• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.349-351
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• 2003

무선 센서 네트웍은 동작 환경과 구조가 매우 특이하du 개발자들은 센서 네트웍의 노드를 디자인할 때 많은 제약 조건들과 요구 조건들을 고려해야 한다. 먼저 우선 센서 네트웍 상의 각 센서 노드에는 극도로 제한된 하드웨어 자원 조건 하에서도 무선 통신 기능뿐만 아니라 동시에 여러 이벤트를 재빠르게 처리할 수 있는 기능이 포함되어야 한다. 또한 환경과 응용 프로그램의 변화에 잘 대처하기 위해 런타임(run-time)에 각 센서 노드들을 동적으로 재구성할 수 있는 기능이 제공되어야 한다. 이러한 디자인 요구 조건들과 제약 조건들은 얼핏 서로 상반된 것처럼 보이는데, 무선 센서 노드들을 위한 실행 환경을 디자인할 때는 이러한 조건들을 모두 만족시킬 수 있는 운영 체제가 반드시 필요하다. 본 논문에서 우리는 무선 센서 노드들을 위한 매우 효율적이고 효과적인 유한 상태 머신(finite state machine) 기반의 운영체제, SenOS를 제안한다. 또한 새로운 운영 체제인 SenOS가 극도의 제한적인 자원에서도 동시성과 반응성, 재구성성의 요구 조건을 모두 만족시키면서 동작할 수 있다는 것을 보일 것이다.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.35-44
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• 2008

In this study, to establish a web-based bridge monitoring system with wireless sensor network environment, we constructed microminiaturized sensor based wireless communication techniques and micro processing, databases for data combination and administration, variable control programs and processors for transferring data by internet. Then those data are measured and analyzed by the constructed bridge monitoring system with wireless sensors. To evaluate the practicability of the bridge monitoring system with wireless sensor, we compared the values measured in the tests with wire sensor under same conditions. The results show that the trend of the data obtained from the monitoring systems with wire sensors and wireless sensors was very similar but the some lost data in the communication process with wireless sensor network environment. And through laboratory and field tests, the effectiveness and the applicability of the proposed methods were verified.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.160-162
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• 2006

현재 국내에서는 안전 운전 서비스 및 교통정보 수집체계 구축에 USN 기술을 적용하기 위한 다양한 연구와 시범사업이 추진되고 있다. 텔레매틱스 교통안전시스템[1][2]은 교차로 주변의 도로 위에 무선 센서 노드를 부착하여 무선 센서 노드 위를 지나는 차량들의 정보(속도, 위치, ID 등)를 수신하여 무선 센서 네트워크를 이용해 교차로 중앙에 위치한 베이스 스테이션으로 전송하고, 베이스 스테이션은 이렇게 실시간으로 수집한 정보를 분석하여 얻은 차량안전 운전정보를 교차로에 접근하는 차량들에게 브로드캐스팅하여 차량충돌을 회피하도록 하는 시스템이다. 본 논문에서 다루는 텔레매틱스 교통안전시스템은 Telematics Scheduling Protocol(TSP)[1]을 무선 센서 노드간 통신 프로토콜로 사용하는데 무선 센서 네트워크 특성상 온도, 날씨 등의 주변환경에 의해 노드간 통신에 있어서 높은 데이터 전송 에러율을 가지고 있다. 본 논문에서는 무선 센서 네트워크 프로토콜로 TSP를 사용하는 교통안전시스템에서 무선 데이터 전송 에러율, 교차로를 지나가는 차량의 숫자 그리고 도로 표면에 부착된 고정노드간 거리변화가 성능에 미치는 영향을 파악하기 위하여 네트워크 시뮬레이터 ns-2[3]를 이용해 시뮬레이션한다.

• The KIPS Transactions:PartC
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• v.19C no.3
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• pp.209-214
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• 2012

Time synchronization is important role in a network, especially in Wireless Sensor Network (WSN) which is required for time-critical applications such as surveillance, tracking, data fusion and scheduling. Time synchronization in WSN should meet the other different requirements than the one in other networks because WSN has critical resource constraints, especially power consumption. This paper presents a new time synchronization scheme for WSN, which is energy efficient by reducing communication overhead. Simulation test shows this new scheme has better energy efficiency and performance of accuracy than existing schemes proposed previously.

