tell me what kind of superiority you have
It's the superior quality of human capital. The Koreans dealing with Chinese labor feel this every day. Just as Chinese feel Indians are slow and dumb-witted, Koreans feel exactly the same way toward the Chinese, slow, uncultured, and dumb-witted.
if US leaves by tmmrw afternoon ... an inferior race according to your bias ... chinese would eat whole korea for snacks
You do not seem to realize that the US provides less than 5% of troop strength in Korea. The US is merely an insurance policy, not the primary deterrent to the enemies of Korea. Heck, the new US deployment policy is that they would take troops out to places like Afghanistan and leave the troop's wives and children behind in the base(Really a Korean government donated high rise city) and it's considered OK because that would still guarantee that the US would send reinforcement in the sake of those servicemen's wives and children.
The ROK has second largest ground troops in the western world, soon to be the largest in the western world after the US troop reduction goes in effect due to budget cuts. This is the last cold-war style army designed to battle 1.5 million communist troops and win in an all out war.
The PLA isn't as strong as you think they are, mainly because they are poorly trained and disorganized. This was proven during the Vietnam War and the following Sino-Vietnamese war, where North Vietnamese Army and Vietcong suffered a 10:1 exchange ratio against Korean troops in ground combat, while suffering a 1:1 exchange ratio against the PLA during 1979 war. Why ROK were so successful against the North Vietnamese Army in jungle warfare(Recall that Korea has no jungle) while China suffered a huge casualty(30K dead in a month) has been extensively studied by military history scholars.
So yes, the PLA is a well-known quantity to the ROK military, as it is the expected primary combatant in the second war, and preparations are being made accordingly. Because of the ROK's massive artillery firepower(If you are impressed by the North Korean artillery force, the ROK artillery is designed to suppress that in two hours), the PLA ground troops doesn't present much of a threat. Ditto for the PLA Navy, the Yellow Sea is a death trap for any navy and anti-ship missiles will take out any PLA fleet that leave port. The only area where the ROK is lagging is the air power, and this is where the US will concentrate its reinforcement.