Today South Korea is in shipbuilding among the top three nations in the world, while most ships built in China during the 1960's were still made from wood like a 1000 years ago. China did start from close to zero and had a Cultural Revolution and all kind of disruptions since then as well as no dollars to import technology, that's why it took such a long time. South Korea doesn't need to train engineers, they have them, and they have dollars too.
Beside, today's Chinese nuclear submarines barely reach the level of 1970 if compared with the US. China didn't catch up so far, they are still limping far behind advanced nations when it comes to submarines. If 40 years behind is not far what is your definition of far behind? :cool2: