1. A method of generating a text sentence in a target language different in a source language, based on one or more words in the source language input as keywords, the method comprising: an input step in which one or more keywords in the source language are input via an input means without inputting a full text sentence in the source language, the one or more keywords being a segment of the full text sentence in the source language; a sentence pair extraction step in which a sentence pair extraction means extracts one or more sentence pairs each including more than one of the keywords from a parallel corpus database including partial correspondence information indicating correspondence between a word/phrase in the source language and a word/phrase in the target language in each sentence pair; a keyword-related phrase storage step in which a target-language keyword-related phrase corresponding to each source-language keyword-related phrase is detected from the partial correspondence information of each sentence pair and stored as a pair of keyword-related phrases in the source language and in the target language in the form of a keyword-related phrase table in a storage means; a text sentence candidate generation step in which a text candidate generation means performs dependency relationships of each keyword-related phrase in the source language and in the target language of the pair of keyword-related phrases assumes dependency relationships among keyword-related phrases in the target language described in the keyword-related phrase table and generates one or more target-language text sentence candidates by using a target language keyword-related phrase generation model and a language model by assuming dependency relationships of two or more pairs of keyword-related phrases; and an output step in which at least one text sentence candidate is output from an output means corresponding to the full text sentence in the source language.
12. The method of claim 1 , wherein, in the text sentence candidate generation step in which a text candidate generation means evaluates one or more text generation candidates assuming dependency relationships among keyword-related phrases in the target language described in the keyword-related phrase table and generates one or more target-language text sentence candidates by using a target language keyword-related phrase generation model and a language model by assuming dependency relationships of pairs of keyword-related phrases, the target language keyword-related phrase generation model depends on the type of information used and includes a trigram, a backward trigram, and one or more modified word sequences.