Another book on TOPIK

In any language, I think it is a good idea to look at the national standard and also certifications for documenting your skill in any given language.  A college degree in a language doesn't really matter because if  you truly cannot read, write, and converse in the language then it doesn't really matter what degree you hold.  These certification exams in any given language, is to certify a level of competency in the language.  Thus, studying and targeting a certification program will help you specify exactly what your strengths and weakness as well as any material you might be missing.

For Korea, the most documented standard is TOPIK.  There are other certification programs, but I just don't see much material for it. Even in TOPIK alone, the documentation is in Korean, so for certification on lower levels, this might be hard.

I came across one book that is a rough guide for TOPIK called Complete Guide to the TOPIK: Basic (ISBN 978-89-5995-810-8) and costs 16,000 weon (about $14).  The book looks pretty good with good layout, graphics, and English explanations. Between this book and sample practice exams, you should be able to assess your skill and competency in Korea.