Problems Saturday with the integrated circuit players used for the English listening component of unified college entrance exams forced 453 examinees to retake that part of the tests, organizers said.
The education ministry's National Center for University Entrance Examinations made the announcement Sunday, the second day of the two-day exams.
There were 461 candidates subject to the second test, which was conducted at the end of the first day of exams. Eight chose not to retake it, the center said.
Tests on science and math were held Sunday, following those on social studies, geography, history, Japanese and foreign languages Saturday.