Hangul
Reforms and suppression under Japanese rule

After the Japanese annexation, which occurred in 1910, Japanese was made the official language of Korea. However, the Korean alphabet was still taught in Korean-established schools built after the annexation and Korean was written in a mixed Hanja-Hangul script, where most lexical roots were written in Hanja and grammatical forms in the Korean alphabet. Japan banned earlier Korean literature from public schooling, which became mandatory for children.

The orthography of the Korean alphabet was partially standardized in 1912, when the vowel arae-a (ㆍ)—which has now disappeared from Korean—was restricted to Sino-Korean roots: the emphatic consonants were standardized to ㅺ, ㅼ, ㅽ, ㅆ, ㅾ and final consonants restricted to ㄱ, ㄴ, ㄹ, ㅁ, ㅂ, ㅅ, ㅇ, ㄺ, ㄻ, ㄼ. Long vowels were marked by a diacritic dot to the left of the syllable, but this was dropped in 1921.

A second colonial reform occurred in 1930. The arae-a was abolished: the emphatic consonants were changed to ㄲ, ㄸ, ㅃ, ㅆ, ㅉ and more final consonants ㄷ, ㅈ, ㅌ, ㅊ, ㅍ, ㄲ, ㄳ, ㄵ, ㄾ, ㄿ, ㅄ were allowed, making the orthography more morphophonemic. The double consonant ㅆ was written alone (without a vowel) when it occurred between nouns, and the nominative particle 가 was introduced after vowels, replacing 이.

Ju Si-gyeong, the linguist who had coined the term Hangul to replace Eonmun or Vulgar Script in 1912, established the Korean Language Research Society (later renamed the Hangul Society), which further reformed orthography with Standardized System of Hangul in 1933. The principal change was to make the Korean alphabet as morphophonemically practical as possible given the existing letters. A system for transliterating foreign orthographies was published in 1940.

Japan banned the Korean language from schools and public offices in 1938 and excluded Korean courses from the elementary education in 1941 as part of a policy of cultural assimilation and genocide.
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