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끝단질량을 갖고 아접선력을 받는 외팔 수직기둥의 동적 안정성
박영필,류봉조,이규섭,김인성,Park, Young-Pil,Ryu, Bong-Jo,Lee, Gyu-Seop,Kim, In-Sung 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.2
The dynamic behavior of elastic columns under the action of the subtangential force is studied in this paper. The subtangential force is the combination of the tip mass dead load and pure follower thrust. In this study, the tip mass is assumed to be a rigid body rather than a point mass. The equations of motion are derived based on the extended Hamilton's principle and the finite element method. Then the equations of motion are trasformed into a dimensionless form, and several parameters are identified. It is found that the critical subtangential force can be changed subtangentially by considering the parameters related to tip mass. It is also shown that the nonconservativeness of the applied force has a significant effect on the type of instability. The influence of the self-weight of the column on the variation of the critical force is also investigated.
Design of Moving Magnet Type Optical Pickup Actuator with High Frequencies of the Flexible Modes
송명규(Song, Myeong-Gyu),김윤기(Kim, Yoon-Ki),박영필(Park, Young-Pil),유정훈(Yoo, Jeong-Hoon),박노철(Park, No-Cheol) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.11
Data transfer rate and storage capacity are main criteria of the performance of the optical disk drive. The highest data transfer rate and the largest storage capacity is most desirable. To increase these performances, the actuator of the optical disk drive should have a high servo bandwidth to compensate the vibration of an optical disk. The servo bandwidth is limited by some flexible modes of the actuator, thus it is essential to increase the natural frequencies of the flexible modes. In this paper, we suggested a moving magnet type actuator having high frequencies of the flexible modes. Generally, the moving magnet type actuator has an advantage to increase the natural frequencies of the flexible modes because the moving magnet type actuator has simple structure and the Young's modulus of magnet is high. However, large moving mass and inefficiency of EM(electromagnetic) circuit cut down driving sensitivities of the actuator. To improve driving sensitivities, we designed the model with the closed electromagnetic circuit for tracking direction. In addition, driving sensitivities and the natural frequencies of the flexible modes were improved by using DOE(design of experiments) for electromagnetic circuit and modifying the lens holder.