He was one of the top seeds for the individual épée competition, but lost 15–11 in the quarter-finals to eventual silver medalist Fabrice Jeannet of France.

In 2011 Jung won the gold medal in the Asian Championships at home in Seoul, a feat he repeated a year later at Wakayama.

In the 2012 London Olympics, he knocked out world No.4 Elmir Alimzhanov, then Jörg Fiedler, but was defeated after a tight bout against surprise semifinalist Bartosz Piasecki of Norway.

In the World Championships in Kazan, he made it to the round of 16 but was stopped by Italy's Enrico Garozzo, who eventually won the bronze medal.

In the team event, No.6 seed South Korea defeated Brazil, Japan, Ukraine, then host Russia to meet France in the final.