• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1477-1483
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• 2020

The stability guarantee of wireless network based control systems is still challenging due to the lossy links and node failures. This paper proposes a hierarchical cluster-based network protocol called robust wireless sensor and actuator network (R-WSAN) by combining time, channel, and space resource diversity. R-WSAN includes a scheduling algorithm to support the network resource allocation and a control task sharing scheme to maintain the control stability of multiple plants. R-WSAN was implemented on a real test-bed using Zolertia RE-Mote embedded hardware platform running the Contiki-NG operating system. Our experimental results demonstrate that R-WSAN provides highly reliable and robust performance against lossy links and node failures. Furthermore, the proposed scheduling algorithm and the task sharing scheme meet the stability requirement of control systems, even if the controller fails to support the control task.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.7
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• pp.1585-1609
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• 2013

Over recent years, enormous amounts of research in wireless sensor networks (WSNs) have been conducted, due to its multifarious applications such as in environmental monitoring, object tracking, disaster management, manufacturing, monitoring and control. In some of WSN applications dependent the energy-efficient and link reliability are demanded. Hence, this paper presents a routing protocol that considers these two criteria. We propose a new mechanism called Reliable Routing Scheme for Energy-Balanced (RRSEB) to reduce the packets dropped during the data communications. It is based on Swarm Intelligence (SI) using the Ant Colony Optimization (ACO) method. The RRSEB is a self-adaptive method to ensure the high routing reliability in WSNs, if the failures occur due to the movement of the sensor nodes or sensor node's energy depletion. This is done by introducing a new method to create alternative paths together with the data routing obtained during the path discovery stage. The goal of this operation is to update and offer new routing information in order to construct the multiple paths resulting in an increased reliability of the sensor network. From the simulation, we have seen that the proposed method shows better results in terms of packet delivery ratio and energy efficiency.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.151-156
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• 2013

The experiment was done on cars travelling at the speeds of 20km/h, 60km/h and 100km/h using the performance testing mode for chassis dynamometer. In this experiment, the relativity between the secondary waveform coming from ignition coil and exhaust emissions were measured in case of cars with failures, in oxygen sensor, spark plugs. The following results obtained by analysis of the relativity between the secondary waveform and exhaust emissions. 1) When the oxygen sensor is failure, the average value of CO emission measured was 6.8 times higher than the standard CO emission value and the average value of HC emission measured was 2.3 times higher than the standard emission level. 2) When engine parts are in failure, more fuel enters the cylinder due to longer opening duration of injector, and it tended to make CO and HC emission values increase. 3) Combustion duration, the shape of flame propagation during spark line, and the size of the discharge-induced energy were the three main elements that directly cause variations in CO and HC emission values.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.6
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• pp.710-715
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• 2006

With recent advances in device fabrication technology, economical deployment of large scale sensor networks, a design of pervasive monitoring and control system has been made possible. In this paper, we present a new algorithm for one of the most likely applications for sensor networks; tracking moving targets. The proposed algorithm uses a cooperations between the sensor nodes which detect moving objects. Therefore, the proposed scheme is robust against prediction failures which may result in temporary loss of the target. Using simulations we show that tile proposed moving object tracking algorithm is capable of accurately tracking targets with random movement patterns.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.175-177
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• 1995

The sensor signal validation and failure detection system must be able to detect, isolate, and identify sensor degradation as well as provide a reconstruction of the measurements. In this study, this is accomplished by combining the neural network, the Generalized Consistency Checking(GCC), and the Sequential Probability Ratio Test(SPRT) method in a decision estimator module. The GCC method is a computationally efficient system for redundant sensors, while the SPRT provides the ability to make decisions based on the degradation history of a sensor. The methodology is also extended to the detection of noise degradation. The acceptability of the proposed method is demonstration by using the simulation data in safety injection accident of nuclear power plants. The results show that the signal validation and sensor failure detection system is able to detect and isolate a bias failure and noise type failures under transient conditions. And also, the system is able to provide the validated signal by reconstructing the measurement signals in the failure conditions considered.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1879-1884
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• 2007

In the electric power industry, it is important that the supply of energy must be guaranteed. Many power utilities control and supervise the transmission line to avoid power failures. In case of underground tunnel, some troubles are reported in cable joint. To stabilize the power, it is needed to monitor the cable joint. Many researches of cable joint monitoring have been going on by partial discharge measurement and temperature measurement using optical cable. These methods need much cost to install and maintain, so it is only used in critical transmission line. In this research, we use wireless sensor technology, because of its low cost and easy installation. We develop the temperature monitoring system for cable joint. Temperature sensor is installed on the surface of cable joint and sends data to server through router node using wireless network. Generally Ad hoc routing is searched in wireless network. However, in this research, we design the static linear routing mechanism, which is suitable for electric power line monitoring and analyze the life time of the sensor node by measuring the amount of the battery consumption.

