• International Journal of Fuzzy Logic and Intelligent Systems
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• 제15권1호
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• pp.35-44
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• 2015

The main purpose of image enhancement is to improve certain characteristics of an image to improve its visual quality. This paper proposes a method for image contrast enhancement that can be applied to both medical and natural images. The proposed algorithm is designed to achieve contrast enhancement while also preserving the local image details. To achieve this, the proposed method combines local image contrast preserving dynamic range compression and contrast limited adaptive histogram equalization (CLAHE). Global gain parameters for contrast enhancement are inadequate for preserving local image details. Therefore, in the proposed method, in order to preserve local image details, local contrast enhancement at any pixel position is performed based on the corresponding local gain parameter, which is calculated according to the current pixel neighborhood edge density. Different image quality measures are used for evaluating the performance of the proposed method. Experimental results show that the proposed method provides more information about the image details, which can help facilitate further image analysis.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제13권1호
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• pp.31-38
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• 2013

Patients with heart disease need long-term monitoring of the electrocardiogram (ECG) signal using a portable electrocardiograph. This trend requires the miniaturization of data storage and faster transmission to medical doctors for diagnosis. The ECG signal needs to be utilized for efficient storage, processing and transmission, and its data must contain the important components for diagnosis, such as the P wave, QRS-complex, and T wave. In this study, we select the vertex which has a larger curvature value than the threshold value for compression. Then, we reconstruct the compressed signal using by radial basis function interpolation. This technique guarantees a lower percentage of root mean square difference with respect to the extracted sample points and preserves all the important features of the ECG signal. Its effectiveness has been demonstrated in the experiment using the Massachusetts Institute of Technology and Boston's Beth Israel Hospital arrhythmia database.

• 조명전기설비학회논문지
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• 제25권4호
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• pp.45-56
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• 2011

This paper is proposed artificial neural network(ANN) rotor resistance estimation of induction motor drive controlled by multi-adaptive fuzzy learning controller(AFLC). A simple double layer feedforward ANN trained by the back-propagation technique is employed in the rotor resistance identification. In this estimator, double models of the state variable estimations are used; one provides the actual induction motor output states and the other gives the ANN model output states. The total error between the desired and actual state variables is then back propagated to adjust the weights of the ANN model, so that the output of this model tracks the actual output. When the training is completed, the weights of the ANN correspond to the parameters in the actual motor. The estimation and control performance of ANN and multi-AFLC is evaluated by analysis for various operating conditions. Also, this paper is proposed the analysis results to verify the effectiveness of this controller.

• Smart Structures and Systems
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• 제16권2호
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• pp.329-345
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• 2015

As commonly known, sensor errors and faulty signals may potentially lead structures in vibration to catastrophic failures. This paper presents a new approach to deal with sensor errors/faults in vibration control of structures by using the Fault detection and isolation (FDI) technique. To demonstrate the effectiveness of the approach, a space truss structure with semi-active devices such as Magneto-Rheological (MR) damper is used as an example. To address the problem, a Linear Matrix Inequality (LMI) based fixed-order $H_{\infty}$ FDI filter is introduced and designed. Modeling errors are treated as uncertainties in the FDI filter design to verify the robustness of the proposed FDI filter. Furthermore, an innovative Fuzzy Fault Tolerant Controller (FFTC) has been developed for this space truss structure model to preserve the pre-specified performance in the presence of sensor errors or faults. Simulation results have demonstrated that the proposed FDI filter is capable of detecting and isolating sensor errors/faults and actuator faults e.g., accelerometers and MR dampers, and the proposed FFTC can maintain the structural vibration suppression in faulty conditions.

• 한국정보통신학회논문지
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• 제5권3호
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• pp.605-611
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• 2001

고수준의 정보 서비스를 제공하기 위해서는 소프트웨어의 고품질화를 추구하여야 한다. 기존에 개발된 품질측정방법들은 모듈내에 포함되어 있는 요인항목들을 서로 다른 관점에서 개별적으로 측정하고있어 통합적인 평가방법이 필요하다. 따라서 본 논문에서는 다수의 측정 방법들을 모두수용 할 수 있는 모델을 제안한다. 제안된 모델은 비율척도들을 선택하고, 러프논리를 이용하여 그들의 중요도를 산출한다. 다음으로 모듈의 품질도를 측정하기 위해서 퍼지적분을 이용하여 척도들의 중요도와 측정값을 종합한다. 마지막으로 척도들과 산출된 품질도의 상관관계를 분석하고, 통계적 방법으로 제안된 모델의 타당성을 보인다.

