Source: http://bbs.black.game.daum.net/gaia/do/black/notice/read?bbsId=BN001&articleId=400
Good evening.
Thursday, June 4, we will be bringing down the servers for weekly maintenance. The servers will be going down between 7AM and 10AM (UTC+9). During this time connection to the game and online pearl store will not be available.
Please ensure that you log out in a safe location because exiting the server in combat zones may result in you or your mount being attacked.
We strive to provide more reliable service.
Thank you.