• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제9권12호
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• pp.321-332
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• 2020

탈중앙화 접근법은 기존 시스템의 데이터 프라이버시 결함을 보완하기 위해 산·학계에서 폭넓게 연구되고 있다. 블록체인은 기록된 데이터는 위조할 수 없으며 합의를 기반으로 의사결정을 이루고 전반적인 거래의 비용은 저렴한 특징을 가지고 있다. 연합학습은 데이터 집합을 공개적으로 노출하지 않고 다수의 장치를 집합적으로 사용 함으로서 딥러닝 모델을 개선할 수 있게 한다. 모델 구축을 위해서는 자원을 사용하도록 참여자들의 동기 부여를 위한 적절하고 참여 비율에 합당한 인센티브 제도가 필수적이다. 그러나 중앙집중화된 인센티브 메커니즘은 중간 계층에 의존하고 여전히 병목현상을 유발하기 때문에 연합학습에 적용하기에는 어려움이 있다. 따라서, 우리는 이더리움 스마트컨트랙트를 활용하여 연합학습 어플리케이션을 위한 인센티브 모델을 제안한다. 구현 결과는 설계 목표를 충족하였고, 마지막 절에서 연합학습에서 프라이버시 및 데이터 유출과 관련된 민감 데이터에 대한 본 구현을 실행할 때 발생할 수 있는 사항들을 설명한다.

• 한국중재학회지:중재연구
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• 제28권2호
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• pp.165-178
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• 2018

Exchanging information with a person without credentials over the Internet does not pose any problems. A decentralized system based on blockchain technology enables the user to exchange new value(currency) with other uncredited users. The blockchain technology creates a new paradigm in which the distribution system can be founded on trust. Various applied distribution systems are being developed based on this paradigm. This study analyzed the problems between an institute's grading system and the central administration system. The limitations of an institute's current central management system were presented through actual cases. To improve the problem, a decentralized system based on block chain technology was presented in order to overcome the fundamental limitations by utilizing blockchain technology, peer-to-peer network, and the distribution system. In the central system, a malicious moderator could create a malicious edit that becomes the cause of a dispute, but in a decentralized system, a problem cannot be created even if there were to be a malicious moderator. However, it is difficult for a single college institute to create a distribution system in order to actualize an effective system. Comparatively, it would be possible to create a decentralized system in which all educational institutes in Korea (elementary schools, middle schools, high schools, colleges) took part in. The application of a decentralized system would improve the public transparency and reliability of educational institutes.

• International Journal of Aeronautical and Space Sciences
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• 제10권1호
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• pp.58-66
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• 2009

Formation controller for multiple spacecrafts is designed based on a decentralized approach. The objective of the proposed controller is to make each spacecraft fly to the desired waypoints, while keeping the formation shape of multiple spacecrafts. To design the decentralized formation controller, the output feedback linearization technique using error functions for goal convergence and formation keeping is utilized for spacecraft dynamics. The primary contribution of this paper is to proposed optimal controller for formation flying based on the decentralized approach. To design the optimal controller, eigenvalue assignment technique is used. To verify the effectiveness of the proposed controller, numerical simulations are performed for three-dimensional waypoint-passing missions of multiple spacecrafts.

• 산업경영시스템학회지
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• 제42권4호
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• pp.116-125
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• 2019

The Dynamic Vehicle Routing Problem (DVRP) involves a combinatorial optimization problem where new customer demands become known over time, and old routes must be reconfigured to generate new routes while executing the current solution. We consider the high level of dynamism problem. An application of highly dynamic DVRP is the ambulance service where a patient contacts the service center, followed by an evaluation of case severity, and a visit by a practitioner/ ambulance is scheduled accordingly. This paper considers a variant of the DVRP and proposes a decentralized algorithm in which collaborators (Depot and Vehicle), both have only partial information about the entire system. The DVRP is modeled as a periodic re optimization of VRP using the proposed decentralized algorithm where collaborators exchange local information to achieve the best global objective for the current state of the system. We assume the existence of a dispatcher e.g., headquarter of the company who can communicate to vehicles in order to gather information and assigns the new visits to them. The effectiveness of the proposed decentralized coordination algorithm is further evaluated using benchmark data given in literature. The results show that the proposed method performed better than the compared algorithms which utilize the centralized coordination in 12 out of 21 benchmark problems.

