He has worked as a researcher at the Academy of Korean Studies and received his PhD from the Academy for his thesis, The Research on the History of Foreign Relations in the Late Goguryeo Period. He is interested in international exchanges among countries in East Asia and North Asia during ancient times. He co-authored The Dictionary of Balhae Relics in China, and his publications include Balhae-Tang Relations in the Later Period of King Go's Reign and the Change of the National Name, Yeoseok Lee Ki-Baik's Scholarship and Understanding of Korean History, and Silla Monument Goseokjeong Pavilion and Silla’s Territorial Expansion to Cheolwon.