• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 2002년도 춘계학술대회 및 임시총회
• /
• pp.289-292
• /
• 2002

2계 선형 상미분방정식의 경계치 문제는 보통 해를 구하고자 하는 구간의 양 끝점에서 도함수의 값을 임의로 선정한 후 각 점에서 초기치 문제의 해를 구한 다음 적절한 1차 결합을 이용하여 구하게 된다. 이 경우 초기값과 도함수 값을 사용한 반복연산이 수반되며 따라서 오차의 누적이 불가피 하게 된다. 이 논문에서는 이같은 오차의 누적을 피할 뿐 아니라 3차 Spline 함수를 사용함으로써 오차가 O( $h^2$)인 해를 구하는 방법에 대하여 기술한다 두 개의 경계조건과 근사값을 구하고자 하는 점에서의 함수 값을 "If x is $B_{i}$, then f is $C_{i}$"와 같은 Fuzzy Rule들로 변형하고 주어진 미분방정식을 상수 $C_{i}$들의 관계식으로 변형하여 해를 구하였다. 산출된 결과로부터의 보간 연산은 Fuzzy System사용에 의하여 대체되었다. 이상의 방법으로 산출한 해의 근사오차가 O( $h^2$).임을 증명하였으며 3개의 예제에 대한 계산결과를 4계 Runge-Kutta 방법에 의한 해와 비교하여 기술하였다였다였다였다

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
• /
• pp.341-344
• /
• 1991

Current controlled pulse width modulation(PWM) for voltage source inverter(VSI) is one of the control method which controls the current directly so that we can perform vector control because it reduces the orders of differential equations of the induction machine. This paper propose a Fuzzy current controlled PWM which properly minimize a current ripple using Fuzzy theory in a constant switching frequency. This technique is applied to an electrical drive system with an induction machine(IM) by simulation. By comparison with the known classical method such as ramp comparison, hysteresis band method, our contribution shows the better performances.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
• /
• pp.1410-1413
• /
• 1993

This paper presents the application of fuzzy control to three links of a Rhino robot and compares its performance to traditional PD control. The dynamics of motion of robot links are governed by nonlinear differential equations. The fuzzy controller, being an adaptive technique, gives better performance than the traditional linear PD controller over a typical operational range. The fuzzy controller reaches the desired position with no overshoot, which is unlikely with the PD controller.

• 한국지능시스템학회논문지
• /
• 제19권5호
• /
• pp.689-694
• /
• 2009

본 논문은 일별 및 주별로 시계열 주가를 예측할 수 있는 퍼지 모델을 구성하는 방법을 제안한다. 전통적인 시계열 분석으로 주가를 예측하는 것은 어렵지만 퍼지 모델은 비선형적인 주가 데이터의 특성을 잘 기술할 수 있는 장점을 갖고 있다. 주가 예측 모델에 사용될 입력 정보를 결정하는 데는 상당한 수고가 필요한데, 본 논문에서는 전통적인 캔들 스틱 차트의 정보를 입력변수로 고려한다. 주가 예측 퍼지 모델은 사다리꼴 멤버쉽함수를 갖는 전건부와 비선형식인 후건부로 된 퍼지 규칙으로 구성된다. 차분 진화를 통해 퍼지 모델은 최적화된다. 일별 및 주별로 코스피 지수의 시가, 고가, 저가 및 종가를 예측하는 모델을 만들고 그 성능을 평가한다.

