1. Research Associate, Dept. of Civil Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; formerly, Graduate Student, Dept. of Civil, Environmental and Geo-Engineering, Asphalt Pavement Research Group, Univ. of Minnesota, Twin Cities, Minneapolis, MN 55455.
2. Senior Researcher, Korea Expressway Corporation, Corporate Strategy and Policy Research Division, Gimcheon 740-220, South Korea; Senior Researcher, Korea Expressway Corporation, Pavement Research Division, Hwaseong 455-812, South Korea; formerly, Graduate Student, Dept. of Civil, Environmental and Geo-Engineering, Asphalt Pavement Research Group, Univ. of Minnesota, Twin Cities, Minneapolis, MN 55455 (corresponding author).