• Journal of Institute of Control, Robotics and Systems
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• v.12 no.8
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• pp.810-817
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• 2006

This paper presents a rotational motion estimation and correction technique for digital image stabilization. An equivalent rotation model is derived so as to accommodate a combined rotational and the translational motion. Thanks to this simplification, the suggested estimation algorithm can directly find the rotational center using geometric characteristic of local motion vectors instead of using searching method. And we also present recursive version of frame to reference algorithm(FRA) for the real time implementation. The proposed DIS system does not require time consuming parameter searching process, while showing comparatively good performance compared with the previous ones. To show the effectiveness of the DIS scheme, the algorithm has been implemented on the DSP based hardware system and experimental results are also discussed.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.1
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• pp.49-57
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• 2016

A modular multilevel converter is widely adapted for a high-voltage direct current power transmission system. This study proposes a design methodology for a novel digital control that mitigates the negative effects caused by time delay, including communication transport delay for a modular multilevel converter. The modeling and negative effect of time delay are analyzed theoretically in a frequency domain, and its compensation methodology based on an inverse model is described fully with practical considerations. The proposed methodology is verified through several simulation results using a modular 21-level converter system.

• Journal of Digital Convergence
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• v.2 no.1
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• pp.57-73
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• 2004

Due to the rapid development of Information Technology and the Internet, e-business has bloomed and prevailed recently. As the result of this phenomenon, enterprises introduce CRM as a new process accessible to customers. The purpose of this study is to examine the factors affecting the performance of CRM based on precedent theoretical studies. So, the empirical test is conducted to various hypotheses related to the research model. 206 questionnaires for this study are collected. The result of how the organizational characteristics influence on the performance of CRM shows that they have a positively significant effect on it in order of expert security, top management's support and customer information-centric culture, and department collaboration. Evaluation and compensation system don't influence on the performance of CRM directly.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.341-342
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• 2015

본 논문에서는 파라미터 오차 보상을 통한 3상 BLDC 전동기의 DC 전류 모델 기반의 센서리스 제어 방식을 제안한다. 기존의 DC 전류 모델 기반의 센서리스 제어 방식은 상 전환 구간마다 발생하는 실제 전류와 모델 전류의 오차로 인해 추정한 역기전력과 속도, 위치에 오차가 그대로 나타난다. 이 오차 성분을 줄이기 위해 본 논문에서는 기계 방정식을 이용하여 개선된 역기전력 추정 식을 제안하였다. 또한 개선된 역기전력 추정 식에 파라미터에 오차가 없다면 센서리스 제어가 가능하지만, 오차가 존재한다면 센서리스 제어가 불안정해진다. 이를 극복하기 위한 파라미터 오차 보상 알고리즘도 제안하였다. 제안한 방법은 시뮬레이션을 통해 검증하였다.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.22-25
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• 2004

In active noise control (ANC) system, the convergence behavior of the Filtered- X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortion in the secondary path as in the power amplifiers (e.g., saturation), loudspeakers and transducers. This distortion may yields degrading the error reduction performance of the ANC systems. In this paper, the authors of this paper propose a more improved and stable FXLMS algorithm to compensate for the undesirable nonlinearity of the secondary-path, whereby the third-order Volterra model was employed for the identification of the nonlinear secondary-path. In particular, the proposed approach was based on the modification of the conventional FXLMS algorithm. Finally, the simulation results showed that the proposed approach yields better convergence property and more stable performance in the ANC systems.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.47-49
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• 2004

In this correspondence, an new approach to design a fuzzy controller for system with uncertain output backlash to have good tracking performance is presented. Without using a compensation mechanism or backlash inverse, the fuzzy control mechanism is designed to implicitly compensate the delay effect arising from an uncertain output backlash and to make the output backlash stable without limit cycles. The proposed method designs a model-based fuzzy controller for a one-input one-output linear plant with output backlash. The effectiveness of the designed fuzzy controller is illustrated by the simulation.

• MALSORI
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• no.60
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• pp.145-164
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• 2006

This paper proposes class histogram equalization (CHEQ) to compensate noisy acoustic features for robust speech recognition. CHEQ aims to compensate for the acoustic mismatch between training and test speech recognition environments as well as to reduce the limitations of the conventional histogram equalization (HEQ). In contrast to HEQ, CHEQ adopts multiple class-specific distribution functions for training and test environments and equalizes the features by using their class-specific training and test distributions. According to the class-information extraction methods, CHEQ is further classified into two forms such as hard-CHEQ based on vector quantization and soft-CHEQ using the Gaussian mixture model. Experiments on the Aurora 2 database confirmed the effectiveness of CHEQ by producing a relative word error reduction of 61.17% over the baseline met-cepstral features and that of 19.62% over the conventional HEQ.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.98-108
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• 2005

Conventional robot manipulators actuated by motors with the speed reducer such as the harmonic drive have weakness in the load capacity, since the speed reducer does not have enough strength. To improve this, a new type of robot actuator based on the four-bar-link mechanism driven by the ball screw was constructed. Also, a new type of revolute robot manipulator composed of the developed actuators was developed. But, modelling errors occur due to the off-set from the nominal model since the exact modeling of the complex inertia variation of the four-bar-link actuator is very difficult. To control the proposed robot along the prescribed trajectory, a sliding mode control algorithm was applied with compensation function for the modeling errors. To show performance of the proposed controller, a computer simulation was performed, and its results was presented.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1760-1770
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• 2018

This paper presents a control bandwidth extension method for inverters with a low carrier ratio. The bandwidth is extended at the price of decreasing the phase margin. Then the phase margin is compensated by introducing an extra leading angle into an inverse Park transformation. The model of the controller with the proposed method is established. The magnitude and phase characteristics are also analyzed. Then the influence on system stability when the leading angle is introduced is analyzed. The proposed method is applied to design an inverter controller with both a large bandwidth and a desired phase margin, and the experimental results verify that the controller performs well in the steady-state and in terms of transient response.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.31-36
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• 2011

Smart Door(SD) is a human friendly power-assisted door system for passenger car doors. It offers comfort and safety to passengers and drivers by supplying additional power. In this study, dynamic system model and the equation of motion derivation are derived. And we propose the disturbance observer based collision detection algorithm for safety when opening the door. A disturbance caused by collision has a fast response compared to a friction, uncertainties and so on. The main idea this study is to estimate a variation of disturbance for stably and effectively detecting a collision. In order to evaluate a performance of collision detection, an experiment set up is constructed. The experimental results validate the usefulness of the proposed collision detection algorithm.