• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1136-1141
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• 2004

This paper presents a control method for time-delay systems and verifies the performance of the designed control system via real experiments. Specifically, the control method is applied to a flexible-link system with time delays. The method combines time- and frequency-domain controllers: linear quadratic optimal controller (or LQR) and lag compensator. The LQR is used to stabilize the system in optimal fashion, whereas the lag compensator is used to compensate time-delay effects by increasing the delay margin of the system. With this methodology, the maximum allowable time delay can be increased significantly. The proposed method is simple but quite practical for time-delay system control as it is based on the conventional loop-shaping method, which gives practical insights on delay-phase relationship. Simulation and experiment results show that the method presented in this paper is feasible and practical.

• Journal of Advanced Marine Engineering and Technology
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• 제41권1호
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• pp.105-110
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• 2017

이 논문에서는 해상에서의 환경 하중과 외력을 고려한 해상 크레인의 상하 동요 보상 시스템에 대해 연구한 내용을 소개한다. 이를 위해 강체라 가정된 해상 크레인과 유압 구동식 윈치, 탄성력을 갖는 로프, 그리고 로프 끝단의 중량물로 구성된 동역학 모델을 먼저 살펴본다. 중량물의 상하 동요 움직임을 보상하기 위해, 선형화를 통한 PD 제어를 적용했다. 또한, 비선형 시스템에 맞춘 슬라이딩 모드 제어기 및 시간 지연을 고려한 비선형 일반 예측 제어 알고리즘을 사용한 제어를 적용했으며, 그 결과 진동폭이 줄어듬을 확인할 수 있다. 결과적으로, 1초의 시간 지연을 고려하여 설계한 강인 제어기를 활용하게 되면, 상하동요 보상시스템에서 오차를 가장 많이 줄여서 본 시스템에 적합한 제어 알고리즘으로써 활용할 수 있음을 볼 수 있다.

• 한국지능시스템학회논문지
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• 제12권6호
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• pp.559-564
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• 2002

This Paper Proposes a design method of a fuzzy output feedback controller for the nonlinear systems with the unknown time- delay. Recently, Cao et ai. proposed a stabilization method for the nonlinear time-delay systems using a fuzzy controller when the time-delay is known. However, the time-delay is likely to be unknown in practical. We represent the nonlinear systems with the unknown time-delay by Takagi-Sugeno (T-5) fuzzy model and design the fuzzy observer and the parallel distributed compensation (PDC) law based on this observer. By applying Lyapunov-Krasovskii theorem to the closed-loop system, the sufficient condition for the asymptotic stability of the equilibrium Point is derived and converted into the linear matrix inequality (LMI) Problem.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.33.1-33
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• 2002

The INS provides high rate position, velocity and attitude data with good short-term stability while the GPS provides position and velocity data with long-term stability. By integrating the INS with GPS, a navigation system can be achieved to provide highly accurate navigation performance. For the best performance, time synchronization of GPS and INS data is very important in GPS/INS integrated system. But, it is impossible to synchronize them exactly due to the communication and computation time-delay. In this paper, to reduce the error caused by the measurement time-delay in GPS/INS integrated systems, error compensation methods using separate bias Kalman filter are suggested for both the...

• Journal of Positioning, Navigation, and Timing
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• 제11권1호
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• pp.23-28
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• 2022

The eLoran system is a high-power terrestrial navigation system that is recognized as the most appropriate alternative to complement the GNSS's vulnerability to radio frequency interference. Accordingly, Korea has conducted eLoran technology development projects since 2016. The eLoran system developed in Korea provides 20 m positioning accuracy to maritime user in Incheon and Pyeongtaek harbor. To accurately calculate the position with the eLoran signal, it is necessary to apply a compensation method that mitigates the propagation delay. In this paper, we develop the compensation method to mitigate the eLoran signal propagation delay and evaluate the positioning performance in Incheon harbor. The propagation delay due to the terrain characteristics is pre-surveyed and stored in the user receiver. Real-time fluctuations in propagation delay compared to the pre-stored data are mitigated by the temporal correction generated at a nearby differential Loran station. Finally, two performance evaluation tests were performed to verify the positioning accuracy of the Korean eLoran system. The first test took place in December 2020 and the second in April 2021. As a result, the Korean eLoran service has been confirmed to provide 20 m location accuracy without GPS.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권3호
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• pp.179-184
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• 2002

