1. Electrical and Electronic Engineering Program, Faculty of Engineering, University of Miyazak, 1-1 Gakuen-kibanadai-nishi, Miyazaki 889-2192, Japan
2. Institute for Tenure Track Promotion, University of Miyazaki, 1-1 Gakuen-kibanadai-nishi, Miyazaki 889-2192, Japan
3. Research Center for Sustainable Energy & Environmental Engineering, University of Miyazaki, 1-1 Gakuen-kibanadai-nishi, Miyazaki 889-2192, Japan