• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.1805-1824
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• 2013

Recently, the use of wireless body area networks (WBAN) has been increasing rapidly in medical healthcare applications. WBANs consist of smart nodes that can be used to sense and transmit vital data such as heart rate, temperature and ECG from a human body to a medical centre. WBANs depend on limited resources such as energy and bandwidth. In order to utilise these resources efficiently, a very well organized medium access control (MAC) protocol must be considered. In this paper, a new, adaptive and energy-efficient MAC protocol, entitled isMAC, is proposed for WBANs. The proposed MAC is based on multi-channel communication and aims to prolong the network lifetime by effectively employing (i) a collision prevention mechanism, (ii) a coordinator node (WCN) selection algorithm and (iii) a transmission power adjustment approach. The isMAC protocol has been developed and modelled, by using OPNET Modeler simulation software. It is based on a networking scenario that requires especially high data rates such as ECG, for performance evaluation purposes. Packet delay, network throughput and energy consumption have been chosen as performance metrics. The comparison between the simulation results of isMAC and classical IEEE 802.15.4 (ZigBee) protocol shows that isMAC significantly outperforms IEEE 802.15.4 in terms of packet delay, throughput and energy consumption.

• Journal of IKEEE
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• v.18 no.4
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• pp.552-558
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• 2014

This paper suggests how to design a ZigBee-chip-based communication module to remotely measure radiation level. The suggested communication module consists of two control processors for the chip as generally required to configure a ZigBee system, and one chip module to configure a ZigBee RF device. The ZigBee-chip-based communication module for remote radiation measurement consists of a wireless communication controller; sensor and high-voltage generator; charger and power supply circuit; wired communication part; and RF circuit and antenna. The wireless communication controller is to control wireless communication for ZigBee and to measure radiation level remotely. The sensor and high-voltage generator generates 500 V in two consecutive series to amplify and filter pulses of radiation detected by G-M Tube. The charger and power supply circuit part is to charge lithium-ion battery and supply power to one-chip processors. The wired communication part serves as a RS-485/422 interface to enable USB interface and wired remote communication for interfacing with PC and debugging. RF circuit and antenna applies an RLC passive component for chip antenna to configure BALUN and antenna impedance matching circuit, allowing wireless communication. After configuring the ZigBee-chip-based communication module, tests were conducted to measure radiation level remotely: data were successfully transmitted in 10-meter and 100-meter distances, measuring radiation level in a remote condition. The communication module allows an environment where radiation level can be remotely measured in an economically beneficial way as it not only consumes less electricity but also costs less. By securing linearity of a radiation measuring device and by minimizing the device itself, it is possible to set up an environment where radiation can be measured in a reliable manner, and radiation level is monitored real-time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.176-186
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• 2006

In this paper, we propose an enhanced symbol detector algorithm for 2.45GHz LR-WPAN(Low-Rate Wireless Personal Area Network) receiver. Because the frequency offset of $\pm$80ppm on 2.45GHz band is recommended in IEEE 802.15.4 LR-WPAN(Low-Rate Wireless Personal Area Network) specification, a symbol detector algorithm having stable operation in the channel environment with large frequency offset is required. For robustness to the frequency offset, non-coherent detection-based symbol detector algorithm is typically applied in the LR-WPAN receiver modem. However, the noncoherent symbol detector has increased performance degradation and hardware complexity due to squaring loss of I/Q squaring operation. Therefore we propose a coherent detection-based symbol detector algorithm with frequency offset compensation using a preamble symbol. The proposed algorithm is more suitable for LR-WPAN receiver aimed at low-cost, low-power and low-complexity than the non-coherent symbol detector, since it can reduce performance degradation due to squaring loss of I/Q squaring operation and implementation complexity. Simulation results show that the proposed algorithm has performance improvement of about 1dB in various channel environments.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.117-123
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• 2007

In this study, a ubiquitous sensor for condition monitoring of insulators and lightning arresters installed in power distribution lines and electric traction vehicles is presented. The sensor consists of two parts; a leakage current measurement and a lightning surge detection. Measured data are transmitted to a supervisory computer through ZigBee protocol based on IEEE 802.15.4. To detect leakage current, a window type Mn-ZCT is used and a low-noise amplifier with a gain of 60dB is designed, and this can measure leakage current in ranges of $100{\mu}A{\sim}5mA$. A sample-hold (S/H) and a Rogowski coil are injected to analyze the magnitude of surge current in ranges from 100A to 10kA with $8/20{\mu}s$-waveform.