Recently, internet-based applications can be found easily in various felds. Internet-based telerobot system becomes one of important applications of internet. Among many important technological issues on the internet-based telerobot, time-delay is inherently critical problem to be solved. Time-delay is classified as micro time-delay and macro time-delay in this paper. Algorithms for compensation of path-error and time-error are proposed for the both types of time-delays using fuzzy logic since fuzzy logic is one of the best tools to represent expert's knowledge. Simulation results show the validity of the proposed algorithms.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.231-231
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• 2000

It is proposed that a novel method which can compensate the time delay occurs in overall system, when voltage and current is measured, owing to LPF, hysteresis control inverter and microprocessor program computation time. The Proposed scheme estimates the time delay using the difference between Q-axis stator current command and time delayed Q-axis stator current in synchronous reference frame, and compensates the time delay of voltage and current using angular displacement of DQ transformation. The proposed scheme compensates accurately the time delay occurs in overall system. Therefore performance of vector control system is improved highly and it is verified by simulation and experiment.

• 대한전자공학회논문지SD
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• 제45권1호
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• pp.56-63
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• 2008

본 논문에서는 WCDMA 통신용 송신기에 적용 가능한 12비트 1GS/s 전류구동 방식의 혼합형 DAC를 설계하였다. 제안된 DAC는 혼합형 구조로써 하위 4비트는 이진 가중치 구조, 중간비트와 상위비트는 4비트 온도계 디코더 구조로 12비트를 구성하였다. 제안된 DAC는 혼합형 구조에서 발생되는 지연시간에 따른 성능 저하를 개선하기 위해 지연시간보정 회로를 사용하였다. 지연시간보정 회로는 위상주파수 검출기, 전하펌프, 제어회로로 구성되어 이진 가중치 구조와 온도계 디코더 구조에서 발생하는 지연시간을 감소시킨다. 제안한 DAC는 CMOS $0.18{\mu}m$ 1-poly 6-metal n-well 공정을 사용하여 제작되었고 측정된 INL/DNL은 ${\pm}0.93LS/$ 0.62LSB 이하로 나타났다. 입력 주파수 1MHz에서 SFDR은 약 60dB로 측정되었고 SNDR은 51dB로 측정되었다. 단일 DAC의 전력소모는 46.2mW로 나타났다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.63-64
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• 2011

• 전력전자학회논문지
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• 제9권3호
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• pp.275-284
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• 2004

본 논문은 동적전압보상기(DVR)의 제어를 위한 우수한 성능의 디지털제어기를 제시하고 제어이득(Control Gain)의 설정에 관하여 논한다. DVR계통의 전력회로를 분석하여 DVR의 운전한계를 찾고 그에 따른 제어목표 및 제어기 구조를 제시한다. 디지털 제어기는 인버터의 PWM 스위칭과 함께 제어시스템의 시간지연을 야기한다. 이러한 시간 지연은 제어시스템의 전달함수를 1차수 높게 하여 제어시스템을 더한층 복잡하고 불안정하게 한다. 본 논문은 제어기의 시간지연을 고려하여 제안된 제어기의 이득을 설정하는 방법을 제시하고 인버터의 스위칭 주파수와 관련하여 출력측 필터요소의 설계지침을 제시한다. 제안된 설계방법에 의하여 전디지털화(Full Digital Control) 된 DVR 시스템을 제작하여 이론을 검증한다.