"Christianity in Modern Korea" - Donald N. Clark (5 pages). This is Korean Christian History 101. If you want a quick overview of how Christianity got started in Korea, how it grew, and where it is now, start here.
"The Puzzle of Korean Christianity" - Danielle Kane and Jung Mee Park (34 pages). These authors analyze geopolitical and national issues to understand the growth of Christianity in Korea and the frustration of Christianity in China and Japan. They try to set the micronetworks that typically lead to conversion into the macrocontext of international relations.
"Holy Spirit Movements in Korea" - Kirsteen Kim (22 pages). This is a rather weighty historical review of major movements within Korean theology. I found this article helpful in understanding Korean Christianity's connections to Confucianism and Shamanism.
"'Serving Two Masters': Protestant Churches in Korea and Money" - Gil-Soo Han, Joy J. Han, Andrew Eungi Kim (22 pages). This is a difficult criticism of some of the problems in contemporary protestantism in Korea - especially related to the ABC's of outward success (attendance, buildings, and cash). On the up side, the authors highlight some Korean churches who are bucking the materialistic trends - including "The Tin Church" in JeonJu - earning its nickname through planting new churches with inexpensive building materials.