• Nuclear Engineering and Technology
• /
• v.50 no.3
• /
• pp.327-339
• /
• 2018

This article presents a new global-local hybrid coarse-mesh finite difference (HCMFD) method for efficient parallel calculation of pin-by-pin heterogeneous core analysis. In the HCMFD method, the one-node coarse-mesh finite difference (CMFD) scheme is combined with a nodal expansion method (NEM)-based two-node CMFD method in a nonlinear way. In the global-local HCMFD algorithm, the global problem is a coarse-mesh eigenvalue problem, whereas the local problems are fixed source problems with boundary conditions of incoming partial current, and they can be solved in parallel. The global problem is formulated by one-node CMFD, in which two correction factors on an interface are introduced to preserve both the surface-average flux and the net current. Meanwhile, for accurate and efficient pin-wise core analysis, the local problem is solved by the conventional NEM-based two-node CMFD method. We investigated the numerical characteristics of the HCMFD method for a few benchmark problems and compared them with the conventional two-node NEM-based CMFD algorithm. In this study, the HCMFD algorithm was also parallelized with the OpenMP parallel interface, and its numerical performances were evaluated for several benchmarks.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.3
• /
• pp.163-169
• /
• 2016

To establish the equitable distribution of total energy load, a representative cluster based routing protocol LEACH selects cluster heads randomly in accordance with the pre-determined probability every round. But because the current energy level of sensor nodes is not considered, if a sensor node which has little residual energy is elected as a cluster head, it can not live to fulfil the role of cluster head which has big energy load. As a result, the first time of death of a node is quickened and the service quality of WSN gets worse. In this regard we propose a new routing method that, by considering the current energy of a cluster head and the distance between cluster heads and a base station, selects the sub cluster head for saving the energy of a cluster head. Simulation results show that the first time of death of a node prolongs, more data arrive at the base station and the service quality of WSN improves.

• Journal of Korea Multimedia Society
• /
• v.11 no.8
• /
• pp.1082-1092
• /
• 2008

In wireless sensor networks, clustering protocol such as LEACH is an efficient method to increase whole networks lifetime. However, this protocol result in high energy consumption at the cluster head node. Hence, this protocol must changes the cluster formation and cluster head node in each round to prolong the network lifetime. But this method also causes a high amount of energy consumption during the set-up process of cluster formation. In order to improve energy efficiency, in this paper, we propose a new cluster formation algorithm. In this algorithm, we define a intra cluster as the sensor nodes within close proximity of each other. In a intra cluster, a node senses and transmits data at a time on the round-robin basis. In a view of whole network, intra cluster is treated as one node. During the setup phase of a round, intra clusters are formed first and then they are re-clustered(network cluster) by choosing cluster-heads(intra clusters). In the intra cluster with a cluster-head, every member node plays the role of cluster-head on the round-robin basis. Hence, we can lengthen periodic round by a factor of intra cluster size. Also, in the steady-state phase, a node in each intra cluster senses and transmits data to its cluster-head of network cluster on the round-robin basis. As a result of analysis and comparison, our scheme reduces energy consumption of nodes, and improve the efficiency of communications in sensor networks compared with current clustering methods.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.8
• /
• pp.889-897
• /
• 2014

With the development of wireless communication and sensor technology, sensor network applications in various fields have been applied. To minimize the power consumption of sensors in sensor network is one of the important factors in oder to extend the system life. The power consumption of each sensor within sensor network can be different depending on the communication method between head(sink) node and its node. In this paper, we propose a new hierarchical communication method to minimize the power consumption of each sensor. The proposed method divides the area of sensor network into four areas using divide-and-conquer method and selects the nearest node to head node in each area as a child node of the node. Next the hierarchical tree in the same way is constructed recursively until each area is no longer divided. Each sensor can communicate to head node using this hierarchical tree. The proposed results were compared with the previous methods through simulation, and showed excellent results in the energy efficiency of sensor network.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.11
• /
• pp.1423-1430
• /
• 2016

The MAC protocols, which are classified into synchronous and asynchronous MAC protocol in the wireless sensor network, have actively studied. Especially, the asynchronous MAC protocol needs to research on the algorithm synchronizing between nodes, since each node independently operates in its own duty cycle. Typically, Receiver-Initiated MAC protocol is the algorithm synchronizing particular nodes by using beacon immediately transmitted by each node when it wakes up. However, the sender consumes unnecessary energy because it blankly waits until receiving the receiver's beacon, even if it does not know when the receiver's beacon is transmitted. In this paper, we propose the MAC protocol which can improve the performance by selecting an optimal node between a sender and a receiver to overcome the disadvantages. The simulation results show that the proposed algorithm improves energy efficiency and decreases average delay time than the conventional algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.2
• /
• pp.495-502
• /
• 2013

In the mobile Ad hoc Network(MANET), improving technique for management and control of topology is recognized as an important part of the next generation network. In this paper, we proposed an efficient node life time management of ATICC(Adaptive Time Interval Clustering Control) in Ad-hoc Networks. Ad-hoc Network is a self-configuration network or wireless multi-hop network based on inference topology. This is a method of path routing management node for increasing the network life time through the periodical route alternation. The proposed ATICC algorithm is time interval control technique depended on the use of the battery energy while node management considering the attribute of node and network routing. This can reduce the network traffic of nodes consume energy cost effectively. As a result, it could be improving the network life time by using timing control method in ad-hoc networks.

• Journal of Korea Society of Industrial Information Systems
• /
• v.17 no.7
• /
• pp.17-24
• /
• 2012

As the resources and power on Ad-hoc networks are limited, new data aggregation techniques are required for energy efficiency. The current research on data aggregation techniques is actively in progress, but existing studies don't consider the density of nodes. If nodes are densely placed in a particular area, the information which the sensor nodes placed on those areas detect can be judged as very strong association. But, the energy spent transmitting this information is a waste of energy. In this paper the densely-concentrated node area is designated as Hotspot_Zone in the multi-hop clustering environment using the AMC and a key node is selected in the area. If the request message of data aggregation is transmitted, the key node among the neighboring nodes sends its environmental information to a manager to avoid duplicate sensing information. Therefore, the life of networks can be prolonged due to this.

• Journal of Korea Multimedia Society
• /
• v.13 no.10
• /
• pp.1423-1435
• /
• 2010

Building wireless sensor networks requires a constituting sensor node to consider the following limited hardware resources: a small battery lifetime limiting available power supply for the sensor node, a low-power microprocessor with a low-performance computing capability, and scarce memory resources. Despite such limited hardware resources of the sensor node, the sensor node platform needs to activate real-time sensing, guarantee the real-time processing of sensing data, and exchange data between individual sensor nodes concurrently. Therefore, in this paper, we propose an energy-efficient real-time task scheduling technique for battery-powered wireless sensor nodes. The proposed energy-efficient task scheduling technique controls the microprocessor's operating frequency and reduces the power consumption of a task by exploiting the slack time of the task when the actual execution time of the task can be less than its worst case execution time. The outcomes from experiments showed that the proposed scheduling technique yielded efficient performance in terms of guaranteeing the completion of real-time tasks within their deadlines and aiming to provide low power consumption.

• Journal of the Institute of Convergence Signal Processing
• /
• v.9 no.4
• /
• pp.313-320
• /
• 2008

The dynamic clustering technique has some problems regarding energy consumption. In the cluster configuration aspect the cluster structure must be modified every time the head nodes are re-selected resulting in high energy consumption. Also, there is excessive energy consumption when a cluster head node receives identical data from adjacent cluster sources nodes. This paper proposes a solution to the problems described above from the energy efficiency perspective. The round-robin cluster header(RRCH) technique, which fixes the initially structured cluster and sequentially selects duster head nodes, is suggested for solving the energy consumption problem regarding repetitive cluster construction. Furthermore, the issue of redundant data occurring at the cluster head node is dealt with by broadcasting metadata of the initially received data to prevent reception by a sensor node with identical data. A simulation experiment was performed to verify the validity of the proposed approach. The results of the simulation experiments were compared with the performances of two of the must widely used conventional techniques, the LEACH(Low Energy Adaptive Clustering Hierarchy) and HEED(Hybrid, Energy Efficient Distributed Clustering) algorithms, based on energy consumption, remaining energy for each node and uniform distribution. The evaluation confirmed that in terms of energy consumption, the technique proposed in this paper was 29.3% and 21.2% more efficient than LEACH and HEED, respectively.

• Journal of Korea Multimedia Society
• /
• v.20 no.2
• /
• pp.254-260
• /
• 2017

Data packets from sensor nodes scattered over measuring fields are generally forwarding to the sink node, which may be connected to the wired networks, in a wireless sensor network. So many data packets are gathered near the sink node, resulting in significant data packet collisions and severe transmission latency. In an event detection application such as object tracking and military, bursty data is generated when an event occurs. So many data packet should be transmitted in a limited time to the sink node. In this paper, we present a delay efficient and bursty traffic friendly MAC protocol called DEBF-MAC protocol for wireless sensor networks. The DEBF-MAC uses a slot-reserved mechanism and sleep period control method to send multiple data packets efficiently in an operational cycle time. Our simulation results show that DEBF-MAC outperforms DW-MAC and SR-MAC in terms of energy consumption and transmission delay.