• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.120-124
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• 1987

Linear time invariant systems are considered. It is assumed that only partial state variables are observable for feedback control. In this study, a new method is presented for designing a stat e feedback controller. It is based on augmenting the original system by additional integrator and using time delayed feedback of observable variables. Several examples and its computer simulation results are given to show the effectiveness of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.433-433
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• 2000

In this paper, we propose a development of internet teleoperation method applying QoS model, which has the real time control capability and the time-delay predicting capability, The QoS model gives a constant bandwidth to a specified application and makes the dynamically irregular time-delay to be predictable and fined so that it can have real-time capability.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.341-341
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• 2000

This paper presents a sliding mode control(SMC) design method for single input linear systems with uncertainties and time delay in the state. We define a sliding surface for the augmented system with a virtual state which is defined from the nominal system. We make a virtual state from optimal control input using LOR(Linear Quadratic Regulator) and the states of the nominal system. We construct a controller that combines SMC with optimal controller. The proposed sliding mode controller stabilizes on the overall closed-loop system.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.591-596
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• 2004

In this paper, a photonic RF true-time delay based on a partially side-polished fiber Bragg grating with heating electrode has been proposed and fabricated. It features continuous voltage-controlled operation, requiring no mechanical perturbation and no moving parts. For an RF signal carried over an optical signal, the time delay has been obtained by controlling the voltage applied to the electrode and thus adjusting its reflection positions from the fiber grating via the thermooptic effect. The achieved time delay is about 100 ps with the electrical power consumption of 280 mW.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.43-44
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• 2013

정상분과 역상분의 전압이 존재하는 삼상 계통의 전압 불평형은 dq 변환에서 맥동전압 성분을 발생시킨다. 인버터의 동작을 위한 PLL의 위상 추적 능력은 맥동 전압에 의해 감소하게 된다. 정상분과 역상분의 분리를 통해 맥동 성분의 제거가 가능하지만 복잡한 PLL 구성을 갖는다. 본 연구는 불평형 상태에서 발생하는 dq 성분의 주파수가 기본파의 짝수 배만 존재하는 성질을 이용하여 comb 필터를 PLL 제어기에 적용하였다. 전압 불평형 및 고조파 성분에 대해서도 맥동 없는 dq 전압 획득이 가능하다. 기본 PLL 제어기에 단순 시간지연의 comb 필터로 견실한 PLL 제어기가 얻어진다. 제안된 PLL 제어기는 시뮬레이션으로 성능을 확인하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.761-764
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• 2008

Most of ready-mixed concrete plants have the problem of construction waste sludge, which pollutes environment and causes economic loss due to the discard and increasing the cost of concrete. Thus, a recycling of the cement sludge has been strongly desired as one of their solution. This research is to the study on the recycling of the cement sludge, especially the study on the hydration control by the sodium gluconate as a set-retarder. The set-retarder can delay the hydration of the cement included in the sludge water, so that the sludge water can be substituted with some of new cement without the property of the cement. And it invests the effect of the sodium gluconate to the hydration of the cement in suspension. The degree of hydration of cement may be controlled by adding the sodium gliconate. The hydration delay time is observed that depends on the concentration of residual sodium gloconate, not how long the cement has been hydrated before the addition of the sodium gluconate.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2114-2116
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• 2002

본 논문은 개선된 Complex 방법을 이용한 하이브리드 퍼지 PID 제어기의 최적 자동동조 알고리즘을 제안한다. 제어응답은 퍼지제어기의 환산계수 값에 의해 여러 종류, 여러 형태로 변화하기 때문에 해당하는 제어계의 평가 기준을 만족하도록 제어 파라미터 값을 정하는 것이 중요하다. PID 파라미터 조정법에는 많은 방법이 제안되어 왔었다. 대표적인 예로서 Ziegler-Nichols, Cohen-Coon, Chien-Hrones-Reswick(CHR) 등에 의해 제안된 방법들이 있다. 본 논문에서는 개선된 Complex 방법을 이용한 강력한 자동동조 알고리즘이 하이브리드 퍼지 PID 제어기의 성능을 자동적으로 개선하기 위해 사용된다. 이 알고리즘은 하이브리드 퍼지 PID 파라미터와 환산계수를 제어출력 변화율과 제한조건에 따라 자동으로 추정한다. 지연시간을 갖는 1계, 2계 공정에 적용하고. 공정출력 기준치는 단위 입력으로 한다. 제어 결과의 성능평가를 위해 ITAE(Integral of Time multiplied by the Absolute value of Error)가 사용되며, 또한 제어기의 오버슈트도 토의된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1844-1851
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• 1999

In this paper, we propose an effective access control scheme based on service characteristics to provide multimedia services such as voice, video and data in broadband CDMA networks. In proposed algorithm, BER characteristics of each service is controlled by different Eb/No, and data traffic is controlled by access probability of data which is determined by activity factor of voice/video traffic. And we perform simulation and analysis of proposed model. As a result, the proposed access scheme shows that the outage probability is decreased by allowing delay of data traffic.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.1-11
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• 2007

In this paper, a new fully digital control method for UPS inverter, which is based on the double control loop such as the outer voltage control loop and inner current control loop, is proposed. In the proposed control system, overshoots and oscillations due to the computation time-delay are compensated by explicit incorporation of the time-delay in the current control loop transfer function. The inner current control loop is adopted by an internal model controller. The internal model controller is designed to a second order deadbeat reference-to-output response which means that its response reaches the reference in two sampling time including computational time-delays. The outer voltage control loop employing P-Resonance controller is proposed. The resonance controller has an infinite gain at resonant frequency, and the resonant frequency is set to the fundamental frequency of the reference voltage in this paper. Thus the outer voltage control loop causes no steady state error as regard to both magnitude and phase. The effectiveness of the proposed control system has been verified by the simulation and experimental results respectively.

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1211-1216
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• 2000

Asynchronous transfer mode (ATM) can be efficiently used to transport packet data services. The switching system will support voice and packet data services simultaneously from end to end applications. To guarantee quality of service (QoS) of the offered services, source rateot send packet data is needed to control the network overload condition. Most existing control algorithms are shown to provide the threshold-based feedback control technique. However, real-time voice calls can be dynamically connected and released during data services in the network. If the feedback control information delays, quality of the serviced voice can be degraded due to a time delay between source and destination in the high speed link. An adaptive algorithm based on the optimal least mean square error technique is presented for the predictive feedback control technique. The algorithm attempts to predict a future buffer size from weight (slope) adaptation of unknown functions, which are used fro feedback control. Simulation results are presented, which show the effectiveness of the algorithm.