Recently, wireless sensor network(WSN) have been used in various fields to implement ubiquitous computing environment. WSN uses small, low cost and low power sensors in order to collect information from the sensor field. This paper proposes a clustering algorithm for energy efficiency of sensor nodes. The proposed algorithm is based on conventional LEACH, the representative clustering protocol for WSN and it prolongs network and nodes life time using sleep technique and changable transmission mode. The nodes of the proposed algorithm first calculate their clustering participation value based on the distance to the neighbor nodes. The nodes located in high density area will have clustering participation value and it ∙제1저자 : 김선철 ∙교신저자 : 조용환 ∙투고일 : 2014. 12. 19, 심사일 : 2015. 1. 13, 게재확정일 : 2015. 3. 25. * 충북대학교 컴퓨터공학과(Dept. of Computer Engineering, Chungbuk National University) ※ 이 논문은 2013년도 충북대학교 학술연구지원사업의 연구비 지원에 의하여 연구되었음 (This paper was supported by the research grant of the Chungbuk National University in 2013) 78 Journal of The Korea Society of Computer and Information April 2015 can turn to sleep mode. Besides, proposed algorithm can change transmission method from conventional single-hop transmission to multi-hop transmission according to the energy level of cluster head. Simulation results show that the proposed clustering algorithm outperforms conventional LEACH, especially non-uniformly deployed network. ▸