• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.736-741
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• 1992

The Stewart platform is one example of a motion simulator which generates 6 DOF motion in space by 6 actuators connected in parallel. The present SISO controllers are designed to track displacement command of each actuator computed from reference 6 DOF motion of platform by Stewart platform inverse kinematics. But this type of control can't cope with external load variation, geometric configuration of motion simulator, and different dynamic behavior of 6 DOF motion. In this paper, a multivariable controller using H- optimal control theory is designed for linerized simulator model with each actuator driving force as control input and platform 6 DOF motion as measured output. Nonlinear simulation result of the H$_{\infty}$ MIMO controller is not satisfied in steady-state characteristics. But the proposed H$_{\infty}$ + PI control scheme shows acceptable performance.e.e.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.235-240
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• 2001

A four degrees of freedom (dof) motion platform for bicycle simulator is developed. The motion platform, capable of the vertical linear and three angular motions, is designed based on analysis of the typical motion characteristics revealed by the existing six dof bicycle simulator. The platform essentially consists of two parts： the three dof parallel manipulator, consisting of a moving platform, a fixed base and three actuators, and the turntable to generate the yaw motion. The nonlinear kinematics and dynamics of the three dof parallel manipulator with multiple closed loop chains are analyzed for tracking control of the motion platform. The tracking performances of the three control schemes are experimentally compared： the computed torque method (CTM), the sliding mode control (SMC) and the PD control. The CTM and SMC, incorporated with the system dynamics model, are found to be equally better in performance than the PD controller, irrespective of the presence of external disturbance.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.1
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• pp.28-36
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• 2002

Regarding efficient development of computer graphic animations, lots of techniques for editing or transforming existing motion data have been developed. Basically, the motion transformation techniques follow optimization process. To make the animation be natural, almost all the techniques utilize kinematics and dynamics in constructing constraints for the optimization. Since the kinematic and dynamic structures of virtual characters to be animated are very complex, the most time-consuming part is known to the optimization process. In order to suggest some guide lines to engineers involved in the motion transformation, in this paper, we analyze the computational complexities for typical motion transformation in quantitative manner as well as the possibility for parallel computation.

• The Journal of Korean Physical Therapy
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• v.27 no.5
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• pp.304-310
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• 2015

Purpose: The purpose of this study was to examine the change in the kinematics and kinetics of the knee joint depending on high-heeled shoes during sit-to-stand (SitTS) task. Methods: Nineteen healthy females participated in this study. The subjects performed the SitTS task wearing high-heeled shoes and barefoot. The experiment was repeated three times for each task with foot conditions. The kinematics and kinetics of the knee joint were measured and analyzed using a 3D motion analysis system. Results: The result of this study showed kinematic and kinetics differences in knee joints during the SitTS task based on high-heeled shoes. Significant differences in knee flexion angle were observed during SitTS. The knee extensor force showed statistically significant differences during SitTS tasks. At the initial of SitTS, the knee flexor and extensor moment showed significant differences. The knee extensor moment showed statistically significant differences at the terminal of SitTS. At the maximum of SitTS, the knee extensor moment showed statistically significant differences. Conclusion: Therefore, wearing high-heeled shoes during SitTS movements in daily life is considered to influence knee joint kinematics and kinetics due to the HH, suggesting the possibility of increased risk of patellofemoral pain, and knee osteoarthritis caused by changes in loading of the knee joint.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1473-1474
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• 2008

In the total knee arthroplasty (TKA), kinematic benefic of a mobile-bearing total knee prosthesis is still arguing. Main reasons for implant failure are loosening and polyethylene wear and should be solved with new designs with mob ile bearings. The kinematics of the knee prosthesis also affects the implant failure. Recently, a second generation of p rostheses with a mobile-bearing was developed. The current study aimed to assess the kinematic path of the 2nd generation mobile knee prosthesis compared to the normal knees. Using 3D/2D registration method, CT-derived 3D knee models were fitted to sequential 2D X-ray images during knee flexion. 3D kinematics of the femur and the tibia were analyzed. The 2nd generation mobile-bearing TKA prosthesis (e.motion, Aesculap, Germany) knees showed less external rotation and knee flexion range compared to the normal knee, but the trend of external rotation was similar each other.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.519-523
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• 2011

Today, one of the most important reasons that 3D software becomes a core part of the essential tools in the video contents field like the movies, animation, CF, motion graphic, games and etc. is that they can save budget of contents makings and can produce better effects than conventional methods like miniature, matt painting, extra mobilization and etc. and can save time and have the merit that they are not limited in space. In this paper, I analyzed IK(Inverse kinematics) system characteristics for the efficient education of 3D character animation particularly most used of 3D applications which is now supposed to be nearly necessary elements in game, animation, movie and contents. And by analyzing merits and demerits of each tool on Bone, Character studio and Character Animation Toolkit, systems which are most used practically in the various Inverse kinematics tools, I showed the result of analyses about the fact that educating which of the above three Inverse Kinematics tools is helpful and beneficial for the students for the efficient education in the university where should teach much in the limited time

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.41-49
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• 2007

This study was to investigate the kinematical analysis using ski simulator. Twelve people(six skilled, six unskilled) participated in the experiment. Each phase of motion time was slight differences between the skilled group and the unskilled group but not significant difference in statistics. In displacement of vertical on COG(Center of Gravity), left and right down motion showed significant difference between group. In velocity of horizontal on COG, both left and right down motion showed significant difference between group, and up motion of between down motion showed significant difference. In displacement of angle on ankle, knee, hip joint almost showed significant difference between group. Almost in body position was lower skilled group than unskilled group.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.170-177
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• 1993

In robotic arc welding, the roll (rotation) of the torch about its direction vector does not have any effect on the welding operation. Thus we could use this redundant degree of greedom for the motion control of the robot manipulator. This paper presents an algorithm for the pseudo- inverse kinematic motion control of the 6-axis robot, which utilizes the above mentioned redunancy. The prototype welding operation and the tool path are also graphically simulated. Since the proposed algorithm requires only the position and normal vector of the weldine as an input data, it is useful for the CAD-based off-line programming of the arc welding robot. In addition, it also has the advantages of the redundant manipulator motion control, like singularity avoidance and collision free motion planning, when compared with the other motion control method based on the direct inverse kinematics.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.494-499
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• 2011

This paper presents the biomechanical analysis and evaluation technology of musculoskeletal system by multi-body human dynamic model and 3-D motion capture data. First, medical image based geometric model and material properties of tissue were used to develop the human dynamic model and 3-D motion capture data based motion analysis techniques were develop to quantify the in-vivo joint kinematics, joint moment, joint force, and muscle force. Walking and push-up motion was investigated using the developed model. The present model and technologies would be useful to apply the biomechanical analysis and evaluation of human activities.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.217-222
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• 2017

Any object located in the earth's gravitational field experiences a force in the direction of the center of the earth. In order to describe the motion of objects in the field, the solutions to a system of simultaneous vector kinematic equations need to be obtained. In the analysis of freely-falling objects, the reference direction +y is usually defined to be the downward direction. In the analysis of the motion of objects thrown upward, the reference direction +y is usually defined to be the upward direction. In the analysis of the motion of objects thrown downward, the reference direction +y is usually defined to be the downward direction. In this paper, we show that the choice of reference axis in either upward or direction gives the same results by adopting a scalar product of two vectors in solving the vector kinematic equations. It is rare to find other examples of using a scalar product of two vectors in solving vector kinematic equations describing the motion of objects. An application of this study is that we can arbitrarily choose the reference direction for objects moving in a horizontal direction, including projectile motions.