1. A method of updating a grammar model used during speech recognition, the method comprising: obtaining a corpus comprising at least one word; obtaining at least one word from the corpus; splitting the obtained at least one word into a prescribed number of segments, wherein the prescribed number is determined based on a size of the grammar model; generating at least one hint for each segment, wherein the at least one hint is for recombining the segments into the at least one word; updating the grammar model by adding each segment to the grammar model with its generated hint; and performing speech recognition based on the updated grammar model.