• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3873-3879
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• 2010

Home service robot are not working in the fixed task such as industrial robot, because they are together with human in the same indoor space, but have to do in much more flexible and various environments. Most of them are developed on the base of the wheel-base mobile robot in the same method as a vehicle robot for factory automation. In these days, for holonomic system characteristics, omni-directional wheels are used in the mobile robot. A holonomicrobot, using omni-directional wheels, is capable of driving in any direction. But trajectory control for omni-directional mobile robot is not easy. Especially, azimuth control which sensor uncertainty problem is included is much more difficult. This paper develops trajectory controller of 3-wheels omni-directional mobile robot using fuzzy azimuth estimator. A trajectory controller for an omni-directional mobile robot, which each motor is controlled by an individual PID law to follow the speed command from inverse kinematics, needs a precise sensing data of its azimuth and exact estimation of reference azimuth value. It has imprecision and uncertainty inherent to perception sensors for azimuth. In this paper, they are solved by using fuzzy logic inference which can be used straightforward to perform the control of the mobile robot by means of the fuzzy behavior-based scheme already existent in literature. Finally, the good performance of the developed mobile robot is confirmed through live tests of path control task.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.149-157
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• 2009

The purpose of this project was to determine biomechanical differences between Type A(Korean brand) and Type B(world top brand) badminton shoes and to make recommendations to improve the fit and function of Type A badminton shoes. Measurements of shoe shape and dimensions, foot movement within the shoe, cushioning of ground reaction forces, in-shoe pressure and outsole traction were performed. In addition, subjective feedback of the fit and function of the shoes was quantified for 17 recreational badminton players. Type A shoe had a much higher heel and shallower heel cup, so the heel was not secured well in the shoe and the ankle joint was higher off the ground. Foot slippage was up to 40% greater in Type A shoe than Type B shoe. Impact forces and peak pressures under the foot were generally higher with Type A shoe compared to Type B shoe. The flexion axis of Type A shoe occurred in the midfoot, not at the ball of the foot like Type B shoe, where you would want the shoe flexion to occur. In summary, there are several characteristics where A Type shoe and B Type differ. Therefore, a few recommendations are provided to help improve the fit and function of A Type shoe.

• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.51-62
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• 2016

Parametric studies for various site conditions by using 3d numerical model were carried out in order to estimate dynamic behavior of soil-pile-structure system in dry soil deposits. Proposed model was analyzed in time domain using FLAC3D which is commercial finite difference code to properly simulate nonlinear response of soil under strong earthquake. Mohr-Coulomb criterion was adopted as soil constitutive model. Soil nonlinearity was considered by adopting the hysteretic damping model, and an interface model which can simulate separation and slip between soil and pile was adopted. Simplified continuum modeling was used as boundary condition to reduce analysis time. Also, initial shear modulus and yield depth were appropriately determined for accurate simulation of system's nonlinear behavior. Parametric study was performed by varying weight of superstructure, pile length, pile head fixity, soil relative density with proposed numerical model. From the results of parametric study, it is identified that inertial force induced by superstructure is dominant on dynamic behavior of soil-pile-structure system and effect of kinematic force induced by soil movement was relatively small. Difference in dynamic behavior according to the pile length and pile head fixity was also numerically investigated.