9. A character input method for automatically switching an input mode in a terminal having a touch screen, the character input method comprising: in a text input mode for inputting a word including one of characters from character groups, each of which includes at least two characters, assigning the character groups to at least two key regions acquired by dividing a region of the touch screen and displaying the character groups in the corresponding key regions based on one-to-one correspondence; if a press event occurs in a first of the key regions, counting time from a point of time at which the press event occurs; if the counted time exceeds a previously stored threshold value, switching to a separate input mode for inputting one of characters from a corresponding character group; upon execution of the separate input mode, assigning each character of the character group associated with the first key region to a different one of the key regions other than the first key region key region and displaying the characters of the character group in the other key regions; determining whether a release event occurs in one of the other key regions assigned to the each character; and outputting a character in the key region where the release event occurs onto a predetermined input editor window of the touch screen.
9. A character input method for automatically switching an input mode in a terminal having a touch screen, the character input method comprising: in a text input mode for inputting a word including one of characters from character groups, each of which includes at least two characters, assigning the character groups to at least two key regions acquired by dividing a region of the touch screen and displaying the character groups in the corresponding key regions based on one-to-one correspondence; if a press event occurs in a first of the key regions, counting time from a point of time at which the press event occurs; if the counted time exceeds a previously stored threshold value, switching to a separate input mode for inputting one of characters from a corresponding character group; upon execution of the separate input mode, assigning each character of the character group associated with the first key region to a different one of the key regions other than the first key region key region and displaying the characters of the character group in the other key regions; determining whether a release event occurs in one of the other key regions assigned to the each character; and outputting a character in the key region where the release event occurs onto a predetermined input editor window of the touch screen. 10. The character input method of claim 9 , further comprising: if the counted time does not exceed the previously stored threshold value, determining whether the release event occurs; if the release event occurs, searching for words including characters of the key region where the release event occurs; detecting a word that is most frequently used based on a search result; and outputting the detected word.