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특정 병진작업경로에서 최소의 관절힘을 받는 병렬형 매니퓰레이터의 설계
양현익,이종우,허원혁 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.3
Recently, need of the parallel manipulator requiring superior precision is increasing for medical application and precision manufacturing. In this study, we convert a given complex translation trajectory of the moving platform into a set of segments and hence a complex motion of the moving platform an be tractable and easily controled in a very limited workspace. In addition force exerted. to each link is minimized so that the minimized force can be transmitted to the end effector of the moving platform. An user friendly program is developed to design Gough-type 6DOF parallel manupulator based on the proposed method.
노홍준,윤희찬,임헌봉,HyunIk Yang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12
The method proposed in this study is to determine the welding sequence to suppress welding de-formation using the strain directed as boundary (SDB) method. Welded joints are modeled by constructing tack welds and gaps as kinematic constraints in shell models. In addition, the SDB method considering the elastoplastic properties is used to evaluate the effect on the previous welding procedure. The results of the constructed analysis model are compared with the experimental results. The residual strain of each weld is calculated using the verified model, and joint stiffness is determined and compared by considering this together with the relationship between tensile stress and shrinkage strain of the weld. The optimal welding sequence is determined by comparing the stiffness of each welding joint, and this is compared and verified with the experimental results. In addition, it is confirmed that the determined welding sequence reduced the out-of-plane deformation by 2.01 % compared to the original welding sequence. The proposed method thus provides an analytical approach for welding sequence design.
Tae-won Kang,Eung-soo Kim,HyunIk Yang 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.2
This study aims to analyze the effects of dynamic motion and structural response of semi-submersible floating off shore wind turbine structures (FOWTs) in waves generated in hurricane environments. The extreme environment utilizes numerical simulation data of hurricanes and is divided into low-frequency and high-frequency components based on wave-age, and a load case combining wind and wave is applied. As the hurricane progresses, a spectrum divided into swell and wind sea components is generated in the ocean, and the swell component is distributed in the natural frequency range of the structure, increasing the dynamic response. Dynamic analysis compares the cumulative response by fitting the response for each wave component generated by the hurricane through the Gaussian mixture model. In the structural analysis, the hydrodynamic pressure calculated through diffraction analysis is mapped to a finite element model using the quasi-dynamics interaction method, and the von Mises stress per wave component is analyzed. Through this, it is possible to grasp the main factors of the dynamic and structural responses of semi-submersible FOWTs.