This paper deals with temporal markers -ess and -(nu)n in Korean, and provides formal interpretations of these markers within the framework of interval semantics. I propose that the truth-conditional interpretation of -ess and -(nu)n sentences is obtained by locating the involved eventuality within a ‘completive interval’ and ‘imcompletive interval’, respectively. Since characterization of these two invervals makes reference to the evaluation time, the basic distinction between the two lies on tense. Furthermore, I will argue that perfective/imperfective aspect meaning that usually arises in -ess/-nun sentences should be explained in terms of a conversational implicature. (Seoul National University)