The World Wide Web is becoming the most important source for surveying the state of research areas all over the world. DynamicView is such a Semantic Web portal implemented for researchers to query distribution of research areas in computer science. From millions of pages in free text available on thousands of web sites, finding the distribution of research areas is a hard task. To resolve this problem, we proposed a page segmentation algorithm for information extraction, which is called DeSeA (Delimiter based Segmentation Algorithm) as it divides a web page into coherent blocks using pre-defined delimiters and finds relevant blocks from them. DeSeA carries out on an Extended DOM Tree (EDT), transforming it into a block tree. Compared with existing algorithms, it considers delimiter?s content splitting level, with higher-level delimiters having higher priority to segment a web page. Experiments show that DeSeA based information extraction algorithm fits commendably with DynamicView.