Korean military technology was ahead of Japan's in 1592! Makes sense, that's why Koreans knew the importance of... guns? Japan adopted guns from European traders in the midst of the chaos of Sengoku Jidai. Did Koreans field trained gunners when the invasion took place? No. There was hardly any communication with the Westerners. And in the 19th Century Japan voluntarily modernized itself. Unjust trade relations were imposed by the Americans but the modernization was something they chose. They have sent students to tour Europe to learn more from them. The entire point of Meiji Restoration was to be on the same level with the West. What happened with the Korean conflict against the French and Americans around the same period? No communication with the West. Under any circumstances. Modernization? Did the opposite of it.