The development of technology that can be used in education and the acceleration of digital transformation through COVID-19 are promoting the use of technology in education called Edutech. Learning analytics is one of the edutech that is increasing in need and importance for its use in the field of education. Learning analytics, which collects and analyzes learning data produced by students and provides personalized feedback, is drawing an attention as a way to provide customized education. However, despite the emphasis on the use of learning analytics, it is hard to find studies that deal with the actual use of learning analytics in educational contexts. The purpose of this study is to explore teachers' experiences of using dashboard based on learning analytics to explore the utility and its utilization plan of learning analytics for customized education. This case study was conducted by comparing and analyzing the teacher's feedback before and after using the dashboard and interviewing the teacher's experience using the dashboard. As a result of the study, it was confirmed that differentiated prescriptions through customized feedback and objective and clear feedback based on learning data were provided as a method of utilizing dashboards for customized education. Regarding the usefulness of using dashboard for customized education, teachers recognized that dashboard is useful for promoting understanding of students' learning behaviors in online learning, reducing teachers' work required to provide customized education, promoting learners' self-understanding of learning processes, and improving satisfaction. The research results not only suggest ways to utilize the learning analysis-based dashboard of teachers for customized education, but also suggest directions for the use of learning analytics in the field of education.