1. Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
2. Digestive Disease Center, Department of Internal Medicine, Gumi CHA Hospital, Gumi, Korea.
3. Department of Internal Medicine, Kang-Il Hospital, Gimhae, Korea.
4. Digestive Disease Center, Department of Internal Medicine, Cheju Halla General Hospital, Jeju, Korea.