Korean is a pinyin based on Chinese characters created by Sejong Wang in 1443.
Because Chinese characters can be understood by literate people, and Korean is easy to master because it is pinyin, senior intellectuals and aristocratic ruling class disdain to use Korean and advocate Chinese. Korean is mostly used by ordinary people and women in informal occasions.
Official proclamations are still written in Chinese characters because they are official and Korean has just been founded for ten years.
Korean official use of Chinese characters has a long history, and it was not until 1895 that Korean was made the official language.
South Korea had to resume Chinese character teaching in 2003 because it was found that a new generation of Koreans could not read ancient books.