Interdisciplinary research has been encouraged through the policies of many governmental and institutional funding agencies in Korea. This paper measured the degrees of interdisciplinarity in individual and collaborative researches and analyzes the factors affecting it. This paper also examined flow of knowledge among different disciplines in science and engineering research using a database obtained from research proposals submitted to Korea Science and Engineering Foundation (KOSEF). The analysis indicated that 54.6% of collaborative research proposals were interdisciplinary, while 35.8% of individual research proposals were interdisciplinary. The analysis of knowledge inflow/outflow structure showed that Natural science served as a link between Life science and Engineering.