• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.28-33
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• 2007

In spite of the large interest in the 802.15.4 standard, no realistic experimental research of its behaviour exists to date except a few works by simulations and analytical modeling. In this paper, we have established realistic environment of IEEE 802.15.4 network and analyze its behaviour under various conditions as like 1) maximum throughput of 802.15.4 MAC, 2) MAC fairness. and 3) throughput and m rate under co-existence of 802.11 Wi-Fi wireless networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.774-776
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• 2014

노령층의 증가로 인하여 독거 노인층이 점점 증가하고 있다. 독거 노인은 외부의 침입이나 갑작스런 건강상의 문제로 위험에 처해질 가능성이 매우 높다. 따라서 독거 노인의 의료복지에 대한 관심이 날로 증가하고 있다. 본 연구에서는 독거 노인의 의료 복지에 적용할 수 있는 활동량 모니터링 시스템을 개발하였다. 이 시스템은 저 전력으로 동작하는 지그비 임베드 네트워크와 DTMF(Dual Tone Multi Frequency) 전화 시스템으로 구성되어, U-Health 케어 개념으로 활동량과 혈압 등의 인체 정보를 일상 생활 속에서 병원 및 보호자에게 전송할 수 있다. 또한 본 연구 결과는 미래의 독거 노인 원격진료 시스템에 적용될 수 있다.

• Annual Conference of KIPS
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• 2010.11a
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• pp.1300-1303
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• 2010

지그비 보안 인증 방법은 총 4가지가 있으며, 하나의 네트워크는 특정 인증 방법을 선택하여 그 인증방법을 통해서만 보안 인증이 가능하다. 이는 효율적이고 유연한 지그비 네트워크를 구성하는 데의 한계점으로 작용하기에, 본 논문에서는 현재 표준 인증 방법의 한계점과 동적 인증 방법의 필요성, 동적인증을 위한 표준 프로토콜 수정 내용을 제시한다. 이를 통해 타 네트워크와의 인증, 인증 방법의 다양성 부여를 통한 보안성 강화가 가능하다.

• Annual Conference of KIPS
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• 2007.11a
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• pp.819-822
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• 2007

최근 유비쿼터스 환경 실현을 위해서 무선 센서 네트워크에 관한 많은 연구가 진행되고 있다. IEEE 802.15.4 에 기반한 ZigBee 에 관한 연구는 이미 많은 진행이 되어 있다. 최근에는 IPv6 기술이 이슈화 되면서 무선 센서 네트워크 환경에도 IPv6 주소를 사용 할 수 있을 것으로 기대되고 있다. 본 논문에서는 IPv6 주소를 갖는 센서가 서비스를 제공하기만 하는 기존의 패러다임에서 벗어나 센서가 서비스를 찾는 모델을 제시한다. 그래서 IPv6 주소를 갖는 센서 네트워크의 보다 효율적인 서비스 디스커버리를 위해 객체 타입을 IPv6 주소의 일부분으로 정의해 준다. 이러한 객체타입을 이용한 IPv6 기반의 센서 네트워크의 효율성을 본 논문에서 검증한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.7
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• pp.1274-1292
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• 2011

Due to the variety of household electric devices and different power consumption habits of consumers at present, general home energy management (HEM) systems suffer from the lack of dynamic identification of various household appliances and a unidirectional information display. This study presented a set of intelligent interconnection network systems for electric appliances, which can measure the power consumption of household appliances through a current sensing device based on OSGi platform. The system establishes the characteristics and categories of related electric appliances, and searches the corresponding cluster data and eliminates noise for recognition functionality and error detection mechanism of electric appliances by applying the clustering algorithm. The system also integrates household appliance control network services so as to control them according to users' power consumption plans or through mobile devices, thus realizing a bidirectional monitoring service. When the system detects an abnormal operating state, it can automatically shut off electric appliances to avoid accidents. In practical tests, the system reached a recognition rate of 95%, and could successfully control general household appliances through the ZigBee network.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06d
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• pp.137-140
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• 2007

전력계통의 환경변화(분산전원 연계, 구역전기사업자 출연 등)에 능동적으로 대응할 소비자-공급자간 양방향 통신/서비스 인프라의 핵심으로 Consumer Energy Portal의 필요성이 점점 증대되고 있다. 이는 에너지 서비스 사업자와 수용가 설비 및 기기들 사이의 양방향 통신을 가능하게 하는 H/W 및 S/W의 결합 또는 수용가의 In-Building Network와 Wide-Access Network를 연결하는 물리적인 Link이자 논리적인 결합 등과 같은 의미를 지닌다. 즉, Consumer Energy Portal은 전력에너지 체인의 운영방식을 물리적인 것에서 웹 방식으로 전환한 것으로 전력사업자와 소비자 사이의 양방향 상호작용을 가능케 하고 최종 소비자의 모든 기기들을 서로 네트워킹하며 이를 통해 과거 물리적인 방식의 운영과는 차원이 다른 다양한 서비스와 운영이 가능하게 하는 Service Portal이다. 본 논문은 수용가의 실시간 원격검침 데이터를 지그비(ZigBee) 통신기술을 이용하여 수집하는 것과 물리적으로 연결된 설비들을 제어할 수 있는 양방향 Network Access 망을 구축하여 전력사업자의 통합자원관리, 수요관리, 부가서비스제공에 기여하고자 한다.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.2
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• pp.82-94
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• 2007

