Knowledge Service Platform For Online Learning And Retrieval Methods

The account of learning resources on the Internet is increasing greatly nowadays, but studying courses through network is still an assistant method. The main reason is: all the learning resources are built in a repeating way simply, lacking of an efficient organization structure of knowledge and information. So the learning content and learning mode can not be built upon the foundation of the individual learners' information to take advantages of e-learning model.The paper believes that affluent teaching resources are close to the base knowledge structures of courses and the main character of individuated learning is variable knowledge organization and material presentation. Thus, the root way lives in enabling the computer to understand domain course knowledge and to process knowledge and to reform the related learning materials smartly. So the paper promotes to build a platform providing knowledge services for e-learning. The platform tries to organize learning contents and materials by a knowledge network to provide a better learning service.The domain knowledge of course is presented using the ontological conceptual network which adopting the views of Ontology; generating the knowledge of courses abstractly with primitive, universal, simple rules and knowledge relations; using the conceptual network model which can be recognize and process by computer to represent knowledge. The model has an eye of object object on connotation of concepts. It has a view that each concept is a compound structure that consists of name, alias, attributes and rules. And the events and relations between concepts make them to form a complex network, which can represent the content and structure of course knowledge and the dynamic categories of domain knowledge. All these build a firm knowledge foundation for organizing learning resources efficiently and building the learning material variably.The platform for e-learning service that adopts a three-layeredstructure of ontology conceptual network, knowledge framework and metadata described materials is built on base of well domain knowledge representation. It takes apart the course contents, the users' learning structures and the learning management system; the ontology of course knowledge, the learning contents and the present forms of learning materials. These make it possible to rebuild learning structure and reform learning materials upon the instructions of teachers or the driving forces of students' leaning tasks.Another essence issue of the paper is concepts based retrieval. The key point of the retrieval method is: try to understand the object of the retrieval user and try to distinguish the difference in the view of conceptual level among retrieval words provided by different users using the semantic relations defined by ontological conceptual network. Tow concepts based retrieval methods are designed to meet the needs of the platform for e-learning service. One is for metadata described learning resources, the other is a navigation method for course knowledge. The concept based retrieval methods meet the need of individual information services.