Here is a quote from Joo after the Olympics from the Korea Times:
Joo, 32, said he received treatment for phlegmon cellulitis. “But I thought that something went wrong since there was few signs of recovery. The initial diagnosis turned out to be wrong. Later, my illness was diagnosed as Behcet’s Disease.
“Behcet’s Disease is a chronic disease. Therefore, I had to play, tolerating the pain,” Joo said.