1. A semantic-based search system comprising: a processor configured to: generate a common log storing knowledge corresponding to general knowledge and a user log stored by reflecting user preference; analyze vector characteristics corresponding to an instance among interpretation alternatives according to a keyword input by a user; calculate weighted values of confidence values and cosine similarity values of interpretation alternatives including vector characteristics of the instance with respect to at least one of the common log and the user log; and align rankings of the interpretation alternatives according to the keyword input on the basis of the calculated weight values of the confidence values and the cosine similarity values.