1. Professor, Dept. of Economics, College of Business, Hallym Univ., 39 Hallymdeahak-gil, Chuncheon-si, Gangwon-do 24252, Korea.
2. Professor, Dept. of Economics, College of Economics, Sungkyunkwan Univ., 25-2, Sungkyunkwan-ro, Jongno-gu, Seoul 03063, Korea (corresponding author).