1. Department of Health Science, Graduate School of Chosun University, Gwangju 61452, Korea
2. Department of Dental Hygiene, Mokpo Science University, Mokpo 58644, Korea
3. Department of Preventive Medicine, College of Medicine, Chosun University, Gwangju 61452, Korea
4. Department of Occupational and Environmental Medicine, College of Medicine, Chosun University, Gwangju 61452, Korea
5. Department of Dental Hygiene, Kwangju Women's University, Gwangju 62396, Korea