• 한국산학기술학회논문지
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• 제11권5호
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• pp.1661-1669
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• 2010

본 논문에서는 센서 네트워크의 수명을 길게 하기 위해 클러스터 헤드에 집중된 에너지 과부하를 클러스터 그룹 헤드와 클러스터 헤드로 분산시켜서 에너지 소모량을 감소시키는 유전 알고리즘 기반의 에너지 효율적인 클러스터링(ECGA: Energy efficient Clustering based on Genetic Algorithm)을 제안한다. ECGA 알고리즘은 예상 에너지 비용 합계, 센서 노드 에너지 잔량의 평균 및 표준 편차를 구하여 이를 적합도 함수에 적용하였다. 이 적합도를 이용하여 최적의 클러스터 그룹 및 클러스터를 형성한다. 실험을 통하여 ECGA 알고리즘이 이전의 클러스터링 기법보다 에너지 소모를 줄이고 네트워크의 수명을 연장시켰음을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권7호
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• pp.3494-3510
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• 2019

Wireless sensor networks encounter energy saving as a major issue as the sensor nodes having no rechargeable batteries and also the resources are limited. Clustering of sensors play a pivotal role in energy saving of the deployed sensor nodes. However, in the cluster based wireless sensor network, the cluster heads tend to consume more energy for additional functions such as reception of data, aggregation and transmission of the received data to the base station. So, careful selection of cluster head and formation of cluster plays vital role in energy conservation and enhancement of lifetime of the wireless sensor networks. This study proposes a new mutation chemical reaction optimization (MCRO) which is an algorithm based energy efficient clustering protocol termed as MCRO-ECP, for wireless sensor networks. The proposed protocol is extensively developed with effective methods such as potential energy function and molecular structure encoding for cluster head selection and cluster formation. While developing potential functions for energy conservation, the following parameters are taken into account: neighbor node distance, base station distance, ratio of energy, intra-cluster distance, and CH node degree to make the MCRO-ECP protocol to be potential energy conserver. The proposed protocol is studied extensively and tested elaborately on NS2.35 Simulator under various senarios like varying the number of sensor nodes and CHs. A comparative study between the simulation results derived from the proposed MCRO-ECP protocol and the results of the already existing protocol, shows that MCRO-ECP protocol produces significantly better results in energy conservation, increase network life time, packets received by the BS and the convergence rate.

• 한국정보통신학회논문지
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• 제13권3호
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• pp.608-614
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• 2009

무선 센서 네트워크에서는 노드들이 제한적인 에너지를 가지고 있기 때문에 효율적인 에너지 사용이 요구된다. 클러스터링 방식은 클러스터를 형성하고 클러스터 멤버 노드들이 전송한 데이터를 클러스터 헤드가 병합하여 싱크 노드로 전송하는 방식을 사용한다. 본 논문에서는 무선 센서 네트워크 환경에서 클러스터 헤드를 효율적인 선정하는 알고리즘을 제안한다. 제안하는 알고리즘은 노드 자신의 과거 헤드 경험의 세분화와 전송할 데이터의 존재 여부, 전송할 데이터를 보유하고 있는 이웃 노드들의 정보를 이용하여 헤드를 선정 함으로 네트워크 전체의 수명을 증가시킨다. 시뮬레이션을 통하여 기존의 방식인 LEACH, HEED 알고리즘에 비해 밸런싱 있는 에너지를 소모하고, 더 나은 네트워크 수명을 보장함을 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.176-179
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• 2002

In recent years, an increasing amount of computer network research has focused on the problem of cluster system in order to achieve higher performance and lower cost. The load unbalance is the major defect that reduces performance of a cluster system that uses parallel program in a form of SPMD (Single Program Multiple Data). Also, the load unbalance is a problem of MPP (Massive Parallel Processors), and distributed system. The cluster system is a loosely-coupled distributed system, therefore, it has higher communication overhead than MPP. Dynamic load balancing can solve the load unbalance problem of cluster system and reduce its communication cost. The cluster systems considered in this paper consist of P heterogeneous nodes connected by a switch-based network. The master node can predict the average execution time of tasks for each slave node based on the information from the corresponding slave node. Then, the master node redistributes remaining tasks to each node considering the predicted execution time and the communication overhead for task migration. The proposed dynamic load balancing uses execution time prediction to optimize the task redistribution. The various performance factors such as node number, task number, and communication cost are considered to improve the performance of cluster system. From the simulation results, we verified the effectiveness of the proposed dynamic load balancing algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권4호
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• pp.665-683
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• 2011

Wireless sensor networks (WSN) consist of a large amount of sensor nodes distributed in a certain region. Due to the limited battery power of a sensor node, lots of energy-efficient schemes have been studied. Clustering is primarily used for energy efficiency purpose. However, clustering in WSNs faces several unattained issues, such as ensuring connectivity and scheduling inter-cluster transmissions. In this paper, we propose a location-based spiral clustering (LBSC) algorithm for improving connectivity and avoiding inter-cluster collisions. It also provides reliable location aware routing paths from all cluster heads to a sink node during cluster formation. Proposed algorithm can simultaneously make clusters in four spiral directions from the center of sensor field by using the location information and residual energy level of neighbor sensor nodes. Three logical addresses are used for categorizing the clusters into four global groups and scheduling the intra- and inter-cluster transmission time for each cluster. We evaluated the performance with simulations and compared it with other algorithms.

