12. The method of claim 9 , wherein generating dialog prosody information includes: generating discourse information for the semantic structure of the system utterance based on the speech act of the user utterance; generating prosody information, including an utterance boundary level, for the discourse information of the semantic structure; and generating an intonation pattern for the semantic structure of the system utterance based on the prosody information.
12. The method of claim 9 , wherein generating dialog prosody information includes: generating discourse information for the semantic structure of the system utterance based on the speech act of the user utterance; generating prosody information, including an utterance boundary level, for the discourse information of the semantic structure; and generating an intonation pattern for the semantic structure of the system utterance based on the prosody information. 15. The method of claim 12 , wherein generating discourse information includes: generating semantic units by referring to a dialog information database and analyzing the semantic structure of the system utterance corresponding to the user utterance; selecting a semantic unit to be emphasized based on the speech act of the user utterance, and adding a first emphasis tag to the semantic unit; and generating a discourse information structure by combining the semantic unit to which the first emphasis tag is added with the remaining semantic units.