1. Department of Anesthesiology and Pain Medicine, College of Medicine, Wonkwang University, Iksan, Korea.
2. Department of Oral and Maxillofacial Surgery, Daejeon Dental Hospital, Wonkwang University, Daejeon, Korea.
3. Department of Anesthesiology and Pain Medicine, Sanbon Hospital, Gunpo, Korea.
4. Department of Surgery, Wonkwang-Gusan Medical Center, Wonkwang University, Gunsan, Korea.
5. Department of Obstetrics and Gynecology, Wonkwang University, Iksan, Korea.
6. Department of Surgery, College of Medicine, Wonkwang University, Iksan, Korea.