Ju Si-gyeong (December 22, 1876 – July 27, 1914) was one of the founders of modern Korean linguistics.
He was born in Bongsan-gun, Hwanghae Province.
He and his students helped standardize the Korean language, based spelling and grammar of the vernacular.
He studied Classical Chinese from his childhood.
After studying modern linguistics in Seoul, he established the Korean Language System Society (Korean: ??????; Hanja: ??????) in 1896.
He hosted several seminars in the National Language Discussion Centre of the Sangdong Youth Academy of the Korean language (Korean: ???????????; Hanja: ???????????).
He proposed that the Korean parts of speech include nouns, verbs, adjectives, adverbs, unconjugated adjectives (Korean: ???; Hanja: ???), auxiliaries (Korean: ??; Hanja: ??), conjunction, exclamations, and sentence-final particles (Korean: ???; Hanja: ???).
In his 1914 publication, Sounds of the Language, he promotes writing Hangul linearly rather than syllabically.
This is one of his few proposals not to have been implemented, although there have been experiments with linear hangul, most notably in Primorsky Krai.