The method according to an embodiment may be implemented in the form of a program instruction executable by various computer means and stored in a computer-readable medium. The computer-readable medium may include a program instruction, a data file, and a data structure solely or in combination. The medium may continue to store a program executable by a computer or may temporarily store the program for execution or download. Furthermore, the medium may be various recording means or storage means of a form in which one or a plurality of pieces of hardware has been combined. The medium is not limited to a medium directly connected to a computer system, but may be one distributed over a network. An example of the medium may be one configured to store program instructions, including magnetic media such as a hard disk, a floppy disk and a magnetic tape, optical media such as CD-ROM and a DVD, magneto-optical media such as a floptical disk, ROM, RAM, and flash memory. Furthermore, other examples of the medium may include an app store in which apps are distributed, a site in which other various pieces of software are supplied or distributed, and recording media and/or storage media managed in a server. Examples of the program instruction may include machine-language code, such as a code written by a compiler, and a high-level language code executable by a computer using an interpreter.