• 대한기계학회논문집B
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• 제29권2호
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• pp.214-223
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• 2005

The characteristics of flow on two parallel plane jets was experimentally investigated. The two nozzles each with an aspect ratio of 20 were separated by 6 nozzle widths. Reynolds number based on nozzle width was set to 5,000 by nozzle exit velocity. The particle image velocimetry and pressure transducer were employed to measure turbulent velocity components and mean static pressure, respectively. In case of unventilated parallel plane jets, it was shown that a recirculation zone with sub-atmospheric static pressure was bounded by the inner shear layers of the individual jets and the nozzles plated. There was no recirculation zone in the ventilated parallel plane jets. It was found that the spanwise turbulent intensities of unventilated jets were higher than those of ventilated jets because of the interaction of jets, and the streamwise turbulent intensities of ventilated jets were higher than those of unventilated jets because of the effect of entrainment.

• Journal of Information Processing Systems
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• 제19권4호
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• pp.417-426
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• 2023

To improve the effect of image restoration and solve the image detail loss, an image dehazing enhancement algorithm based on mean guided filtering is proposed. The superpixel calculation method is used to pre-segment the original foggy image to obtain different sub-regions. The Ncut algorithm is used to segment the original image, and it outputs the segmented image until there is no more region merging in the image. By means of the mean-guided filtering method, the minimum value is selected as the value of the current pixel point in the local small block of the dark image, and the dark primary color image is obtained, and its transmittance is calculated to obtain the image edge detection result. According to the prior law of dark channel, a classic image dehazing enhancement model is established, and the model is combined with a median filter with low computational complexity to denoise the image in real time and maintain the jump of the mutation area to achieve image dehazing enhancement. The experimental results show that the image dehazing and enhancement effect of the proposed algorithm has obvious advantages, can retain a large amount of image detail information, and the values of information entropy, peak signal-to-noise ratio, and structural similarity are high. The research innovatively combines a variety of methods to achieve image dehazing and improve the quality effect. Through segmentation, filtering, denoising and other operations, the image quality is effectively improved, which provides an important reference for the improvement of image processing technology.

• 대한원격탐사학회지
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• 제33권6_1호
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• pp.1003-1017
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• 2017

지표면의 공간 정보를 정확히 추출하기 위해서는 고 해상도의 다중 분광 영상 자료를 사용할 필요가 있다. 범색 영상에 비해 상대적으로 낮은 공간 해상도를 갖는 다중 분광 자료의 해상도를 범색 영상 급으로 높이기 위해 PAN-sharpening 융합 기술을 사용한다. 이러한 고해상도 자료를 분석하기 위해서는 화소기반보다는 객체 기반 분석이 주목을 받고 있다. 객체 기반 영상 분석을 위해서 영상을 구성하는 화소들의 집단으로 영상 객체를 생성하는 영상 분할 과정이 선행되어야 한다. RAG(Regional Adjancy Graph)에 의해 형성된 인접 지역을 합병하는 지역 확장을 통해 효과적으로 영상 분할을 할 수 있다. 위성 원격 탐사에서 불 완전한 관측 환경으로 수집한 영상 자료에 질 저하가 일어 난다. 정확한 영상 분할을 위해서 동일 지역으로 관측된 분광 값의 변이가 최소화되도록 질의 개선이 필요하다. 동일 지역에 속하는 공간적으로 인접한 이웃들의 화소 값과 차이를 반복적으로 줄여 나가는 과정을 통해 동일 지역에서의 화소 값의 변이를 감소시킬 수 있다. 영상 객체를 단위로 사용하는 영상 분류에서 오류를 감소시키기 위해 영상 분할 결과에서 적정한 분할 지역 크기를 생성하여야 한다. 분할 지역 크기는 지역 확장 과정에서 합병을 중지하는 단계에 의해 정해지므로 중지 규칙은 영상 분할 결과의 품질을 결정한다. 본 연구에서는 모의 자료 실험을 통하여 분할의 정확성에 대해 정량적 평가를 실시하였으며 3개의 PAN-sharpened 고해상도 다중 분광 영상 자료에 대해 적용하여 복원의 효과에 대해 실험하였다. 실제 자료의 분석에서는 중지 규칙과 관련된 분할 지역 크기에 대해 정성적으로 평가 하였다. 사용된 원격 탐사 자료는 1m급의 미국 LA지역에서 수집된 Dubaisat-2 자료와 0.7 m급의 한반도 대전 지역과 충청남도 지역에서 각각 수집된 KOMPSAT-3 자료이다. 실험 결과는 영상 복원은 PAN-sharpened 고해상도 다중 분광 자료의 영상 분할 결과의 정확성을 상당히 제고시킬 수 있다는 것을 보여준다.

