he wrote the hwarang segi (lit. Annals of Hwarang or Generations of the Hwarang) – a historical record of the Hwarang (lit. flower boys) of the Silla kingdom in ancient Korea.This manuscript contains biography of Sadaham, Sejong, Seolwonrang, Munno, Miseng, Hajong, Yongchun, Kim Yusin & others. 
