• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1190-1194
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• 2007

In sensor network, the importance of transporting data with reliability is growing gradually to support communications. Data flow from sink to nodes needs reliability for the control or management, that is very sensitive and intolerable, however relatively, data flow from nodes to sink is tolerable. In this paper, with emphasis of the data flow from sink to nodes, we proposed the mechanism that establishes confidence interval for transport. Establishing confidence interval herby-hop, not end to end, if errors happen or there's missing data, this mechanism recovers them with selective acknowledgement using fixed window. In addition, this mechanism supports franc congestion control depending on the buffer condition. Through the simulation, we showed that this mechanism has an excellent performance for error recovery in sensor network.

• The KIPS Transactions:PartC
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• v.16C no.5
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• pp.629-636
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• 2009

Since all sensor nodes in wireless sensor networks work by their own embedded batteries, if a node runs out of its battery, the sensor network can not operate normally. In this situation we should employ the routing protocols which can consume the energy of nodes efficiently. Many protocols for energy efficient routing in sensor networks have been suggested but LEACH and PEGASIS are most well known protocols. However LEACH consumes energy heavily in the head nodes and the head nodes tend to die early and PEGASIS - which is known as a better energy efficient protocol - has a long transfer time from a source node to sink node and the nodes close to the sink node expend energy sharply since it makes a long hop of data forwarding. We proposed a new hybrid protocol of LEACH and PEGASIS, which uses the clustering mechanism of LEACH and the chaining mechanism of PEGASIS and it makes the life time of sensor networks longer than other protocols and we improved the performance 33% and 18% higher than LEACH-C and PEGASIS respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.645-648
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• 2016

Cluster based wireless sensor networks have a characteristic that the cluster heads collect and aggregate data from sensor nodes and send data to sink node. In addition, between the adjacent sensor nodes deployed in the same area is characterized to the similar sensing data. In this paper, we propose a transmission algorithm for improving the energy efficiency using these two features in the cluster-based wireless sensor networks. Adjacent neighboring nodes form a pair and the two nodes sense data on shifts for one round. Additionally, two cluster heads are selected in a cluster and one of them alternately collects data from nodes and transmits data to the sink. This paper describes a transmission rounding method and a transmission frame for increasing energy efficiency and compared with conventional methods. We perform computer simulations to evaluate the performance of the proposed algorithm, and show better performance in terms of energy efficiency as compared with the LEACH algorithm.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.3
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• pp.201-205
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• 2009

This paper addresses issues to efficiently collect and aggregate data of sources within a local and adjacent region in geographic routing for wireless sensor networks. We first introduce the concept of a local sink which collects and aggregates data form source nodes in the region and delivers the aggregated data to a global sink. We also design a model to determine an optimal location of the local sink and propose a mechanism to collect data through the local sink. Simulation results show that the proposed mechanism with the local sink is more efficient in terms of the energy and the data delivery ratio than the existing mechanism without the local sink in a geographic routing.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.2
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• pp.53-64
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• 2005

Previous secure routing protocols for wireless sensor networks assume that a sink is static. In many cases, however, a sink operated by man or vehicle is moving. A mobile sink creates a lot of technical problems such as reconfiguration of routing path exposure of sink location. and selection of secure access point node, which are not considered by many previous researches. In this paper, we propose a new secure routing scheme for solving such problems using hi-directional hash chain and delegation nodes of grid structure. This scheme provides a secure routing path and prevents attacker from recognizing the location of a mobile sink in sensor networks. This new method reduces the resource requirements compared to the cashed routing schemes. Simulation results also show that the system is secure and efficient enough.

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

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.539-540
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• 2021

In this paper, we consider the management scheme of the crowd group in the sensor networks. In the case of the networks searching the critical area, the operation of crowd group can affect the mission implement. The mobile sink system leading the group networks can change the network configuration as the dangerous data gathered from group sensor nodes. The dynamic network management provides the important role to the mission of mobile sink to react the dangerous environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.847-856
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• 2009

In geographic routing for wireless sensor networks, sources need the location of sinks destined for delivering their data packets. Most of the existing geographic routing protocols merely assume that the sources can get the locations of sinks by some location service. How source nodes find out the location of sinks is not easy. In this paper, we propose a sink location dissemination scheme in geographic routing for wireless sensor networks. In this scheme, a source node and a sink node send sink location announcement and query messages along two paths respectively by geographic routing. The node located on the crossing point of the two paths informs the source about the sink location. Then the source can send data packet to the sink by geographic routing. How to guarantee that these two paths have at least one crossing point in any irregular profile of sensor network is the challenge of this paper Simulation results show that our protocol is significantly superior to other protocols in terms of energy consumption and control overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1B
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• pp.48-57
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• 2008

Wireless sensor networks are composed of a lot of sensor nodes and they are used to monitor environments. Since many studies on wireless sensor networks have considered a stationary sink node, they cannot provide fully ubiquitous applications based on a mobile sink node. In those applications, routing paths for a mobile sink node should be updated while a sink node moves in order to deliver sensor data without data loss. In this paper, we propose a method to continuously update routing paths for a mobile sink node which can be extended on hierarchical multi-hop routing protocols in wireless sensor networks. The efficiency of the proposed scheme has been validated through comparing existing method using a location based routing protocol by extensive computer simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.896-905
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• 2010

The sensor networks can be used attractively for various application areas. Time synchronization is important for any Ubiquitous Sensor Networks (USN) systems. USN makes extensive use of synchronized time in many contexts for data fusion. However existing time synchronization protocols are available only for homogeneous sensor nodes of USN. It needs to be extended or redesigned in order to apply to the USN with heterogeneous sensor nodes. Because heterogeneous sensor nodes have different clock sources with the SinkNode of USN, it is impossible to be synchronized global time. In addition, energy efficiency is one of the most significant factors to influence the design of sensor networks, as sensor nodes are limited in power, computational capacity, and memory. In this paper, we propose specific time synchronization based on master-slave topology for the global time synchronization of USN with heterogeneous sensor nodes. The time synchronization master nodes are always able to be synchronized with the SinkNode. Then time synchronization master nodes enable time synchronization slave nodes to be synchronized sleep periods. The proposed master-slave time synchronization for heterogeneous sensor nodes of USN is also helpful for power saving by maintaining maximum sleep time.