• 한국멀티미디어학회논문지
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• 제13권4호
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• pp.526-534
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• 2010

본 논문에서는 노출 시간을 달리해 촬영한 두 장의 HDR 사진을 LCD, CRT 같은 LDR 장치에 출력할 수 있도록 융합하는 알고리즘에 대해 기술하였다. 제안된 기법은 레이디언스 맵을 만들지 않고 직접 입력 영상에 대해 계산된 가중치를 이용해 융합한다. 가중치는 처음에는 화소 단위로 만들어져 추후 가우시안 함수로 혼합된다. 이러한 작업은 급격한 가중치 변화로 발생할 수 있는 스파클 잡음을 방지하고 두 영상 정보의 연결 부분을 부드럽게 만드는데 기여한다. 색상 정보의 융합은 RGB와 이들의 평균값과의 차이를 이용해 두 영상의 색차 정보를 가중평균하여 이루어진다. 본 알고리즘은 두 원본 영상에서 포화되지 않은 부분을 잘 표현하고 포화, 불포화 영역간의 연결이 부드러운 특징이 있다. 제안된 기법은 2장의 사진만을 사용하고 영상에 따라 자동으로 내부 인자를 조절하기 때문에 향후 이중 노출이나 이중 센서 셀을 이용한 HDR 카메라에 내장하여 자동화 처리가 가능한 장점이 있다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.571-574
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• 2005

In this paper, we propose an efficient image segmentation technique for large-sized monochrome images using a hybrid approach which combines threshold and region-based techniques. First, an image is partitioned into fixed-size blocks and for each block the representative intensity is determined by averaging pixel intensities within the block. Next, the neighborhood blocks that have similar characteristics with respect to a specific threshold are merged in order to form candidate regions. Finally, those candidate regions are refined to get final target object regions by merging regions considering the spatial locality and certain criteria. We have performed experiments on images selected from various domains and showed that our technique was able to extract target object regions appropriately from most images.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.525-528
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• 1999

Abstract - In this paper, a segmentation method for brain Magnetic Resonance(MR) image using region clustering technique with statistical distribution of gradient image and fuzzy rules is described. The brain MRI consists of gray matter and white matter, cerebrospinal fluid. But due to noise, overlap, vagueness, and various parameters, segmentation of MR image is a very difficult task. We use gradient information rather than intensity directly from the MR images and find appropriate thresholds for region classification using gradient approximation, rayleigh distribution function, region clustering, and merging techniques. And then, we propose the adaptive fuzzy rules in order to extract anatomical structures and diseases from brain MR image data. The experimental results shows that the proposed segmentation algorithm given better performance than traditional segmentation techniques.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2343-2346
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• 2003

The spatial resolution of multispectral images can be improved by merging them with higher resolution image data. A fundamental problem frequently occurred in existing fusion processes, is the distortion of spectral information. This paper presents a spatially adaptive image fusion algorithm which produces visually natural images and retains the quality of local spectral information as well. High frequency information of the high resolution image to be inserted to the resampled multispectral images is controlled by adaptive gains to incorporate the difference of local spectral characteristics between the high and the low resolution images into the fusion. Each gain is estimated to minimize the l$_2$-norm of the error between the original and the estimated pixel values defined in a spatially adaptive window of which the weight are proportional to the spectral correlation measurements of the corresponding regions. This method is applied to a set of co-registered Landsat7 ETM＋ panchromatic and multispectral image data.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1678-1680
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• 2002

Stereo matching technique is used in many practical fields like satellite image analysis and computer vision. In this paper, we suggest a method to extract a target object image from a complicated background. For example, human face image can be extracted from random background. This method can be applied to computer vision such as security system, dressing simulation by use of extracted human face, 3D modeling, and security system. Many researches about stereo matching have been performed. Conventional approaches can be categorized into area-based and feature-based method. In this paper, we start from area-based method and apply area tracking using scanning window. Coarse depth information is used for area merging process using area searching data. Finally, we produce a target object image.

• 반도체디스플레이기술학회지
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• 제7권2호
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• pp.69-76
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• 2008

Recently, as the multimedia processing application increases rapidly by going on increasing multimedia data, the efficient retrieval method of image information is required in many fields of application and becoming the matter of major concern. Furthermore, in the last few years rapid improvements in hardware technology have made it possible to process, store and retrieve huge amounts of data in a multimedia format. As a result, Content-Based Image Retrieval (CBIR) has been receiving widespread interest during the last decade. This paper propose the content-based retrieval system as a method for performing image retrieval through the effective feature analysis of the object of significant meaning by using YCbCr channel merging on the basis of the characteristics of man's visual system.

• 한국멀티미디어학회논문지
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• 제20권2호
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• pp.179-187
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• 2017

The fourth industrial revolution is a phenomenon where productivity is improved in each field by the convergence of IT technology and existing industries. In the dental treatment process, prosthetic treatment time is drastically shortened through AI and expert software. Oral imaging, prosthesis design, and prosthesis manufacturing are performed continuously, so the treatment can be completed in a few hours. In this paper, we introduce the research trend of multimedia technology in the prosthetic process. We also propose a new method for accelerating the fusion of surface data during the optical impression. Proposed method enables high-speed optical impression and accelerates the overall automated production process of dental prosthesis.