• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1286-1293
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• 2008

This paper proposes a realization of robust trajectory tracking for an industrial robot by using PD-sliding mode hybrid control. The PD control has a good performance in the transient period while the sliding mode control has robustness against the system uncertainties. The proposed control method is proposed for the control of a multi-joint robot by taking advantages of both the PD and sliding mode controls. The embodiment of distributed controllers that drive 4-DOF axes has evaluated through experiments with the multi-joint robot AT1. The PD-sliding mode algorithm which is proposed in this paper shows a good performance in the transient period and robustness against disturbances and This paper shows accuracy of end-effector.

• 로봇학회논문지
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• 제12권3호
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• pp.339-349
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• 2017

In this paper, we present a finite-time sliding mode control (FSMC) with an integral finite-time sliding surface for applying the concept of graph theory to a distributed wheeled mobile robot (WMR) system. The kinematic and dynamic property of the WMR system are considered simultaneously to design a finite-time sliding mode controller. Next, consensus and formation control laws for distributed WMR systems are derived by using the graph theory. The kinematic and dynamic controllers are applied simultaneously to compensate the dynamic effect of the WMR system. Compared to the conventional sliding mode control (SMC), fast convergence is assured and the finite-time performance index is derived using extended Lyapunov function with adaptive law to describe the uncertainty. Numerical simulation results of formation control for WMR systems shows the efficacy of the proposed controller.

• 방송공학회논문지
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• 제19권2호
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• pp.257-267
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• 2014

분산 압축 비디오 센싱 (DCVS) 기술은 압축센싱 및 분산 비디오 부호화 기술의 결합을 통해 저 비용의 샘플링을 실현하는 새로운 패러다임이다. 본 논문에서는 프레임 간 높은 시간 상관성을 활용한 DCVS에서의 스킵모드 부호화 방법을 제안한다. 제안하는 방법은 일정조건을 만족하는 비 키-프레임에 대한 측정값을 복호화기에 전송하지 않아도 시간적 보간법을 통해 해당 비 키-프레임의 복원이 가능하도록 하여 율-왜곡 측면에서 좋은 압축 성능을 보장한다. 이와 더불어, 더 나은 시간적 보간을 위하여 계층적 구조를 사용하는 방법을 제안한다. 실험 결과, 제안하는 스킵모드 부호화 방법은 약간의 PSNR 감소에 비해 매우 높은 측정율 절약이 되는 것을 확인하였다. 또한, 제안하는 방법을 높은 시간 연관성을 갖는 비디오 영상에 적용할 경우, 복호화기의 연산 복잡도가 평균 43.75% 감소하는 것을 확인하였다.

• 전기학회논문지
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• 제61권11호
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• pp.1584-1589
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• 2012

The grid-interconnected microgrid can be able to operate with and without the utility microgrid to supply electricity. when the microgrid operates in grid-connected mode, the frequency of the microgrid synchronizes with the system frequency. In this case, the frequency of the microgrid has small variation which is able to change the output of distributed generation with a droop controller. Thus, the small variation of frequency can make the distributed generation generate unnecessary electricity consistently. In this paper, we propose a frequency droop control with a dead band so as to prevent the distributed generations from generating unnecessary output while in grid-interconnected mode. In addition, a distributed generation can have a restoration control to restore the frequency changed by a droop control as a rated frequency. Also, we state the problem of restoration control with a dead band, and propose its solution when the microgrid operates in stand alone mode. We simulate the proposed droop control using PSCAD/EMTDC to verify the validity of the control.

• 전기학회논문지
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• 제57권11호
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• pp.1954-1961
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• 2008

Microgrid usually consists of a cluster of distributed generators(DGs), energy storage systems and loads, and can operate in the grid-connected mode and the islanded mode. This paper presents detailed descriptions of two different options for controlling the active power of DGs in the microgrid. One is regulating the power injected by the unit to a desired amount(Unit output power control) and the other is to regulate the flow of active power in the feeder where the unit is installed to a constant(Feeder flow control). Frequency-droop characteristics are used to achieve good active power sharing when the microgrid operates in the islanded mode. The change in the frequency and the active power output of DGs are investigated according to the control mode and the configuration of DGs when the microgrid is disconnected from the main grid. From the analysis, this paper proposes a method to determine the droop constant of DGs operating in the feeder flow control mode. Simulation results using the PSCAD/EMTDC are presented to validate the approach, which shows good performance as opposed to the conventional one.

