K. S. Kwak

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In this paper, we propose a scheme to save power during the execution of backoff algorithm by avoiding idle listening. Existing MAC protocols for sensor networks reduces energy consumption by introducing an active/sleep duty cycle. But they can't save energy during the execution of backoff algorithm. The propose scheme could further improve the energy(More)
In this paper, we study the low complexity user-relay assignment problem in amplify-and-forward (AF) cooperative communication systems, where multiple users compete for the same group of relays. In order to reduce the great computational complexity of the exhaustive user-relay assignment algorithm which provides the best performance in multi-user(More)
In order to solve the pilot pollution problem and realize the low complexity pilot allocation in 5G massive multiple-input and multiple-output (MIMO) communication system, we propose an artificial fish swarm algorithm based pilot allocation scheme in this paper. The algorithm is an imitation of the natural fish activities. Through the search of the region(More)
Bereaved family members of cancer patient are at risk of having psychological problems such as anxiety and depression. However, prevalence and associated factors of anxiety and depressive symptoms among this population have not been explored in Korea.We conducted a nation-wide cross-sectional questionnaire survey of 3522 bereaved family members of cancer(More)
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