There is a thread in this forum about the military strength of Japan compared to Korea. Here's a recent article about that. This article makes it clear that Japan's military is superior compared to koreas. Also bear in mind that Japan's military isn't a normal one yet.
You can read the full article here.
Japan's Military Superior Say Experts
AUGUST 14, 2006 03:07
The admiral (Dokgo Young-jae starred) in the film "The Korean Peninsula" featuring conflict with Japan says, "The military strength of our navy is 30 percent that of Japan's," when he receives a call from the president (Ahn Seong-ki starred) just before a battle with Japan. However, he expresses fighting spirit, saying, "We learned that numbers don't always control a war. If we have to defend, we will."
In August 2006, what if military conflict between Korea and Japan happens in reality, not in a film? Most professionals analyze that the difference between objective military strength will surely lead Korea to defeat.
First, in terms of naval strength according to military professionals, Japan's Naval Self-Defense Force is rated second in size worldwide. Japan is forth or fifth in composite naval strength, one of the nations with the strongest naval forces in the world.
You can read the full article here.