1. International Shipping and Logistics Group, Univ. of Plymouth Business School, Drake Circus, Plymouth PL4 8AA, U.K.
2. Professor, International Shipping and Logistics Group, Univ. of Plymouth Business School, Drake Circus, Plymouth PL4 8AA, U.K. (corresponding author).
3. Dept. of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Bukgu, Gwang-Ju 500-712, Republic of Korea.