South Korea’s running and academic communities are mourning the sudden death of Yoo Ji-won. The amateur distance runner and artificial intelligence semiconductor researcher at the Korea Advanced Institute of Science and Technology (KAIST) died after collapsing during the 2026 Seoul Race on Sunday, 11 October. She was in her early twenties.
The incident occurred during the final stretch of the 21-kilometre half-marathon course through central Seoul.
At approximately 8:49 a.m., Yoo lost consciousness at the 20.6-kilometre mark, roughly 500 metres from the finish line.
On-site emergency medical personnel administered cardiopulmonary resuscitation immediately before a 119 emergency services crew transported her to a nearby hospital. Despite emergency treatment, she passed away. Medical authorities have not confirmed an official cause of death.
Race Organisers Issue Formal Condolences
The Seoul Race Organising Committee confirmed the fatality in an official statement to participants on 12 October.
“We bring devastating news to all participants who joined the 2026 Seoul Race,” the organising committee stated. “At around 8:49 AM on October 11th, an emergency situation occurred when a participant in the half course collapsed at the 20.6 km mark. After immediate first aid on site, the participant was transported to a medical facility by 119 ambulance for treatment, but unfortunately, passed away.”\
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The committee extended its support to her family as investigations continue.
“We respectfully pray for the deceased’s peaceful rest and extend our deepest sympathies to the bereaved family facing this sudden sorrow,” the statement added. “We will carefully examine this incident and proceed with necessary follow-up measures without fail.”
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A Standout Athletic and Academic Talent
Born in 2001, Yoo gained widespread respect across South Korean running circles for pairing elite physical stamina with rigorous scientific research at KAIST.
She took up distance running in 2022 and built a dedicated online following by sharing training routines alongside her lab work on next-generation computing hardware.
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Her athletic achievements put her among the top amateur long-distance competitors in the nation. On 15 March 2026, Yoo completed the full Seoul Marathon in two hours, fifty-six minutes, and thirty-two seconds. The performance earned her a coveted “sub-3” marathon finish, an exceptionally rare benchmark for non-professional runners.
Earlier in the spring, she won the women’s masters division in the 10-kilometre division at the Gunsan Saemangeum Marathon.
Friends Dispel Online Rumours
Following her collapse, incorrect rumours circulated on social media claiming hospital staff had treated and discharged her to recover at home. Close friends and running partners intervened online to correct the record and urge privacy for her family.
“Jiwon continued to be hospitalised after collapsing, and she continued to have a hard time without ever being discharged,” an acquaintance posted on social media.
Her friend asked running peers to focus on remembering her life and offering prayers for her family rather than spreading unverified claims: “I want Ji-won to be comfortable now.”
Tributes have since filled Yoo’s social media platforms from fellow club runners, engineers, and athletics supporters across South Korea.
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