• 소음진동
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• 제9권6호
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• pp.1240-1246
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• 1999

A prior error estimator which is solving structural dynamic problems and which is based on the generalized-method, is developed. Since the proposed error estimator is computed with only previous information, the time step size can be adaptively selected without the feedback mechanism. This paper shows that the automatic time stepping algorithm using the error estimator performs an efficient time integration. To verify its efficiency, several examples are numerically investigated.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.215-218
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• 2000

In this paper, a new algorithm for adaptive IIR filters based on equation error methods using the RLS algorithm is proposed. In the proposed algorithm, the concept of feedback of the scaled output error proposed by tin and Unbehauen is employed and the forgetting factor is varied in adaptation process for avoiding the accumulation of the estimation error for additive noise . The proposed algorithm has the good convergence property without the parameter estimation error under the existence of mea-surement noise.

• 한국통신학회논문지
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• 제21권6호
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• pp.1447-1452
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• 1996

In this papre, a complex fuzzy adaptive decision feedback equalizer using the RLS algorithm is proposed. The proposed equalizer is based on the complex fuzzy adaptive equalizer. The 'IF'-part of the complex fuzzy adaptive decision feedback equalizer has membership functions which are characterized by the sate of decision feedback. The role of decision feedback is to reduce the computational complexity. Computer simulation shows that the proposed equalizer not only reduces the computational complexity but also improves the performance compared with the conventional complex fuzzy adaptive equalizers under the assumption of perfect knowledge of the linear and nonlinear channels. The effects of error propagation due to wrong decision feedback is also shown.

• International Journal of Internet, Broadcasting and Communication
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• 제13권4호
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• pp.22-29
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• 2021

This study evaluates the accuracy of corrective feedback from Grammarly, an online grammar checker, on essays written by cyber university learners in terms of detected errors, suggested replacement forms, and false alarms.The results indicate that Grammarly has a high overall error detection rate of over 65%, being particularly strong at catching errors related to articles and prepositions. In addition, on the detected errors, Grammarly mostly provide accurate replacement forms and very rarely make false alarms. These findings suggest that Grammarly has high potential as a useful educational tool to complement the drawbacks of teacher feedback and to help learnersimprove grammatical accuracy in their written work. However, it is still premature to conclude that Grammarly can completely replace teacher feedback because it has the possibility (approximately 35%) of failing to detect errors and the limitationsin detecting errors in certain categories. Since the feedback from Grammarly is not entirely reliable, caution should be taken for successful integration of Grammarly in English writing classes. Teachers should make judicious decisions on when and how to use Grammarly, based on a keen awareness of Grammarly's strengths and limitations.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.345-348
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• 2000

In this paper, A Feedforward Linear Power Amplifier for IMT-2000 which IMD characteristics was improved was designed and fabricated. To improve the main power amplifier IMD characteristics, the Feedback loop was added to basic Feedforward Power Amplifier structure. Therefore, the output power of error amplifier can be reduced, and it is easy to control the linearization circuit to cancel total IMD. The designed power amplifier represented the 40㏈m(l0W) output power and -55㏈C 3rd IMD at Center frequency 2.14㎓ (@5㎒).

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1124-1127
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• 1996

Asymmetric cylinders are usually used as an actuator of active suspensions. Since the force is influenced not only by the control but by the road roughness, force control is needed to track the desired force. But the conventional error feedback control treats the valve-cylinder dynamics at its operating point and many use the symmetric model which differ in all respects. We adopt an asymmetric cylinder model and apply a feedback linearization method for the force control to compensate both the valve nonlinearities and the effects of the road roughness.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.332-337
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• 1988

A digital series-feedback compensator algorithm for tracking time-varying signal is presented. The series-feedback compensator is composed of one closed loop pole / zero cancellation compensator and one desired-input generator. This algorithm is applied to nonlinear hydraulic position control system. The hydraulic servo system is modelled as a second order linear model and cancellation compensator is modelled from it. The desired input generator is inserted to reduce modelling error. Digital computer simulation output using this control method is present and the usefulness of this control algorithm for nonlinear hydraulic system is verified.

• 전자공학회논문지B
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• 제31B권6호
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• pp.33-42
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• 1994

The sampling is inevitable in controlling the nonlinear continuous time system. This paper deals with digital feedback linearization problem which eliminates or reduces the effect of the sampling. Necessary and sufficient condition for reducing the sampling error up to O$(h^5)$ are obtained. Also, the effectiveness of our control scheme in accuracy and robustness is shown by comuter simulations.

• 한국통신학회논문지
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• 제36권5A호
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• pp.441-449
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• 2011

Orthogonal frequency division multiplexing (OFDM) 환경에서 sample timing offset(STO)과 carrier frequency offset(CFO)은 inter-symbol interference (ISI), inter-carrier interference (ICI) and phase error를 발생 시키는 원인으로 작용하고 있다. OFDM의 특성상 STO와 CFO에 민감하고, 특히 ICI 가 발생될 경우 보상이 어렵다. 또한 보상을 위해 많은 복잡도를 가진 equalizer가 요구된다. 이 논문에서는 블록 파일럿과 동기화 신호를 가지고, feedback방법을 이용해 STO와 CFO의 효과적인 정정 방법을 제시한다. 주파수 축에서 동기화 신호와 pilot을 이용해 추정한 값들을 시간 축으로 피드백 시킨 후, 시간 영역에서 sample & holder의 시간 타이밍과 oscillator의 주파수의 교정을 통해 정정한다. 시뮬레이션 결과 보상기 없이 피드백 구조만으로 STO와 CFO를 보상하여 성능을 개선 시켰다.

• 대한전기학회논문지
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• 제39권12호
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• pp.1306-1316
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• 1990

A controller using a multilayer neural network is proposed to the dynamic control of a PUMA 560 robot arm. This controller is developed based on an error back-propagation (BP) neural network. Since the neural network can model an arbitrary nonlinear mapping, it is used as a commanded feedforward torque generator. A Proportional Derivative (PD) feedback controller is used in parallel with the feedforward neural network to train the system. The neural network was trained by the current state of the manipulator as well as the PD feedback error torque. No a priori knowledge on system dynamics is needed and this information is rather implicitly stored in the interconnection weights of the neural network. In another experiment, the neural network was trained with the current, past and future positions only without any use of velocity sensors. Form this thim window of position values, BP network implicitly filters out the velocity and acceleration components for each joint. Computer simulation demonstrates such powerful characteristics of the neurocontroller as adaptation to changing environments, robustness to sensor noise, and continuous performance improvement with self-learning.