• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.325-329
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• 2011

We are developing a minimized integrated public address system that has facilities such as external input, Mic., CD, MP3 and Radio. In this paper, developing an integrated public address system with operational MICOM will make it possible to control the facilities of digital devices centrally. The operational MICOM is composed of 3 layers which are a control layer, a processing layer and a user interface layer. The control layer controls digital devices in the integrated public address and the processing layer is for processing voice data editing, controlling signals of devices and providing status information of the device. The user interface layer displays the status of control devices and the data processing of a user. A remote control is used for the central control.

• Journal of Digital Contents Society
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• v.14 no.3
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• pp.283-290
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• 2013

The current centralized mobility control protocols such as proxy mobile IPv6 (PMIPv6) are dependent on a central mobility anchor to process all control/data traffic. However, such centralized mobility control protocols have some drawbacks such as traffic concentration into the core network and serious service degradation in case of the failure of such a centralized mobility anchor, etc. In this paper, therefore, in order to alleviate these drawbacks, we propose a PMIPv6-based distributed mobility control scheme considering a user's movement locality. Performance evaluation results demonstrate that the proposed scheme has apparent potentials to alleviate serious drawbacks of S-PMIP, which is a closely-related distributed mobility control scheme, as well as PMIPv6, while reducing the total mobility control cost.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1141-1149
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• 1992

This paper presents a robust centralized control scheme for a magnetic bearing system which supports a rigid rotor at both shaft ends in the radial direction. The negative stiffness element and the inductive force associated with bearing magnetic field are considered in the dynamic model of the system. For this model, the controllability and observability are examined, and then a robust control theory is applied to design two types of multi-input multi-output servocontrollers. A general servocompensator is embedded in the first one and a centralized PID controller is suggested as a second one. By simulation study, the performance of two types of servocontrollers are compared in the aspects of disturbance rejection, reference tracking and the robustness limit.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.4
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• pp.99-105
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• 2011

This paper presents a method to design a centralized repetitive controller that is robust to variations in the multiple system parameters. The uncertain parameters are specified probabilistically by their probability distribution functions. Instead of working with the distribution functions directly, the centralized repetitive controller is designed from a set of models that are generated from the specified probability functions. With this multiple-model design approach, any number of uncertain parameters that follow any type of distribution functions can be treated. Furthermore, the controller is derived by minimizing a frequency-domain based cost function that produces monotonic convergence of the tracking error as a function of repetition number. Numerical illustrations show how the proposed multiple-model design method produces a repetitive controller that is significantly more robust than an optimal repetitive controller designed from a single nominal model of the multiple system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.2
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• pp.66-74
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• 1985

An idea is presented in this paper that control panel be implemented with a ${\mu}$-processor instead of interrupt based logic circuits. To prove that the idea is reasonable, a ${\mu}$-computer controlled traffic light control system is chosen as a model, and its control panel is imple-mented witll a f-processor. The result is that the microprocessor-based control panel performs its function very well.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.761-767
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• 2007

In centralized control system, complicated control systems including sensors, power supply and dampers should be required to satisfy the target response of large-scale structures. The practical applications of the centralized control system, however, is very difficult due to high order finite element model of structures, uncertainty of models, and limitations of the excitation system. In this study, the decentralized response-dependent MR damper of which magnetic field is automatically modulated according to the displacement or velocity transferred to the damper without any sensing and computing systems. this decentralized response-dependent MR damper are investigated according to the ranges of relative magnitude between the control force of MR damper and the story shear force of structures by nonlinear time history analysis. Finally, its performance is compared with centralized LQR algorithm which is used in general centralized control theory for a three story building structure.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.323-327
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• 2005

본 논문에서는 홈네트워크에서 댁내의 디바이스가 제공하는 서비스에 대해 불법적인 사용을 제한하고 각 사용자 별로 허가된 권한 내에서만 서비스를 이용할 수 있게 하는 접근제어 방식을 제안한다. 기존의 중앙집중 접근제어 방식과, 분산 접근제어 방식은 홈네트워크에 적용했을 때 중앙기기의 부하집중, 비밀정보의 침해 가능성. 사용자의 불편함 등의 문제를 가지고 있다. 본 논문에서는 기존의 접근제어 방식의 문제점을 분석하고 이를 해결하기 위하여 홈네트워크에 적합한 접근제어 방식을 제안한다.

• The KIPS Transactions:PartC
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• v.11C no.1
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• pp.47-54
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• 2004

The growth of computer resource and network speed has increased requests for the use of remotely located computer systems by connecting through computer networks. This phenomenon has hoisted research activities for application service provision that uses server-based remote computing paradigm. The server-based remote computing paradigm has been developed as the ASP (Application Service Provision) model, which provides remote users through application sharing protocol to application programs. Security requirement such as confidentiality, availability, integrity should be satisfied to provide ASP service using centralized computing system. Existing Telnet or FTP service for a remote computing systems have satisfied security requirement by a simple access control to files and/or data. But windows-based centralized computing system is vulnerable to confidentiality, availability, integrity where many users use the same application program installed in the same computer. In other words, the computing system needs detailed security level for each user different from others, such that only authorized user or group of users can run some specific functional commands for the program. In this paper, we propose windows based centralized computing system that sets security policies for each user for the use of instructions of the application programs, and performs access control to the instructions based on the security policies. The system monitors all user messages which are executed through graphical user interface by the users connecting to the system. Ail Instructions, i.e. messages, for the application program are now passed to authorization process that decides if an Instruction is delivered to the application program based on the pre-defined security polices. This system can be used as security clearance for each user for the shared computing resource as well as shared application programs.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.424-425
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• 2011

한국전력공사 전력연구원에서는 2005년 전력IT 과제인 "전력계통 무효전력 관리시스템 개발"을 통하여 '전압관리시스템(VMS, Voltage Management System'을 개발하여 시범사업지역인 제주지역에 설치, 스마트그리드 실증사업에 참여하여 2013년 까지 운영할 예정이다. 전압관리시스템은 발전기 등의 순동무효전력원을 제어하여 계통 전압을 유지하는 중앙집중형 전압/무효전력 제어기이다. 이와 함께 한국전력공사에서는 제주지역의 전압/무효전력 특성 개선을 위하여 신제주변전소, 한라변전소에 각각 50MVA급 STATCOM을 설치하여 2011년 하반기부터 운영에 들어갈 예정이다. STATCOM 설비는 국부적인 전압/무효전력 개선을 위한 순동 무효전력원이다. 본 논문에서는 중앙집중형 전압/무효전력제어기인 전압관리시스템과 국부적인 전압/무효전력제어기인 STATCOM과 병렬 운전 에 따른 효과를 시뮬레이션을 통하여 검토하였다.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.146-149
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• 2002

컨덴서식 저항 용접기는 용접에 필요한 에너지를 전해컨덴서에 축척 시킨 후 이것을 순시에 용접변압기로 방전하여 큰 용접전류를 흘리게 된다. 아날로그 제어방식에 의한 기존 컨덴서 용접 시스템은 용접 세팅이 어려웠으며, 시스템의 소손 가능성이 높았고, 크기면에서도 비대해질 우려가 있었다. 이에 비해 디지털제어방식의 중앙집중식 자동화시스템은 사용자가 세팅을 쉽게 할 수 있으며, 전원을 제어함에 따라서 전력소비를 최소화 할 수 있다. 본 연구에서는 마이크로프로세서를 이용한 디지털제어방식의 중앙 집중식 컨덴서식 저항용접 시스템을 제안한다.