1. A computer device for retrieving a document, the computer device comprising: a memory storing a document to establish a document database; a processing unit comprising: a document feature writing unit extracting attribute information of the document stored in the document database and generating an index information for the document based on the attribute information, the index information being stored in the memory to establish a document feature database; a query input unit receiving a query input that includes at least a portion of a document and at least one or more hint keywords inputted by a user; a keyword extraction unit extracting one or more keywords from the at least the portion of the document and the at least one or more hint keywords inputted by the user; a weighting unit assigning a weight to the extracted keyword using the index information and the weighting unit assigning higher weight to the one or more hint keywords inputted by the user than the extracted one or more keywords from the at least the portion of the document; a document retrieving unit retrieving a similar document using the one or more keywords with the assigned weight and at least one of classificational information, regional information, subject information, time information and the one or more hint keywords inputted by the user that is assigned higher weight than other keywords; an output unit outputting the similar document retrieved by the document retrieving unit to the user; and a similar word extraction unit extracting a plurality feature keywords for each stored document using the index information, selecting at least two feature keywords from the extracted feature keywords in accordance with an evaluation value of the keyword and clustering the selected feature keywords as similar words, wherein the document retrieving unit retrieves the similar document using the clustered similar words in addition to the keyword extracted from the query.
1. A computer device for retrieving a document, the computer device comprising: a memory storing a document to establish a document database; a processing unit comprising: a document feature writing unit extracting attribute information of the document stored in the document database and generating an index information for the document based on the attribute information, the index information being stored in the memory to establish a document feature database; a query input unit receiving a query input that includes at least a portion of a document and at least one or more hint keywords inputted by a user; a keyword extraction unit extracting one or more keywords from the at least the portion of the document and the at least one or more hint keywords inputted by the user; a weighting unit assigning a weight to the extracted keyword using the index information and the weighting unit assigning higher weight to the one or more hint keywords inputted by the user than the extracted one or more keywords from the at least the portion of the document; a document retrieving unit retrieving a similar document using the one or more keywords with the assigned weight and at least one of classificational information, regional information, subject information, time information and the one or more hint keywords inputted by the user that is assigned higher weight than other keywords; an output unit outputting the similar document retrieved by the document retrieving unit to the user; and a similar word extraction unit extracting a plurality feature keywords for each stored document using the index information, selecting at least two feature keywords from the extracted feature keywords in accordance with an evaluation value of the keyword and clustering the selected feature keywords as similar words, wherein the document retrieving unit retrieves the similar document using the clustered similar words in addition to the keyword extracted from the query. 5. The computing device according to claim 1 , wherein the output unit provides various kinds of user interface to a client connected through a network, and the user interface is an environment where a user inputs a query through various routes, and includes one of a first user interface where a query is input in sentence units, a second user interface where retrieved documents are used as a query, and a third user interface where a query is input by attaching or uploading a text file.