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조형래,홍금식 釜山大學校生産技術硏究所 1996 生産技術硏究所論文集 Vol.51 No.-
본 논문은 병렬형 매니퓰에이터의 구동부에 입력되는 힘과 상판으로 출력되는 힘과 모우멘트의 전달특성을 연구하였다. 이러한 전달특성을 연구하기 위하여 상관좌표계의 원점을 기준으로한 힘과 모우멘트 벡터로 구성되는 행렬을 힘과 모우멘트의 2부분으로 분리한 후 특이값 분해를 통하여 힘 및 모우멘트의 조종성능, 민감도, 방향성 등을 해석하였다. 이렇게 해석된 결과들은 병렬형 매니퓰레이터의 설계변수의 한 지침으로 사용되어질 수 있다. This paper presents how the input forces through the prismatic joints of the Stewart platform manipulator are transmitted to the upper plate. The matrix containing unit vectors along the legs and moment vectors about the origin of platform based on the plucker coordinate system is splitted into two parts to consider the force and moment transmissions, respectively. Manipulability and sensitivity were investigated in accordance with the changes of radius of platform and angle between legs. Acquired results could be useful in-determining design parameters like radius of platform, angle between joints in the base and platform, etc.
Hong, Keum Shik,Kim, Y. M.,Choi, J. T.,Shin, K. T.,Yeom, Y. I. 대한기계학회 1996 International Sessions in Celebration of the 50th Vol.1 No.1
An inverse kinematics problem of a reclaimer which excavates and 'transports raw materials in the raw yard is investigated. Two approaches are investigated in obtaining the inverse kinematics solution. The first method pre-assigns the 1eight of excavation point which is determined through path planning. A closed form solution is obtained for the first approach. The second method exploits the orthogonality between the normal vector at an excavation point and the rotational axis of rotating drum. The geometry near the reclaiming point has been approximated as a plane, and the plane equation has been obtained by the least square method considering 8 adjacent points near the point. A closed form solution is not found for the second approach, however a linear approximate solution is provided.
Vortex-induced vibrations and control of marine risers: A review
Hong, Keum-Shik,Shah, Umer Hameed Elsevier 2018 Ocean engineering Vol.152 No.-
<P><B>Abstract</B></P> <P>This paper reviews the dynamics and vibration control techniques for marine riser systems. The riser pipes are modeled as Euler-Bernoulli beams that vibrate under the effects of ocean loads and the movements of the surface vessel, resulting in hybrid ODE-PDE equations. Chronological development of such hybrid models is first discussed, and their approximated ODE models for simulation are examined. Theoretical and experimental techniques for instability and fatigue analyses on the riser systems are also summarized. To increase the fatigue life against ocean currents, passive vibration suppression devices (e.g., strakes and spoilers) were mounted on the surface of the riser. Whereas to tackle the instability problem caused by sea waves, active control techniques utilizing the movements of the vessel were employed. In Conclusions, as future riser technologies, seven research issues are identified.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A review on the dynamics and vortex-induced vibration control methods of marine riser systems. </LI> <LI> The focuses are on mathematical formulations, analyses, and controls (both active and passive methods) of marine risers. </LI> <LI> Identification of future research topics in the area of dynamics and vibration control of marine riser systems. </LI> </UL> </P>