Cathy, to find someone who served with him your best chance is no doubt through a unit vet group. To pursue that, you first must establish his unit to the lowest level possible.You should be able to get his personnel record from NPRC in St. Louis. For more info on how to do so, go to this web address: http://www.archives.gov/st-louis/military-personnel/index.htmlhttp://www.archives.gov/st-louis/military-personnel/index.html
Once you know his outfit, you can search for their vet group, in the hope that one exists, and that it has members who served with him. The odds are somewhat long, but I do know people who have had success in this manner.
There is an inconsistency in your post that I think is worth noting. You said he, "served in the Korean War" and, "was honorably discharged in 1948". The Korean War began in 1950. If he was discharged in 1948 he would have had to re-enlist, or be re-called from inactive reserve, to serve in the Korean War.