• IEIE Transactions on Smart Processing and Computing
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• v.1 no.1
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• pp.34-49
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• 2012

Recently, the smart grid (SG) has been introduced to solve the serious network issues caused by the increasing electrical demand and the complex nonlinear nature of the electric power distribution network. The SG, regarded as the next generation power grid, can transmit power in more efficient ways by building an automatic and distributed energy delivery network. In this paper, we first assess how various existing networking technologies, such as IEEE 802.11 (WiFi) and IEEE 802.15.4 (ZigBee), meet the requirements of the SG communication protocols. Specifically, we classify the existing network protocols into three categories: WSN-based networking, WiFi-based networking, and wireline-based networking. We then survey the security issues regarding the SG. Finally, we propose an agile SG networking architecture and show the effectiveness of different adopted networking technologies and, as a result, present a candidate solution to implement agile networking in SGs.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.432-436
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• 2009

This paper is described that advanced study on network design of remote diagnosis system for power facilities of electric railway. In the field, it is very difficult for worker to diagnosis power facilities including catenary because workers should be maintenance on AC power supply. Therefore, to properly design on remote diagnosis system, we have searched the inside and outside of the country-related technology trends. Also we confirmed that required technologies to design interface technology required for the development of sensor devices and the USN network was designed in accordance with required skills. Throughout variety of requirements, we have development iRFS based ZA sensors and iRFM to receive data of sensor. Also CC2420 is applied as single-chip which used 2.4GHz IEEE802.15.4 compliant RF tranciver designed for low-power and low-voltage wireless applications for ZigBee communication.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.96-102
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• 2011

There are many problems with the fire detection devices being used in currently, because it is difficult to find location of the source of fire and determine where devices are working or not. In this paper, we proposed fire detection and rescue system using wireless sensor network that can be real-time monitoring and determine safe exit. Fire detection and rescue system based on ubiquitous sensor network can know exactly source of fire and help determine rescue tactics using sensing data from wireless sensor nodes. Transmitted wirelessly in real-time thermal sensor and gas sensor information to analyze the GUI to monitor the status information output to the screen by use of a system implemented in everyday life, looked at the possibility.

• Journal of Ubiquitous Convergence Technology
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• v.1 no.1
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• pp.42-46
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• 2007

In this paper, we proposed an efficient short address allocation mechanism for WiBEEM devices using NAA(Next Address Available) algorithm. The proposed addressing mechanism is based upon the NAA information that is delivered over the beacons every time it is transmitted at the beginning of each super-frame. The NAA-based addressing mechanism is not a systematic way of allocating short addresses to newly joining devices and thus tree-routing cannot be supported. However, it has great advantages when U-City core services including U-Parking Lot System or ATIS(Advanced Traveler Information System) services that require high-speed mobility are considered. Moreover, the proposed addressing mechanism can provide significant expandability of the wireless network to various applications and fast device discovery.

• Information and Communications Magazine
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• v.24 no.8
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• pp.7-13
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• 2007

유비쿼터스 사회 실현의 핵심 기술인 RFID/USN 기술은 우리 정부의 USN구축 기본계획과u-IT839기술개발 정책에 따라 국산화, 기술 고도화 및 핵심 원천기술 개발을 전략적으로 추진하여 그 성과가 나타나고 있다. RFID/USN 기술은 가장 기본적인 사물의 식별 단계로부터, 이력 추적, 상태정보의 모니터링, 실시간 감시 및 제어, 자율형 서비스로 진화함에 따라 전통적인 RFID 및 무선센서네트워크에서 출발하여 궁극적으로 다양한 응용서비스를 지원하는 USN기술로 발전될 것이다. 향후 RFID 기술 분야는 상태정보처리 및 위치 추적 등 복합 기능과 성능 고도화로 발전되고 Item단위까지 적용하기 위한 새로운 리더, 초저가의 Printed 태그 및 불법 복제 방지 등의 새로운 기술이 개발될 전망이다. 센서네트워크 분야에서는 기존의 IEEE802.15.4와 ZigBee를 뛰어넘어 저전력, 고신뢰성, 확장성, 이동성 등을 지원하기 위해 효율적인 무선전송, 초경량의 노드, 네트워킹, Cross-layer최적화, 데이터 융합 등의 핵심기술 이 요구되고 USN 미들웨어 기술은 다양한 USN응용 서비스를 위해 공통 S/W 플랫폼을 제공하고 다양한 센서네트워크로부터 수집한 정보를 가공하여 서비스간 연계 통합하는 플랫폼으로 발전될 전망이다.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.25-26
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• 2007

최근 유비쿼터스 센서 네트워크의 등장으로 다양한 환경에서 센서 노드 혹은 소형 단말기를 이용하여 원하는 정보를 수집하고 가공하여 사용자에게 전달할 수 있게 되었다. 이러한 센서 네트워크의 효율적인 지원을 위해 IEEE 802.15.4를 비롯한 ZigBee Alliance 등 많은 기술이 제시되고 있다. 그러나 현재 제시된 알고리즘들은 화재 및 재난 등과 같은 긴급을 요구하는 상황에서의 긴급메시지에 대한 처리는 제시하지 않고 있다. 따라서 본 논문에서는 Network 계층에서 각 메시지별로 QoS를 정의하여 차별화된 서비스를 제공하는 프로토콜을 제시한다.