A Dave's poster scanned in an article on Korea from a 1919 edition of National Geographic magazine. There are 25 pages in all, starting with this one. Just change the file name in the url to go to the next one. The next page would become ng26.jpg, for example. Interesting perspective, but as you know National Geographic was pretty objectionable at times in its depiction of strange places and exotic peoples. This article certainly has its moments. My favorite is the caption on page 29: "The Korean peasant woman's neck muscles are as well developed for burden-bearing upon the head as are those of the southern darky." Offensive on a couple of levels right there.
* Update: It's now available here as a .pdf file and here as a collection of images on flickr.
* Update 2: Here's another National Geographic article on South Korea from 1950, right before the war broke out.