Li Rusong
The term was introduced in the "Muyesinbo" of 1759, and the system was supposedly a creation of Crown Prince Sado. It contrasts with Jedok geom, or "admiral sword", a system supposedly introduced by the Chinese admiral Li Rusong during the 16th-century Imjin War (the "national sword" system is conspicuously absent from the older "Muyejebo" manual of 1610).