Hanja
Although a phonetic Korean alphabet, now known as Chosŏn'gŭl or Hangul, had been created by Sejong the Great, it did not come into widespread official use until the late 19th and early 20th century. Thus, until that time it was necessary to be fluent in reading and writing Hanja in order to be literate in Korean, as the vast majority of Korean literature and most other Korean documents were written in Literary Chinese, using Hanja as its primary script. Today, a good working knowledge of Chinese characters is still important for anyone who wishes to study older texts (up to about the 1990s), or anyone who wishes to read scholarly texts in the humanities. Learning a certain number of Hanja is very helpful for understanding the etymology of Sino-Korean words, and for enlarging one's Korean vocabulary. Today, Hanja are not used to write native Korean words, which are always rendered in Hangul, and even words of Chinese origin—"Hanja-eo" ()—are written with the Hangul alphabet most of the time, with the corresponding Chinese character often written next to it in order to prevent confusion with other characters or words with the same phonetics.
Samuel Martin (linguist)
In the 1950s Martin worked on issues relating to Japanese and Korean orthography and romanizations. At this time he coined the term "Sino-Xenic" in creating a common nomenclature for Sino-Vietnamese vocabulary, Sino-Korean vocabulary and Sino-Japanese vocabulary. He published a monograph on Japanese orthography in 1952, and in 1954 he was invited by Syngman Rhee, President of South Korea, to give his ideas on the orthographic reform of the Korean script, which were published in 1954 in various Korean newspapers. In 1954 he devised the Yale romanization system for transliterating Korean, which is extensively used by linguists. During this period he also made important contributions on Chinese, producing a monograph on the phonemes of Ancient Chinese in 1953, and an important article on Mandarin phonology in 1957.