• International Journal of Automotive Technology
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• 제6권5호
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• pp.545-554
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• 2005

Passive velocity field control (PVFC) was previously developed for fully mechanical systems, in which the motion task was specified by behaviors in terms of a velocity field and the closed-loop was passive with respect to the supply rate given by the environment input. However, the PVFC was only applied to a single manipulator. The proposed control law was derived geometrically and the geometric and robustness properties of the closed-loop system were also analyzed. In this paper, we propose a virtual passivity-based algorithm to apply decentralized control to multiple 3­wheeled mobile robotic systems whose subsystems are under nonholonomic constraints and convey a common rigid object in a horizontal plain. Moreover, it is shown that multiple robot systems ensure stability and the velocities of augmented systems converge to a scaled multiple of each desired velocity field for cooperative mobile robot systems. Finally, the application of proposed virtual passivity-based decentralized algorithm via system augmentation is applied to trace a circle and the simulation results is presented in order to show effectiveness for the decentralized control algorithm proposed in this research.

• 전자공학회논문지B
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• 제29B권11호
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• pp.31-35
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• 1992

This paper presents a decentralized adaptive controller design for a robot manipulator to track the given desired trajectory in the joint space. The controller is of distributed structure and does not require the complex manipulator dynamic model, thereby it is computationally very efficient. Each joint is independently controlled by a PID feedback part and a velocity-acceleration feedforward part. Simulation results for a two-link direct drive manipulator conform that the proposed decentralized scheme is feasible.

• Journal of applied mathematics & informatics
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• 제18권1_2호
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• pp.1-23
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• 2005

The decentralized static output feedback design problem is considered. A constrained trust region method is developed that solves this optimal control problem when a complete set of state variables is not available. The considered problem is interpreted as a non-linear (non-convex) constrained matrix optimization problem. Then, a decentralized constrained trust region method is developed for this problem class exploiting the diagonal structure of the problem and using inexact computations. Finally, numerical results are given for the proposed method.

• International Journal of Control, Automation, and Systems
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• 제3권2호
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• pp.143-151
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• 2005

This paper considers a robust decentralized $H_\infty$ control problem for uncertain large-scale interconnected systems. The uncertainties are assumed to be time-invariant, norm-bounded, and exist in subsystems. A design method based on the bounded real lemma is developed for a dynamic output feedback controller, which is reduced to a feasibility problem for a nonlinear matrix inequality (NMI). It is proposed to solve the NMI iteratively by the idea of homotopy, where some of the variables are fixed alternately on each iteration to reduce the NMI to a linear matrix inequality (LMI). A decentralized controller for the nominal system is computed first by imposing structural constraints on the coefficient matrices gradually. Then, the decentralized controller is modified again gradually to cope with the uncertainties. A given example shows the efficiency of this method.

• International Journal of Control, Automation, and Systems
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• 제3권spc2호
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• pp.363-375
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• 2005

The paper describes some of the challenges that face the control of nonlinear interconnected power systems. The challenges include the selection of appropriate control and information structures that could range from a completely decentralized to a fully centralized structure. Once a structure is proven to be feasible, the effectiveness of control signals needs to be assessed. Analytical tools are derived for this purpose in the first part of the paper, and they are illustrated with a case study that involves the design of a damping decentralized controller using a Thyristor Controlled Series Compensation device. The second part of the paper deals with the load following and tracking problem through automatic generation control for a system that has been re-structured or deregulated. This problem can be solved using a completely decentralized scheme. It is solved here using fuzzy rules and with an emphasis on compliance with NERC's standards and reduction of wear and tear of the equipment. It is illustrated with a test system that has three interconnected control areas. Finally, comments on the economics of control and the author's vision are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.291-294
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• 2006

This paper presents a decentralized input-output feedback linearizing controller for a multi-machine power system. Firstly, the controller is designed using input-output feedback linearization for modified outputs. Then we present a guideline for selecting gains of the controller and parameters in the modified outputs. Simulations illustrate the effectiveness of the proposed control scheme and the selection guideline.