• Journal of the Korean Institute of Intelligent Systems
• /
• v.12 no.6
• /
• pp.543-548
• /
• 2002

It is well known that FCM is an indispensible tool for fuzzy clustering. The problems of using FCM are 1) it is sensitive to the initial random membership functions and 2) FCM inherently requires the number of clusters. Hence we need to run FCM algorithms with an appropriate validity measure until we find a suitable number of clusters. In this paper, we suggest the Majority-Voting FCM with implied validity measure. With this algorithm, we can solve the aforementioned problems. The working simulation results are provided. The contributions are 1) MV-FCM algorithm and 2) its definitive capability of being an excellent validity measure.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.1
• /
• pp.39-46
• /
• 2011

Clustering is one of the well-known unsupervised learning methods, in which a data set is grouped into some number of homogeneous clusters. There are numerous clustering algorithms available and they have been used in various applications. Fuzzy c-means (FCM), the most well-known partitional clustering algorithm, was established in 1970's and still in use. However, there are some unsolved problems in FCM and variants of FCM are still under development. In this paper, the problems in FCM are first explained and the available solutions are investigated, which is aimed to give researchers some possible ways of future research. Most of the FCM variants try to solve the problems using domain knowledge specific to a given problem. However, in this paper, we try to give general solutions without using any domain knowledge. Although there are more things left than discovered, this paper may be a good starting point for researchers newly entered into a clustering area.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.11 no.1
• /
• pp.58-64
• /
• 2001

정밀을 요하는 자동차 부품의 측정 시스템은 온도에 따라 보상이 필수적이다. 부품의 측정값의 신뢰도를 유지하기 위해서 단순히 제품의 합격 영역을 상온에서 51.786~51.819mm로 했을 때, 온도가 상온에서 따러져 있는 경우 그 부품의 측정영역을 신뢰하기가 어려워진다. 본 논문에서는 이 문제를 해결하기 위해서 2개의 카메라를 사용하여 한쪽은 표준 제품을 두고, 다른 쪽은 실제 제품을 둠으로서 온도에 따라 달라지는 표준 제품의 측정값의 Offset를 실제 제품에 반영함으로써 측정값을 보상하려고 하였다. 자동차의 부품은 여러 가지가 있으나, 이 중에서 현재 공장에서 측정에 어려움을 겪고 있는 에어콘 스윗치인 마그네트 코일 하우징을 대상으로 하였다. 특히 측정 대상이 크고, 카메라의 화소수가 40만 이하일 경우, 측정의 중요한 포인트는 화소수와 배경과 대상의 구별이다. 이를 정확히 알아내는데, FCM (Fuzzy C-means) 알고리듬이 좋은 결과를 주지만 속성 공간에서 유사성만을 고려하고, 공간영역에서 유사성은 고려되지 않기 때문에 FCM은 \"equal evidence\"와 \"ignorance\"를 구분하지 못한다. 이를 개선하기 위해서 FCM를 수정하여 먼저 FCM로 처리하고 이를 바탕으로 PCM (Possibilistic C-means)를 사용하였다. 결과를 모니터에 보여주고, RSC-232 포트를 통하여 신호를 마이크로 프로세서에 전달하여 제품의 양호(good), 불량(bad)을 판별하는 신호를 발생하게 하였다.을 판별하는 신호를 발생하게 하였다.

• Journal of Korea Multimedia Society
• /
• v.3 no.4
• /
• pp.339-346
• /
• 2000

Medical image is analyzed to get an anatomical information for diagnostics. Segmentation must be preceded to recognize and determine the lesion more accurately. In this paper, we propose automatic segmentation algorithm for MR brain images using T1-weighted, T2-weighted and PD images complementarily. The proposed segmentation algorithm is first, extracts cerebrum images from 3 input images using cerebrum mask which is made from PD image. And next, find 3D clusters corresponded to cerebrum tissues using scale filtering and 3D clustering in 3D space which is consisted of T1, T2, and PD axis. Cerebrum images are segmented using FCM algorithm with its initial centroid as the 3D cluster's centroid. The proposed algorithm improved segmentation results using accurate cluster centroid as initial value of FCM algorithm and also can get better segmentation results using multi spectral analysis than single spectral analysis.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.12
• /
• pp.102-107
• /
• 2009

As technology gets developed, medical equipments are also modernized and leading-edge systems, such as PACS become popular. Many scientists noticed importance of medical image processing technology. Technique of region segmentation is the first step of digital medical image processing. Segmentation technique helps doctors to find out abnormal symptoms early, such as tumors, edema, and necrotic tissue, and helps to diagnoses correctly. Segmentation of white matter, gray matter and CSF of a brain image is very crucial part. However, the segmentation is not easy due to ambiguous boundaries and inhomogeneous physical characteristics. The rate of incorrect segmentation is high because of these difficulties. Fuzzy-based segmentation algorithms are robust to even ambiguous boundaries. In this paper a modified Fuzzy-based segmentation algorithm is proposed to handle the noise of MR scanners. A proposed algorithm requires minimal computations of mean and variance of neighbor pixels to adjust a new neighbor list. With the addition of minimal compuation, the modified FCM(mFCM) lowers the rate of incorrect clustering below 30% approximately compared the traditional FCM.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2011.01a
• /
• pp.85-88
• /
• 2011

