• Structural Engineering and Mechanics
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• 제67권5호
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• pp.457-464
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• 2018

This paper presents a method for detecting damage in irregular 2D and 3D continuum structures based on combination of wavelet transform (WT) with fuzzy inference system (FIS) and particle swarm optimization (PSO). Many damage detection methods study regular structures. This method studies irregular structures and doesn't need response of healthy structures. First the damaged structure is analyzed with finite element methods, and damage response is obtained at the finite element points that have irregular distance, secondly the FIS, which is optimized by PSO is used to obtain responses at points, having equal distance by response at those points that previously obtained by the finite element methods. Then a 2D (for 2D continuum structures) or a 3D (for 3D continuum structures) matrix is performed by equal distance point response. Thirdly, by applying 2D or 3D wavelet transform on 2D or 3D matrix that previously obtained by FIS detail matrix coefficient of WT is obtained. It is shown that detail matrix coefficient can determine the damage zone of the structure by perturbation in the damaged area. In order to illustrate the capability of proposed method some examples are considered.

• 대한전기학회논문지:전력기술부문A
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• 제52권10호
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• pp.602-609
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• 2003

This paper describes the fault location calculation using neuro-fuzzy systems in combined transmission lines with underground power cables. Neuro-fuzzy systems used in this paper are composed of two parts for fault section and fault location. First, neuro-fuzzy system discriminates the fault section between overhead and underground with normalized detail coefficient obtained by wavelet transform. Normalized detail coefficients of voltage and current in half cycle information are used for the inputs of neuro-fuzzy system. As the result of neuro-fuzzy system for fault section, impedance of selected fault section is calculated and it is used as the inputs of the neuro-fuzzy systems for fault location. Neuro-fuzzy systems for fault location also consist of two parts. One calculates the fault location of overhead, and the other does for underground. Fault section is completely classified and neuro-fuzzy system for fault location calculates the distance from the relaying point. Neuro-fuzzy systems proposed in this paper shows the excellent results of fault section and fault location.

• 대한의용생체공학회:의공학회지
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• 제27권4호
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• pp.189-196
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• 2006

Micro computed tomography (micro-CT) has been used for in vivo animal study owing to its noninvasive and high spatial resolution capability. However, the sizes of existing detectors for micro-CT systems are too small to obtain whole-body images of a small animal object with $\sim$10 micron resolution and a part of its bones or other organs should be extracted. So, we have introduced the zoom-in micro-tomography technique which can obtain high-resolution images of a local region of an live animal object without extracting samples. In order to verify our zoom-in technique, we performed in vivo animal bone study. We prepared some SD (Sprague-Dawley) rats for making osteoporosis models. They were divided into control and ovariectomized groups. Again, the ovariectomized group is divided into two groups fed with normal food and with calcium-free food. And we took 3D tomographic images of their femurs with 20 micron resolution using our zoom-in tomography technique and observed the bone changes for 12 weeks. We selected ROI (region of interest) of a femur image and applied 2D FDT (fuzzy distance transform) to measure the trabecular bone thickness. The measured results showed obvious bone changes and big differences between control and ovariectomized groups. However, we found that the reliability of the measurement depended on the selection of ROI in a bone image for thickness calculation. So, we extended the method to 3D FDT technique. We selected 3D VOI (volume of interest) in the obtained 3D tomographic images and applied 3D FDT algorithm. The results showed that the 3D technique could give more accurate and reliable measurement.

• 한국지능시스템학회논문지
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• 제14권5호
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• pp.642-647
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• 2004

The relations of fuzzy entropy, distance measure, and similarity measure are discussed in this paper. For the purpose of reliable signal selection, the fuzzy entropy is proposed by a distance measure. Properness of the proposed entropy is verified by the definition of the entropy measure. Fourier and Wavelet transform are applied to the stator current signal to obtain the fault features of an induction motor. Membership functions for 3-phase currents are obtained by the Bootstrap method and Central Limit Theorem. Finally, the proposed entropy is applied to measure the fault signal of an induction machine, and the fuzzy entropy values of phase currents are illustrated.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제11권3호
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• pp.165-170
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• 2011

Due to advances in hardware performance, user-friendly interfaces are becoming one of the major concerns in information systems. Linguistic conversation is a very natural way of human communications. Fuzzy techniques have been employed to liaison the discrepancy between the qualitative linguistic terms and quantitative computerized data. This paper deals with linguistic queries using clustering results on data sets, which are intended to retrieve the close clusters or distant clusters from the clustering results. In order to support such queries, a fuzzy technique-based method is proposed. The method introduces distance membership functions, namely, close and distant membership functions which transform the metric distance between two objects into the degree of closeness or farness, respectively. In order to measure the degree of closeness or farness between two clusters, both cluster closeness measure and cluster farness measure which incorporate distance membership function and cluster memberships are considered. For the flexibility of clustering, fuzzy clusters are assumed to be formed. This allows us to linguistically query close or distant clusters by constructing fuzzy relation based on the measures.

