*.hwp files

These files are document files created by the Korean equivalent to Microsoft Word, Hangul Word Processor by Haansoft. For non-Koreans, there's a bunch of information already on the web, including this English translation of the corporate and product page, some information about the history of Hangul and entry on Wikipedia that mentions:

To open HWP files in a non-Korean Windows system, users can download and execute a conversion program [1], which enables files to be opened with Microsoft Word. This program, however, can only be used with files created with Microsoft Word 2000 and below. Haansoft has also a Hangul document viewer program freely available on its website called "Hangul Viewer 2005" (한/글 뷰어 2005) [2].

The information on the wiki is a bit outdated since navigating the Haansoft website reveals a 2007 viewer and another search reveals updated information regarding Microsoft Office 2007. And if you're dealing with this file, then you are probably doing so because of school; most schools have a site license for Hangul so installing the application could be as easy as a short call to the school's IT department.