• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.358-361
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• 1996

In this paper, we discuss decentralized optimal fault tolerant supervisory control issues on the basis of failure analysis and diagnosis from the angle of discrete event dynamic system. We address the detectability and the observability problems, and develope fault tolerant supervisory control system upon the failure analysis and diagnosis schemes. A complete min-cut is introduced and the procedure for finding the achievable or nonachievable layered optimal legal sublanguages is suggested for a preferential option among the reachable states in the controlled plant. A layered optimal supervisory control framework is proposed upon these. We extend the concept of decentralized supervisory control by considering the problem of combination of decentralized with centralized control in case pure decentralized control happens to be inadequate. We introduce the concept of locally controllable pair and present a hybrid decentralized supervisory control framework. Finally, we propose the analytical framework for a decentralized optimal fault tolerant supervisory control systems.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.2
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• pp.255-262
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• 2008

In this study, seismic response control performance of decentralized response-dependent MR damper which generates the control force using only the response of damper-installed floor, was experimentally investigated through the tests of a full-scale structure installed with large MR dampers. The performance of the decentralized control algorithm was compared to those of the centralized ones such as Lyapunov, modulated homogeneous friction, and clipped-optimal control. Hybrid mass damper were controlled to induce seismic response of the full-scale structure under El Centro earthquake. Experimental results indicated that the proposed decentralized MR damper provided superior or equivalent performance to centralized one in spite of using damper-installed floor response for calculating input voltage to MR damper.

• Smart Structures and Systems
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• v.11 no.2
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• pp.163-183
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• 2013

Control systems have been greatly studied in recent years and can be classified as: passive, active, semi-active or hybrid systems. Most forms of control systems have been applied in a centralized manner where all the information is sent to a central node where control the algorithm is then calculated. One of the possible problems of centralized control is the difficulty to scale its application. In this paper, a completely decentralized control algorithm is analytically implemented. The algorithm considers that each of the control systems makes the best decision based solely on the information collected at its location. Semi-active control is used in preference to active control because it has minimal energy consumption, little to no possibility of destabilization, a reduction in the possibility of data saturation, and a reduction in the response time in comparison to centralized control.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.12
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• pp.689-697
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• 2005

In this paper, an application of a decentralized $H_{\infty}$ controller(DHC) to multiple controlled-permanent magnet(CMAG) magnetic levitation(Maglev) systems is presented. The designed DHC using two Riccati equations iteratively has simpler structure and needs less computational loads than conventional centralized $H_{\infty}$ controller. A target plant is a hybrid-type CMAG system with permanent magnet and coil, and its mathematical model is firstly derived to design the DHC. To implement the designed algorithm, a real Maglev vehicle system including digital controller, chopper, sensor, etc., is manufactured. To compare the performances of the DHC method with an observer-based state feedback control(OSFC), the input tracking and disturbance rejection characteristics are experimentally tested. As performance indices(PI), integral of squared error(ISE), integral of absolute error(IAE), integral of time multiplied by absolute error(ITAE) and integral of time multiplied by squared error(ITSE) are used. From the experimental results, it can be seen that the input tracking and disturbance rejection performances of the DHC are better than those of the conventional controller.

• Membrane and Water Treatment
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• v.7 no.1
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• pp.11-22
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• 2016

The characterization of treatment performance with respect to mixed liquor suspended solids (MLSS) concentration enables greater control over system performance and contaminant removal efficiency. Hybrid membrane bioreactors (HMBRs) have yet to be well characterized in this regard, particularly in the context of greywater treatment. The aim of this study, therefore, was to determine the optimal MLSS concentration for a decentralized HMBR greywater reclamation system under typical loading conditions. Treatment performance was measured at MLSS concentrations ranging from 1000 to 4000 mg/L. The treated effluent was characterized in terms of biochemical oxygen demand ($BOD_5$), chemical oxygen demand (COD), turbidity, ammonia ($NH_3$), total phosphorus (TP), total kjeldahl nitrogen (TKN), and total nitrogen (TN). An MLSS concentration ranging from 3000 to 4000 mg/L yielded optimal results, with $BOD_5$, COD, turbidity, $NH_3$, TP, TKN, and TN removals reaching 99.2%, 97.8%, 99.8%, 99.9%, 97.9%, 95.1%, and 44.8%, respectively. The corresponding food-to-microorganism ratio during these trials was approximately 0.23 to 0.28. Operation at an MLSS concentration of 1000 mg/L resulted in an irrecoverable loss of floc, and contaminant residuals exceeded typical guideline values for reuse in non-potable water applications. Therefore, it is suggested that operation at or below this threshold be avoided.

• The Journal of the Korea Contents Association
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• v.12 no.10
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• pp.11-21
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• 2012

Hybrid network infrastructure has been deployed as the most important technology for the advanced research networking community such as Internet2, SURFnet, etc. However, further research needs to be performed in terms of feasible design and implementation of architecture for inter-domain collaborative network infrastructure, which is essential to end-to-end collaborative research based on high-end applications. In this paper, we suggest a framework for distributed and virtual network operations based on hybrid research networks and efficient cooperation between multi-domain hybrid networks, which aims to provide collaborative network environment for high-end applications. Suggested framework is designed to adopt decentralized model of multi-domain hybrid research network management. A collaborative and distributed virtual model that is characterized by cooperation among hybrid research networks that insist on maintaining their autonomy and control, can also contribute for researchers and other end-users to manage and operate their own virtual networks.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.9
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• pp.64-72
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• 2012

The interest in wind power generation area such as developing and operating wind-diesel pilot complex in remote and island regions that have difficulty in having power plant and connecting to power system is growing rapidly in the world. We have installed and researched the hybrid system in Sekgok Pilot Complex to meet the new generation system. From the monitored data of the system, the performance of each diesel power plant is outstanding. However, step out problem was detected with respect to load sharing and synchronization with decentralized power supply. An advanced controller design having better response time and stability is needed to solve such problem. In this paper, we proposed the algorithm, through digital controller of Governor, which is applied to hybrid system. As a result, we obtained the stable frequency value in variable loading conditions. Also, we proved the advanced response time and stability through the simulation and experiment by applying additional current signal to the control algorithm.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.662-671
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• 2012

Plug-in hybrid electric vehicles (PHEVs) will be widely used in future transportation systems to reduce oil fuel consumption. Therefore, the electrical energy demand will be increased due to the charging of a large number of vehicles. Without intelligent control strategies, the charging process can easily overload the electricity grid at peak hours. In this paper, we consider a smart charging and discharging process for multiple PHEVs in a building's garage to optimize the energy consumption profile of the building. We formulate a centralized optimization problem in which the building controller or planner aims to minimize the square Euclidean distance between the instantaneous energy demand and the average demand of the building by controlling the charging and discharging schedules of PHEVs (or 'users'). The PHEVs' batteries will be charged during low-demand periods and discharged during high-demand periods in order to reduce the peak load of the building. In a decentralized system, we design an energy cost-sharing model and apply a non-cooperative approach to formulate an energy charging and discharging scheduling game, in which the players are the users, their strategies are the battery charging and discharging schedules, and the utility function of each user is defined as the negative total energy payment to the building. Based on the game theory setup, we also propose a distributed algorithm in which each PHEV independently selects its best strategy to maximize the utility function. The PHEVs update the building planner with their energy charging and discharging schedules. We also show that the PHEV owners will have an incentive to participate in the energy charging and discharging game. Simulation results verify that the proposed distributed algorithm will minimize the peak load and the total energy cost simultaneously.