Recently, the statistical machine translation (SMT) method is very popular for machine translation. This SMT method uses an automatically calculated translation model and language model for large translation pair sentences. The translation model provides the probability that the foreign string is the translation of the native string and is normally controlled using a phrase table.
However, the phrase table is automatically made; it has high coverage but low reliability. On the other side, there are many translation word pairs made by hand, especially in Japanese English translation. These translation word pairs have low coverage but high reliability. Therefore, we added these handmade translation word pairs into the automatically made phrase table.
In this paper, we used 130,000 translation word pairs and the phrase table with added word pairs. As a result of the experiments, we obtained a BLUE score of 13.4% for simple sentences and 8.5% for complex sentences. On the other side, with the base line system, the score was 12.5% for simple sentences and 7.7% for complex sentences. We also studied an ABX test. In simple sentences, 5 sentences were good using the base line, and 23 sentences were good using the proposed method. In complex sentences, 15 sentences were good using the base line, and 35 sentences were good using the proposed method.
As a result of these experiments, the effectiveness of the proposed method was shown.