12. The method of claim 11 , wherein the non-parametric Bayesian hidden Markov model is a hierarchical Dirichlet process hidden Markov model.
11. The method of claim 1 , wherein the main act clustering is performed using a non-parametric Bayesian hidden Markov model, under conditions that the main act is a hidden state and words included in the spoken sentences, named entities extracted from the spoken sentences and system activities corresponding to the spoken sentences are observation values.