• Journal of The Korean Association of Information Education
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• v.17 no.4
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• pp.409-419
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• 2013

The aims of this paper were to review the usable possibility of the educational App Inventor Program in the field of programming education and to develop programming teaching materials that can overcome limitations of the established programming instruction. The study showed that the learners' motivations were strengthened through smart device programs. Containing the elements of STEAM, the teaching materials were developed for the logical and systematic learning that deals with elementary students' real-life situations, and that helps children follow the procedures of software development. By introducing the Waterfall Model to the process of programming, students are able to follow the software developers' thinking process. In addition, beyond the simplistic programming language and simply acquiring related knowledge, the App Inventor programming was designed to enhance students' higher-order thinking skills such as creativity, problem solving ability, collaborative thinking, and so forth.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.40-49
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• 2006

A novel disturbance measurement method, model based disturbance observer (MBDO) for optical disk drives (ODDs), is proposed and the disturbance analysis using the proposed method is performed under various conditions. In ODDs, the quantitative and qualitative analysis for the generated disturbance during normal operation is very important to successful servo loop design. However, the disturbance measurement is difficult, and high precision measurement is necessary. Furthermore, the conventional disturbance measurement method using a LDV (laser Doppler vibrometer) has many difficulties in eccentricity direction due to the vertical movement of an optical disk. To solve this problem, the MBDO is proposed. First, the relationship between the servo loop for ODDs and the generated disturbance are briefly reviewed. Second, the principle of the MBDO is introduced, and the disturbance measurement results, which are measured by the MBDO and a LDV, are compared. In these experiments, test DVD-ROM disks are used to generate quantitative/qualitative disturbance. Then, the disturbance analysis under various conditions is performed using waterfall technique. This technique clearly shows the disturbance trend from the inner part of an optical disk to the outer part of it. Finally, the various disturbances measurement results are summarized and some remarks for it are commented.