Three small-size cannons (right) and stone cannon balls are believed to have been used in the Myeongryang Naval Battle of 1597 with legendary Korean admiral Yi Sun-shin of the Joseon Dynasty are on display Wednesday. All three cannons have the characters "エ," "〃" and "マ" in-between the letters 小 and 勝, and the former are symbols indicating repetition of the same character to indicate small-size cannons. The cannons are believed to be an advanced form of a previous larger version.