• Journal of the Institute of Convergence Signal Processing
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• v.7 no.1
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• pp.38-44
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• 2006

The omnidirectional mobility of a mobile robot may lose significance in motion control, unless the isotropy characteristics of the mechanism is maintained well. This paper investigates the local and global isotropy of an omnidirectional mobile robot with three caster wheels. All possible actuations with different number and combination of rotating and steering joints are considered. First, the kinematic model based on velocity decomposition and the algebraic conditions for the local isotropy are obtained. Second, the geometric conditions for the local isotropy are derived and all isotropic configurations are fully identified. Third, the global isotropy index is examined to determine the optimal parameters in terms of actuation set, characteristic length, and steering link length.

• Computers and Concrete
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• v.1 no.4
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• pp.433-455
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• 2004

The paper presents results of FE-calculations on shear localizations in quasi-brittle materials during both an uniaxial plane strain compression and uniaxial plane strain extension. An elasto-plastic model with a linear Drucker-Prager type criterion using isotropic hardening and softening and non-associated flow rule was used. A non-local extension was applied in a softening regime to capture realistically shear localization and to obtain a well-posed boundary value problem. A characteristic length was incorporated via a weighting function. Attention was focused on the effect of mesh size, mesh alignment, non-local parameter and imperfections on the thickness and inclination of shear localization. Different methods to calculate plastic strain rates were carefully discussed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.11a
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• pp.101-105
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• 2002

FRP(Fiber glass reinforced plastics) is compound with materials, which are created to combine each other materials, of which nature of mechanical and chemical are different. Even though the weight and the thickness are identic, its physical figure of characteristic changes with consisting of lay-up and work situation. It is also a method of creating after manufacturing of mould. It has feature that manufacturing of FRP runs parallel design of material with design of structure simultaneously. The rule of FRP structure is distinguished from the length of a ship and it is hard to catch the feature of structure mechanics due to identical formula and figure used for it regardless of the shape of a ship or the speed. This studying, basing on a small FRP ship, will show te fundamental data needed to design of structure analysing the feature of intensity with direction, the method of Lay-up, and the characteristic of materials of FRP.