Young-Seok Seo is currently CTO of WON TECH Co., Ltd., Daejeon, Korea, working on medical device research and development. He obtained a joint Ph.D. degree in physics from Chungnam National University and Korea Atomic Energy Research Institute (KAERI) in February 2003. From March 1999 to September 2003, it was with Quantum Optics Laboratories of the KAERI, working on a high-power laser delivery system by adaptive optics (AO) technologies such as wavefront sensing and aberration compensation closed-loop control of AO systems. In October 2003, he joined the Laser Power Photonics Group of the Institute of Laser Engineering (ILE) at Osaka University, Osaka, Japan, engaged in optical fiber communication research. His research interests are fiber amplifiers, fiber lasers, and new laser materials. In October 2006, he returned to KAERI and established High energy laser facility of KAERI.