• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.1
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• pp.18-23
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• 2009

The conventional channel selection method for a ZigBee communication network basically detects the energy values in all channels. In the ISM band, no license is required to use channels in this band, so there may exist various interference factors in this band. It is well known that WLAN is the major interference factor degrading the performance of ZigBee in the ISM band. In this paper, we propose an efficient channel selection algorithm which uses the pattern of two types of WLAN channel uses as the a priori information of IEEE 802.11 band IEEE 802.11g. By using the proposed algorithm, we may save the time required to select channels for the ZigBee communications.

• Journal of Korea Multimedia Society
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• v.11 no.6
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• pp.835-844
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• 2008

ZigBee devices are limited in resources especially on power and computational capacity but also require real-time operation at MAC layer. Therefore, it is important to take those requirement into consideration of system software design. In this paper, we proposed a compact system software design to support simultaneously ZigBee and IEEE802.15.4. The design strictly respects the resource and real-time constraints while being optimized for specific functions of both Zigbee and IEEE802.15.4. Various evaluations are done to show significant metrics of our design.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.695-697
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• 2012

Zigbee와 같은 무선 네트워크에서 전력 절감을 위하여서는 슈퍼프레임을 구성하는 비콘주기내에서 액티브구간과 인액티브구간으로 운용될 시 전력 소모를 줄이기 위하여 네트워크의 트래픽 특성과 부하 정도에 따라 액티브 구간을 적응 제어하는 방법이 제안되었다. 제안 방법에 따른 성능을 분석하여 전력 소모가 감소하여 보다 효과적인 센서 네트워크를 구축할 수 있음을 보인다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.724-730
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• 2015

The safety-related accident in which the field operators of all sorts of industrial sites don't fasten the seat belt properly and which it generates is the tendency that it increases constantly every year. By sounding the announcement sound in case the operator did not fasten the seat belt and the person seat belt monitoring system proposed in this paper progressed the work the operator fastened the seat belt properly. In addition, at the same time with that, since the administrator monitored the seat belt wearing or no of the operators on a real time basis the safety-related accident which did not wear the safety equipment properly and which it generates was prevented.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.262-265
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• 2009

최근 각광받고 있는 위치기반 서비스의 모델인 긴급 SOS 시스템은 기지국망을 이용한 광역위치추적과 IEEE 802.15.4를 기반으로 하는 근거리 위치추적 시스템이 결합된 새로운 형태의 하이브리드형 위치추적 기법이다. 본 시스템에서 근거리 위치추적 범위를 정확히 추정하는 것은 중요한 이슈라 할 수 있다. 따라서 본 논문에서는 IEEE 8020.15.4를 기반으로 하는 Zigbee 통신방식을 추정 할 수 있는 최대 거리를 log distance model과 two ray ground 모델을 기반으로 추정 하였다.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.11-14
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• 2009

유비쿼터스도시서비스에서의 가장 핵심적인 기술을 유비쿼터스도시서비스를 제공하기 위하여 설치된 도시기반시설물과 도시기반시설물로터 정보를 수집하고, 시설물을 관리하기 위하여 설치된 센서이다. 시설물에 설치된 센서는 USN으로 연결되어서 도시통합운영센서와 통신을 하여 센서로부터 수집된 정보를 전송한다. 도시통합운영센터에서는 USN을 통해서 센서 또는 시설물을 제어한다. 이러한 USN에는 Zigbee, 6LoWPAN등 센서의 특징에 따른 프로토콜이 있고, 유선네트워크, 무선네트워크 등을 통해서 USN의 네트워크를 구성한다. 본 논문에서는 유비쿼터스도시의 시설물 관리를 위해서 사용되어지는 센서 및 USN의 특성을 분석하고, 센서 및 USN의 다양성에서 발생하는 문제점을 분석하고 이를 해결하기 위한 방안을 제시하고자 한다.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.162-164
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• 2009

IEEE 802.15.4에서 채널 간 충돌을 회피하기 위해 제안된 CSMA/CA 알고리듬은 수신되는 신호의 상관관계를 나타내는 지표인 LQI (Link Quality Indicator) 값과 수신되는 신호의 크기를 나타내는 지표인 RSSI (Received Signal Strength Indicator) 값을 이용한다. 지그비 모듈에서 측정되는 LQI 값은 수신되는 신호의 크기에 따라 변화하는데, 그 상관관계가 매우 부정확한 문제가 있어 왔다. 본 논문에서는 CC2430과 CC2591을 이용해 제작된 지그비 모듈을 기반으로 수신 신호의 크기와 LQI 값을 실험적으로 측정하여 RSSI 값에 따른 LQI 값의 상관관계를 분석하였다.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.55-58
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• 2008

This article describes power supply infrastructure construction methods which are considered from U-City infrastructure. For the eisting city and town, it is one the issue to find an economic method to construct outside infrastructure including ubiquitous service device. Because the economic construction method could minimize the construction budget which cost big portion of U-City. And the power supply infrastructure is the fundamental layer to keep network and service layer stable. This paper suggests several ways to construct methods with keeping pre-constructed underground power cable by attaching inepensive power nodal controller working in zigbee network and introduces how to monitor and mana ge the status of power supply to network and service device.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.265-269
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• 2008

Home health care with compact wearable units sounds to be a convenient solution for the elderly people living independently. This paper presents a method to detect fall from the other activities of daily living and also to classify those activities. This kind of ambulatory monitoring enables them to get an emergency help in the case of the fatal fall event and can provide their general health status by observing the activities being performed in daily life. A tri-axial accelerometer sensor is used to get the acceleration anomalies associated with the user's movements. The three axis acceleration data are transferred to the base station sensor node via an IEEE 802.15.4 compliant zigbee module. The base station sensor node sends the data to base station PC for an offline processing. This work shows the feature set preparation using the principal component analysis (PCA) for the designing of neural network. The work includes the most common activities of daily living (ADL) like Rest, Walk and Run along with the detection of fall events from ADL. The angle from the vertical is found to be the most significant feature parameter for classification of fall while mean, standard deviation and FFT coefficients were used as the feature parameter for classifying the other activities under consideration. The accuracy for detection of fall events is 86%. The overall accuracy for ADL and fall is 94%.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.116-120
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• 2008

The conventional channel selection method for a ZigBee communication network basically detects the energy values in all channels. In the ISM band, no license is required to use channels in this band, so there may exist various interference factors in this band. It is well known that WLAN is the major interference factor degrading the performance of ZigBee in the ISM band. In this paper, we propose an efficient channel selection algorithm which uses the pattern of WLAN channel uses as the a priori information. By using the proposed algorithm, we may save the time required to select channels for the ZigBee communications.