• Journal of KIISE:Databases
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• v.33 no.1
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• pp.32-41
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• 2006

In data-centric networks, various data items, such as temperature, humidity, etc. are sensed and stored in sensor nodes. As these attributes are mostly scalar values and inter-related, multi-dimensional range queries are useful. To process multi-dimensional range queries efficiently in data-centric storage, data addressing is essential. The Previous work focused on efficient query processing without considering overall network lifetime. To prolong network lifetime and support multi-dimensional range queries, we propose a dynamic data distribution method for multi-dimensional data, where data space is divided into equal-sized regions and linearized by using Hilbert space filling curve.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1021-1033
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• 2008

In recent years, the growing interest in wireless sensor network has resulted in thousands of publications. Most of this research is concerned with delivering raw data such as temperature, pressure, or humidity. Recently, the focus of sensor network paradigm is changing for delivering multimedia contents. However, most existing routing protocols are not very practical for transmitting multimedia contents in resource constrained sensor networks. In this paper, we propose an optimized node-disjoint multi-path routing protocol for throughput enhancement and load balancing. We focused on how to allocate traffic to independent multiple end-to-end routes. Decentralized transmission using our node-disjoint multi-path routing scheme results in bandwidth aggregation and throughput enhancement. In addition, our scheme provides ways to remove link-joint routes for decreasing routing overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.153-164
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• 2010

In this paper, we propose a multi-channel MAC protocol to improve the channel efficiency and network performance in wireless ad hoc networks. There are two main problems encountered in designing multi-channel MAC protocols. The first problem is the rendezvous problem and the second is multi-channel hidden node problem. In order to solve these problems, most of previous researches that have considered multi-channel MAC protocols use a common control channel to exchange control packets. However, they have a bottleneck problem at common control channel as increasing the number of data channels. The proposed MAC protocol solves the multi-channel hidden node problem using a TDMA scheme and increases the network throughput because transmitting and receiving data at the same time is possible. Also, since there is no common control channel, the network does not suffer from the common control channel saturation problem. Moreover, it achieves energy savings by allowing nodes that are not involved in communication to go into sleep mode. Simulation results show that the proposed MAC protocol improves the network throughput and channel efficiency and provides energy savings.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2744-2754
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• 1997

Recently, the Multi-Layer Restoration(MLR) algorithm was proposed by British Telecom(BT) to restore the network failures in Digital Cross-connect System(DCS) mesh survival network[1, 2]. This algorithm has multi restoration stage which is composed of the pre-planned and dynamic restoration. This algorithm is effective its ability in link or node failures. This reason is that it does not restore in the pre-planned rstoration stage but in dynamic restoration stage. In this paper, we propose the MLR with pre-planned Multi-Chooser(PMC) and successive restoration ratio algorithm. This proposed algorithm has a excellent performance for restortion time and ratio, spare channel availability and fast restoration from multiple link failure or node failure. This paper proposed the modeling and restoration algorithm, and analyzed the performance of the algorithm by simulation using OPNET(OPtimized Network Engineering Tools).

• 한국디지털정책학회:학술대회논문집
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• 2005.06a
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• pp.277-283
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• 2005

In this paper, the performance of high data rate-wirelesss personal area network(HDR-WPAN) system is analyzed under multi-path indoor channel. In the analysis, Saleh and Valenzuel channel model is used for the multi-path indoor channel. From the results, HDR-WPAN system has reliability of 10-5 at Eb/No = 18.5dB in multi-path indoor channel. It is a suitable performance for high data rate personal area network applications.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.3
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• pp.116-121
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• 2009

A novel method for improving the reliability of sensing data using multi-sensors in wireless sensor network systems is presented in this paper. This method is successfully applied a fog monitoring system in the mountain area.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.119-124
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• 2002

We consider a multi-state flow network consisted of undirected links and focus on how to find efficiently the union of minimal paths transmitting a required flow when minimal paths are known.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.2
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• pp.109-116
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• 2017

In this paper, we propose an Internet of Things (IoT) platform for ocean observation buoys. The proposed system consists of various sensor modules, a gateway, and a remote monitoring site. In order to integrate sensor modules with various communications interfaces, we propose a controller area network (CAN)-based sensor data packet and a protocol for the gateway. The proposed scheme supports the registration and management of sensor modules so as to make it easier for the buoy system to manage various sensor modules. Also, in order to extend communication coverage between ocean observation buoys and the monitoring site, we implement a multi-hop relay network based on a mesh network that can provide greater communication coverage than conventional buoy systems. In addition, we verify the operation of the implemented multi-hop relay network by measuring the received signal strength indication between buoy nodes and by observing the collected data from the deployed buoy systems via our monitoring site.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.389-392
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• 2017

Previously, PCC and RFCC were proposed for the network coding possibility test of flow-intersecting nodes in a multi-hop wireless network. PCC works correctly only if there is only one intersecting node. RFCC solves this problem by defining the network coding conditions with considering decoding possibility at intermediate nodes. However, this may increase decoding possibility test overhead and coding operations at intermediate nodes. In this paper, we define DCC which can decrease this overhead by allowing decoding only at destinations. We analyze the performance of DCC by simulations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.385-389
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• 2009

Multi-hop wireless mesh networks (WMNs) suffer from significant packet losses due to insufficient available bandwidth and high channel error probability. To conquer packet losses, end-to-end (E2E) error control schemes have been proposed. However, in WMNs, E2E error control schemes are not effective in adapting to the time-varying network condition due to large delay. Thus, in this paper, we propose a network-adaptive error control for video streaming over WMNs that flexibly operates E2E and hop-by-hop (HbH) error control according to network condition. Moreover, to provide lightweight support at intermediate nodes for HbH error control, we use path-partition-based adaptation. To verify the proposed scheme, we implement it and evaluate its transport performance through MPEG-2 video streaming over a real IEEE 802.11a-based WMN testbed.