This study first presents acoustic data on the phonetic realization of an underlying liquid in Yonbyon Korean which is not nasalized after a surface nasal, but rather appears as a tap. It also presents the phonetic realization of a pre-liquid obstruent. It then presents an optimality-theoretic account of the different surface forms of an underlying liquid (McCarthy and Prince 1993, 1995, etc.) and those of a pre-liquid obstruent in Yonbyon Korean.