1. Biomedical Materials Division, Faculty of Material Science Kim Il Sung University Pyongyang Democratic People's Republic of Korea
2. Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt‐Universität zu Berlin Berlin Germany
3. Clinical Research Division Pyongyang Cosmetic Research Institute Pyongyang Democratic People's Republic of Korea