• Journal of Korea Multimedia Society
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• v.17 no.8
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• pp.977-987
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• 2014

Many of the recent performance evaluation of clustering schemes in wireless sensor networks considered one sink node operation and fixed sink node location without mentioning about any network application requirements. However, application environments have variable requirements about their networks. In addition, network performance is sufficiently influenced by different sink node location scenarios in multi-hop based network. We also know that sink location can influence to the sensor network performance evaluation because of changed multipath of sensor nodes and changed overload spots in multipath based wireless sensor network environment. Thus, the performance evaluation results are hard to trust because sensor network is easily changed their network connection through their routing algorithms. Therefore, we suggest that these schemes need to evaluate with different sink node location scenarios to show fair evaluation result. Under the results of that, network performance evaluation results are acknowledged by researchers. In this paper, we measured several clustering scheme's performance variations in accordance with various types of sink node location scenarios. As a result, in the case of the clustering scheme that did not consider various types of sink location scenarios, fair evaluation cannot be expected.

• Journal of the Korea Society of Computer and Information
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• v.22 no.9
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• pp.33-40
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• 2017

In this paper, we propose a sink-location management and data-routing scheme to effectively support the mobile sink in solar-powered WSN. Battery-based wireless sensor networks (WSNs) have a limited lifetime due to their limited energy, but solar energy-based WSNs can be supplied with energy periodically and can operate forever. On the other hand, introduction of mobile sink in WSNs can solve some energy unbalance problem between sink-neighboring nodes and outer nodes which is one of the major challenges in WSNs. However, there is a problem that additional energy should be consumed to notify each sensor node of the location of the randomly moving mobile sink. In the proposed scheme, one of the nodes that harvests enough energy in each cluster are selected as the cluster head, and the location information of the mobile sink is shared only among the cluster heads, thereby reducing the location management overhead. In addition, the overhead for setting the routing path can be removed by transferring data in the opposite direction to the path where the sink-position information is transferred among the heads. Lastly, the access node is introduced to transmit data to the sink more reliably when the sink moves frequently.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1431-1439
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• 2016

In this paper, we propose a new location service and location-based routing for data dissemination from a source to a mobile group sink in less energy consumption of the sensor node. Unlike the existing protocols, the proposed protocol uses a leader sink instead of a group area as the location information to represent a mobile sink group. The proposed protocol also uses grid leaders on virtual grid structure to support sink mobility in location service. By using a leader sink as a representative and grid leaders for mobility supporting, the proposed protocol can exploit an efficient hierarchical location service and data dissemination method without using flooding. Accordingly, the proposed protocol carries out upper layer location services and data dissemination between a leader sink and a source and lower layer location services and data dissemination between the leader sink and member sinks. Simulation results demonstrate that the proposed protocol achieves energy-efficiency.

• 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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.1
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• pp.1-9
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• 2018

Thermal performance of a heat sink for an inverter power stack was analyzed in terms of array and installation location of an Insulated Gate Bipolar Transistor (IGBT). Thermal flow around the heat sink was calculated with a numerical model that could simulate forced convection. Thermal performance was calculated depending on the array and location of high- and low-power IGBTs considering the maximum temperature of IGBT. The optimum array and installation location were found and causes were analyzed based on results of numerical analysis. For the numerical analysis, experiment design considered the installation location of IGBT, ratio of heat generation rates of high- and low-power IGBTs, and velocity of the inlet air as design variables. Based on numerical results, a correlation that could calculate thermal performance of the heat sink was suggested and the maximum temperature of the IGBT could be predicted depending on the installation method.

• Journal of the Korea Society of Computer and Information
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• v.22 no.10
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• pp.55-62
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• 2017

In this paper, we proposes a multi-ring based mobile sink location scheme for solar-powered wireless sensor network (WSN). The proposed scheme maintains the multi-rings in which nodes keep the current location of sink node. With the help of nodes in multi-rings, each node can locate the sink node efficiently with low-overhead. Moreover, because our scheme utilizes only surplus energy of a node, it can maintain multiple rings without degrading any performance of each node. Experimental results show that the proposed scheme shows much better latency and scalability with lower energy-consumption than the existing single-ring based scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.1
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• pp.63-71
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• 2013

In order to support mobility for sink groups, it is important to get the current location of a mobile sink group and then to offer the location to a source. Typically, previous works calculate a region including all member sinks by flooding; then, it notifies this region information to a source. However, flooding and location updates are periodically performed regardless of the group movement so that it causes considerable control overhead. In this paper, we propose an energy-efficient scheme supporting mobile sink groups. The proposed scheme obtains a location of a group without flooding. It exploits the inherent property of mobile sink groups which could approximate entire group movement by only partial member sinks movement. Also, the scheme learns group location by back-propagation learning method through exploiting overhearing feature in wireless communication environment. Our simulation studies show that the proposed scheme significantly improves in terms of energy consumption compared to the previous work.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.585-593
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• 2010

Geographic routing has been considered as an efficient, simple, and scalable routing protocol for wireless sensor networks since it exploits pure local location information instead of global topology information to route data packets. Geographic routing requires the sources nodes to be aware of the location of sinks. Most existing geographic routing protocols merely assume that source nodes are aware of the locations of sinks. How can source nodes get the locations of sinks was not addressed in detail. In this paper, we propose a sink location service via circle path for geographic routing in wireless sensor networks. In this scheme, a sink sends a Sink Location Announcement (SLA) message along a circle path, and a source node sends a Sink Location Query (SLQ) message along a straight path that certainly passes through the circle path. By this way we can guarantee the SLQ path and SLA path have at least one crossing point. The node located on the crossing point of the two paths informs the source node the sink location. This procedure can correctly work in any irregular profile sensor networks such as network that has holes or irregular shape by some rules. Simulation results show that our protocol is superior to other protocols in terms of energy consumption and control overhead.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.240-243
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• 2007

Geographic routing has been considered as an efficient simple, and scalable routing protocol for wireless sensor networks since it exploits pure location information instead of global topology information to route data packets. Geographic routing requires the sources nodes to be aware of the location of the sinks. In this paper, we propose a scheme named Sink Location Service for geographic routing in wireless Sensor Networks, in which the source nodes can get and update the location of sinks with low overhead. In this scheme, a source and a sink send data 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 location of the sink. 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.

• Journal of KIISE
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• v.41 no.11
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• pp.967-973
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• 2014

A continuous object is large phenomenon diffusing continuously. Therefore, a large number of sources is a major problem in researches for continuous object. Existing studies for continuous object detecting focus on reducing communication cost generated by the sources. But, they only deal with the static sink located in fixed position. In this paper, we propose the location update scheme for mobile sinks in continuous object detecting. Generally, to receive data, a mobile sink should notice its current location to sources. Previous studies for location update of mobile sinks consider individual object. So they need a lot of energy for location update when a mobile sink notices its current location toward many sources of a continuous object independently. Proposed scheme exploits regional locality of the sources involved one continuous object. The regional locality makes the location update of mobile sinks efficient. Our simulation results show that the proposed scheme superior to existing schemes in terms of energy efficiency.