• 정보처리학회논문지B
• /
• 제15B권6호
• /
• pp.603-608
• /
• 2008

본 논문에서는 주가의 일별 시가, 종가, 최고가, 최저가를 예측하기 위한 퍼지모델을 제안한다. 주가는 시장의 여러 경제 변수에 의존하므로 주가예측 모델의 입력변수를 선택하는 것은 쉽지 않은 일이다. 이와 관련하여 많은 연구가 있지만 정답이 있는 것은 아니다. 본 논문에서는 이를 해결하기 위해 주가 움직임 자체에 주목하는 스틱차트의 기술적 분석에 이용되는 정보를 퍼지규칙의 입력변수로 선택한다. 퍼지규칙은 사다리꼴 멤버쉽함수로 이루어진 전건부와 비선형 수식의 후건부로 구성된다. 최적의 퍼지규칙으로 구성된 퍼지모델을 찾아내기 위해 차분진화가 사용된다. 본 논문에 제안된 방법은 수치 예를 통해 다른 방법과의 비교로 타당성이 검토되며 KOSPI(KOrea composite Stock Price Index) 일별 데이터를 사용, 주가예측 퍼지모델을 구축하고 신경회로망 모델과 비교, 검토된다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2264-2269
• /
• 2003

This paper presents an improved method that constructs an equivalent T-S fuzzy model for nonlinear systems expressed by nonlinear differential equations including terms of power series. The method in this paper has fewer numbers of the rules than the previous methods as well as exactly expresses nonlinear systems. Moreover, this method can get wider feasible area satisfying the stability conditions than the previous methods. We show the improvement of modeling by comparing the proposed method with two previous methods through an inverted pendulum on a cart.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
• /
• pp.379-384
• /
• 1994

In this paper, a fish-drying control method is proposed, which utilizes prediction of proper change in- weight of material fish based on skilled worker's performance. The function of the proposed system is largely broken down into two procedures: The procedure before drying and the one during drying. The procedure before drying is the determination of necessary drying conditions and the required drying time. Required drying time and proper changes in weight for a specific product are obtained by using fuzzy inference and regression models. The procedure during drying is the prediction of the state of material at the end of drying, or the state of product and regulation of drying conditions to attain the prescribed goal before drying. The prediction of product is obtained by using a set of linear-differential equations obtained by the authors' previous work. Drying conditions are regulated by using fuzzy inference. A good agreement between the results of simulation and experiments is obtained, which implies the usefulness of the present control method.

• Advances in nano research
• /
• 제14권2호
• /
• pp.141-154
• /
• 2023

Effects of viscoelastic foundation on vibration of curved-beam structure with clamped and simply-supported boundary conditions is investigated in this study. In doing so, a micro-scale laminate composite beam with two piezoelectric face layer with a carbon nanotube reinforces composite core is considered. The whole beam structure is laid on a viscoelastic substrate which normally occurred in actual conditions. Due to small scale of the structure non-classical elasticity theory provided more accurate results. Therefore, nonlocal strain gradient theory is employed here to capture both nano-scale effects on carbon nanotubes and microscale effects because of overall scale of the structure. Equivalent homogenous properties of the composite core is obtained using Halpin-Tsai equation. The equations of motion is derived considering energy terms of the beam and variational principle in minimizing total energy. The boundary condition is assumed to be clamped at one end and simply supported at the other end. Due to nonlinear terms in the equations of motion, semi-analytical method of general differential quadrature method is engaged to solve the equations. In addition, due to complexity in developing and solving equations of motion of arches, an artificial neural network is design and implemented to capture effects of different parameters on the inplane vibration of sandwich arches. At the end, effects of several parameters including nonlocal and gradient parameters, geometrical aspect ratios and substrate constants of the structure on the natural frequency and amplitude is derived. It is observed that increasing nonlocal and gradient parameters have contradictory effects of the amplitude and frequency of vibration of the laminate beam.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
• /
• pp.132-137
• /
• 1993

In this paper, a fish drying process control system is proposed, which predicts the proper change with time in weight of the material fish and the drying conditions in advance, based on the performance of skilled worker. In order to implement a human expertise into an automated fish drying process control system, an experimental analysis is made and a model for the process is built. The proposed system divided into two procedures: The procedure before drying and the one during drying. The procedure before drying is for the prediction of necessary drying time. To estimate the necessary drying time, first, the proper change in weight for the product is obtained by using fuzzy reasoning. The condition part of the production rule consists of the factors of fish body and the expected degree of dryness. Kext, the necessary drying time is obtained by regression models. The variables employed in the models are the factors, inferred change in weight and drying conditions. The model for the procedure during drying is also proposed for more accurate estimation, which is described by a system of linear-differential equations.