1. Professor, School of Mechanical Engineering, Chonnam National Univ., 77 Yongbong-ro, Buk-gu, Gwangju 61186, Republic of Korea.
2. Professor, School of Mechanical Engineering, Hanyang Univ., 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea (corresponding author).