Korean is very different from Vietnamese and English in not only grammar but also in how to make sounds and intonation. And Koreans put emotions and feelings in their pronunciation and intonation.
When learning a new language that is very different from the mother tongue, it is necessary to steadily correct the wrong pronunciation habits at the beginning of speaking. And you need to correct the intonation of your mother tongue so you can speak naturally and confidently later.
O. K. If you are ready to learn Korean now, let’s do it step by step with me.