This study investigated the structural relationship between the characteristics of K-MOOC(Korean Massive Open Online Courses) and educational effectiveness, and verified the PUU(perceived usefulness and usability) and the mediating effect of learning expectation. This survey was conducted on 369 learners who took the K-MOOC. Among them, 51.5%(190 learners) were female learners and 48.5%(179 learners) were male learners. 50.1%(185 learners) completed the course, and 49.9%(184 learners) did not complete the course. As a result of the analysis, among the characteristics of K-MOOC, teaching presence had the greatest influence on the PUU, followed by interest and trust. It was analyzed that PUU not only had a positive effect on the educational effectiveness, but also partially mediated the characteristics of K-MOOC and the educational effectiveness. The analysis results suggest that the PUU for educational effectiveness is a very important factor in that most of the higher education is conducted online due to the recent spread of the COVID-19. Finally, learning expectation was analyzed to partially mediate the relationship between the PUU and educational effectiveness, and it was confirmed that the learner s expectations for K-MOOC had a positive effect on the educational effectiveness. The research results support the need for K-MOOC, which is expected to expand further in the post-corona era, to provide PUU by reinforcing trust, teaching presence, and interest factors.