• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권8호
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• pp.363-367
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• 2003

Robust control for feedback control system is needed according to the highest precision of industrial automation. However, when a feedback control system has an effect of disturbance, it is very difficult to guarantee the robustness of control system. As a compensation method solving this problem, in this paper, Hybrid control method of feedback and Differential Supervisory controller is presented. A Feedback Controller is operated as a main controller, A Differential Supervisory Controller is a controller which operates only when some undesirable phenomena occur, e. g., when the error hits the boundary of constraint set. The robust control function of Differential Supervisory Controller, as a assistant controller is operated when state is unstable by disturbance. it demonstrated by speed control of motor.

• 한국통신학회논문지
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• 제34권1C호
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• pp.81-89
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• 2009

본 논문에서는 임펄스 라디오 기반의 D-ATR UWB (Differential-Average Transmitted Reference Ultra Wide Band) 시스템을 제안한다. 기존의 TR (Transmitted Reference), ATR (Average TR) 등의 TR-UWB 시스템은 송신기에서 참조 신호를 추가로 전송하므로 데이터 전송률이 절반으로 감소하는 문제점을 가지고 있다. 이러한 단점을 극복하기 위해 제안된 시스템의 송신기는 일반적인 D-TR (Differential-TR) 시스템과 같이 차동부호 방식을 사용한다. 또한, 제안된 D-ATR 시스템의 수신기는 일반적인 ATR 시스템과 유사하게 시스템의 비트오율 성능을 향상시키기 위해 수신된 참조 신호들을 재귀적으로 평균 취하여 자기상관에 사용되는 참조 템플릿의 신호대잡음비를 향상시킬 수 있는 구조로 설계된다. IEEE 802.15.4a UWB 다중경로 채널 모델에서 모의실험 결과, 제안된 D-ATR 시스템은 일반적인 D-TR 시스템에 비해 비트오율 성능이 크게 향상되는 것을 확인하였다.

• 대한전자공학회논문지TC
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• 제49권5호
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• pp.37-43
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• 2012

LTE 시스템에서는 폐회로 기반의 다중 안테나 기술이 적용되었으며, 차분 코드북을 비롯한 다양한 다중 안테나 기반의 선부호화 기술들이 향상된 LTE (LTE-Advanced) 시스템의 요구조건을 만족시키기 위해 제안되었다. 차분 코드북 설계와 관련하여 이전에 연구된 내용은 준 대각(quasi-diagonal) 단위 행렬 및 구면 캡(spherical cap)에 중점을 두었지만, 이는 동 이득 성질을 만족하지 못한다. 동 이득 성질은 특히 상향 링크에서 첨두 전력 대 평균 전력비 (PAPR)에 상당한 영향을 미치므로 매우 중요하다. 본 논문에서는 각 송신 안테나에 동 이득을 유지하는 성질을 이용한 새로운 차분 코드북을 상향 링크 기반 차분 선부호화 시스템에 적용하고, 이를 통해 비트 오류율(BER)과 첨두 전력 대 평균 전력비를 분석하였다. 특히, 송신기의 비선형 증폭기를 고려하여 다양한 차분 선부호화 기법들의 성능을 분석하였다. 모의 실험을 통해 선형 증폭기를 고려할 경우 기존에 제안된 차분 코드북이 우수한 성능을 보이지만, 비선형 증폭기를 고려할 경우에는 제안하는 차분 코드북의 우수함을 증명하였다.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제21권1호
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• pp.11-21
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• 2014

The present paper is concerned with the notions of Lipschitz and asymptotic stability for perturbed nonlinear differential system knowing the corresponding stability of nonlinear differential system. We investigate Lipschitz and asymtotic stability for perturbed nonlinear differential systems. The main tool used is integral inequalities of the Bihari-type, in special some consequences of an extension of Bihari's result to Pinto and Pachpatte, and all that sort of things.

• 대한수학회논문집
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• 제35권3호
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• pp.879-890
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• 2020

In this paper we study the stability properties of solutions of nonlinear impulsive integro-differential systems by using an integral inequality under the stability of the corresponding variational impulsive integro-differential systems. Also, we give examples to illustrate our results.

• East Asian mathematical journal
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• 제33권3호
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• pp.309-315
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• 2017

In this paper, we investigate the regularities of the hyper-complex valued functions of the split quaternion variables. We define several differential operators for the split qunaternionic function. We research several left split regular functions for each differential operators. We also investigate split harmonic functions. And we find the corresponding Cauchy-Riemann system and the corresponding Cauchy theorem for each regular functions on the split quaternion field.

• Journal of applied mathematics & informatics
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• 제30권5_6호
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• pp.773-785
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• 2012

In this paper, we establish sufficient conditions for the existence and uniqueness of solutions to a general class of three-point boundary value problems for a coupled system of nonlinear fractional differential equations. The differential operator is taken in the Caputo fractional derivatives. By using Green's function, we transform the derivative systems into equivalent integral systems. The existence is based on Schauder fixed point theorem and contraction mapping principle. Finally, some examples are given to show the applicability of our results.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제22권1호
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• pp.1-11
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• 2015

The present paper is concerned with the notions of Lipschitz and asymptotic for perturbed functional differential system knowing the corresponding stability of functional differential system. We investigate Lipschitz and asymptotic stability for perturbed functional differential systems. The main tool used is integral inequalities of the Bihari-type, and all that sort of things.

• 전력전자학회논문지
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• 제27권1호
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• pp.63-73
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• 2022

The differential power processor (DPP) system is used to prevent a decrease in the total power generation due to the partial shading of photovoltaic modules. Compared with traditional series strings and full power processing (FPP) converter solutions, the DPP converter system shows advantages in terms of modularization process, volume, and transformation losses. However, the system has a limitation in that the power generation process of differential power processors produces lower power under certain irradiation conditions. This paper proposes a structure and operating algorithm for differential power processing modules that can use a single power converter for multiple strings. The operational algorithm for the differential power regulators allows the maximum power generation to be maintained in comparison with conventional series-connected and differential power processing methods even under various partial shading conditions. The operation algorithm of the proposed DPP is verified by Matlab/Simulink simulations.

• 제어로봇시스템학회논문지
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• 제7권1호
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• pp.1205-1210
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• 2001

This paper describes a methodology using neural network to compensate the nonlinear error of deriving speed for electric differential system included in electric vehicle. An electric differential system which drives each of the left and right wheels of the electric vehicle independently. The electric vehicle driven by induction motor has the nonlinear speed error which depends on a steering angle and speed command. When a vehicle drives along a curved road lane, the speed unblance of inner and outer wheels makes vehicles vibration and speed reduction. To compensate for the speed error, we collected the speed data of the inner wheel and outer wheel in various speed and the steering angle data by using an manufactured electric vehicle and the real system. According to the analysis of the acquisited data, we designed the differential speed control system based on a speed error compensator using neural network.