Im Pang & Yi Yuk - Korean Folk Tales: Imps, Ghosts and Fairies (1913)
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This book collects folk tales from two different writers - Im Pang (1640-1724) and Yi Yuk (1438-1498). (I've used the more common current romanization rather than what's actually in this book.) The translator James S. Gale was a Canadian missionary who not only set up a church but translated works into Korean (the Bible, Pilgrim's Progress) and into English (including Cloud Dream of the Nine - no, I hadn't heard of it either but that's an intriguing title). Stories include "The Wild-Cat Woman", "The Grateful Ghost", "The Thousand Devils", "The Old Woman Who Became a Goblin", "The Magic Invasion of Seoul", "The Snake's Revenge" and "A Visit from the Shades".
James H. Grayson's Myths and Legends from Korea: An Annotated Compendium of Ancient and Modern Materials (2001) seems like a worthwhile source of broad background.