First you should go through the scrapbook with a fine-tooth comb, and maybe a magnifying glass as well.
First, you need to find out what unit he was in. If you have no items such as letters he wrote home from Korea that would have his address on them, you can always look if anyone in the photos is wearing a unit patch on their uniform. That would give you at least the division he served in. Looking at uniforms can also reveal the branch (you know, like infantry, armor, etc) he served in.
Second, you want to identify locations. Maybe there are some notes in your scrap book that reveal locations in Korea or maybe those can be found on the backside of the photos. Checking won't hurt. If you have a location and at least a division, that already narrows your search down.
If you need any help with identifiying uniforms and insignia you may want to seek help from re-enactors. I know that there are very very few Korean War re-enactors around, but the website www.re-enactor.net may help you get in touch with the right people. These folks really know their uniforms and insignia and I am sure they could help you out.