I wish I knew before coming to Korea that life here won't be that easy. Where you are indeed expected to work from 9 AM to 6 PM, these official timings don't really matter. A lot of professors expect you to stay till 8, 9, 10, or 11 PM. It's perfectly normal for students to go back to their dorm at midnight or sleep in their labs. This does sound very difficult and indeed is difficult; however, it prepares you to handle any difficult situation in your life ahead, be it work, or research, or your future PhD degree. Hence, while it might sound painful, it has its own advantages as well and that is that you can become not only a good researcher, but a researcher who is prepared to handle any situation, anywhere!