There are lots of great places online to find images related to Korea. While I’m still looking for a good website which compiles links to some of the many fine online image databases out there, I’ll just mention two places I have enjoyed so far. The image shown here (original) is a rather bizarre 1926 postcard showing Japanese colonial traffic statistics in Korea found on the Boston Museum of Fine Arts web page. You can run a search there for a keyword like Korea.
I found a second source, which has many photos of various Korean cultural objects thanks to Professor Sunjoo Kim here at Harvard. In a posting to the Koreanstudies mailing list she notes that Roger Marshutz had donated lots of photographs to the Peabody museum of Archaelogy and Ethnology.
Visit the Peabody website and run a search for “Korea” in the “keyword” field, which will return over 1500 photos that can be viewed or refined with further searches.