"Saudi citizens do not need a visa to stay in the country up to 30 days, but what would be the procedures if the student wants to stay for 6-8 weeks as in this case? Does she have to apply for a visa from her home country or can she extend her visa locally in Seoul?"
Frida Test,
アメリカからの学生
They can only stay up to 30 days as you know and there is no available longer term visa for Saudi students.