First I suggest you to use korean alphabet, both reading and learning korean, not romanization. As for your question "i'll work hard, so please take care of me", 열심히 일하겠습니다. 잘 부탁드립니다. If you don't know how to read hangul, use google translate to speak it for you. http://translate.google.com/#auto/ko/열심히%20일하겠습니다.%20잘%20부탁드립니다.