• 한국지능시스템학회논문지
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• 제8권2호
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• pp.128-133
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• 1998

본 논문에서는 주어진 칼라 영상열을 분석하여 이동물체 추적을 할수 있는 병렬 프레임워크를 구축한다. 병렬 프레임워크는 크게 탐색 공간 축소 부분과 추적 부분으로 나뉘며 탐색 공간 축소 부분은 퍼지 클러스터링과 칼만 필터를 이용한 예측부분으로 구성되고 추적은 거리변환에 기반을 둔 하우스돌프 거리를 이용해 경계선 정합을 함으로써 이루어진다.

• 한국정보통신학회논문지
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• 제9권4호
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• pp.782-791
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• 2005

본 연구는 개선된 거리변환 알고리즘을 사용하여 로봇이 이동해야 할 경로를 생성하고, 퍼지 시스템을 사용하여 경로추적 행위기와 장애물 회피 행위기를 구현해서 로봇이 그 경로를 안전하고 효율적으로 추적하는 것을 목적으로 하였다. 개선된 거리변환 알고리즘을 이용하여 로봇의 유연한 주행을 가능하게 했으며, 또한 주행거리와 주행시간도 단축되는 것을 확인할 수 있었다. 경로생성 후 경로를 추적할 때는 퍼지 시스템을 이용한 경로추적 행위기와 장애물 회피 행위기를 선택적으로 사용해서 경로추적 중에 예상치 못한 장애물이 발견되었을 경우에도 장애물을 회피한 후에 계속해서 경로를 추적하는 것을 확인함으로써 경로생성 후의 외부환경변화에도 강인함을 볼 수 있었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.295-299
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• 2005

본 연구는 개선된 거리변환 알고리즘을 사용하여 로봇이 이동해야 할 경로를 생성하고, 퍼지 시스템을 사용하여 경로추적 행위기와 장애물 회피 행위기를 구현해서 로봇이 그 경로를 안전하고 효율적으로 추적하는 것을 목적으로 하였다. 개선된 거리변환 알고리즘을 이용하여 로봇의 유연한 주행을 가능하게 했으며, 또한 주행거리와 주행시간도 단축되는 것을 확인할 수 있었다. 경로생성 후 경로를 추적할 때는 퍼지 시스템을 이용한 경로추적 행위기와 장애물 회피 행위기를 선택적으로 사용해서 경로추적 중에 예상치 못한 장애물이 발견되었을 경우에도 장애물을 회피한 후에 계속해서 경로를 추적하는 것을 확인함으로써 경로생성 후의 외부환경변화에도 강인함을 볼 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제26권5호
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• pp.295-300
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• 2005

We introduce an x-ray micro tomography system capable of high resolution imaging of a local region inside a small animal. By combining two kinds of projection data, one from a full field-of-view (FOV) scan of the whole body and the other from a limited FOV scan of the region of interest, we have obtained zoomed-in images of the region of interest without any contrast a nomalies. We have integrated a micro tomography system using a micro-focus x-ray source, a $1248\times1248$ flat-panel x-ray detector, and a precision scan mechanism. Using the cross-sectional images taken with the zoom-in micro tomography system, we measured trabecular thicknesses of femur bones in postmortem rats. To compensate the limited spatial resolution in the zoom-in micro tomography images, we used the fuzzy distance transform for the calculation of the trabecular thickness. To validate the trabecular thickness measurement with the zoom-in micro tomography images, we compared the measurement results with the ones obtained from the conventional micro tomography images of the extracted bone samples.

• 한국지능시스템학회논문지
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• 제7권2호
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• pp.34-42
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• 1997

본 논문은 산업분야의 군사적으로 많이 사용되고 있는 planar shape의 인식을 스펙트럼 분석기를 이용하여 FFT 스펙트럼으로부터 추출된 3차원 특징 벡터와 신경회로망인 fuzzy ARTMAP을 이용하여 시도되었다. 외곽선 정보를 추출하여 이를 원점으로 이동시키고 각 경계점들과 원점들과의 유클리드 거리를 구하여 이를 다시 FFT스펙트럼과 스펙트럼 분석기를 통하여 3차원 특징 벡터를 추출하였다. 이 3차원 데이터는 이동, 회전, 크기에 무관한 값으로 fuzzy ARTMAP에 입력값으로 사용하였다. Fuzzy ARTMAP은 두개의 fuzzy ART 모듈을 가지고 있으며 위에서 구한 특징 벡터들에 의해 학습되고 실험되어 진다.본 논문에 포함된 실험은 4개의 비행기와 4개의 산업부품을 이용하여 잡음이 섞인 shape의 인식에 있엇 제시된 방법이 좋은 인식률을 기록함을 보여주고 있다.