1. An RDF (Resource Description Framework) network construction device using an ontology schema, comprising: a computer processor; an ontology schema storing module, executed by the computer processor, that stores an ontology schema defining a relationship system between concepts in a domain; a class managing module, executed by the computer processor, that connects and stores, in a set, authority data composed of classes, terms classified by the classes, identifiers of the terms, representative terms, and identifier of the representative terms, wherein the representative terms comprises terms that represent characteristic of the concepts; a mining rule managing module, executed by the computer processor, that connects and stores, in a set, properties of the ontology schema, one or more mining patterns corresponding to the properties, and one or more RDF triples corresponding to the one or more mining patterns, wherein each RDF triple comprises of a subject, an object, and a relationship between the subject and the object; a mining pattern creating module, executed by the computer processor, that is linked with the class managing module, recognizes terms from an input text document and represents the recognized terms into corresponding classes and properties representing relationships between the represented classes, and converts the text document, which represents the classes into properties, and into a mining pattern; and an RDF triple creating module, executed by the computer processor, that is linked with the mining rule managing module and creates an RDF triple by comparing the one or more mining patterns stored in the mining rule managing module with the mining pattern of the text document, wherein the classes of the class managing module are set by a key value and properties of the mining rule managing module are set by another key value, and wherein the RDF tripe creating module includes: a mining pattern comparing unit that compares the one of more mining patterns stored in the mining rule managing module with the mining pattern of the text document, in link with the mining rule managing module; a first RDF triple creating unit that determines a class-based RDF triple composed of at least one class and at least one property that correspond to the corresponding mining pattern of the mining pattern managing module, on the basis of a result of the compared patterns; a second RDF triple creating unit that creates a term-based RDF triple composed of properties and terms, by converting the at least one class of the class-based RDF triple into corresponding terms, in link with the class managing module; and a third RDF triple creating unit that converts the corresponding terms of the term-based RDF triple into corresponding identifiers, in link with the class managing module, and creates an identifier-base RDF triple composed of the identifiers and the properties.