The goal is to take a closer look at progress of knowledge engineering in the field of Semantic Web. Along with theory of Knowledge Representation (KR) and knowledge processing methods such as Description Logic (DL), reasoning mechanisms and ontology modelling languages (OWL, RDF, RDFS), the thesis shows the practical usage of the mentioned approaches in building systems driven by ontologies. A working prototype of ontology-driven application, written in Java, has been developed within the scope of this thesis. The system main assumption is an attempt to integrate database and ontology approach, for storing and inferring desired information about domain of traffic dangers. For the needs of the system, domain model of traffic danger concept has been also designed.