1. Department of Preventive Medicine, Chosun University College of Medicine, Kwangju, Korea.
2. Department of Preventive Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
3. Department of Preventive Medicine and Public Health, College of Medicine, Yonsei University, Seoul, Korea.
4. Department of General Surgery, Yonsei University Wonju College of Medicine, Wonju, Korea.