If Windows is logging in Korean, then Splunk can't translate that for you. You have to change the OS language to be English, and then Splunk will have it in English. The Korean UTF code only tells Splunk to use a non-standard coding to read the text, not to translate it.
@benazir - Did the answer provided by alacercogitatus help provide a solution to your question? If yes, please don't forget to resolve this post by clicking "Accept". If no, please leave a comment with more feedback/clarification. Thanks!