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In this study, non-stoichiometric composition of lead-free (K<inf>0.5</inf>Na<inf>0.5</inf>)<inf>0.97</inf>(Nb<inf>0.96</inf>Sb<inf>0.04</inf>)O<inf>3</inf> ceramics were fabricated. And then, their dielectric and piezoelectric properties were investigated according to the CeO<inf>2</inf> addition. In this ceramic composition, CeO<inf>2</inf> addition… (More)
Power of piezoelectric transformer was also limited for higher power application, therefore structures with multilayer and various shapes were researched to increase the output power and decrease heat distribution, but existing problems such as complicated manufacturing process and mechanical durability.
— The purpose of this study is to determine the appropriate network system for using the Digital Textbook in a u-Learning environment. South Korea has invested a substantial amount of capital in the Digital Textbook project. However, its network system is not sufficient to support the u-Learning network system. To ensure the success of the Digital Textbook… (More)