1. A machine implemented method of converting a source character string to a target character string, comprising: receiving a first character string having the source character string; dividing the first character string into a plurality of sub-strings; converting the plurality of sub-strings to second character strings, through a dictionary; creating third character strings corresponding to the plurality of sub-strings; analyzing the second character strings and the third character strings; constructing fourth character strings from the second and third character strings based on the analysis; creating a candidate list based on the fourth character strings; selecting the target character string from the candidate list; and outputting the target character string;