Rather than "Old Japanese Chinese Character(漢字)", "Old Chinese Character" itself is used in Korea. By the time of middle ages in Korea, Chinese character had been for the educated and ruling class. In modern time, Chinese character had been "written by hand" less frequently due to HanGul(한글) than in Chinese and Japan. So in Korea, There was no need for Old Chinese Character to be simplified for popular use unlikely the case of China and Japan. (Reading Chinese Character is easier than Writing that, As you know.) As I know, Chinese Character used in Korea is almost same form with that of Taiwan. And it is maybe similar with that of Japan before being simplified. (Just my guessing :) )