This study investigates how Korean universal quantifier-long-form negation constructions are used in naturally occurring written and spoken language. While previous experimental research has examined how Korean speakers interpret such sentences using researcher-constructed stimuli, little is known about how these constructions appear in authentic discourse. Using the NIKL Written and Spoken Corpora, this study extracted and analyzed sentences containing motun ‘all’ and the long-form negation -ci anh. The results reveal that these constructions occur infrequently overall but appear more often in written texts than in spoken data. The corpus analysis also uncovers greater structural and morphological variation than has been reported in earlier studies, showing that long-form negation can co-occur with a range of particles such as -nun, -man, -to, -ka, and -lul, and that these constructions appear across various tense forms. Interpretation patterns differ by grammatical position and construction type: in written data, the plain -ci anh form overwhelmingly favors the all>not reading, while constructions containing -ci-nun and -ci-man-un tend to yield the not>all interpretation. In spoken data, the distribution is more mixed, particularly in subject position. Taken together, these findings highlight the need for future experimental studies to incorporate materials that more closely reflect naturally occurring usage patterns.