• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.429-430
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• 2013

대용량 계통연계형 인버터에서 필터의 사이즈와 가격을 줄이고, 빠른 동적 특성을 얻기 위해서 LCL필터가 많이 사용된다. LCL필터 설계 시에 계통으로 유입되는 고조파 전류를 제한하는 것이 주된 목적이지만, LCL필터가 가지는 공진 특성 또한 고려되어야 한다. 그리고 인버터 전류 피드백으로 전류 제어 루프를 구성하는 경우와는 달리 계통 전류 피드백으로 인버터의 전류 제어 루프를 구성하게 되면 전자보다 더 안정적인 운전영역을 확보하게 된다. 하지만 이러한 운전영역 또한 LCL필터를 어떻게 설계하느냐에 따라 달라진다. 본 논문에서는 계통전류의 고조파 제한과 함께 전류제어기의 안정성을 고려한 LCL필터 설계 기법을 제안하고자 한다. 제안된 설계 기법을 통해서 얻어진 결과를 7.5kW급 계통연계형 인버터 시작품을 통해서 검증하였다.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.2
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• pp.227-236
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• 2017

Quantum-dot cellular automata(QCA) consists of nano-scale cells and demands very low power consumption so that it is one of the alternative technologies that can overcome the limits of scaling CMOS technologies. Various circuits on QCA have been researched until these days, a latch required for counter and state control has been proposed as a component of sequential logic circuits. A latch uses a feedback loop to maintain previous state. In QCA, a latch uses a square structure using 4 clocks for feedback loop. Previous latches have been proposed using many cells and clocks in coplanar. In this paper, in order to eliminate these defects, we propose a SR and D latch using multilayer structure on QCA. Proposed three dimensional loop structure is based on multilayer and consists of 3 layers. Each layer has 2 clock differences between layers in order to reduce interference. The proposed latches are analyzed and compared to previous designs.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.4
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• pp.7-14
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• 2010

Stable-state behaviors of asynchronous sequential machines represented as finite state machines can be corrected by feedback control schemes. In this paper, we propose a state feedback control scheme for input/state asynchronous machines with uncertain transitions. The considered asynchronous machine is deterministic, but its state transition function is partially known due to model uncertainty or inner logic errors. The control objective is to compensate the behavior of the closed-loop system so that it matches a sub-behavior of a prescribed model despite uncertain transitions. Furthermore, during the execution of corrective action, the controller reflects the exact knowledge of transitions into the next step, i.e., the range of the behavior of the closed-loop system can be enlarged through learning. The design procedure for the proposed controller is described in a case study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.97-103
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• 2006

This paper described the design and performance evaluation of fiber optic gyro using digital closed-loop processing. For the feedback to null the gyro input rate, digital serrodyne modulation was employed, and for scale factor stabilization, the control circuits of modulation amplitude and optical power are implemented. Performance tests show that prototype fiber optic gyro has bias stability of 0.34 deg/hr, scale factor non-lineality of about 100ppm, and maximum measurement range of ${\pm}500$ deg/sec.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.54-56
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• 2018

본 논문은 평균 전류 분담 기법을 적용한 UPS(Uninterruptible Power Supply) 시스템의 병렬 운전 기법을 제안한다. 각각의 UPS는 전류 정보를 공유하기 위하여 CAN 통신을 사용하며, 이중 루프 방식의 전압, 전류제어기로 구성되어 있다. UPS의 전류 분담 성능을 내부 전류 제어기의 피드백 전류인 인덕터 전류, 커패시터 전류 그리고 통신 시지연에 따라 영향을 분석하고 3상 30kVA급 UPS에 적용하여 그 유효성을 검증하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.570-576
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• 2000

This paper proposed LQ-Servo PI controller by considering LQ-Servo structure as PI controller with a partial state feedback and concerns about the development of the flexible design algorithm by introducing weights to the design parameters of the previous LQ-Servo design method. the propose algorithm improves the matchings of the maximum and minimum singular values at high and low frequencies of the design loop transfer function as well as its loop shaping for performance.

• Journal of Korean Port Research
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• v.14 no.4
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• pp.387-394
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• 2000

If a system such a port and regional economy has a large boundary and complexity, the system's substance is considered as a black box, forecast accuracy will be very low. Futhermore various components in a port and regional economy exert significant influence on each other. To copy with these problem the from of structure models were introduced by using SD model. This study has the issue of simplifying the regional economic effects of the port as contributing to raising the regional income. The regional economic effects of port have various indirect ones except for this. So, SD(System Dynamics) was presented, and applied to simulate port and regional economy.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.3-9
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• 2014

ECMA-392 is the first cognitive radio (CR) specification for personal/portable devices in TV white space. It supports two transmit antennas, for which only open-loop transmit diversity schemes are included. In this paper, we design a simple closed-loop transmit diversity scheme using sub-carrier grouping for ECMA-392 systems. First, sub-carrier grouping types suitable for ECMA-392 systems are described, and then a transmit antenna selection scheme is proposed. In order to reduce feedback information, decision on the transmit antenna selection in the given channel environments is made at the receiver side and the only index of the decided transmit antenna is sent to the transmit side. Through performance comparison to open-loop transmit diversity schemes of ECMA-392, it will be shown that with only a slight feedback overhead, the proposed scheme can improve receiver performance of ECMA-392 systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.562-568
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• 1998

During the past three decades, several techniques have been suggested for robust performance design of multivariable systems within the framework of Quantitative Feedback Theory. They are all characterized and limited by the use of loop transmission inversion. A new approach within framework is described which leads to a design tehnique without loop transmission inversion. Complete sequential design algorithms are derived for performance specifications in terms of plant input disturbance, sensitivity, complimentary sensitivity and control effort.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.143-146
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• 2007

컴퓨터 네트워크에서 전송제어 프로토콜 상에서 다중시간 간격으로 혼잡제어의 지연을 피드백 루프의 시간간격을 조정하여 명시적 예측을 실행해 제어의 단점을 개선하는데 연구한다. 먼저 TCP의 모둘 형 확장에서 Tahoe, Reno, Vegas등 다양한 버전의 TCP에 적용되는 간단한 인터페이스를 통한 함수 호출을 정의하고, 이것이 성능을 크게 향상시는 것을 입증한다. 두 번째로, 광대역 WAN에서 지연-대역폭의 곱이 높을 경우 더욱 심각해지는 사후 제어의 불확실성 차이를 해소함으로써 MTS TCP가 기반 피드백 제어에 사전성을 부여한다는 것을 입증한다. 세번째는 트래픽 제어의 3가지 차원인, 즉 추적 능력, 연결 지속 기간, 공정성이 성능에 미치는 영향 등을 비교 분석하여 입증한다.