1. School of Mechanical Engineering, Yeungnam University, 214-1 Dae-dong, Kyungsan, Korea 712-749
2. School of Electrical Engineering, Yeungnam University, 214-1 Dae-dong, Kyungsan, Korea 712-749
3. Department of Economics and Finance, Yeungnam University, 214-1 Dae-dong, Kyungsan, Korea 712-749
4. Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon, Korea 305-343