even in a head to head confrontation (DPRK vs ROK only), im confident that the Republic Of Korea would prevail against the crazy North... i mean, the Korean People's Army.
the North has severe budget limitations, spending only 5.2174billion or 22.9% of its GDP in FY02 (
Source), with the ROK spending 21.06 billion or 2.5% of its GDP in FY 05 (
Source).
this big difference in budget would lead to a few problems, namely the sustainability of the Korean People's Army in a protracted war and of course, how high, or rather low, tech its military is, and how well they are armed and trained.
the modern battlefield is ruled by the Air Force. the ROKAF has a modern Air Force, which fields advanced fighters like the KF-16, KAI A-50, F-15Ks, and the not so advanced F-5s, F-4s.
the North's airforce, is a mere air farce. although it fields about twice as many aircraft, they are mostly obsolete types with only 20 MiG-29s. how well these pilots are trained is certainly questionable, with
sources stating that due to severe aircraft fuel shortages, their pilots receive less than 10 hours of flight training per year. translation: these flying tin cans would be swatted out of the skies by the ROKAF if the KPA has enough fuel to get them flying in the first place.
however, 70% of the active KPA's forces are stationed near the DMZ and artillery guns are in range of Seoul in secure bunkers. if they have enough ammo

, this would mean that the KPA can either flatten Seoul, or attempt to take Seoul in the opening hours of another Korean War. although the KPA is numerically superior, the ROKHRF can call up the reserves, and with technologically superior weapons, should be able to stand up against the onslaught by the crazy North.
not to mention that the US has forces stationed there, the Japanese are doing some sabre rattling, and China is in the midst of modernizing itself and one would imagine how likely it is to support the DPRK, when it has problems in it's backyard too.
the delusional Kim doesnt know how badly he is going to die if he starts a war.