1. A non-transitory computer readable medium having stored thereon a computer program for causing a computer to model a user interest pattern, the computer readable medium comprising: code for a history collection unit, the history collection unit being operable to collect a user's use history of a content; code for a keyword extraction unit, the keyword extraction unit being operable to extract a keyword from the use history of the content; code for a time pattern extraction unit, the time pattern extraction unit being operable to extract a first time pattern of the keyword; code for a keyword extension unit, the keyword extension unit being operable to extract an extended keyword through searching for related words of the keyword; code for a time pattern analysis unit, the time pattern analysis unit being operable to analyze a second time pattern of the extended keyword based on the first time pattern; and code for a pattern modeling unit, the pattern modeling unit being operable to model a user interest pattern for the keyword and the extended keyword based on the first and second time patterns.