1. School
of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
2. LED Convergence Research Center, LED R&D Division, Korea Photonics Technology Institute, 9, Chumdan venture-ro, 108 beon-gil, Buk-gu, Gwangju 61007, South Korea