Sohn, competing for the Empire of Japan, won the gold medal at the 1936 Summer Olympics in the marathon. He ran the 42.195 kilometres  course in 2:29:19.2, breaking the Olympic record. His Korean teammate Nam Sung-yong took the bronze medal. As Korea was under Japanese occupation at the time, the International Olympic Committee  officially credited Japan with Sohn's gold and Nam's bronze in the 1936 Summer Olympics medal count. On December 9, 2011, the IOC recognized Sohn's Korean nationality in his official profile. It cited his efforts to sign his Korean name and stressing Korea's status as a separate nation during interviews. The move was part of the Korean Olympic Committee's repeated requests to acknowledge Sohn's background. However, the IOC ruled out changing the nationality and registered name per official records to prevent historical distortions.

What did the IOC use to support changing Sohn's nationality?
sign his Korean name