1. Department of Logistics Research, Division for Logistics Technology and Market Analysis, Korea Transport Institute, 315 Goyangdaero, Ilsanseo-Gu, Goyang City, Gyeonggi-Do 411–701, South Korea.
2. Department of Civil and Environmental Engineering, Seoul National University, 1 Gwanak-Ro, Gwanak-Gu, Seoul, South Korea, 151–744.