Ri Jang Son, inventor of the time bomb

Ri Jang Son was an engineer of the 16th century who invented and made a powerful shell during the Imjin Patriotic War.

He was in a low social position as a handicraftsman who made a fire gun and so he was held in contempt by the feudal rulers.

With a strong sense of patriotism, he had made every effort to produce a powerful weapon capable of dealing a heavy blow to the Japanese aggressors.

At last, during the Imjin Patriotic War, he succeeded in inventing and manufacturing a more powerful shell - Pikyokjinchonroe by improving the Jinchonroe of which use was limited before then.

There were three types of Pikyokjinchonroes: extra big, big and medium. Pikyokjinchonroes were fired by cannons such as extra big Wangu, big Wangu and medium Wangu, ranging about 750 to 900 m.

The shell was a time bomb with a fuse. It was a time bomb that either accelerated or slowed down the time of the explosion depending on the number of screw grooves (the length of the fuse).

The enemy, without knowing the principle of the shells, gathered to see the shells which had been flown from a distance, and were hit hard to wholesale death by steel fragments when they were explored with loud explosion sound.

Like this, Ri Jang Son invented a new weapon, thus making a great contribution to the victory of the then Imjin Patriotic War.