Ju Si-gyeong (December 22, 1876 - July 27, 1914) was one of the founders of modern Korean linguistics. He was born in Bongsan County (봉산군; 鳳山郡), Hwanghae Province. He and his students helped standardize the Korean language, based spelling and grammar of the vernacular.
He studied the Classical Chinese from his childhood. After studying modern linguistics in Seoul, he established the Korean Language System Society (조선문동식회; 朝鮮文同式會) in 1896. He hosted several seminars in the National Language Discussion Centre of the Sangdong Youth Academy of the Korean language (상동청년학원국어강습소; 尚洞青年學院國語講習所).
He proposed that the Korean parts of speech include nouns, verbs, adjectives, adverbs, unconjugated adjectives (관형사; 冠形詞), auxiliaries (조사; 助詞), conjunction, exclamations, and sentence-final particles (종지사; 終止詞).
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.
Read more about Ju Si-gyeong: Publications, Miscellaneous