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FUZZY를 이용한 GPS 수신기 위치데이터의 정확도 개선
이경웅,최한수 조선대학교 에너지.자원신기술연구소 2003 에너지·자원신기술연구소 논문지 Vol.25 No.2
The global positioning system(GPS) is a satellite based precise positioning system avaliable worldwide. The GPS have many error sources. The earth's ionosphere and atmosphere cause delays in the GPS signal that translate into position errors. Some errors can be factored out using mathematics and modeling. The configuration of the satellites in the sky can magnify other errors. The problem of accuracy on GPS measurement data can be meaningful In this study, we propose the method for GPS positioning accuracy improvement. The fuzzy set theory on PDOP(position dilution of precision) and SNR(signal to noise ratio) provide improved for measured positioning data. The accuracy of positioning has been improved by selecting data from original using the fuzzy set theory on PDOP and SNR.
비철특수합금에서 금속원소의 이온교환 크로마토그라프에 관한 연구
이경웅,유영진,Kyung Woong Lee,Young Jin Yoo 대한화학회 1985 대한화학회지 Vol.29 No.2
The purpose of this study was to develop a separation method of Zn(II), Cu(II) and Mg(II), by ion exchange chromatography using cation exchange resion (Dowex 50w${\times}$8, 80-100 mesh) and anion exchange (Amberlite IRA-400). Ion exchange resions were packed into 25 ${\times}$ 2cm ID column and flow rate was controlled to 0.30 ml/min. Good eluents for separation of nonferrous metal ions such as Zn(II), Cu(II), Mg(II) were as follow: 0.5M $NaNO_3$ (pH 3.1), 0.2~0.5M HCl + 50~60% Acetone, and 1M HAc + 0.1M NaAcf(pH 3.7) aqueous solution. The mixed solution of 0.1M NaAc(pH 3.7), 0.5M HCl + 50% Acetone were found to be the best eluent for step elution. Analysis of metals were determined by atomic absorption spectrophotometer. In addition, separated Zn(II) fraction was obtained by eluted with 0.12N HCl and 1.5N $NH_4OH$ aqueous solution. This solution was titrated by the E. D. T. A. 비철특수합금중 아연(II) 구리(II)와 마그네슘(II)을 양이온 교환수지(Dowex 50w${\times}$8, 80-100 mesh)와 음이온 교환수지(IRA-400)을 이용하여 이온교환크로마토그라프로서 분리하는 방법을 연구 하였다. 이온교환수지는 25 ${\times}$ 2cm ID 칼럼에 넣고 흐르는 속도는 0.30 ml/min으로 조절하였다. 아연(II), 구리(II), 마그네슘(II)와 같은 비철금속 이온들을 분리하기 위한 좋은 용리액의 조건은 다음과 같다. 0.5M $NaNO_3$ (pH 3.1), 0.2~0.5M HCl + 50~90% Acetone과 1M HAc + 0.1M NaAcf(pH 3.7)였으며 0.1M NaAc + 1M NaAc(pH 3.7), 0.5M HCl + 50% Acetone이 가장 좋은 용리액으로 판명되었다. 분리된 용출액은 원자흡광 광도계로 측정하였으며 특히 아연 (II)은 음이온 교환수지에서 0.12N HCl과 1.5N $NH_4OH$ 수용액으로 분리하고 E.D.T.A로 적정하였다.
이경웅(Kyoung-Woong Lee),최한수(Hansoo Choi) 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.9
This paper presents a TS (Takagi-Sugeno) type FLC (Fuzzy Logic Controller) with only 3 rules. The choice of parameters of FLC is very difficult job on design FLC controller. Therefore, the choice of appropriate linguistic variable is an important part of the design of fuzzy controller. However, since fuzzy controller is nonlinear, it is difficult to analyze mathematically the affection of the linguistic variable. So this choice is depend on the expert’s experience and trial and error method. In the design of the system, we use a variety of response characteristics like stability, rising time, overshoot, settling time, steady-state error. In particular, it is important for a stable system design to predict the steady-state error because the system"s steady-state response of the system is related to the overall quality. In this paper, we propose the method to choose the consequence linear equation’s parameter of T-S type FLC in the view of steady-state error. The parameters of consequence linear equations of FLC are tuned according to the system error that is the input of FLC. The full equation of T-S type FLC is presented and using this equation, the relation between output and parameters can represented. As well as the FLC parameters of consequence linear equations affect the stability of the system, it also affects the steady-state error. In this study, The system according to the parameter of consequence linear equations of FLC predict the steady-state error and the method to remove the system"s steady-state error is proposed using the prediction error value. The simulation is carried out to determine the usefulness of the proposed method.
Circle Criterion을 이용한 FLC의 안정도에 대한 고찰
이경웅(Kyoungwoong Lee),최한수(Hansoo choi) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.5
Most of FLC received input data from error e and change-of-error e’ with no relation with system complexity. Basic scheme follows typical PD and PI or PID Controller and that has been developed through fixed MF. In this paper, We studied the relationship between MF and system response and system response through changing Fuzzy variable of consequence MF and propose the simple FLC using this relationship. The response of FLC is changed according to the width of Fuzzy variable of consequence MF. As changing the Fuzzy variable of consequence MF shows various nonlinear characteristic, we studied the relation between response and MF using analytical method. We designed the effective FLC using three-variable MF and nine rules and took simulation for verification. In this study, we propose the method to design system with FLC in stability point which is an impotent characteristic of designing system. The circle criterion which is adapted to analysis the nonlinear system is put to use for proposed method. Since SISO FLC has a time-invariant and odd characteristic we can use the critical point not disk which is generally used to determine the stability in the circle criterion, to determine the stability. Using this, we can get the maximum critical point plot of SISO FLC with changing the consequence fuzzy variables. The predetermined critical point plot of FLC can be used to decide the region of the system to be stable. This method is effectively used to design the SISO FLC.
이경웅(Kyoung-Woong Lee),최한수(Hansoo Choi) 제어로봇시스템학회 2011 제어로봇시스템학회 국내학술대회 논문집 Vol.2011 No.5
Analysis and design of FLC is difficult for the its nonlinear characteristic. Therefore, when designing the FLC relies heavily on experts’ knowledge and response characteristics and stability of the system is difficult to predict and the mathematical representation is not easy. The mathematical analysis on consequent Part variable to FLC response to changes is easier then the premise part of the change in response characteristics. In this paper, steady state error, one of the system’s response to predictions, including the system’s 3 rule as to the SISO Takagi-Sugeno (TS) type Fuzzy was defined as a function of output to input. Input-output function was defined that was answered by a variable defined by consequent part of FLC. Sector condition to be satisfied with steady-state error for a nonlinear system can be applied to prediction algorithm which Consequent Part of the FLC with the variable with the steady-state error relationship was expressed as a function which was verified through simulations.