In this thesis, I revisit the nature of a negation-dependent expression awmu- in Korean. The central claim is that amwu-s do not fall within one of the two well-established categories of Negative Polarity Item (NPI) and Negative Concord Item (NCI). Hence, the taxonomy of negation-dependent expressions needs to be expanded to include a new, third type. Furthermore, I argue that this third type of expression, as exemplified in Korean, calls for a different principle of grammar, which is syntactic in nature, to properly account for its distribution. The thesis is organized as follows. In chapter 1, I introduce the taxonomy and theoretical background of negation-dependent expressions that have been discussed in the previous literature. Then, ...