1. Department of Agricultural Economics, Chonnam National University, Buk-gu, Gwangju 61186, Republic of Korea
2. Department of International Trade, Jeonbuk National University, 567 Baekje-Daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea
3. Division of Applied Social Science and the Food and Agricultural Policy Research Institute, University of Missouri, 130 Mumford Hall Columbia, MO 65211, USA
4. Department of Agricultural Economics, University of Kentucky, Lexington, KY 40546, USA