• 한국신뢰성학회지:신뢰성응용연구
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• 제5권4호
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• pp.465-486
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• 2005

A unreliable network system results in unsatisfied performance. A performance criterion of a network is throughput and availability. One of the most compelling technological advances of this decade has been the advent of deploying wireless networks of heterogeneous smart sensor nodes for complex information gathering tasks, The advancement and popularization of wireless communication technologies make more efficiency to network devices with wireless technology than with wired technology. Recently, the research of wireless sensor network has been drawing much attentions. In this paper, We evaluate throughput and availability of wireless sensor network, which have hierarchical structure based on clustering and estimate the maximum hroughput, average throughput and availability of the network considering several link failure patterns likely to happen at a cluster consisted of sensor nodes. Also increasing a number of sensor nodes in a cluster, We analysis the average throughput and availability of the network.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.91-96
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• 2012

Ad-hoc 네트워크는 음영지역, 재난지역, 전쟁 시와 같은 통신 인프라가 구축되기 어려운 상황에서 유용하게 사용 될 수 있다. 그러나 음성 및 데이터 서비스 등과 같은 무선 서비스의 제공을 위해 많은 양의 네트워크 용량이 필요하게 되지만 기존의 제한된 주파수 자원에 따른 주파수 부족 상황 및 주파수 자원정책의 규제에 따라 원활한 주파수 사용이 어려운 상황이다. 이에 따라 높은 주파수 활용을 제공하는 인지 무선 시스템을 ad-hoc 네트워크에 적용하여 보다 다양하고 확장된 네트워크 서비스를 제공할 수 있다. 하지만 인지무선 기반 ad-hoc 네트워크에서 1차 사용자의 센싱 정보를 취합해서 1차 사용자의 존재 유무를 판단하는 클러스터 헤드의 선정에 대한 연구는 아직 미비한 상태이다. 따라서 본 논문에서는 인지 무선 기반 ad-hoc 네트워크 시스템에서 각 ad-hoc 단말기내의 클러스터 헤드 선정 방법과 그에 따른 신호 검출 성능을 보여준다.

• Journal of information and communication convergence engineering
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• 제19권2호
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• pp.67-72
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• 2021

Wireless sensor networks (WSNs) require an enormous number of sensor nodes (SNs) to maintain processing, sensing, and communication capabilities for monitoring targeted sensing regions. SNs are generally operated by batteries and have a significantly restricted energy consumption; therefore, it is necessary to discover optimization techniques to enhance network lifetime by saving energy. The principal focus is on reducing the energy consumption of packet sharing (transmission and receiving) and improving the network lifespan. To achieve this objective, this paper presents a novel improved energy-efficient cluster-based routing protocol (IECRP) that aims to accomplish this by decreasing the energy consumption in data forwarding and receiving using a clustering technique. Doing so, we successfully increase node energy and network lifetime. In order to confirm the improvement of our algorithm, a simulation is done using matlab, in which analysis and simulation results show that the performance of the proposed algorithm is better than that of two well-known recent benchmarks.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 2005년도 27회 하계학술발표회 논문집
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• pp.116-139
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• 2005

ICT(information and communication technology) has played a pivotal role in the world economy, and the out look for ICT has improved markedly. One of the noticeable characteristics in the ICT sector Is the global rationalization of its technology and service. Specialization on the specific ICT capability is a pressing problem for many countries. Along the line of classical innovation cluster and network studies, this paper suggests a way to find and analyze the role of core technologies on the ICT network First, technology network is constructed by using patent citation data from USPTO. Then, a couple of cluster is generated by K-means clustering technique. Finally, brokerage analysis is applied to manifest the role of principal technologies. The network visualization and some stylized facts on dynamics are briefly given altogether Based on the role and relationship of technologies across clusters, it is expected that this research could contribute to the ICT cluster formation and the vision-making for ICT specialization at the viewpoint of technology Policy.

• International journal of advanced smart convergence
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• 제6권3호
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• pp.53-58
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• 2017

A WSN (Wireless Sensor Network) is a network that is composed of wireless sensor nodes. There is no restriction on the place where it can be installed because it is composed wirelessly. Instead, sensor nodes have limited energy. Therefore, to use the network for a long time, energy consumption should be minimized. Several protocols have been proposed to minimize energy consumption, and the typical protocol is the LEACH protocol. The LEACH protocol is a cluster-based protocol that minimizes energy consumption by dividing the sensor field into clusters. Depending on how you organize the clusters of sensor field, network lifetimes may increase or decrease. In this paper, we will improve the network lifetime by improving the cluster head selection method in LEACH Protocol.