Yum turned professional on March 7, 1970. He became the WBC and Lineal Super Bantamweight champion when he defeated Royal Kobayashi by majority decision over 15 rounds.[1] In the following year, he successfully defended his titles against Jose Cervantes but lost to Wilfredo Gómez in his third title defense.
He retired in 1980 with an impressive record of 53 wins with 21 knockouts, 5 defeats and 8 draws.
