• 한국정보통신학회논문지
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• 제14권9호
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• pp.2127-2133
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• 2010

본 논문에서는 범용 운영체제에서 제공하는 디바이스 투명성을 센서노드 운영체제에 적용한 센서 투명성 아키텍처를 제안하였다. 센서 투명성을 지원하기 위한 표준 API와 센서 디바이스 추상화를 설계하고 TinyOS 운영체제에서 구현하였다. 본 논문에서 제안한 센서 투명성 지원 센서노드 운영체제를 사용하면 응용 개발자는 운영체제에서 제공되는 표준 API를 통해 센서 디바이스에 독립적으로 응용 프로그램을 개발할 수 있고, 센서 디바이스 공급자 또한 표준화된 하드웨어 인터페이스와 HAL 인터페이스를 통해 센서노드 하드웨어 플랫폼에 독립적으로 센서 디바이스 드라이버를 개발하고 공급할 수 있다.

• 전자공학회논문지CI
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• 제44권5호
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• pp.28-37
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• 2007

IEEE 1451 standard는 네트워크와 transducer간에 표준 interface를 정의한다. 본 논문에서는 IEEE 1451 Standard 기반의 data acquisition system과 무선 smart sensor node를 구성하기 위한 구조적인 모델을 제안한다. 제안 된 Network Capable Application Processor(NCAP)은 data acquisition의 역할과 smart sensor node와 네트워크 사이에 가교 역할을 한다. 또한 무선 sensor node에게 영향을 주지 않으면서 재구성이 가능하고 DB를 이용하여 transducer의 정확한 정보를 얻는다. Smart sensor node는 그 자신에 관한 기본적인 정보를 디지털 형식으로 제공하는 능력을 가지고 있다. 이 디지털 형식은 Transducer Electronic Data Sheet(TEDS)라 하며 sensor node의 plug-and-play 기능을 가능하게 한다. IEEE 1451.4에서 정의하고 있는 TEDS와 Template를 무선 환경에서 적용하기 위해 형식을 간략화 하였으며 ad-hoc routing을 통해 전송이 이루어진다. 본 연구 시스템은 의료정보 서비스를 제공하기 위한 목적으로 체온과 ECG(Electrocardiogram) 센서를 사용하였다. Template 형식은 센서들의 data sheet를 통해 결정하였으며 센서의 특징을 정확히 표현하기 위해 재구성하였다. NCA의 DB는 다양한 센서 개발에 따라 새로운 Template 및 하부 항목의 등록이 가능하도록 구현하였다.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.689-709
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• 2010

In this paper, a low cost, low power but multifunctional wireless sensor node is presented for the impedance-based SHM using piezoelectric sensors. Firstly, a miniaturized impedance measuring chip device is utilized for low cost and low power structural excitation/sensing. Then, structural damage detection/sensor self-diagnosis algorithms are embedded on the on-board microcontroller. This sensor node uses the power harvested from the solar energy to measure and analyze the impedance data. Simultaneously it monitors temperature on the structure near the piezoelectric sensor and battery power consumption. The wireless sensor node is based on the TinyOS platform for operation, and users can take MATLAB$^{(R)}$ interface for the control of the sensor node through serial communication. In order to validate the performance of this multifunctional wireless impedance sensor node, a series of experimental studies have been carried out for detecting loose bolts and crack damages on lab-scale steel structural members as well as on real steel bridge and building structures. It has been found that the proposed sensor nodes can be effectively used for local wireless health monitoring of structural components and for constructing a low-cost and multifunctional SHM system as "place and forget" wireless sensors.

• 센서학회지
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• 제16권5호
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• pp.361-368
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• 2007

Small size real-time ECG signal analysis function by QRS-complex detection was put into sensor nodes. Wireless sensor nodes attached on the patient’s body transmit ECG data continuously in normal u-healthcare system. So there are heavy communication traffics between sensor nodes and gateways. New developed platform for real-time analysis of ECG signals on sensor node can be used as an advanced diagnosis and alarming system for healthcare. Sensor node does not need to transmit ECG data all the time in wireless sensor network and to server PC via gateway. When sensor node detects suspicion or abnormality in ECG, then the ECG data in the network was transmitted to the server PC for further powerful analysis. This system can reduce data packet overload and save some power in wireless sensor network. It can also increase the server performance.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.147-151
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• 2005

CAN(Controller Area Network) is a simple and efficient network system for real time control and measurement. As it is not only good at error detection but also strong in electromagnetic interference, CAN has been widely used all over the industries. Basically, CAN needs a master node in charge of sensor data collection, node scheduling for data transmission to a monitoring system and error detection. According to the number of mater nodes, the CAN system is classified into two type of master system. One is a single master system that has only one master node and the other is a multi-master system where any sensor node can become a master node depending on the system's conditions. While it has the advantage of its fault tolerance, the multi-master system will suffer form the overall performance degradation when a defect is found in the master node. It is because all sensor nodes pertaining to a defective master node lose their position. Moreover, it is difficult and expensive to implement. For a single master system, the whole system will be broken down when a problem happens to a single master. In this paper, a dynamic master system is presented that there are several sub-master nodes of which basic functions are those of other sensor nodes at ordinary times but dynamically changed to replace the failing master node. An effective scheduling algorithm is also proposed to choose an appropriate node among sub-master nodes, where each sub-master node has its precedence value. The performance of the dynamic master system is experimented and analyzed.

