To apply for English teaching, you need to submit TOEFL IBT80 or above certificate or IELTS 6.5 (valid for two years)
Education requirements must be an ordinary high school graduate or above, and the results of the college entrance examination are not limited as supplementary reference.
Students who want to enroll in Seoul National University, in addition to their language ability and academic qualifications, can also accept the CET-4 graduation certificate from the Language Institute of other schools. In addition, the main admission targets are key high school graduates. No matter what major, the additional assessment of students' English ability is also attached great importance, and the results of college entrance examination are also used as reference.
Seoul National University and Yonsei University, as two of SKY's three key universities, are both famous universities as you said, but they are not hopeless. They just require high language ability of applicants, and the survival of the fittest is more obvious. Therefore, as far as possible in the application materials to show their language advantages, it is best to attach an English proficiency certificate in addition to the Korean proficiency certificate, so as to be more sure of admission.