22. A system for determining a relation between search queries, the system comprising: a database for maintaining a search session associated with at least one search query which has been received from a user terminal during the search session, wherein the database is updated at predetermined time intervals; a counter configured for counting a total number of search sessions for each user terminal during a time interval, a first number of search sessions where a first search query is initially received and a second query is subsequently received from said each user terminal during the time interval, a second number of search sessions where a third search query is received from said each user terminal during the time interval, and a third number of search sessions where the first search query and the second search query are initially received, and the third search query is subsequently received from said each user terminal during the time interval, by referring to the database; a conditional probability information unit configured for calculating conditional probability from comparing said first number of search sessions with said third number of search sessions; a correlation information generation unit configured for calculating correlation by using the total number of search sessions, the first number of search sessions, the second number of search sessions, and the third number of search sessions; and a relation determination unit configured for determining a relation between the first search query and the second search query, and the third search query based, at least in part, upon the conditional probability and the correlation.
22. A system for determining a relation between search queries, the system comprising: a database for maintaining a search session associated with at least one search query which has been received from a user terminal during the search session, wherein the database is updated at predetermined time intervals; a counter configured for counting a total number of search sessions for each user terminal during a time interval, a first number of search sessions where a first search query is initially received and a second query is subsequently received from said each user terminal during the time interval, a second number of search sessions where a third search query is received from said each user terminal during the time interval, and a third number of search sessions where the first search query and the second search query are initially received, and the third search query is subsequently received from said each user terminal during the time interval, by referring to the database; a conditional probability information unit configured for calculating conditional probability from comparing said first number of search sessions with said third number of search sessions; a correlation information generation unit configured for calculating correlation by using the total number of search sessions, the first number of search sessions, the second number of search sessions, and the third number of search sessions; and a relation determination unit configured for determining a relation between the first search query and the second search query, and the third search query based, at least in part, upon the conditional probability and the correlation. 26. The system of claim 22 , wherein the search session is set when a search window is provided to the user terminal, and terminated when data is not transmitted from the user terminal during a predetermined time, and an additional search session is started when an additional search query is received from the user terminal after the search session is terminated.