CHOONG-MOO was the name given to the great Admiral Yi Soon-Sin of the Lee Dynasty. He was reputed to have invented the first armoured battleship (Kobukson) in 1592, which is said to be the precursor of the present day submarine. The reason why this pattern ends with a left hand attack is to symbolize his regrettable death, having no chance to show his unrestrained potentiality checked by the forced reservation of his loyalty to the king.

The Kobukson, also known as the Turtle Ship, was the first ironclad warship in the world.
Boasting unparalleled firepower and mobility, it proved a pivotal instrument for victory in the sea battles under Admiral Yi. Effectively a sea tank, it was capable of sinking large numbers of enemy vessels, and so did much to maintain the morale of Korean sailors, so often outnumbered by the vast fleets of the Japanese navy.
It should not be supposed that Admiral Yi designed and built the Turtle Ship entirely by himself. The planning and the actual construction of the Kobukson required the combined efforts of a large number of people, both craftsmen and naval officers. On the practical side of the work, for instance, Na Dae-yong (1556-1612) played one of the most important roles in bringing the plans for the first ship to fruition.