• Journal of Convergence Society for SMB
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• v.4 no.4
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• pp.1-6
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• 2014

A wireless sensor network is being actively researched around the world that are connected to the mesh are a plurality of sensor nodes in a wireless manner that span different regions of the techniques. However, wireless communications use the limitation of resources, so it is very weak due to the properties of the network itself secure in comparison to the normal network. Wireless sensor network is divided into tapped-based attacks, forgery based attacks, denial of service attacks based largely by securities laws must defend against various attacks such as insertion of the wrong information being sent eavesdropping or modification of information, which is usually sensor network applications need to do. The countermeasure of sensor network attack is described in this research, and it will contribute to establish a secure sensor network communication.

• Journal of KIISE:Information Networking
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• v.35 no.1
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• pp.21-33
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• 2008

The wireless sensor nodes near to the fixed sink node suffer from the quickly exhausted battery energy. To address this problem, the mobile sink node has been applied to distribute the energy consumption into all wireless sensor nodes. However, since the mobile sink node moves, the data collection scheduling scheme is necessary for the sink node to receive the data from all sensor nodes as fair as possible. The application fields of wireless sensor network need the real-time processing. If the uneven data collection occurs in the wireless sensor network, the real-time processing for the urgent events can not be satisfied. In this paper, a new method is proposed to support the lair data collection between all sensor nodes. The proposed method performs the scheduling algorithm based on the resident time of the sink node staying in a radius of communication range and the amount of data transferred already. In this paper, the proposed method and existing data collection scheduling schemes are evaluated in wireless sensor network with the mobile sink node. The result shows that the proposed method provides the best fairness among all data collection schemes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.858-861
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• 2012

Distributed sensor nodes for environmental monitoring, have a problem of difficult and expensive battery change. In this case, renewable energy such as solar energy is helpful. We can use high-quality solar energy everyday. In this paper, we model photovoltaic energy prediction model for sensor nodes, which includes charge and discharge characteristics as well as seasonal and monthly characteristics of the solar energy. Our model is useful to predict energy consumption of solar-powered sensor nodes realistically using real world use data of the nodes.

• Journal of Korea Multimedia Society
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• v.14 no.7
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• pp.949-963
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• 2011

Generally, It is indispensible to use an ISP(In System Programming) tool for upgrading, patching, or changing the system software of the each sensor nodes in wireless sensor networks. While under a small number of nodes, the upgrading task is not a serious burden, however if there are a large number of nodes to be updated, the task is almost impossible to do for the given constrains such as limited budgets and resources. Based on this observation, in this paper we have proposed a novel upgrading scheme based on a single hop in IEEE 802.15.4 PAN(Personal Area Network)s. Simulation results have shown the scheme outcomes the conventional methods in the performance measures.

• Journal of KIISE:Information Networking
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• v.36 no.6
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• pp.505-513
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• 2009

In some wireless sensor networks, each wireless sensor network has its own target lifetime (desired lifetime after deployment). However, satisfying the target lifetime is not a trivial problem since the nodes in wireless sensor networks often rely on batteries as their power source. In this paper, we propose an energy efficient routing algorithm that satisfies the target-lifetime requirement of a wireless sensor network. The proposed routing algorithm not only finds energy efficient paths but also optimizes the sensing rate of each sensor node. Through simulation, we compare the performance of the proposed scheme with several other existing algorithms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.402-403
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• 2014

Micro-magnetic detection system is used to detect small particles in an automatic transmission valve body, which signal noise and time-delay may occurs in process of signal transmitting and filtering. In this paper, we present the design and implement of a micro-magnetic detection system based on wireless sensor networks. Micro-magnetic detection system consists of five modules which are magnetic sensor detector, signal processing unit, wireless sensor networks, system control unit and system monitoring unit. The experimental results show that signal noise and time-delay decreased.