Research On Construction Mode Of Knowledge Organization Of Digital Library Based On Ontology

The term"Ontology"derived from philosophy . Later Ontology is extensively applied to Artificial Intelligence(AI) , computer and network fields , so its definition has also been integrated into a lot of new contents . It provides common understanding knowledge of the fields for people and widely heterogeneous application systems and it offers a high-quality assurance for access , interoperability and exchange of knowledge which bases on contents in the third-generation Internet (semantic Web) . At present , Ontology is widely concerned and extensively applied to Knowledge Engineering , Natural Language Processing , Intelligence Systems Integration , Object-oriented Design and other fields . Ontology is defined as an explicit formal specification of a shared conceptualization . It can provide semantic meaning through relations between concepts . Ontology is also widely concerned in Library & Information sciences .Along with development of network technology , multimedia technology , virtual reality technology and other technologies , many informantion resources organization are transforming information organization into knowledge organization in the digital library . In the digital library when the digital knowledge resources are organized , the existing knowledge organization modes all have some problems . For example , facing to knowledge of digital library rapidly update and change , structure and content of the taxonomy and thesaurus are difficult to automatically update . They have huge systems and complex structures , so ordinary users master these methods are difficult. They all focus on indexing and organization of the literature , but retrieval services are considered less in the digital library . As far as machine languages are concerned , their interoperability and expression still are relatively poor . Since the development background of metadata is Web documents and metadata's application format is HTML documents , XML documents or hypertext documents of other types , leding to great limitations when metadata describing knowledge of other fields . Simple metadata can not solve the problem of heterogeneous semantic among the heterogeneous resources and also can not completely and systemicly embody complex interdependencies among different objects . So existing knowledge organization modes can not meet the request of knowledge organization in the digital library .Ontology brings a new vitality for knowledge organization of digital library . It intents to deal with knowledge of specific fields and its background is knowledge resources in some specific areas . In certain fields some formal ontologies enable organize knowledge of the field and construct a knowledge system based on ontology . As the same time Ontology is a modeling tool which describes information systems conceptual model in the semantic and knowledge level . Ontology can accurately describe meaning of the concept and inherent correlation among the concepts , and it can make use of the logical reasoning to access implicative relationgship among the concepts . So ontology have a strong expressive ability and a semantic reasoning ability . As a new knowledge organization mode , ontology can effectively solve the problems which traditional knowledge organization modes appear to in the digital library .In the future digital library , ontology will undoubtedly become the most essential and most important techniques and methods of knowledge organization . Ontology can be seen as abstract and description of knowledge norms and it is methods of sharing and reusing knowledge . At present , ontology has become a kind of tools of extraction , processing and understanding knowledge in the field . If knowledge is abstracted into a set of concept system in a certain field , and is made"clear","formal"and"sharing", domain ontology is constructed in this science . As for as specific subject fields are concerned , domain ontology's characteristics are descriptions about concepts , properties of the concepts and relationships among the concepts and restriction between properties and relations . A certain domain ontology can organize domanial knowledge in this special field , so that knowledge expression of digital library changes collection informationg into knowledge network and knowledge map .The author researches on"Construction Mode of Knowledge Organization of Digital Library Based on Ontology", and the paper can be divided into four parts :First , study on relevant theory of knowledge organization of digital library . The paper makes a compararive study on digital library and traditional library and discusses the content and principles of knowledge organization in the digital library . The paper surveys existing knowledge organization modes of digital library such as taxonomy, thesaurus ,"integration of taxonomy- thesaurus"and metadata , but we find when they organize the knowledge of digital library , they will expose some of their disadvantages in the knowledge organization . The paper brings forward ontology-based contruction mode of knowledge organization .Then , ontology will be introduced to knowledge organization of digital library . The paper mainly recounts ontology is the base of knowledge organization of digital library and introduces concept , classification , functions and characteristics of ontology . The paper expounds formal model of ontology and relationship between ontology and semantic . the paper analyses the principles and effects of knowledge organization , which based on Ontology , and makes a comparative analysis between Ontology-based knowledge organization mode and existing knowledge organization modes , so we find Ontology has many advantages in knowledge organization , such as , achieving knowledge sharing of the field ; achieving knowledge reuse of the field ; Analysing knowledge of the field , supporting knowledge acquisition of the field ; the standardized of knowledge .Next , the author discusses the process of construction of knowledge organization mode in the digital library . On the basis of Gruber's five rules of building ontology the paper introduces RDF,RDFS,OIL,DAML+OIL and OWL,especially the syntax of the OWL . The paper briefly introduces each languages and gives an annlysis and comparison of these languages , points out their characteristics with respect to some key aspects . At present , there are many development method of ontology , such as Mike Uschold & King's"skeleton", Gruninger & & Fox's"evaluation", Berneras et al. , Methontology , Sensus ,"the seven-step method", etc. These methods are born in specific ontology-building projects , and are acquired in the corresponding projects ,so there is not a mature methodology as support . Therefore , the author synthesizes above several methods of ontology-building , and combinates software engineering thinking , builds a ontology-based knowledge organization mode of digital library . The processing mainly includes : (1)building a knowledge organization module ; (2)confirming the scope and objectives of knowledge ; (3)multiplexing inspection ontology ; (4)ontology design ; (5)ontology evaluation ; (6)ontology realization ; (7)ontology integration ; (8)management and maintenance of ontology-knowledge-base .Finally , the paper gives an example about domain ontology of"Apple diseases and insect pests"and this ontology is described by OWL . This ontology provides an example of building ontology for other field construction ontology in the digital library .Researching on ontology-based construction modes of knowledge organization of digital library can effectively solve justice , redundancy and other issues of concepts and can achievenment sharing and reuse of knowledge , and avoid doing unwanted workforce and repetitious creation . The research ontology can greatly improve the efficiency of knowledge organization of digital library so that digital library will achieve semantic information services and intelligent services .