- Academic career
- Ph. D. 1984  : Univ. of Pennsylvania Dept. of Systems Eng.
- M. S. 1982 : Univ. of Pennsylvania Dept. of Systems Eng.
- B. S. 1978 : Seoul National Univ. Dept. of Electrical Eng.
- Professional career
- 1984 ~ 1991 : Bell Communications Research, MTS
- 1991 ~ 2003 : KT, R&D Group, PM, Lab Head, CTO
- 2003 ~ 2005 : KT, Network Group, COO
- 2005 ~ 2013 : KT, Global & Enterprise Group, President
- 2013 ~ 2015 : KAIST, Professor
- 2015 ~ present : ETRI, President
- Services
- 2000 ~ present : Fellow, IEEE
- 2003 ~ present : Member, National Academy of Engineering