• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.978-983
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• 2003

In this paper, we propose a fault detection method for extended Kalman filter in decentralized filter structure. To detect a fault, a consistency between filter output and a monitoring signal is tested. State propagators are used to obtain the monitoring signal. However, the output of state propagator increases in magnitude and finally diverges as time runs. To solve such problem, two-propagator method was proposed for linear system. Two propagators are reset by Kalman filter output, alternatively, to avoid divergence. But a test statistics change abruptly at the reset instant in that method. Hence a N-step propagator method is proposed to fix up the problem. In the N-step propagator, only time propagations are performed from k-N+1 step to k step without measurement updates. A test statistics are defined by errors and its covariance between extended Kalman filter and N-step propagator. These fault detection methods are applied to integrated strapdown inertial navigation system (SDINS). By computer simulation, it is shown that the proposed methods detect a fault effectively.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.452-464
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• 2015

This paper proposes a DC microgrid operational strategy and control method for improved service reliability. The objective is to supply power to as many non-critical loads as possible, while providing an uninterrupted power supply to critical loads. The DC bus signaling method, in which DC voltage is an information carrier, is employed to implement the operational strategy in a decentralized manner. During grid-connected operation, a grid-tied converter balances the power of the microgrid by controlling the DC voltage. All loads are connected to the microgrid, and operate normally. During islanded operation, distributed generators (DGs), a backup generator, or an energy storage system balances the power. However, some non-critical loads may be disconnected from the microgrid to ensure the uninterrupted power supply to critical loads. For enhanced service reliability, disconnected loads can be automatically reconnected if certain conditions are satisfied. Control rules are proposed for all devices, and detailed microgrid operational modes and transition conditions are then discussed. Additionally, methods to determine control parameter settings are proposed. PSCAD/EMTDC simulation results demonstrate the performance and effectiveness of the proposed operational strategy and control method.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.3
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• pp.91-98
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• 2022

With the recent increase in interest in metaverse in which virtual and physical spaces are digitally fused, many activities in physical spaces are expected to take place in web-based virtual spaces. Therefore, there is a need for research on a self-sovereign identity system that can secure privacy and mutual trust in a DID(decentralized identifier)-based virtual space environment. We, in this paper, developed and validated a reliable communication method consisting of DIDComm messages, a procedure for generating distributed identifiers, asymmetric keys, and DID documents based on Hyperledger Indy and DIDComm open sources. The developed communication method can be applied to verify each other by exchanging additional information and verifiable credentials for trust among communication participants.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.1-9
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• 2014

Structural loading on a wind turbine is due to cyclic loads acting on the blades under turbulence and periodic wind field. The structural loading generates fatigue damage and fatigue failure of the wind turbine. The individual pitch control(IPC) is an efficient control method for reducing structural loading. In this paper, we present an IPC design method using Decentralized LQR(DLQR) and Disturbance accommodating control(DAC). DLQR is used for regulating rotor speed and DAC is used for canceling out disturbances. The performance of the proposed IPC is compared with CPC, which was designed with a gain-scheduled PI controller. We confirm the effect of fatigue load reduction with the use of damage equivalent load(DEL).

• KIPS Transactions on Software and Data Engineering
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• v.3 no.5
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• pp.169-178
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• 2014

In this paper, we present a research utilizing decentralized LTL specifications for ensuring a quality for interaction-centralized system. In this system, for ensuring the quality, we need to validate interactions between modules of the system and then we should check whether the system achieves the expected requirements. This task remains difficult and labor-intensive and requires an expert. In this paper, we present a method to assist such a task. First of all, the requirements of the system is written as multiple LTL specifications. Interactions between modules mean that behaviors of one module are related with other one's behavior. We generate the automaton model fully achieving specification through GR(1) synthesis. And we simulate them using the simulator based on the software agent for checking behaviors of the system. Finally, we validate the whole system whether it achieves given requirements.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.4
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• pp.329-340
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• 1994

This paper presents a dynamic compensation methodology for robust trajectory tracking control of uncertain robot manipulators. To improve tracking performance of the system, a full model-based feedforward compensation with continuous VS-type robust control is developed in this paper(i.e,. robust decentralized adaptive control scheme). Since possible bounds of uncertainties are unknown, the adaptive bounds of the robust control is used to directly estimate the uncertainty bounds(instead of estimating manipulator parameters as in centralized adaptive control0. The global stability and robustness issues of the proposed control algorithm have been investigated extensively and rigorously via a Lyapunov method. The presented control algorithm guarantees that all system responses are uniformly ultimately bounded. Thus, it is shown that the control system is evaluated to be highly robust with respect to significant uncertainties.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.10
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• pp.1498-1506
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• 1989

A new stabilization scheme is proposed in which the local state feedback is utilized in each decentralized controller for large-scale interconnected systems. In the proposed scheme, the controller is designed in two steps. First, the feedback gain of each decentralized controller is temporarily chosen so that the eigenvalues of each isolated subsystem are placed at the desired locations in the complex plane. Secondly, the feedback gain of each controller is compensated so that the time derivative of the Lyapunov function candidate for the overall closed-loop system should be negative. A sufficient condition which assures the global system to stable is given.

• The Journal of Information Systems
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• v.6 no.1
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• pp.5-26
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• 1997

The demands for continuous process optimization require a radical rethinking of how information systems are designed and constructed. Information systems must be capable of sustained, graceful change in response to evolving business requirements. This proposition is supported by the fact that information systems have helped increase productivity only when they were built to support new and better ways of conducting the business. In such context, business process engineering (BPF) is recognized the first but most critical stage in developing information systems as well as in launching business improvement and innovation projects. However, more often, there exist great gaps and inconsistencies between the results of BPE and the business itself, which turn into huge maintenance overhead during an information system lifecycle. In order to solve such an ever lasting problem, this paper orthogonal models, procedure, guide, and work flow are constructed in our engineering discussions focus on decentralized organizations, the method is general enough to be applied easily to other types of organizations without difficulties.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1119-1125
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• 1999

In this paper, a decentralized multilevel-adaptive controller for a boiler-turbine system is designed by using multiple model adaptive method. It is applied to the drum type boiler-turbine system which is simplified from Boryung T/P #1,2 model. A linearlized model is decomposed into three subsystems by means of linear transformation. Then the DMC based on such subsystem is designed and a Multiple Model Adaptive Control(MMAC) scheme is applied for the purpose of the good tracking to variable load demands of the thermal power plant. The good performance of the designed controller is shown by simulations in various conditions that have the large step and ramp change of power demamd.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.376-377
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• 2018

A hardware-in-the-loop (HIL) platform for a power management control of islanded DC microgrids is established. In order to avoid the complexity and high costs, a decentralized control based on the DC Bus Signaling (DBS) method is applied to the HIL system. The simulation results for the HIL microgrid platform have verified the effectiveness of power management strategy.