This is a tough one. Asian persona in general are the red headed stepchildren of the SCA, and i think Korean is about as obscure as you can get within that already underrepresented subcategory. I have done some limited research on this before and am happy to share it with you.

I can start you off in a couple places. First.

en.wikipedia.org/wiki/Hanbok
Wikipedia's article on Hanbok is a little weak on sources that aren't themselves online, but has quite a few images from primary sources If your man can read Korean he may want to check out the references listed on that page.

folkwear.com/asian.html
Folkwear.com does have a a Hanbok pattern and they can generally be trusted with accurate representations of ancient clothing. I was very happy with their Japanese stuff.

www.amazon.com/Hanbok-Kor...pd_bbs_sr_1
This book is also heavy on pictures but relatively loose on historical information. A couple of the commentators there speculate this is because there is an actual shortage of data and it may very well be that not much original research has gone into this during the time period you are looking for. One advantage that less academic books like this one have though is that photos are very good and could give you some inspiration for your own outfits.

I hope this helps!!

--Genjiro