1. Department of Dermatology Seoul St Mary's Hospital, College of Medicine The Catholic University of Korea Seoul Korea
2. Department of Biostatistics College of Medicine, The Catholic University of Korea 222, Banpo‐daero, Seocho‐gu Seoul 137‐701 Korea
3. Department of Business Management Kwangwoon University Seoul Korea
4. Department of Dermatology Uijeongbu St Mary's Hospital College of Medicine, The Catholic University of Korea 271 Chunbo Street Uijeongbu 07345 Korea