1. A method of searching information using web, comprising: generating a basic word vector about at least one of a provided user query and a linguistic analysis result, and searching a vector space corresponding to the basic word vector in a vector space database using the at least one basic word vector; determining a degree of similarity between the basic word vector and the searched vector space; generating an expanded word vector based on a web search result performed using at least one of the provided user query and the linguistic analysis result, and searching a vector space corresponding to the expanded word vector in the vector space database using the expanded word vector, when the degree of similarity is equal to or less than a threshold value; and searching knowledge information based on the searched vector spaces in the basic search step or in the expanded search step.