I would wait for your son to show interest before going to Korea. I think different adoptees have different needs. What's good for one may be very upsetting for another. As long as your son knows you are open if he's curious about his past or his culture, I think you can follow his cues.

My friend felt like an outsider in America and really felt like an outsider when she visited Korea because of the language barrier. It was painful having people assume she was "Korean" and then not being able to communicate.

Some people struggle more than others with having a sense of identity, whether they are adopted or not. I'm no expert but I think the reason for this comes from whether a person's parents accept them for who they are and encourage them in their interests. My Korean friend and I didn't have that. So my self acceptance and feelings of peace came when I found my birth family and found how similar our interests and personalities are. Although I may not be "normal" in the overall world, I am very normal within my family.