1. Department of Materials Science & Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744, Republic of Korea
2. Marine Energy Convergence & Integration Laboratory, JGRC of Korea Institute of Energy Research, Gimnyeong-ri, Gujwa-eup, Jeju-si, Jeju-do 695-971, Republic of Korea
3. Department
of Mechanical Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyunggi-do 440-746, Republic of Korea