• Journal of Advanced Marine Engineering and Technology
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• 제28권4호
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• pp.603-610
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• 2004

Time delays are included in most of actual systems, and some of which are shown as time varying. To analyze the time varying time delay system in the time domain. a useful delay module to express the function as a tool is much helpful to get corresponding outputs under given conditions. A method is proposed here to design the algorithm of time delay module for simulation or control purposes, including the problems of initializing and reallocating data in buffer. After classifying the time varying time delay into the distributed mode and lumped mode, an object to describe delay module is configured and tested under the defined input signal and given time delay variation. The simulation results show that the output of module matches reasonably with the case of real system.

• 에너지공학
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• 제18권3호
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• pp.147-155
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• 2009

신 재생에너지를 비롯하여 분산전원의 사용이 매년 증가하고 있다. 분산전원의 그 특성에 의해 배전계통 및 수용가에 근접하여 위치하며 단독운전 또는 배전계통 망에 연계하여 운영될 수 있다. 만약 분산전원이 배전계통에 연계되어 운영될 경우 현재의 배전계통 운영방식과는 다르기 때문에 효율적인 분산전원의 관리 및 안정적인 배전계통을 운영하기 위해서는 분산전원의 연계에 대한 기준 및 새로운 계통운영지침 등이 재정립되어야 할 것이다. 본 논문에서는 향후 분산전원이 배전계통에 연계되어 운전될 때 분산전원의 상태를 감시 및 제어 또는 관리하기 위해서 국제 표준 프로토콜인 IEC-60870으로 분산전원 연계용 FEP(Front-End Processor, FEP)을 설계하였다. 설계한 사항을 검증하기 위하여 분산전원 상위 시스템인 주장치와 하위 시스템인 분산전원 연계용 RTU(Remote Terminal Unit, RTU)를 가지고 시험을 실시하였다. 그 결과 정상적인 데이터를 상위 시스템에서 확인을 통하여 입증하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.34-35
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• 2014

we designed a distributed mass dynamic vibration absorber for vibration reduction in a dual mode system. And we were subjected to evaluation of the vibration reduction performance of the distributed mass dynamic vibration absorber through experiments.

• 한국군사과학기술학회지
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• 제19권5호
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• pp.606-612
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• 2016

A Captive Flight Test(CFT) is used to verify the performance of missile component such as seeker and guiding algorithm of missile. Recently most of surface to air missile adapts multi-mode guidance method which include command guidance and active/passive guidance. A CFT system for missile system adapting multi-mode guidance method consists of pod equipment, command transmitting system and measuring system. In this paper, we proposed CFT system and testing method for missile which adapt multi-mode guidance, and system integration procedure by using distributed missile system integration method and procedure. The proposed CFT system and system integration method was applied to CFT of surface to air missile, and brought successful result.

• 한국항행학회논문지
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• 제19권4호
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• pp.323-329
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• 2015

장거리 ($50\;fiber\;spans{\times}80km$) 전송 링크의 융통적 구성을 위해 단일 모드 광섬유 (SMF; single mode fiber)의 길이와 중계 구간 당 잉여 분산 (RDPS; residual dispersion per span)이 랜덤하게 분포하는 링크에서 광 위상 공액과 결합된 분산 제어 (DM; dispersion management)를 통한 왜곡된 WDM 채널의 보상 특성을 살펴보았다. WDM 채널들의 입사 전력이 0 dBm 이하로 제한된다면 SMF 길이와 RDPS가 랜덤하게 분포하는 링크를 통한 보상 효과가 균일하게 분포하는 링크에서의 보상 효과와 유사하게 나타나는 것을 확인하였다. 이는 제안한 랜덤 분포 링크 구조를 이용하면 장거리 WDM 전송 링크 설계와 구축에서 융통성을 확보할 수 있다는 것을 의미한다.