As a rough estimate, I looked up the use of an illustration, interior textbook, for use in Hong Kong on the Getty Image site. Interestingly Korea was not even on the list of Country choices...
First edition use was $290, subsequent Edition use was $180.
Corbis gave a flat $175 for textbook inside, 1/2 page image. They did have South Korea on their pick list.
As you can see they are not asking for large amounts. I think you may want to ask at that level at least. Send them a contract (digitally) and have them sign it and return it digitally, and have them put the money in your Paypal account before you send them the permission.
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