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수열처리에 의한 세리아가 코팅된 실리카 연마재의 제조 및 Oxide Film의 연마특성
유대선,김대성,이승호,Ryu Dae Sun,Kim Dae Sung,Lee Seung-Ho 한국재료학회 2005 한국재료학회지 Vol.15 No.12
Sub-micron colloidal silica particles coated with nano-sized ceria were prepared by mixing of its silica and cerium salts hydrolysis, and modified by hydrothermal reaction. By using the slurries with and without hydrothermal modification containing above particles, oxide film coated on silicon wafer was polished. The modified slurries had higher polish rate due to increase of ceria fraction to silica through hydrothermal reaction. They revealed higher stability in wide range of pH $2\~10$ than ceria coated silica slurries without its modification.
전력기기 특성 및 가동 지연 불편도를 고려한 실시간 급작 수요 협상 프레임웍 기반 스마트 그리드 시스템
유대선(Daesun Yoo),이현수(Hyunsoo Lee) 대한전기학회 2019 전기학회논문지 Vol.68 No.3
The considerations of the electrical device’ characteristics and the customers’ satisfaction have been important criteria for efficient smart grid systems. In general, an electrical device is classified into a non-interruptible device or an interruptible device. The consideration of the type is an essential information for the efficient smart grid scheduling. In addition, customers’ scheduling preferences or satisfactions have to be considered simultaneously. However, the existing research studies failed to consider both criteria. This paper proposes a new and efficient smart grid scheduling framework considering both criteria. The framework consists of two modules – 1) A day-head smart grid scheduling algorithm and 2) Real-time sudden demand negotiation framework. The first method generates the smart grid schedule efficiently using an embedded genetic algorithm with the consideration of the device’s characteristics. Then, in case of sudden electrical demands, the second method generates the more efficient real-time smart grid schedules considering both criteria. In order to show the effectiveness of the proposed framework, comparisons with the existing relevant research studies are provided under various electricity demand scenarios.
고령토로부터 알루미나 추출에 관한 연구(Ⅱ) : 질산에 의한 추출
유대선,이희수,김정한 연세대학교 산업기술연구소 1990 논문집 Vol.22 No.2
The preparation conditions of alumina powder extracted from domestic San-Cheong Kaolin by nitric acid were investigated. The experimental conditions which have an effect on the yield of alumina were as follows ; the calcination temperature and time, the acid concentration, the reaction temperature and time, pH of the extracted solution, and particle size of the raw material. The aggolomeration of pseudo-boehmite precipitated by NH₄OH at pH 8 was controlled by various drying methods. α-Al₂O₃powder prepared by heating of the dried powder for 1 hour at 1200℃. Under the optimum condition, the yield and purity of α-Al₂O₃powder were 73.6 percent and 95.5 percent, respectively. The alumina particles prepared by the freeze drying method revealed narrower size distribution and less agglomerate than others. And impurities of the raw material which have an effect on the extraction of alumina were Kyanite and Anorthite.
고령토로부터 알루미나 추출에 관한 연구(Ⅰ) : 황산에 의한 추출
유대선,윤종석,이희수 연세대학교 산업기술연구소 1990 논문집 Vol.22 No.1
The preparation conditions of alumina powder extracted by sulfuric acid were investigated. The raw material was domestic San-Cheong Kaolin. The experimental conditions which have an effect on the yield of alumina were varied as follows; the calcination temperature and time, the reaction temperature and time, and the acid concentration. The agglomeration of aluminum hydroxides precipitated by ammonia water was controlled by various drying methods. And the dried power was heated to obtain α-Al₂O₃for 1 hour at 1200℃. The yield of alumina was up to 58 percent under the optimum condition and its purity was 96.4 percent. The alumina particles prepared by the freeze drying method revealed narrower size distribution and less agglomerate than others.