• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.12
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• pp.43-49
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• 2009

We present an efficient estimation method of the battery lifetime considering various power consumption profiles in wireless sensor nodes. The power profiles in single and periodic modes and the current dissipations in different operating modes are taken into account to find the total current consumption. Also, the self-discharge rate of a battery is taken into account to estimate the battery lifetime of a given sensor node. Finally we present a governing equation for finding the battery lifetime. We believe the proposed estimation method of the battery lifetime can be an efficient and effective method for low power design of sensor nodes.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.7
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• pp.769-774
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• 2015

Sensor network as an infrastructure of IoT(Internet of Things) has reliability issue because sensor nodes have limited memory as well as bounded battery. To improve the reliability of network, this paper proposes a data distribution scheme. The proposed algorithm distributes the data which each sensor node periodically produces into neighbor nodes that have enough memory as well as battery. This distribution process goes on more than 1 hop for overcoming unexpected spatial crash. Through simulation, we have confirmed that the proposed scheme can improve the resilience of IoT without affecting the life time of sensor network.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.70-76
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• 2007

The main purpose of this study was to realize Mountain Search and Rescue System based on Ubiquitous Sensor Network for applying search and rescue operations in the mountains. The on-site survey was conducted in order to test the possibility of data reception rate and sensor network stability, ten nodes was installed on the trail at 100m intervals Unson waterfall to Kwanumbong in Kyeryongsan national park. The results showed that the data reception rate was over 90.0% at least. To test sensor network stability, nodes were randomly turned off one by on. The result was 100% functionality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1051-1057
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• 2009

USN(Ubiquitous Sensor Network) is used to provide many services such as bridge monitoring, cultural properties monitoring, river monitoring, protection of an old and feeble person, management and control of a city and circumstance monitoring, etc. A RF transceiver is needed for implementing USN. In this paper the implementation and the design of a RF transceiver for sensor nodes operating in 2.4GHz frequency band are presented. The design procedure of AGC, a receiver and a transmitter is described. And the performance of the implemented RF transceiver is also tested. The test results of receiver sensitivity, receiver dynamic range, frequency stability, phase noise, output power of transmitter, flatness and spectrum mask are presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.445-448
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• 2007

In this paper, we present an energy efficient MAC protocol for WSN(Wireless Sensor Networks). WSN is a self organized network to collect environmental data by small size sensor nodes which consist of wireless communication unit, MPU, sensing module etc.. In the WSN, such sensor nodes operate with limited energy and how efficient use this network has been debated recently. Therefore. we present a method to consume energy equaly by modifying existing S-MAC for efficient scheduling and data transmission.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.12
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• pp.1173-1178
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• 2007

Ubiquitous sensor network (USN) is composed of many sensor nodes which are one of the simplest form of embedded system. In developing the sensor network system, a debugging tool is necessary to test and verify the system. Recently, a so-called packet analyzer has been developed for this purpose, and it supports IEEE 802.15.4 which is considered as the standard for the sensor network protocols. The major function of the packet analyzer is to take RF packets from sensor nodes and show the structure and the data of the packets graphically to the user. However, the conventional packet analyzers do not support remote control because they require a USB interface along with a personal computer. To make it available for remote control, we propose a new packet analyzer based on a server-client scheme in which a server program is implemented on embedded Linux and a client program is implemented on Windows for convenient use.

• Journal of Information Processing Systems
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• v.14 no.4
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• pp.926-940
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• 2018

In clustering-based approaches, cluster heads closer to the sink are usually burdened with much more relay traffic and thus, tend to die early. To address this problem, distance-aware clustering approaches, such as energy-efficient unequal clustering (EEUC), that adjust the cluster size according to the distance between the sink and each cluster head have been proposed. However, the network lifetime of such approaches is highly dependent on the distribution of the sensor nodes, because, in randomly distributed sensor networks, the approaches do not guarantee that the cluster energy consumption will be proportional to the cluster size. To address this problem, we propose a novel approach called CACD (Clustering Algorithm Considering node Distribution), which is not only distance-aware but also node density-aware approach. In CACD, clusters are allowed to have limited member nodes, which are determined by the distance between the sink and the cluster head. Simulation results show that CACD is 20%-50% more energy-efficient than previous work under various operational conditions considering the network lifetime.

• Smart Media Journal
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• v.5 no.1
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• pp.55-60
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• 2016

Mobility of the sensor networks proposed a new way to the efficient design of sensor networks and improvement of network system performance. Mobility results in a number of functional changes in the MAC protocol and routing protocol. Especially, the mobility of the nodes may occur the increase of the overhead of transmission or disconnection of the link. Therefore, the study of the energy efficient transmission is very important in mobile sensor networks. This paper proposed adaptive transmission mechanism on the distance-based power control. The proposed mechanism was analyzed better than conventional method in the average energy consumption and network life by simulation results.

• Journal of Internet Computing and Services
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• v.10 no.6
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• pp.37-50
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• 2009

In this paper, we proposed a mechanism for effective cooperation in sensor network. There are a few mechanism like RBS, TPSN, FPSN for sensor network. However these are supporting synchronization among nodes without global state. Therefore, we proposed SGSM(Simple Global State Management) to maintain global state among sensor nodes. As experimental results, we confirmed loss rate is within 1% as maintaining global state with SGSM mechanism. In this paper, we defined global state in sensor network and introduced SGSM for improving timming accuracy in sensor environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.2
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• pp.71-80
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• 2006

To guarantee secure communication in wireless sensor networks, secret keys should be securely established between sensor nodes. Recently, a simple key distribution scheme has been proposed for pair-wise key establishment in sensor networks by Anderson, Chan, and Perrig. They defined a practical attack model for non-critical commodity sensor networks. Unfortunately, the scheme is vulnerable under their attack model. In this paper, we describe the vulnerability in their scheme and propose a modified one. Our scheme is secure under their attack model and the security of our scheme is proved. Furthermore, our scheme does not require additional communication overhead nor additional infrastructure to load potential keys into sensor nodes.