korea except the precedent of Yunghung Machine Co., Ltd, which is located in Sungseu factory town of Taegu city. This paper is a result of the research and development Yunghung Machine Co., Ltd outsourced to me.
TMS320F240을 이용한 PWM 인버터 유도전동기 구동 시스템의 전도노이즈 저감을 위한 스위칭 기법
朴奎炫,金利勳,元忠淵,金奎植,崔世琓,咸年根 성균관대학교 2003 학술회의지원논문목록집 Vol.2003 No.-
PWM 인버터에 의해 구동되는 유도전동기에 발생되는 고주파 커먼 모드 전압은 전도성 EMI, 전동기 접지전류, 베어링 전류 및 다른 원치 않는 결과의 주원인이 된다. 인버터 제어의 무효벡터 스위칭 상태는 나머지 유효벡터 스위칭 상태에 비교하여 큰 커먼 모드 전압을 일으킨다. 그러므로 이 논문은 커먼 모드 전압을 완화하는 스위칭기법을 다룬다. 즉 정현파 PWM기법을 기본으로 한 커먼 모드 전압 제거방법을 제안하였다. PWM 신호는 각각의 정현파 기준신호와 120˚위상차가 나는 3개의 캐리어 파형과 비교하여 발생된다. 시뮬레이션과 실험적결과는 제안된 PWM 기법에서 커먼 모드 전압이 종래의 PWM 기법보다 약 66% 더 저감됨을 보였다. High frequency common mode voltage produced by PWM inverter fed induction motor is a major cause of conducted EMI. creation motor ground currents, bearing currents and other hamful products. The zero switching states of inverter control invoke large in comparison with the non-zero switching state of inverter control. We proposed a common mode voltage reduction method based on sinusoidal PWM technique. PWM signal are generated by comparing respective sinusoidal reference signal with three triangular carrier wave displaced of 120˚. Simulation and experimental result show that common mode voltages in the propsed PWM technique are reduced by approximate 66% more than conventional PWM technique.