• 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 Institute of Information and Telecommunication Facilities Engineering
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• v.11 no.1
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• pp.1-9
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• 2012

In this paper, we proposed a method of improving the location estimation error existing in RTLS (Real Time Location Service) system for the individual mobility. As ubiquitous age comes, interest for indoor location tracking system is getting more increased. However, existing indoor location tracking system does not correspond actively to frequent changes in indoor environment, and there is a problem that correct location measurement of moving object is difficult due to NLOS (non-line-of-sight) property of indoor environment. Purpose of this paper is to propose an environment accommodation location tracking system that improves the location precision of moving object and grasps location of the object effectively, which is essential an element effectively to provide service and satisfy various users' request.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.01a
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• pp.265-268
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• 2013

홈 네트워크 산업은 인간의 욕구와 맞물려 앞으로의 발전 가능성이 큰 분야이다. 미 가전협회의 조사에 따르면 소비자들도 홈 네트워크 시스템에 많은 관심을 가지고 있고, 애널리스트 샘 루세노는 "홈 오토메이션 시장은 해를 거듭할수록 규모가 커질 것이다."라고 예상하고 있다. 최근 네트워크 기술은 유선에서 무선으로 발전되고 있으며 홈 네트워크 서비스에는 유선보다 무선 네트워크 기술이 많이 쓰이고 있다. 본 논문에서는 각종 무선 네트워크 통신 기술에 대해 비교분석하고 홈 네트워크 서비스와의 연관성을 살펴보기 위하여 현재 홈 네트워크 서비스에 널리 사용되고 있는 무선 네트워킹 기술인 IEEE 802.11 무선랜 그룹과, IEEE 802.14.1의 블루투스 및 IEEE 802.14.5에 정의된 지그비 통신 기술에 대한 비교분석 한다.

• Journal of Sensor Science and Technology
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• v.20 no.5
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• pp.322-328
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• 2011

There are many ways to detect the heart rate non-invasively such as ECG, PPG, strain gauge, and pressure sensor. In this paper, the pulse wave measurement system using bipolar biased head on mode of the Hall sensor is proposed for measuring the radial artery pulse. TMS320F2812 was used to implement the proposed system and a portable wireless network(zig-bee) was used to show the experimental result. It was confirmed from experiment that the performance of the implemented system was more stable and faster than PPG sensor or piezoelectric film pressure sensor.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.1
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• pp.7-12
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• 2016

With due to the recent development of USN (Ubiquitous Sensor Network) technology, a monitoring system has been developing for assuring the structural integrity of infrastructure through normal or long term measurements during their lifetime. An accident such as a collapse of infrastructure may cause not only loss of life but also damage to the economy of the nation. In order to enhance the availability of infrastructure and to be able to maintain their lifetime, it is necessary to monitor and to evaluate continuously the structural integrity throughout their entire lifetime. The purpose of this paper is to develop a monitoring system integrated with evaluation function based on the ubiquitous technology. The most essential part of this study is focusing more on developing a specific module convertible to A/D, which is to enhance the applicability of sensors that had not been applied to existing monitoring systems. Conclusively it has been successfully enhanced to make more diverse the number of sensors and measuring techniques for the monitoring system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1937-1938
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• 2008

본 논문에서는 868/915MHz 대역 IEEE 802.15.4b LR-WPAN(Low-Rate Wireless Personal Area Network; ZigBee)시스템의 수신기를 위한 주파수 옵셋 영향을 감소시키는 알고리즘을 제안한다. 저가 구현을 지향하는 LR-WPAN 시스템의 특성에 맞추어 반송파 중심주파수의 $\pm$80ppm에 해당하는 주파수 옵셋 환경에서 안정된 수신을 보장할 수 있는 알고리즘으로 868/915MHz수신기 Correlator에 multiple delay differential filter를 적용함으로써 주파수 옵셋에 대한 강인성 및 수신 성능의 안정성을 증대시켰다.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.2
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• pp.67-72
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• 2014

Zigbee is a wireless communication technology optimized for Wireless Sensor Network environment. Implementation of location estimation system is based on Zigbee. In this paper, we implement mobile information system using zigbee technology. The proposed system is composed of mobile terminal software and mobile reader softwrae. We also used our hardware in previous system.

• 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.

• 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.

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.3
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• pp.1-8
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• 2008

Recently, a great many people are concerned about promoting their health because medical science and scientific technology has become much larger and more develop. Thus, the person who interested in health wants to confirm his condition whatever he may take a meal or exercise. But it is disappointed of our expectation. By reason that many people doesn't know what changes will occur in their body. In this paper, we are going to introduce our Health Care Managing System which could display a physical variation, in addition, we will also propose how to control serial data from wireless sensors. We implemented this system using ZigbeX and Java application.