• 한국지능시스템학회논문지
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• 제22권1호
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• pp.94-99
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• 2012

본 논문은 대규모 비선형 시스템의 분산 샘플치 제어 문제를 논한다. 대상 시스템은 타카기-수게노 퍼지모델로 표현된다. 중복분해 기법을 이용하여 아날로그 분산 제어기를 설계하고 이것은 지능형 디지털 재설계 기법에 의하여 샘플치 제어기로 변환된다. 설계조건은 선형행렬부등식으로 표현된다. 모의실험 결과에 의하여 제안된 기법의 효용성을 입증한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.5-8
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• 2003

This paper presents a methodology to be able to select an appropriate RP system that suits the end use of a part. Evaluation factors used in process selection include major attributes such as accuracy, roughness, strength, elongation, part cost and build time that greatly affect the performance of RP systems. Crisp values such as accuracy and surface roughness are obtained with a new test part developed. The test part is designed with conjoint analysis to reflect users' preference. The part cost and build time that have approximate ranges due to cost and many variable parameters are presented by linguistic values that can be described with triangular fuzzy numbers. Based on the evaluation values obtained, an appropriate RP process for a specific part application is selected by using the modified TOPSIS(Technique of Order Preference by Similarity to Ideal Solution) method. It uses crisp data as well as linguistic variables, and each weight on the alternatives is assigned by using pair-wise comparison matrix. The ranking order helps the decision making of the selection of RP systems.

• 제어로봇시스템학회논문지
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• 제16권11호
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• pp.1074-1081
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• 2010

Today, the research related to the robot is achieved in various part. With the high interest in means of transport, various researches about autonomous mobile robot and next generation transport is continuing. The unicycle robot among these needs much control technique like balance control model and driving model. For autonomous driving of this unicycle robot, from the basic balance control to direction switching control and velocity control are needed. But the environment elements like a gradient and frictional force or unbalanced elements from the structural feature. The unicycle needs the real time balance control so more complex, harder to control. And when functional addition is made, the problem that fall entire reaction velocity or accuracy would be happen. This paper introduces entire dynamics modeling of the unicycle robot and reduced model. And propose the new balance control algorithm using fuzzy controller. Also the evaluation about performance would be made through the test.

• 한국항해항만학회지
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• 제26권1호
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• pp.8-14
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• 2002

해난사고에 있어 어선의 사고율은 높은 비율을 차지한다. 특히, 소형어선의 사고율이 가장 높아, 이러한 사고를 예방할 수 있는 기술들이 필요한 실정이다. 본 논문에서는 충돌회피를 위한 자동제어를 두 가지 과정으로 구성하고 있다. 하나는 퍼지추론을 이용한 위험도의 추론이며 나머지는 첫 번째 과정에서 계산된 위험도를 토대로 선박을 조종하는 과정이다. 위험도를 평가하기 위해서 선박의 위치와 충돌예상시점에 의한 정보(DCPA and TCPA)를 이용하였다. 이 방법의 실효성을 검증하기 위해 어선의 충돌회피운동을 MMG 수학모델에 의해 시뮬레이션 하였다. 시뮬레이션 결과는 선박의 충돌회피에 유효함을 알아다.

• Journal of Power Electronics
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• 제16권2호
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• pp.654-665
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• 2016

The pumping of electric power from photovoltaic (PV) farms is normally carried out using transformers, which require heavy mounting structures and are thus costly, less efficient, and bulky. Therefore, transformerless schemes are developed for the injection of power into the grid. Compared with the H4 inverter topology, the H6 topology is a better choice for pumping PV power into the grid because of the reduced common mode current. This paper presents how the perturb and observe (P&O) algorithm for maximum power point tracking (MPPT) can be implemented in the H6 inverter topology along with the improved sinusoidal current injected to the grid at unity power factor with the average current mode control technique. On the basis of the P&O MPPT algorithm, a power reference for the present insolation level is first calculated. Maintaining this power reference and referring to the AC sine wave of bus bars, a sinusoidal current at unity power factor is injected to the grid. The proportional integral (PI) controller and fuzzy logic controller (FLC) are designed and implemented. The FLC outperforms the PI controller in terms of conversion efficiency and injected power quality. A simulation in the MATLAB/SIMULINK environment is carried out. An experimental prototype is built to validate the proposed idea. The dynamic and steady-state performances of the FLC controller are found to be better than those of the PI controller. The results are presented in this paper.