1. Korea Heavy Ion Medical Accelerator Project, Korea Institute of Radiological and Medical Science, Seoul 01812, South Korea
2. Department of Physics and Astronomy, Seoul National University, Seoul 151-747, South Korea
3. Institute for Basic Science Center for Axion and Precision Physics Research, Daejeon 305-701, South Korea
4. Seoul-Teracom, Inc., Seoul 151-747, South Korea
5. Hanwha Corporation, Gumi 730-030, South Korea