• 제목/요약/키워드: slow phase

검색결과 372건 처리시간 0.023초

염화지르코늄(IV)으로부터 질화지르코늄 미분체의 합성에 관한 연구 (A Study on the Synthesis of Fine Zirconium Nitride Powder from Zirconium Chloride(IV))

  • 김영우;장윤식;박홍채;오기동
    • 한국세라믹학회지
    • /
    • 제25권2호
    • /
    • pp.184-190
    • /
    • 1988
  • ZrN powder was prepared from the powder mixture of ZrCl4 and Al by the halogenide process in nitrogen gas flow (100-150ml/min) at the temperatures from 200$^{\circ}$to 1050$^{\circ}C$. ZrN powder was formed about 600$^{\circ}C$ and in the slow nitriding reaction, however, an intermediate product of Al3Zr was formed. The fine powder (0.1-10$\mu\textrm{m}$) of single phase ZrN was obtained at 1050$^{\circ}C$ after 1 hour. The lattice parameter and crystallite size of ZrN were 4.5787A and 360A, respectively. According to SEM observation, the particles were apt to agglomerates. The apparent activation energy for the formation of ZrN was approximately 13.2kcal/mole(750$^{\circ}$-1000$^{\circ}C$).

  • PDF

일본의 ICT 국가연구개발 예산의 배분체계 고찰 (Investigation of the Japanese ICT R&D budget distribution system)

  • 김방룡
    • 한국정보통신학회:학술대회논문집
    • /
    • 한국정보통신학회 2016년도 춘계학술대회
    • /
    • pp.625-626
    • /
    • 2016
  • 일본은 과거 수십 년간 구조적 저성장을 경험하고 있으며, 한국도 최근 들어 이와 유사한 상황에 접어들고 있다. 일본 정부는 국가 연구개발 혁신정책을 통하여 저성장 경제를 극복하기 위한 노력을 기울이고 있다. 본고는 일본의 국가 연구개발 혁신정책과 이를 수행하기 위한 국가 연구개발 예산의 편성체계의 변화를 조사 분석함으로써 한국의 상황에 적용할 수 있는 정책적 시사점을 도출하는 것을 목적으로 한다.

  • PDF

저분해능 위치센서를 갖는 표면부착형 영구자석 동기전동기의 전류센서 없는 단위 전류 당 최대 토크 제어 (Current-Sensorless Maximum Torque per Ampere Control for a Surface Mounted Permanent Magnet Synchronous Motor with Low-Resolution Position Sensor)

  • 이광운
    • 전력전자학회논문지
    • /
    • 제14권3호
    • /
    • pp.204-210
    • /
    • 2009
  • 본 논문에서는 저분해능 위치센서를 갖는 표면부착형 영구자석 동기전동기의 새로운 전류센서 없는 단위 전류당 최대 토크 제어를 제안한다. 영구자석 동기전동기의 수학적 모델로부터 d축 전류를 추정하고, 추정된 d축 전류가 영(零)이 되도록 d축과 q축 전압지령 사이의 위상 각을 제어하여 단위 전류 당 최대 토크 제어를 구현한다. 제안된 방식은 동적 응답 특성이 느린 저가 응용 분야에 적합하다.

성장온도를 변화시킨 $YBa_2Cu_3Ox$ 단결정의 자기적 특성 (Magnetic Characterization of $YBa_2Cu_3Ox$ Single Crystal with a Variation of Growth Temperature)

  • 한영희;성태현;한상철;이준성;김상준
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 1999년도 춘계학술대회 논문집
    • /
    • pp.251-254
    • /
    • 1999
  • A new multi-seeding process for the growth of YBa$_2$Cu$_3$Oxx single crystals was developed. This process introduces an additional heating step to peritectic temperature and a subsequent slow cooling step to the growth temperature following the point when the crystals contacted. The crystal growth was resumed thereafter. The results obtained with this new process were compared with those of the conventional growth process, in which materials were only kept at the growth temperature. It was observed that the liquid phase between crystals were almost completely eliminated, but that Y2ll grains were grown during this new process. There was no significant improvement in trapped magnetic field over the conventional process, which is believed to be due to the cracks generated during the oxygen heat treatment or to the growth of YBa$_2$Cu$_3$Ox grains.

