This study provides empirical evidence of how self-monitoring tasks contribute to improving the Korean pronunciation of foreign learners of Korean in blended courses, which combine face-to-face classes with online assignments. The study focuses on lateralization and nasalization rules, which are obligatory assimilation rules that frequently occur in spoken Korean. These rules involve the phoneme at the syllable boundary turning into a nasal or lateral sound during the assimilation process. For example, the words "j[open-mid back unrounded vowel]nlak" ("call") and "apmun" ("front door") are pronounced as "j[open-mid back unrounded vowel]l.lak" and "am.mun," respectively. Nasalization rules have been identified by Hasan et al. (2024. A study on intelligibility, comprehensibility, and accentedness is based on the application pattern of lateralization and nasalization rules in foreign-accented speech of Korean. "Cogent Arts & Humanities," 11(1), 2384708) and Hong (2018. A Study on Korean Pronunciation Education for Laotian Learners, Seoul National University, Ph.D. Dissertation) as problematic for learners of the Korean language, particularly with regard to intelligibility. Previous research has emphasized the need to develop new instructional designs for teaching these rules to improve students' intelligibility. This study assumes that self-monitoring tasks will enable students to learn the targeted pronunciation elements and correct them independently. Pre- and post-tests were prepared to investigate the impact of the self-monitoring tasks. A 5-week-long explicit instruction period on the phonological rules was followed by online assignments incorporating self-monitoring tasks. A total of 39 students majoring in the Korean language participated in the pre- and post-tests. The results show that students' ability to correctly apply nasalization and lateralization rules in their speech increased by approximately 50-70% after the designated period.