You won't be able to find the meaning of these characters unless you know which Chinese character they represent. Each character for the majority of Korean names/words represents (or to be more precise, is the sound of) a Chinese character, aka Hanja. Chinese characters, or Hanja, all have a meaning and a sound. Many Hanja have the same sound, so there are probably 20+ different meanings for Sung, and just as many for Tae. The meaning of a name is derived from the combination of only the given name. The surname is not included in the meaning. Because there are so many possible combinations, it's impossible to know what the name means unless you know the Chinese character. Your friend will have to ask his/her parents for the Chinese characters of his name. They should know what it is.
Han, while it does mean Korea, is very unlikely to be that character since it's a surname.