http://book.daum.net/bookdetail/bookmed ... 8957262824
I wish I could help you find this book...I actually found it in the States, but I think it was imported from Korea. I haven't seen it in stores in Seoul, but apparently you can get it on-line in you're in Korea.
It is a collection of Korean folk tales and legends retold in really simple language. If you already have a basic understanding of Korean grammar, and some vocabulary this book will be you new best friend. Each story is followed by a glossary.
Again, good luck hunting it down!