Um competed at the 2014 Winter Olympics for South Korea. She teamed with Kim Ji-sun, Lee Seul-bee, Shin Mi-sung and Gim Un-chi in the women's tournament. She began the tournament as the alternate, but played lead in five of the team's last six games, as the South Korean team went 3–6 to finish in a tie for 8th. She curled 85%, which was 6th out of the 10 leads. Later that year, Um made her World Curling Championships at the 2014 World Women's Curling Championship. The team would have great success, finishing the round robin with a 8–3 record, tied for fourth. The team would win the tiebreaker 7–5 over Sweden's Margaretha Sigfridsson to qualify for the playoffs. After winning the 3 vs. 4 page playoff game 9–5 over Russia's Anna Sidorova, the team would lose the semi-final 7–2 to Switzerland's Binia Feltscher and then lost the bronze medal game 7–6 to the Russians, settling for fourth place. The following season, the team finished runner-up at the 2015 Pacific-Asia Curling Championships to Japan's Satsuki Fujisawa. The team played in the 2016 World Women's Curling Championship but would not be as successful as in 2014. They missed the playoffs with a 5–6 record.