• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.658-665
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• 2015

In the production of medical images, noise reduction and contrast enhancement are important methods to increase qualities of processing results. By using the edge-based denoising and adaptive nonlinear histogram stretching, a novel medical image enhancement algorithm is proposed. First, a medical image is decomposed by wavelet transform, and then all high frequency sub-images are decomposed by Haar transform. At the same time, edge detection with Sobel operator is performed. Second, noises in all high frequency sub-images are reduced by edge-based soft-threshold method. Third, high frequency coefficients are further enhanced by adaptive weight values in different sub-images. Finally, an adaptive nonlinear histogram stretching method is applied to increase the contrast of resultant image. Experimental results show that the proposed algorithm can enhance a low contrast medical image while preserving edges effectively without blurring the details.

• Investigative Magnetic Resonance Imaging
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• v.4 no.2
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• pp.120-127
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• 2000

Adaptive template filtering has been proposed recently for enhancement of signal-to-noise ratio without loss of resolution. In the adaptive template filtering, an optimal template among multiple templates is selected, then linear least square error filtering based on the template is applied in vowel by vowel basis. In some magnetic resonance imaging, where the distribution of gray level has relatively small dynamic range, e.g., $T_1$ imaging, however, artificial stair-like artifact is observed at near edges. This is partially due to the edge enhancement effect in such yokels that contain multiple compounds at the boundaries of tissues. The gray levels of these yokels become similar gray levels of near dominant vowels that contain single compound by the adaptive filtering, which enlarges edge discontinuities. In this paper, we propose a technique to eliminate such artifact by identifying those yokels that contain multiple compounds and assigning the largest template for them. Filtered images with the proposed technique show substantial visual enhancement at the edges without degradation of peak signal-to-noise ratio compared to the original adaptive template filtering for both magnetic resonance images and phantom images.

• Wind and Structures
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• v.35 no.3
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• pp.177-191
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• 2022

Trains emerging on a streamlined bridge-girder may have salient interference effects on the aerodynamic properties of the bridge. The present paper aims at investigating these interferences by wind tunnel measurements, covering surface pressure distributions, near wake profiles, and flow visualizations. Experimental results show that the above interferences can be categorized into two primary effects, i.e., an additional angle of attack (AoA) and an enhancement in flow separation. The additional AoA effect is demonstrated by the upward-moved stagnation point of the oncoming flow, the up-shifted global symmetrical axis of flow around the bridge-girder, and the clockwise-deflected orientation of flow approaching the bridge-girder. Due to this additional AoA effect, the two critical AoAs, where flow around the bridge-girder transits from trailing-edge vortex shedding (TEVS) to impinging leading-edge vortices (ILEV) and from ILEV to leading-edge vortex shedding (LEVS) of the bridge-girder are increased by 4° with respect to the same bridge-girder without trains. On the other hand, the underlying flow physics of the enhancement in flow separation is the large-scale vortices shedding from trains instead of TEVS, ILEV, and LEVS governed the upper half bridge-girder without trains in different ranges of AoA. Because of this enhancement, the mean lift and moment force coefficients, all the three fluctuating force coefficients (drag, lift, and moment), and the aerodynamic span-wise correlation of the bridge-girder are more significant than those without trains.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.244-248
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• 2003

DHCP를 이용한 동적 IP주소 할당방식에서 클라이언트가 네트워크 접속을 해제하면서 IP 주소를 자동적으로 반납하지 않음으로 인해 IP 주소 회수가 즉각 이루어지지 않아 IP 주소 재활용을(reusability)이 저하된다. IP 주소의 재활용율을 증가시키면서 DHCP 서버의 부하증가 및 네트워크의 트래픽 증가 최소화를 위한 두 가지 기법으로 DHCP 서버에서 IP 주소의 임대시간을 적응적으로 조정하는 기법과 ICMP echo request 및 reply 메시지를 통한 클라이언트의 동작유무 확인을 통해 비동작 클라이언트의 IP 주소 회수 기법을 제안한다.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.188-195
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• 2017

The paper presents a histogram equalization method using the edge information of an image to be processed. The basic idea of this method is to carry out histogram equalization with edge information, which is important and essential for object conformation. In the proposed method, the edge information is used to generate histogram for the equalization process. It is found to be effective to suppress the histogram spikes that cause quantum jumps in mapping function for the equalization process. The proposed method is tested for randomly selected 30 images and compared to conventional approaches with a quantitative measure to check it preserves the structural similarity. Experimental results show that the proposed method has better performance and no artifacts caused by histogram spikes.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.6
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• pp.71-80
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• 1994

The purpose of this paper is to explore the use of fuzzy set theory for image processing and analysis. As an application example, the fuzzy method of edge detection is proposed to extract the edges of raised characters on tires.In general, Sobel, Prewitt, Robert and LoG filters are used to detect the edge, but it is difficult to detect the edge because of ambiguity of representations, noise and general problems in the interpretation of tire image. Therefore, in his paper, the fuzzy property plane has been extracted from the spatial domain using the ramp-mapping function. And then the ideas of fuzzy MIN and MAX are applied in removing noise and enhancement of the image simultaneously. From the result of MIN and MAX procedure a new fuzzy singleton is generated by extracting the difference between adjacent membership function values. And the edges are extracted by applying fuzzy $\alpha$-cut set to the fuzzy singletion, Finally, these ideas are applied to the tire images.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.790-809
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• 2019

The design of an efficient scaler to enhance the edge data is one of the most important issues in video signal applications, because the perceptual quality of the processed image is sensitively affected by the degradation of edge data. Various conventional scaling schemes have been proposed to enhance the edge data. In this paper, we propose an efficient scaling algorithm for this purpose. The proposed method is based on the discrete cosine transform-based interpolation filter (DCT-IF) because it outperforms other scaling algorithms in various configurations. The proposed DCT-IF incorporates weighting parameters that are optimized for training data. Simulation results show that the quality of the resized image produced by the proposed DCT-IF is much higher than that of those produced by the conventional schemes, although the proposed DCT-IF is more complex than other conventional scaling algorithms.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1405-1408
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• 1987

X-ray filmed data converted by Image digitizer were processed through the digital computer for edge detections. Sobel operator with the high-pass and the low-pass filtering of the histogram of the images were applied to this work and 3 examples were processed.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1186-1191
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• 1991

This paper represents a new edge relaxation algorithm that enhances the noisy boundary informations in images. The proposed algorithm employes relaxation process that reduces or eliminates ambiguities of derivative operator response via contextual informations. The contextual informations are the neighborhood patterns of a central edge which are estimated using fuzzy pattern matching technique. The algorithm is developed on crack edges. Experimental results show that the proposed scheme is effective even for noisy images or low contrast images.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.9
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• pp.59-67
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• 1992

Color image enhancement can be achieved easily by using linear form of coordinate system. But some popular color coordinate systems almost have nonlinear characteristics in the geometric form. In this paper, the proposed coordinate system has pseudo-linear form and based on IHS system which represents human color perception appropriately. And for the image intensity processing, an edge-preserving smoothing algorithm is presented.