Myung-Hyun Yoon

The Implementation of Indoor Location System to Control ZigBee Home Network

This paper implements the indoor location system to control ZigBee home network. Indoor location system requires periodic update data from a location information service to determine the users current position data. This paper implements the indoor location home control system which uses ZigBee. We have implements IPS-M (indoor position system-M), IPS-I (indoor position system-infrastructure), IPS-G (indoor position system-gateway) to indoor location based home control system. The IPS-I device has active beacons that periodically transmit signals to a passively listening IPS-M device, which in turn estimates distances to the beacons. Because the active mobile architecture receives simultaneous distance estimates at multiple receivers from IPS-M device, it is likely to perform better tracking than the passive mobile system in which the device obtains only one distance estimate at a time and may have moved between successive estimates. In the IPS-M (Indoor Position System-Mobile) architecture receives wireless signals (e.g., radio and ultrasound) from an IPS-I (indoor position system-infrastructure) device, allowing the IPS-I to track the IPS-M. We implements ZigBee stack to control home network system with indoor location data

Design of online auto-tuning PID controller for power plant process control

In the power plant process control, classical PID controllers are widely used. In order to obtain the desired control performances, the correct tuning of PID controllers is very important. In this paper, a new auto-tuning method of PID controller without using the test signal generator has been developed. This method uses only the measured process output and controller output signals to identify the unknown control process. From the estimated process model, a controller design rule is derived such that it minimizes the average mean squared error between the desired closed-loop step response and that of the control system. Since it is possible to estimate the process without using any special test signal generator, this method can be applied to the safety-related processes such as nuclear power plant control system.

Automatic tuning algorithm of the PID controller using two Nyquist points identification

This paper deals with an advanced automatic tuning algorithm of the PID controller using two Nyquist points identification. The critical point on the Nyquist plot and its neighboring point are identified from the modified relay feedback experiment and used to make the formulas to determine the parameters of the PID controller. The formulas are derived from the dominant poles approximation and placement method. We can consider the time domain response of the process with damping ratio (/spl zeta/) as a design specification.

Opportunistic Scheduling with Power Control in Ad Hoc Wireless Networks

To exploit the multiuser diversity in the CSMA/CA based wireless ad hoc networks, this paper proposes a new algorithm for opportunistic scheduling that will take advantage of both multiuser diversity and power control. The scheduling scheme is performed first before power control to further enhance throughput. The scheduling scheme ensures that the transmission is successful since a best candidate receiver is chosen for transmission and hence minimizes retransmissions. Likewise, the power control algorithm helps reduce interference between links and maximizes spatial reuse. In our study, we provided the scheduling scheme and the power control algorithm. We also showed optimal solutions for minimizing power consumption and maximizing net utility

An Approach to Mitigating Sybil Attack in Wireless Networks using ZigBee

Various sensors employing ZigBee protocol send environment information to a home gateway. The home gateway manages every devices, sensors and services according to the information. However, if an attacker fabricates the information with malevolent purpose, the system may perform any inadvertent service, which may be harmful to users. Sybil attack is one of serious threats that uses such vulnerability. In this paper, we propose a Sybil attack detection method and its response method to mitigate the effect of the attack in wireless network using ZigBee. The proposed method employs a challenge-response approach. A verifier send a node a request that corresponds to an identity, and the receiver should respond the request properly within threshold time. The performance of the proposed method is reasonable for applying it to the practical networks. This will help the wireless networks using ZigBee to enhance its security.

Joint Optimization of Link Scheduling, Power Control, and Routing in Ad Hoc Wireless Networks

Cross-layer design is an extensive research area in ad hoc wireless networks and is particularly important under energy constraints. The physical layer, link layer, and network layer are known to have great impact on network performance as well as on energy consumption; hence, the interactions between these layers should be studied. In this paper, we formulate an optimal link scheduling and power control policy that supports a particular data rate on each link in the network while satisfying the Signal to Interference plus noise ratio (SINR) and the maximum transmission power constraints at each node. We present an optimization problem considering both the energy consumed of each node in the routing path and the delay associated on each link as the link cost metrics. The problem is to find an optimal link scheduling, power control and routing policy that minimizes the end-to-end delay as well as the energy link cost subject to certain constraints. We provide numerical examples for our schemes and relationships between the parameters i.e. the higher the required data rate and the higher the SINR requirement; the system will become less energy-efficient since a high transmission power is needed. This paper is a preliminary step towards our distributed joint scheduling, power control and routing algorithm for ad hoc networks using cross layer approach

Adopting Modem Computer System Technology to Nuclear Power Plant Operations

Abstract Instrumentation, control and monitoring systems in operating nuclear power plants generally utilize analog technology. As these systems age and become obsolete, utility companies are beginning to incorporate digital technology due to its proven record of high reliability in other industries, as well as wide spread availability. One of the major choices facing utilities in the I&C upgrade process is the use of digital computer-based systems to replace the existing analog control systems. Digital computer-based control systems provide improved functional control capabilities and the potential for communications with other plant control and monitoring systems. In addition, new challenges are associated with digital technology that must be faced by the utility. These include items such as evaluating the effects of electromagnetic and radio frequency interference on the system reliability, the need for software verification and validation, the review of abnormal conditions and events analysis (ACEs), as well as overall licensing aspects and the need to increase use of commercial-grade equipment to decrease cost, particularly for safety systems. This paper will review these aspects of adopting digital control technology and improvements in plant monitoring and network communications to nuclear power plants.