Doyeon, Jaepeel, Jiseon, and Jun-Seo visited San Francisco, USA for 1 week (from Jan. 31st, to Feb. 6th) to participate SPIE 2020 conference. SPIE is one of the biggest international conference, in which many researchers in a wide variety of research topics according to optics gather. It was very nice for them because they could meet many researchers and discuss their reserach works with the researchers. Also, they could get access to the different optics topics and broaden their research insight.