He has previously served as Chief Economist and head of the Office of Regional Economic Integration at the Asian Development Bank.
[1] He worked as an economist at the International Monetary Fund from 1992 to 1993 and taught at Harvard University from 1999 to 2000 as a visiting professor.
He helped promote the set up of the institutional framework for regional cooperation and integration of Asian countries, especially the Chiang Mai Initiative Multilateralization (CMIM) and the Asian Bond Markets Initiative (ABMI) by the ASEAN+3 economies that included the 10 members of the Association of Southeast Asian Nations (ASEAN) plus China, the Republic of Korea and Japan to guard against future financial crises.
[2][3] From 2011 to 2013 he served as the senior adviser for International Economic Affairs to former president Lee Myung-bak.
[6][7] His studies in collaboration with Robert J. Barro measuring educational attainment of the population for a broad group of countries are widely cited.