1. Department of Neurology, Chonnam National University Hospital, Gwangju, Korea.
2. Department of Neurology, Aerospace Medical Center, Republic of Korea Air Force, Cheongju, Korea.
3. Department of Occupational and Environmental Medicine, Chonnam National University Hwasun Hospital, Hwasun, Korea.
4. Department of Occupational and Environmental Medicine, Aerospace Medical Research Center, Republic of Korea Air Force, Cheongju, Korea.