This study investigates the effect of different cue weightings in Seoul and Yanbian Korean on loanword adaptation. The two Korean dialects have the same set of obstruents. However, obstruents in each dialect exhibit different cue weightings among f0, VOT and frication duration. Phonetic similarity is central in mapping source sounds to loan sounds (Silverman, 1992; Kang, 2003). However, which acoustic cue should be used to calculate phonetic similarity is still little understood. By conducting a comparative study of English stops and /s/ adaptation into Seoul and Yanbian Korean, we found that perceptual similarity is heavily influenced by the acoustic cue that mainly characterizes the phonological contrast in a borrowing language. Furthermore, a default segment in the borrowing language can be assigned for a source sound when the primary acoustic cue is not available. We provide a formal analysis using the Correspondence Theory (McCarty & Prince, 1995) to account for the different patterns of adapting English obstruents into two dialects. Our findings will be discussed in light of the diachronic variability of loanword adaptation.