• Journal of Information Processing Systems
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• 제16권5호
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• pp.1158-1168
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• 2020

The distance vector-hop wireless sensor node location method is one of typical range-free location methods. In distance vector-hop location method, if a wireless node A can directly communicate with wireless sensor network nodes B and C at its communication range, the hop count from wireless sensor nodes A to B is considered to be the same as that form wireless sensor nodes A to C. However, the real distance between wireless sensor nodes A and B may be dissimilar to that between wireless sensor nodes A and C. Therefore, there may be a discrepancy between the real distance and the estimated hop count distance, and this will affect wireless sensor node location error of distance vector-hop method. To overcome this problem, it proposes a wireless sensor network node location method by modifying the method of distance estimation in the distance vector-hop method. Firstly, we set three different communication powers for each node. Different hop counts correspond to different communication powers; and so this makes the corresponding relationship between the real distance and hop count more accurate, and also reduces the distance error between the real and estimated distance in wireless sensor network. Secondly, distance difference between the estimated distance between wireless sensor network anchor nodes and their corresponding real distance is computed. The average value of distance errors that is computed in the second step is used to modify the estimated distance from the wireless sensor network anchor node to the unknown sensor node. The improved node location method has smaller node location error than the distance vector-hop algorithm and other improved location methods, which is proved by simulations.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2009년도 추계학술발표논문집
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• pp.190-193
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• 2009

무선 센서 네트워크에서 가장 중요하고 기본적인 요소는 환경 정보를 수집하고 이를 사용자 응용시스템에 전송하는 무선 센서 노드이다. 무선 센서 노드는 센서로 환경 정보를 수집하고 이를 저장, 가공하여 처리된 데이터를 사용자에게 전송하는 무선 송수신 장치로 기술의 발전에 따라 소형화, 지능화되고 있다. 특히 마이크로컨트롤러, RF 모듈, 메모리 등을 하나의 칩 내부에 모두 통합하는 SoC(System-on-Chip)기술은 센서 노드의 소형화와 제조 단가를 낮추는데 중요한 역할을 한다. 본고에서는 상용 SoC를 사용하여 무선 센서 네트워크를 위한 소형 무선 센서 노드를 설계하였으며 이를 이용한 여러 활용 방안 및 추가적인 고려사항에 대하여 논하였다.

• 센서학회지
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• 제14권3호
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• pp.198-205
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• 2005

Recently, the systems using multiple sensors such as magnetic, acoustic and pressure sensor are used for detection of underwater objects or vehicles. Those systems have difficulty of maintenance and repair because they operate underwater. Thus, this paper describes a hybrid detection system with long term operating reliability. This has a multi-signal transmission structure to have a high reliability. First, a signal transmission & receiving part, which transfers data from underwater sensors to land and receive control message from land through optical cable, has 4 multi-path. Second, the nodes for signal transmission are connected dually each other with single-hop construction and sensors are connected to a couple of neighboring nodes. This enables the output signal to transmit from a node to the next node and the next but one node together. Also, the signal from a sensor can be transmitted to two nodes at the same time. Therefore, the system with this construction has high reliability in long term operation because it makes possible to transmit sensor data to another node which works normally although a transmission node or cable in system have some faults.

• 대한임베디드공학회논문지
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• 제1권2호
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• pp.37-42
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• 2006

In this paper, we study a problem of providing reliable data transmission in wireless sensor network(WSN). A system with forward error correction9FEC) can provide an objective reliability while using less transmission power than a system without FEC. We propose the use of LDPC codes of various code rate (0.53, 0.81, 0.91) of FEC for WSN. Node-node-node interference is considered in the simulation in addition to AWGN in the channel. It is shown that the rate of 0.91 LDPC coded system obtained 7dB gain in signal to noise ratio over a system without FEC.

• 제어로봇시스템학회논문지
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• 제19권3호
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• pp.268-274
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• 2013

In this paper, the performance analysis of optics-based sensor node localization using ToF (Time of Flight) scheme is conducted. Generally, the position of the sensor node is calculated on the base station. And the base station scans neighboring sensor nodes with a laser. The laser which is reflected from one sensor node, however, can be reached to the base station at different angles according to the scanning resolution. This means that the error of the reached angle can increase and one node may be recognized as different nodes. Also the power of laser can decrease because the laser signal spread. Thus the sensor node which is located at a long distance from the base station cannot be detected. In order to overcome these problems which can be occurred in localization using ToF, the beam spot, the scanning resolution, the size of reflector and the power of laser at the sensor node were analyzed. It can be expected that the consequence of analysis can be provided in acquisition of accurate position of sensor node and construction of optics-based sensor node localization system.