As Kim Ki-duk's protégé (along with Jang Hoon and Jang Cheol-soo), Juhn honed his directorial skills as an assistant director on Kim's films "Time" (2006) and "Breath" (2007). He was also a crew member on "Rough Cut" (2008) and helped with the online marketing of "Dream" (2008). In between, Juhn worked on his short film "Fish" (), which was later invited to compete in the short film section of the 64th Venice International Film Festival.