• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.301-302
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• 2008

In this paper, we present an algorithm which decrease a frequency offset effect for 868MHz IEEE 802.15.4b LR - WPAN (Low Rate - Wireless Personal Area Network) receiver. The proposed method improve the robustness to frequency offset and receiver's stability using the multiple delay differential filter of receiver correlator.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.762-765
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• 2009

무선 센서 네트워크상에서 센서노드의 소프트웨어 변경, 패치 등의 작업을 위해서 센서노드별로 ISP와 같은 케이블을 이용하여 프로그램 해야 한다. 이는 네트워크 내에 존재하는 노드의 수가 소량인 경우 크게 문제되지 않지만 대량의 노드로 구성된 경우 프로그래밍을 위한 시간적인 측면과 투여되는 인력적인 측면에서 매우 높은 비용이 소요된다. 본 논문에서는 현재 많이 사용하고 있는 IEEE 802.15.4기반의 단일-홉 무선 센서 네트워크 환경에서 노드의 수와 무관하게 고속 병렬로 센서노드 내부의 프로그램을 무선으로 업데이트 할 수 있는 기법을 제시하고 실험을 통하여 그 성능을 검증한다.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.1
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• pp.35-42
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• 2022

Visible light communication (VLC) is a method of transmitting data through LED blinking and is vulnerable to eavesdropping because the illumination affects the wide range of area. IEEE standard 802.15.7 defines On-Off Keying (OOK), Variable Pulse Position Modulation (VPPM), and Color Shift Keying (CSK) as modulation. In this paper, we propose an encryption method in VPPM for secure communication. The VPPM uses an encoding method called 4B6B where 16 different outputs are represented with 6-bit. This paper extends the number of outputs to 20, to add complexity while not violating the 4B6B generation conditions. Then each entry in the extended 4B6B table is scrambled using vigenère cipher. The probability of decrypting each 6-bit data is $\frac{1}{20}$. Eavesdropper should perform $\sum\limits_{k=1}^{n}20^k$ number of different trials to decrypt the message if the number of keys is n. The proposed method can be applied to OOK of PHY II and CSK of PHY III. We further discuss the secure encoding that can be used in OOK and CSK without performance degradation.

• Journal of Sensor Science and Technology
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• v.15 no.5
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• pp.362-370
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• 2006

The wireless sensor network (WSN) based ECG and body temperature measuring system for ubiquitous health-care were designed and developed. The system was composed of a wireless sensor network node, base station and server computer for the continuous monitoring of ECG signals and body temperatures of patients at home or hospital. ECG signal and body temperature data, important vital signals which are commonly used in clinical and trauma care, were displayed on a graphical user interface (GUI). The data transfer from sensor nodes on patients' body to server computer was accomplished through a base-station connected to a server computer using Zigbee compatible IEEE802.15.4 standard wireless communication. Real-time as well as historical, ECG data of elderly persons or patients, can also be retrieved and played back to assist the diagnosis. The ubiquitous health care system presented in this study can effectively reduce social medical expenses, which will be increased greatly in the coming aging society.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.7
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• pp.56-64
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• 2012

A smart grid is the next generation power grid which combines the existing power grid with information technology, so an energy efficient power grid can be provided. In this paper, in order to build an efficient smart grid an AMI system, which gears with the existing home network and provides an user friendly management function, is proposed. The proposed AMI system, which is based on an extended home network, consists of various functional units; smart meters, communication modules, home gateway, security modules, meter data management modules (MDMM), electric power application modules and so on. The proposed home network system, which can reduce electric power consumption and transmit data more effectively, is designed by using IEEE 802.15.4. The extended home gateway can exchange energy consumption information with the outside management system via web services. The proposed AMI system is designed to enable two-way communication between the home gateway and MDMM via the Internet. The AES(Advanced Encryption Standard) algorithm, which is a symmetric block cipher algorithm, is used to ensure secure information exchange. Even though the results in this study could be limited to our experimental environment, the result of the simulation test shows that the proposed system reduces electric power consumption by 4~42% on average compared to the case of using no control.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.47-48
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• 2008

UML(Unified Modeling Language) is the most frequently used modeling language in the process of analysis, design, implementation and etc. The main reason of using UML is not only to help users to work visually but also to draw better communication among developers. In addition, UML is one of the global standards and supports MDA. In this paper embedded software development method for USN using UML is discussed To show how the development method is used, IEEE 802.15.4 radio module are programmed using UML software tool.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.268-270
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• 2006

본 논문에서는 ZigBee Alliance에서 다루어지고 있는 IEEE 802.15.4틀 기반으로 하는 USN을 위한 라우팅 프로토콜을 연구한다. 현재 ZigBee Specification v1.0의 표준에서는 AODV라우팅 프로토콜과 Hierarchical 라우팅 프로토콜을 사용하고 있다. 하지만 ZigBee Specification v1.0의 표준에서 사용하고 있는 이 두 가지 라우팅 프로토콜은 대규모의 센서네트워크에 적용하였을 때, 많은 단점들이 존재한다. 이러한 단점들은 센서네트워크가 가지고 있는 여러 가지 특성들을 고려하지 않은 일반적인 Adhoc 네트워크에서 사용하는 라우팅 프로토콜을 사용했기 때문이다. 따라서 본 논문에서는 이러한 단점들을 해결 할 수 있는 클러스터 기반의 라우팅 프로토콜을 제안한다.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.67-70
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• 2004

This paper describes and analyzes the performance of MB-OFDM (Multi-Band OFDM) technology that is suggested as one of standards in IEEE 802.15 TG3a for uwb application. Also the performance of newly proposed SFBC MB-OFDM scheme is compared with that of conventional MB-OFDM system in this paper. Simulation results show that SFBC MB-OFDM system outperforms conventional MB-OFDM system about 1.5dB Eb/No at target BER of $10^{-4}$.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1077-1080
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• 2006

IEEE 표준인 802.15.4와 ZigBee는 적어도 기술적으로는 우리의 삶에 언제어디서든지 네트워킹을 할 수 있게 해주는 청사진을 보여준다. 이것은 아주 간단하고, 본질적으로 네트워크에서 그 자체로만으로 작동하는 장치이고, 그리고 다수의 새로운 응용들을 적용할 수 있을 뿐만 아니라, 현재 존재하는 홈 네트워킹상의 다른 응용들에게 가치를 부여 할 수 있을 것이다.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.394-395
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• 2008

본 논문에서는 ZigBee (IEEE 802.15.4b Low-Rate Wireless Personal Area Network; LR-WPAN) 915MHz 대역 수신기에 주파수 옵셋에 따른 성능을 알아보고 수신기 Correlator에 Multiple delay differential filter를 적용하여 주파수 옵셋의 영향을 최소화하는 방법을 제시한다. AWGN 환경에서 주파수 옵셋의 영향이 최대와 최소(ZigBee frequency tolerance) ${\pm}80ppm$, $0{\sim}73200Hz$)일 때의 환경에서 시뮬레이션을 통해 제안한 수신기의 성능을 검증한다.