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인터넷과 전자상거래(Electronic Commerce)
이재규,Lee, Jae-Gyu 한국정보통신집흥협회 1996 정보화사회 Vol.108 No.-
전자상거래의 기원은 미국의 Lawrence Libermore National Laboratory가 미국 국방부의 프로젝트를 수행하면서 처음으로 사용한 용어인데, 거래가 시작되면서부터 끝날 때까지 서류가 사용되지 않는 기업환경을 정보기술에 의해 달성하려는데 그 목적이 있었다.
이재규,김옥현,Lee, Jae-Gyu,Kim, Ock-Hyun 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.8
This paper presents a new type of hydraulic servo chllinder which is characterized by its simple construction and an ubtegrated feedback mechanism. Piston position of the cylinder is controlled by eletrical input and mechamical feedback deduced from its own structure. Hydraulic pressure in each cylinder room is controlled by a poppet valve. The poppet is activated by a solenoid and is linked to the piston. Solenoid input current pulls up the poppet, which results in pressure drop and thus piston motion. The piston motion generates pull down force on the poppet by the linkage and the motion stops at equilibrium. In that way the piston position is controlled by an expernal input current. Characteristics of the servo cylinder is verified by stability analysis, tranient vehavior and steady state positing for step input. Design parameter analyses have been executed by derivation of analytical approximate solutions and by computer simulations. A prototype hydraulic servo cylinder is developed and tested. The experimental results show successful function of the servo cylinder and consistency with the theoritical results.