Fuzzy C-Means (FCM) 알고리듬은 가장 널리 사용되는 군집화 알고리듬 중 하나로 다양한 응용 분야에서 사용되고 있다. 하지만 FCM은 여러 가지 문제점을 가지고 있으며 초기 원형 설정이 그 중 하나이다. FCM은 국부 최적해에 수렴하므로 초기 원형 설정에 따라 클러스터링 결과가 달라진다. 이 논문에서는 이러한 FCM의 초기 원형 설정 문제를 개선하기 위하여 커널밀도 추정 (kernel density estimation) 기법을 활용하는 방법을 제안한다. 제안한 방법에서는 먼저 커널 밀도 추정을 수행한 후 밀도가 높은 지역에 클러스터의 초기 원형을 설정하고 원형이 설정된 영역의 밀도를 감소시키는 과정을 반복함으로써 효율적으로 초기 원형을 설정할 수 있다. 제안된 방법이 일반적으로 사용되는 무작위 초기화 방법에 비해 효율적이라는 사실은 실험결과를 통해 확인할 수 있다.

• Journal of Biomedical Engineering Research
• /
• v.21 no.4
• /
• pp.333-338
• /
• 2000

In this paper, an automated segmentation algorithm is proposed for MR brain images using T1-weighted, T2-weighted, and PD images complementarily. The proposed segmentation algorithm is composed of 3 step. In the first step, cerebrum images are extracted by putting a cerebrum mask upon the three input images. In the second step, outstanding clusters that represent inner tissues of the cerebrum are chosen among 3-dimensional(3D) clusters. 3D clusters are determined by intersecting densely distributed parts of 2D histogram in the 3D space formed with three optimal scale images. Optimal scale image is made up of applying scale space filtering to each 2D histogram and searching graph structure. Optimal scale image best describes the shape of densely distributed parts of pixels in 2D histogram and searching graph structure. Optimal scale image best describes the shape of densely distributed parts of pixels in 2D histogram. In the final step, cerebrum images are segmented using FCM algorithm with its initial centroid value as the outstanding clusters centroid value. The proposed cluster's centroid accurately. And also can get better segmentation results from the proposed segmentation algorithm with multi spectral analysis than the method of single spectral analysis.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2000.11a
• /
• pp.323-332
• /
• 2000

정밀을 요하는 자동차 부품의 측정 시스템은 온도에 따른 보상이 필수적이다. 부품의 측정값의 신뢰도를 유지하기 위해서 단순히 제품의 합격 영역을 상온에서 51.786～51.819mm로 했을 때, 온도가 상온에서 떨어져 있는 경우 그 부품의 측정영역을 신뢰하기가 어려워진다. 본 논문에서는 이 문제를 해결하기 위해서 2개의 카메라를 사용하여 한쪽은 표준 제품을 두고, 다른 쪽은 실제 제품을 두므로서 온도에 따라 달라지는 표준 제품의 측정값의 Offset를 실제 제품에 반영하므로 측정값을 보상하려고 하였다. 자동차의 부품은 여러 가지가 있으나, 이 중에서 현재 공장에서 측정에 어려움을 겪고 있는 에어콘 스윗치인 마그네트 코일 하우징을 대상으로 하였다. 특히 측정 대상이 크고, 카메라의 화소수가 40만 이하일 경우, 측정의 중요한 포인트는 화소수이기 때문에 이를 정확히 알아 내는데, FCM(Fuzzy C-means) 알고리듬이 좋은 결과를 주지만 속성 공간에서 유사성만을 고려하고, 공간영역에서 유사성을 고려되지 않기 때문에 FCM은 \"equal evidence\"와 \"ignorance\"를 구분하지 못한다. 이를 개선하기 위해서 FCM를 수정하여 먼저 FCM로 처리하고 하고 이를 바탕으로 PCM(Possibilistic C-means)를 사용하였다. 결과를 모니터에 보여주고, RSC-232 포트를 통하여 신호를 마이크로프로세서에 전달하여 제품의 양호(good), 불량(bad)을 판별하는 신호를 발생하게 하였다.을 판별하는 신호를 발생하게 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.8
• /
• pp.1659-1664
• /
• 2011

Fuzzy C-Means (FCM) is one of the most widely used clustering algorithms and has been used in many applications successfully. However, FCM has some shortcomings and initial prototype selection is one of them. As FCM is only guaranteed to converge on a local optimum, different initial prototype results in different clustering. Therefore, much care should be given to the selection of initial prototype. In this paper, a new initialization method for FCM using kernel density estimation (KDE) is proposed to resolve the initialization problem. KDE can be used to estimate non-parametric data distribution and is useful in estimating local density. After KDE, in the proposed method, one initial point is placed at the most dense region and the density of that region is reduced. By iterating the process, initial prototype can be obtained. The initial prototype such obtained showed better result than the randomly selected one commonly used in FCM, which was demonstrated by experimental results.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.25 no.6
• /
• pp.680-687
• /
• 1988

When only global or local features of images are considered, the segmented results exhibit inevitable errors. To reduce these errors, first we divide the image into uniform and nonuniform regions by considering the local properties of the image. Next we obtain the segmented results by applying the Fuzzy C-means (FCM) algorithm to the picture and determining to which uniform reigons each pixel of the nonuniform regions belongs. To reduce the computational burden and memory required for the FCM algorithm, the equations used for FCM algorithm are modified. The performance of the proposed method is quantitatively compared to existing ones using only global or local features of the picture. Computer simualtion result shows that the segmented results obtained by applying the proposed method are superior to existing ones.