  • PDF

진행파형 증폭기를 위한 저속파회로 (Slow Wave Circuits for Traveling-Wave-Type Amplifiers)

  • 김봉열;황금찬
    • 대한전자공학회논문지
    • /
    • 제7권2호
    • /
    • pp.13-20
    • /
    • 1970
  • 진행파형 메이저에 사용할 수 있는 테이프 메안더라인의 지연방정식을 전자계의 쌍대성에 의하여 유도하였다. 프린트동판을 포토칭하여 메안더라인을 제작하였으며, 메안더라인의 공극폭, 테이프폭, 회로폭의 변화에 따른 지연곡선의 변화를 상위브릿지 방법으로 측정하여 이론곡선과 비교고찰하였다.

  • PDF

모바일 BIM 공사관리시스템을 위한 클라우드 컴퓨팅 기술 활용 방안 (Applying the Cloud Computing Technology for Mobile BIM based Project Management Information System)

  • 이종호;엄신조
    • 한국건축시공학회:학술대회논문집
    • /
    • 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
    • /
    • pp.145-148
    • /
    • 2011
  • As a futuristic construction model, building information model(BIM) based project management system(PMIS) and mobile PMIS have been showing visible sign. However, researches on the 3D BIM based PMIS using mobile device are hard to find, result from limitation of mobile device application(slow speed at huge BIM file, display size, and etc.) and undefined standard of business processes. Therefore, this research aims at studying feasibility of mobile BIM PMIS based on cloud computing as a business model. In case of applying mobile BIM PMIS, 3D drawings and integrated building informations are possible on mobile devices in real time. it would support increasing the productivity of project participants as designer, engineer, supervisor, and etc. Globally, BIM based PMIS and Mobile BIM system, cloud computing based mobile BIM simulator are in the concept or experimental phase, therefore it is possible to secure global leading technology of IT and construction merger in the mobile BIM.

  • PDF

칼코게나이드 박막에서의 conductivity 변화에 관한 연구 (The study of conductivity transition on chalcogenide thin films)

  • 양성준;신경;박정일;정홍배
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
    • /
    • pp.112-115
    • /
    • 2003
  • There is a growing need for a nonvolatile memory technology with faster speed than existing nonvolatile memories. $T_c$(crystallization temperature) is confirmed by measuring the conductivity with the varying temperature. The sample is heated on the hotplate and slow down to the room-temperature. We prepared Te based alloy bulk. The materials can be used for nonvolatile random access memory.

  • PDF

플라이 애쉬-석회계 수열반응에 있어서 석고 및 시멘트의 영향 (Effect of Gypsum and Cement on Hydrothermal Reaction in Fly Ash-Lime System)

  • 안민선;박태균;황인수;김병익
    • 한국세라믹학회지
    • /
    • 제35권10호
    • /
    • pp.1030-1039
    • /
    • 1998
  • In fly ash-lime system the effects of reaction condition amounts of gypsum and cement and CaO/SiO2 ratio on the hydrates by hydrothermal reaction were investigated. The tobermorite phases were not observed in hy-drothermal reaction of fly ash lime because of the hydrate rate was very slow. The compressive strength and the hydration rate increased with increasing the amount of gypusm and cement and the optimum amounts of gypsumo and cement were 5wt and 20wt% respectively. The specimen which CaO/SiO2 ratio is 0.85 was shown the maximum compressive strength and the tobermorite phase within reaction time 2 hours.

  • PDF

QAM 복조용 삼중 모드 채널 등화 알고리즘 (Triple-mode Blind Equalization Algorithm for QAM Demodulation)

  • 위정화;황유모
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 1999년도 하계학술대회 논문집 G
    • /
    • pp.3138-3140
    • /
    • 1999
  • We propose a robust blind equalization algorithm based on dual-mode algorithm which incorporates a stop-and-go technique. The constant modulus algorithm(CMA) exhibits very slow convergence when applied to QAM signals and generates phase error. We show that convergence properties of the dual-mode MCMA can be significantly improved by simply adding a stop-and-go technique. To speed up the convergence rate, the TMA-MCMA operates in triple mode that is based on the dual-mode of the MCMA incorporated with the tap-updating control modes of the SGA.

  • PDF

제품수명주기관리(PLM) 기반의 소셜매뉴팩처링 기술 고찰 (Review of Social Manufacturing Technology on Product Life Cycle Management(PLM) Base)

  • 박종만;김봉선
    • 대한산업공학회지
    • /
    • 제39권3호
    • /
    • pp.156-162
    • /
    • 2013
  • Social manufacturing architecture is based on information delivery through social media and SNS, PLM and social platform, crowd source and knowledge base on whole phase of product life cycle. Although advanced social manufacturing issues are rising globally, its technology emerging into domestic industry is likely to be slow. We focused to review technological changes and R&D trend, patent issues, and then suggest assignments and advices to be practiced for social manufacturing modeling.