In the Facebook group "Troublesome Catalogers and Magical Metadata Fairies", Sharon Domier recommended two tools for cataloguing Korean books:

// If you have Korean books to catalog and are stuck: You can almost always find the book by ISBN in the Kyobo Bookstore catalog http://www.kyobobook.co.kr/ AND there is a wicked good Korean romanizer program developed by the Committee on Korean Materials (Council on East Asian Libraries). http://library.princeton.edu/eastasian/k-romanizer together they can work miracles.//