No. I left Korea last November. I would not say that it is absolutely necessary to know Hangul but it will definitely make a difference. The more traditional Korean restaurants, for example, do not always have English in their menus so it helps to read Hangul. Knowing Hangul also helps a lot to understand why Koreans pronounce English words the way they do so it can also help you understand their culture. If you have a good memory, Hangul can be learned in a matter of hours. If not, you can still do it in a couple of days.