Wireless sensor networking technology is one of the basic infrastructures for ubiquitous environment. It enables us to gather various sensory data such as temperature, humidity, gas leakage, and speed from the remote sensor devices. To support these networking functions, IEEE WPAN working group makes standards for PHY and MAC, while ZigBee Alliance defines the standards for the network, security, and applications. The low-rate WPAN was emerged to have the characteristics of network resilience, low cost, and low power consumption. It has a broad range of applications including, but not limit to industrial control and monitoring, home automation, disaster forecast and monitoring, health care. In order to provide more intelligent and robust services, users want voice-based solutions to accommodate to low-rate WPAN. In this paper, we have evaluated voice quality of an IEEE 802.15.4 standard compliant voice node. Specifically, it includes the design of a voice node and experiments based on the prediction of voice quality using the E-model suggested by ITU-T G.107, and the network communication mechanisms considering beacon-enabled and nonbeacon-enabled networks for real-time voice communications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7A
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• pp.669-677
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• 2011

Superframe in IEEE 802.15.4 Standard is subdivided into an active period and an inactive period to reduce energy consumption. But communication nodes use same data transmission range in an active period, thus communication nodes spend a lot of energy to send data another nodes. In this paper, we proposed reduce energy consumption algorithm that nodes use different transmission power. Cordinator split transmission area into four group and transmit becon message to nodes. Nodes adjust transmission power according to becon message and wates lowe energy than normal nodes. We proposed energy-efficient cross layer protocol that have different PAN (Personal Area Network) by four range group.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.1
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• pp.149-156
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• 2016

In this experiment, we proposed and implemented a disease forecasting system using a received signal strength indication ZigBee-based wireless network with a 3-axis acceleration sensor to detect illness at an early stage by monitoring movement of experimentally infected weaned piglets. Twenty seven piglets were divided into control, Salmonella enteritidis (SE) infection, and Escherichia coli (EC) infection group, and their movements were monitored for five days using wireless sensor nodes on their backs. Data generated showed the 3-axis movement of piglets (X-axis: left and right direction, Y-axis: anteroposterior direction, and Z-axis: up and down direction) at five different time periods. Piglets in both infected groups had lower weight gain and feed intake, as well as higher feed conversion ratios than the control group (p<0.05). Infection with SE and EC resulted in reduced body temperature of the piglets at day 2, 4, and 5 (p<0.05). The early morning X-axis movement did not differ between groups; however, the Y-axis movement was higher in the EC group (day 1 and 2), and the Z-axis movement was higher in the EC (day 1) and SE group (day 4) during different experimental periods (p<0.05). The morning X and Y-axis movement did not differ between treatment groups. However, the Z-axis movement was higher in both infected groups at day 1 and lower at day 4 compared to the control (p<0.05). The midday X-axis movement was significantly lower in both infected groups (day 4 and 5) compared to the control (p<0.05), whereas the Y-axis movement did not differ. The Z-axis movement was highest in the SE group at day 1 and 2 and lower at day 4 and 5 (p<0.05). Evening X-axis movement was highest in the control group throughout the experimental period. During day 1 and 2, the Z-axis movement was higher in both of the infected groups; whereas it was lower in the SE group during day 3 and 4 (p<0.05). During day 1 and 2, the night X-axis movement was lower and the Z-axis movement was higher in the infected piglets (p<0.05). Overall, the movement of infected piglets was altered, and the acceleration sensor could be successfully employed for monitoring pig activity.

• Journal of Computing Science and Engineering
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• v.9 no.2
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• pp.83-97
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• 2015

IEEE 802.15.4 is a global standard designed for emerging applications in low-rate wireless personal area networks (LR-WPANs). The standard provides beneficial features, such as a beacon-enabled mode and guaranteed time slots for realtime data delivery. However, how to optimally operate those features is still an open issue. For the optimal operation of the features, this paper proposes a holistic optimization method that jointly optimizes three cross-related problems: cluster-tree construction, nodes' power configuration, and duty-cycle scheduling. Our holistic optimization method provides a solution for those problems so that all the real-time packets can be delivered within their deadlines in the most energy-efficient way. Our simulation study shows that compared to existing methods, our holistic optimization can guarantee the on-time delivery of all real-time packets while significantly saving energy, consequently, significantly increasing the lifetime of the network. Furthermore, we show that our holistic optimization can be extended to take advantage of the spatial reuse of a radio frequency resource among long distance nodes and, hence, significantly increase the entire network capacity.