The Universalist mission to Korea didn't last long, and tantalizingly little has been written about it. It was surely a subset of the Japanese mission work, and during this period -- some time in the 1920s -- Korea was occupied by Japan.
This photo, from the 1927 Universalist Year Book, is the first I've ever seen related to the work, but as you can see by the caption, there's not much detail here either. It's printed between two pages about the Japanese Universalist Convention, but there's no reference within that convention's entry.
Can't wait to get the 1928 Year Book.