• Research in Mathematical Education
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• v.11 no.3
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• pp.209-218
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• 2007

The purpose of this study is to create an interactive tool Geometry Player for geometric explorations. In designing this software, we referred to van Hiele's geometric learning theory of and Duval's cognitive comprehension theory of geometric figures. With Geometry Player, it is easy to construct and manipulate dynamic geometric figures. Teachers can easily present the dynamic process of geometric figures in class, and students can use it as a leaning tool to construct geometric concepts by themselves. It is hoped that Geometry Player can be a useful assistant for teachers and a nice partner for students. A brief introduction to Geometry Player and some application examples are included in this paper.

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.370-373
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• 2004

The rapid proliferation of mobile device such as PDA allows users more ubiquitous access to multimedia information. The user mobility provides users a uniform vision of their preferred working environment independently of their current points of attachment. Supporting the user mobility requires the Player capable of efficiently presenting the multimedia contents. MPEC-4 provides not only the description for coding audio and video (as its predecessors MPEG-1 and MPEG-2), but also for coding images, animations, interactivity and protecting content. With MPEG-4, we present interactive media using multiple objects - audio, video, image, 2D geometry, and text - in a single format. Therefore we propose the MPEC-4 Player for PDA. The proposed MPEG-4 Player for PDA supports mobility, portability and personality.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1626-1629
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• 2003

The study is expressed on the web browser using virtual reality of developer manufacturing process and method or manufactured goods conviction for designer and developer with visualized model. This study purpose of basic feature with VRML file and Java and VRML with AWT to get WC code was presented. The study process is equal to the real thing modeling on using Pro/Engineer and exports on the VRML1.0. The condition converts VRML1.0 to VRML2.0 on the CROSS ROADS. And then Cosmo World is coding and manufacturing simulation is expressed on the Cosmo Player.

• Advances in concrete construction
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• v.15 no.4
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• pp.287-301
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• 2023

Hockey games attracts many fans around the world. This game requires a specific type of ball and a stick for controlling the motion and trace of the ball. This control of motion involves hitting the ball which is a direct intensive dynamic loading. The impact load transferred directly to the hand of the player and in the professional player may cause long term medical problems. Therefore, dynamic motion of the stick should be understood. In the current study, we analyze the dynamic motion of a hockey stick under impact loading from a hockey ball. In doing so, the stick geometry is simplified as a beam structure and quasi-2D relations of displacement is applied along with classical linear elasticity theory for isotropic materials. The governing equations and natural boundary condition are extracted using Hamilton's principle. The final equations in terms of displacement components are solved using Galerkin's numerical method. The results are presented using indentation and contact force values for variations of different parameters.

• Geomechanics and Engineering
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• v.33 no.6
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• pp.529-542
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• 2023

Wave propagation with high transverse deflection could affect the stability of the ball in its trajectory. For low stiffness balls similar to soccer and volleyball balls, the waves are more noticeable in comparison to other balls like ping-pong ball. On the other hand, the soccer balls are under heavy impact loads from shoots and contacting different objects in the field. The maximum recorded speed of a soccer ball after kicking is the 211 km/hr and the average maximum speed is around 112 km/hr. Therefore, in such speeds the aerodynamic forces become important which are directly related to geometrical shape of the ball. In this regard, the wave propagation in soccer ball is examined in the current study using large deformation shear deformable formulations. Classical relations of stress-strain components are taken into consideration along with minimum total energy principle. The final derived relations were solved by using harmonic differential quadrature method. The results are generally presented ion term of phase velocity as function of different influencing parameters of the materials, geometry and mass of the ball.