• 영어어문교육
• /
• 제15권3호
• /
• pp.83-104
• /
• 2009

This study examined whether self-correction or metalinguistic explanation might make a difference in the ability to accurately write two English grammatical structures when learners received indirect teacher feedback in the form of underlining target errors in a Korean EFL college classroom. With the goal of helping low-proficiency students improve their ability to accurately write sentences including nonfinite present participial relative clauses and present participial constructions, four groups were formed: a group which received indirect feedback, a group which received indirect feedback and metalinguistic explanation, a group which received indirect feedback and self-corrected errors, and a group which received indirect feedback and self-corrected errors after receiving metalinguistic explanation. The results showed that the effects of either metalinguistic explanation or self-correction integrated with indirect feedback on learners' ability to accurately write the target structures were not meaningful, while the combined effects of metalinguistic explanation and self-correction were statistically significant.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제8권2호
• /
• pp.39-49
• /
• 2004

Model of the novel Surface motor (SFM) is briefly discussed, and two types of control method including two-order feedback circuit control, indirect acceleration feedback control are analyzed to solve unstable characteristic such as low damp and negative stiffness. The simulation results demonstrate that the system has plain amplitude and wide frequency band arranging from 0 to 8kHz with no resonant peak through indirect acceleration feedback control.

• 영어어문교육
• /
• 제16권4호
• /
• pp.133-152
• /
• 2010

There is disagreement, among researchers, on the benefits of corrective feedback on L2 learners' written output. Some scholars advocate the usefulness of corrective feedback while some claim that error correction is ineffective and even harmful. So far, however, research outcomes cannot settle this debate. Based on this debate, this study examines whether there is a difference among diverse types of feedback on the effects of L2 learners' writing improvement. This study found that teacher's direct feedback was more effective than any other types of feedback on the effect of participants' writing improvement. In particular, teacher's direct feedback helped their improvement on grammar, mechanics, and form. Among the types of peer feedback, self-correction was the most effective. In teacher feedback, form-focused feedback had more effects than content-focused feedback, but no difference with regard to peer feedback. In addition, teacher's content-focused feedback was more effective than peer's content-focused feedback. Overall, in all types of feedback, teacher feedback was more effective than peer feedback. However, direct (form-focused) feedback was the most effective in teacher feedback, and self-correction in peer feedback. The least effective feedback in both teacher and peer feedback was indirect (form-focused) feedback, which is simple underlining of errors.

• 대한전기학회논문지
• /
• 제38권11호
• /
• pp.922-933
• /
• 1989

This paper deals with an indirect pole placement adaptive controller design problem for discrete-time plants with arbitrary zeros in the presence of unmodeled dynamics and/or disturbances. The plant and controller parameters are estimated by separate estimators. The nonlinear feedback is introduced so that the estimated plant has as high degree of controllability as possible. The nonlinear feedback will be used in a finite time, after which the control algorithm becomes a standard pole placement one.

• 한국지능시스템학회논문지
• /
• 제12권6호
• /
• pp.554-558
• /
• 2002

In this paper, we propose a robust indirect adaptive fuzzy state feedback regulator based on Takagi-Sugeno fuzzy model. The proposed adaptive fuzzy regulator is less sensitive to singularity than the conventional one based on the feedback linearization method. Furthermore, the proposed control method is applicable to not only plants with a perfect model but also plants with an imperfect model, which causes uncertainties. We verify the global stability of the proposed method by using Lyapunov method. In order to support the achievement, the application of the proposed adaptive fuzzy regulator to the control of a nonlinear system under the external disturbance is presented and the performance was verified by some simulation result.

• 대한임베디드공학회논문지
• /
• 제10권6호
• /
• pp.373-379
• /
• 2015

A hybrid navigation system is implemented to apply for a mobile robot. The hybrid navigation system consists of an inertial navigation system and a global positioning system. The inertial navigation system quickly calculates the position and the attitude of the robot by integrating directional accelerations, angular speed, and heading angle from a strap-down inertial measurement unit, but the results are available for a short time since it tends to diverge quickly. Global positioning system delivers position, heading angle, and traveling speed stably, but it has large deviation with slow update. Therefore, a hybrid navigation system uses the result from an inertial navigation system and corrects the result with the help of the global positioning system where an indirect feedback Kalman filter is used. We implement and confirm the performance of the hybrid navigation system through driving a car attaching it.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -3
• /
• pp.1471-1474
• /
• 2002

In this paper, we propose a robust indirect adaptive fuzzy state feedback regulator based on Takagi-Sugeno fuzzy model. The proposed adaptive fuzzy regulator is less sensitive to singularity than the conventional one based on the feedback linearization method. Furthermore, the proposed control method is applicable to not only plants with a perfect model but also plants with an imperfect model, which causes uncertainties. We verify the global stability of the proposed method by using Lyapunov method. In order to support the achievement, the application of the proposed adaptive fuzzy regulator to the control of a nonlinear system under the external disturbance is presented and the performance was verified by some simulation result.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.195-198
• /
• 1997

This paper proposes the effective compensation method of the rotor time constant of induction motor. An indirect vector control method is highly dependent on the motor parameters. To solve the problem of performance degradation due to parameter variation in an indirect vector control of induction motor, we compensate the rotor time constant by current error feedback. The proposed method is a simple on-line rotor time constant compensation method using the information from terminal voltages and currents. As the current error, difference between current command and estimated current, approaches to zero, the value of rotor time constant in an indirect vector controller follows the real value of induction motor. This scheme is valid transient region as well as steady state region regardless of low or high speed. This method is verified by computer simulation. For this, we constructed the simulation model of induction motor, indirect vector controller and current regulated PWM (CRPWM) voltage source inverter (VSI) using SIMULINK in MATLAB.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.454-457
• /
• 1997

As in most industrial processes, the dynamic characteristics of an electric power system are subject to changes. Amongst those effects which cause the system to be uncertain, faults on transmission lines are considered. For the stabilization of the power system, we present an indirect adaptive control method, which is capable of tracking a sudden change in the effective reactance of a transmission line. As the plant dynamics are nonlinear, an input-output feedback linearization method equipped with nonlinear damping terms is combined with an identification algorithm which estimates the effect of a fault. The stability of the resulting adaptive nonlinear system is investigated.

• 한국군사과학기술학회지
• /
• 제20권1호
• /
• pp.25-32
• /
• 2017

Most of weapon systems use aided navigation system which integrates inertial navigation and aiding sensors to compensate the INS errors increasing with the passage of time. Various aid sensors can be applied such as Global Navigation Satellite System (GNSS), radar, barometer, etc., but there might exist time delay caused by signal processing or transferring aid information. This time delay leads out-of-sequence measurements (OOSM) systems. Previously, optimal and suboptimal measurment update method for OOSM systems, where the time delay length are known, are proposed. However, previous algorithm does not guarantee the positive definite property of covariance matrix. In order to improve numerical stability for aided navigation using delayed-measurement, this paper proposes a new measurement covariance update algorithm be similar to Joseph-form in Kalman filter. Futhermore, we propose how to implement it in indirect feedback Kalman filter structure, which is commonly used in aided navigation systems, for time-delayed measurement systems. Simulation and vehicle test results show effectiveness of a proposed algorithm.