[5] While playing basketball in high school, Yun's natural athletic ability was noticed by his physical education teacher, Kim Young-tae, who was also serving as one of the officials at the Korea Bobsleigh Skeleton Federation at the time.

[7] Yun started skeleton at the age of 18 in early 2012, and after three-month training, he won the national championship in September 2012.

[8] Yun made his international debut in the 2012–13 season, appearing at the North American Cup Tour.

He won gold in the sixth round of the tour in Whistler, Canada on 5–6 January 2014, becoming the first Korean skeleton slider to finish on top of the podium at an international event.

In the overall 2014–15 World Cup rankings, Yun finished his rookie season in sixth place with one silver and two bronze.