Yoo Ji-won

Yoo Ji-won was a South Korean graduate researcher and amateur distance runner who shared her training and races with a large online following. She died on October 11, 2026, after collapsing near the finish of the half marathon at the 2026 Seoul Race in central Seoul. She was 25.

Born in 2001, she studied at the Korea Advanced Institute of Science and Technology (KAIST), where she worked as a graduate student on artificial intelligence semiconductors. Friends and Korean news outlets described a demanding daily pattern: mornings in the lab and classes, then about two hours of running from 8 p.m., sometimes returning to research afterward. She began running in 2022 and, from the summer of 2025, focused more intently on faster times while still framing the sport as something to enjoy over a long career.

Her competitive results put her among strong Korean amateurs. On March 15, 2026, she finished the full Seoul Marathon in 2:56:32, a sub-three-hour mark that is rare among recreational runners. On April 5, 2026, she won the women's masters 10-kilometer race at the Gunsan Saemangeum Marathon. Through social media she documented that progress, and she became known in the Korean running community as a young scientist who treated training as seriously as her research.

On the morning of October 11, 2026, she lined up for the half marathon course of the Seoul Race, co-hosted by the Seoul Metropolitan Government and drawing about 12,000 runners from Seoul Plaza. At about 8:49 a.m. she collapsed at the 20.6-kilometer mark near Gwancheol-dong in Jongno District, roughly 500 meters from the finish. A race official found her, called emergency services, and performed CPR. She was taken by ambulance to a hospital and did not regain consciousness. The organizing committee announced the death on October 12 and offered condolences to her family. As of mid-October 2026, no official cause of death had been made public.

Tributes came from fellow runners, classmates, and entertainment figures who also run. Condolence messages filled her recent social posts, and Korean outlets reported that broadcasters and actors known for fitness left notes of mourning. She is remembered both for the discipline of balancing KAIST research with serious amateur racing and for the openness with which she shared that life with others.