Browsing by Author "Wu, Wen-Hsuan"

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The Effects of Mobile Natural-science Learning Based on the 5E Learning Cycle: A Case Study
(2009-10-01)
Liu, Tzu-Chien
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Peng, Hsinyi
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Wu, Wen-Hsuan
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Lin, Ming-Sheng
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教育研究所
This study has three major purposes, including designing mobile natural-science learning activities that rest on the 5E Learning Cycle, examining the effects of these learning activities on students' performances of learning aquatic plants, and exploring students' perceptions toward these learning activities. A case-study method is utilized and the science club with 46 fourth-grade students is selected as the study case in the study. Besides, a set of quantitative and qualitative data were collected from the case to document the learning effects of and the students' perceptions of the learning activities, and to discuss factors underlying these effects and students' perceptions. The results indicate that the learning activities can enhance students' scientific performances, including both knowledge and understanding levels. Students' perceptions of these learning activities appear to be positive. The study identifies two factors that are prominent in the positive effects: students' engaging in "mobile-technology supported" observation during their scientific inquiry; and students' engaging in "mobile-technology supported" manipulation during their scientific inquiry. Finally, the conclusions that our study has drawn could constitute a useful guide for educational practitioners concerned with the potentials of mobile computing in school settings.
The Study of High Breakdown Voltage Vertical GaN-on-GaNp-i-nDiode with Modified Mesa Structure
(2020-08-01)
Ho, Wen-Chieh
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Liu, Yao-Hsing
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Wu, Wen-Hsuan
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Huang Chen, Sung-Wen
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Tzou, Jerry
In this paper, we fabricated Gallium Nitride (GaN) verticalp-i-ndiodes grown on free-standing GaN (FS-GaN) substrates. This homogeneous epitaxy led to thicker GaN epi-layers grown on the FS-GaN substrate, but a high crystalline quality was maintained. The vertical GaNp-i-ndiode showed a low specific on-resistance of 0.85 m ohm-cm(2)and high breakdown voltage (BV) of 2.98 kV. The high breakdown voltage can be attributed to the thick GaN epi-layer and corresponds to the mesa structure. Improvement of the device characteristics by the mesa structure was investigated using device simulations. We proved that a deeper mesa depth is able to decrease the electric field at the bottom of the mesa structure. Furthermore, a smaller mesa bevel angle will assist the BV up to 2.98 kV at a 60 degrees bevel angle. Our approach demonstrates structural optimization of GaN verticalp-i-ndiodes is useful to improve the device performance.