• Structural Monitoring and Maintenance
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• v.1 no.2
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• pp.183-195
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• 2014

Scour is one of the leading causes of overwater bridge failures worldwide. While monitoring systems have already been implemented or are still being developed, they suffer from limitations such as high costs, inaccuracies, and low reliability, among others. Also, most sensors only measure scour depth at one location and near the pier. Thus, the objective is to design a simple, low cost, scour hole topography monitoring system that could better characterize the entire depth, shape, and size of bridge scour holes. The design is based on burying a robust, waterproofed, piezoelectric sensor strip in the streambed. When scour erodes sediments to expose the sensor, flowing water excites it to cause the generation of time-varying voltage signals. An algorithm then takes the time-domain data and maps it to the frequency-domain for identifying the sensor's resonant frequency, which is used for calculating the exposed sensor length or scour depth. Here, three different sets of tests were conducted to validate this new technique. First, a single sensor was tested in ambient air, and its exposed length was varied. Upon verifying the sensing concept, a waterproofed prototype was buried in soil and tested in a tank filled with water. Sensor performance was characterized as soil was manually eroded away, which simulated various scour depths. The results confirmed that sensor resonant frequencies decreased with increasing scour depths. Finally, a network of 11 sensors was configured to form a distributed monitoring system in the lab. Their exposed lengths were adjusted to simulate scour hole formation and evolution. Results showed promise that the proposed sensing system could be scaled up and used for bridge scour topography monitoring.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.201-209
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• 2009

In power plant operations, sensor values often exhibit erroneous values due to their failures or the intrusions of various noises. However, most of the power plant monitoring and fault diagnosis systems perform their tasks based on the assumptions that the collected sensor values are correct all the times. These assumptions, which are not valid, often lead to serious consequences such as power plant trips. In this paper, we propose a power plant sensor value validation technique that can utilize the relationships existing among the sensor values as the sensor redundancy. The proposed technique is applied to the flow meters installed along boiler feed water systems of a typical tubular type boiler thermal power plant and shows a good potential of future applications.

• Journal of IKEEE
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• v.13 no.2
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• pp.108-117
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• 2009

In recent years, one of alternatives for constructing RFID networks that provide mobile services is using wireless sensor networks (WSN) to enhance network capacity, utility and scalability. Due to absence of compatible reader anti-collision control and channel capture phenomenon, the medium access control protocols as used in the RFID networks lead to reader collision and starvation problem. In this paper, we develop a MAC protocol which is called Enhanced Collision Avoidance MAC (ECO) to avoid reader to reader collisions in an integrated RFID network. ECO is a CSMA-based MAC protocol, and operates on integrated nodes which consist of a RFID reader and a mote. Performance evaluation shows superior results to pure-CSMA protocols under dense deployment environments, both in number of failures and in throughput.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.211-217
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• 1999

감지기의 고장 발견, 확인, 보완은 복잡한 항공 시스템의 중요한 문제로 부각되어 왔으며, 그동안 칼만 필터를 이용한 기존 추정기술 혹은 온라인 학습 인공지능 알고리듬 등이 이 같은 문제를 해결하기 위해 제시되어 왔다. 본 연구에서는 여분의 감지기가 없는 항공제어계에 대해 온라인 학습 신경망을 이용한 감지기의 고장 발견, 확인, 그리고 보완에 관해 초점을 둔다. 이 내고장성 항공제어계는 주 신경조직망과 n개의 국소 신경조직망으로 이루어지는데, 포괄적인 감지기의 고장을 발견하는 능력을 가진다. 어떤 경우에서는 기존의 감지기 고장 발견 방법의 성능을 향상시키기 위해 수정된 감지방법이 소개되고 그 보완된 감지방법을 이용하여 기존의 방법과 성능비교가 이루어졌다.