• 대한전기학회논문지:시스템및제어부문D
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• 제50권7호
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• pp.332-338
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• 2001

A visually adaptive quantization method of DCT-based images based on Human Visual System(HVS) is proposed. This approach uses the spatial masking in HVS characteristics to obtain higher compression ratio with relatively small degradation in the image quality. HVS is nonsensitive to an edge area, so a high complexity area is quantized coarsely in contrast to fine quantization of the low complexity area. The complexity of an area is estimated by the variance of DCT coefficients of the image. Experimental results demonstrate the performance of the proposed method and the resulting images show little difference from the original image in the subjective perception.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.275-278
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• 2002

Sharpness enhancement, which strengthen the edge(high frequency) of image, is widely studied for image processing research area. In this paper, psychophysical experiment is conducted by the 20 observers with simple linear unsharp masking for sharpness enhancement. The experimental results extracted using z-score analysis and linear regression suggests observer preferable sharpness enhancement method for digital television.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.25-28
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• 2006

We propose a new method of masking cloud-affected pixels in satellite ocean color imageries such as of GLI. Those pixels, mostly found around cloud pixels or in scattered cloud area, have anomalous features in either in chlorophyll-a estimate or in water reflectance. This artifact is most likely caused by residual error of inter-band registration correction. Our method is to check the pixel-wise 'soundness' of the spectral water reflectance Rw retrieved after the atmospheric correction. First, we define two spectral ratio between water reflectance, IRR1 and IRR2, each defined as RW(B1)/RW (B3) RW (B3) and as RW (B2)/RW(B4) respectively, where $B1{\sim}B4$ stand for 4 consecutive visible bands. We show that an almost linear relation holds over log-scaled IRR1 and IRR2 for shipmeasured RW data of SeaBAM in situ data set and for GLI cloud-free Level 2 sub-scenes. The method we propose is to utilize this nature, identifying those pixels that show significant discrepancy from that relationship. We apply this method to ADEOS-II/GLI ocean color data to evaluate the performance over Level-2 data, which includes different water types such as case 1, turbid case 2 and coccolithophore bloom waters.

• 한국정보통신학회논문지
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• 제4권2호
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• pp.389-395
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• 2000

디지털 워터마킹은 멀티미디어 컨텐츠(영상, 오디오, 비디오 등)에 비밀스러운 정보를 은닉시키는 기술이다. 본 논문에서는 웨이브렛 변환과 확산스펙트럼 방법 그리고 웨이브렛 계수를 고려한 다중 임계치를 이용하여 시각적으로 인식 가능한 심벌을 삽입할 수 있는 새로운 워터마킹 방법을 제안한다. 워터마크 검출은 원 영상과 워터마크된 영상 모두를 삽입 시와 동일한 레벨로 웨이브렛 변환을 수행하고 워터마크를 삽입한 각 부대역간의 차신호를 이용하여 워터마크를 검출한다. 제안한 방법으로 여러 영상에 적용해 본 결과 우수한 영상의 화질을 얻을 수가 있었으며 JPEG 손실압축 뿐만 아니라 Resizing, LSB(Least Significant Bit) Masking, Filtering 등의 다양한 공격에서도 삽입한 심벌 워터마크를 쉽게 검출할 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제18권4호
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• pp.439-446
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• 1997

증가하고 있는 주요 족부질환인 엄지발가락외반증의 특성을 이해하기 위하여 본 연구를 수행하였다.23명의 엄지발가락외반증 환자들에 관한 방사선학적 연구와 함께 자유보행시의 족저압력분포를 측정하였다. 또한 본 연구에서는 족저압력 분포를 상세히 분석하기 위한 해부학적으로 적절한 구역설정을 제시하였다. 족저압력분포를 측정한 결과, 엄지발가락외반증이 심한 환자일수록 중족골 부위의 압력, 접촉면 적과 시간, 충격량 등이 현저하게 증가함을 알 수 있었다. 엄지발가락외반증은 신발의 선정이 잘못됨에 의하는 경우가 적지 않았다. 족저압력집중은 족부질환에 있어서 매우 중요하므로, 신발의 설계에 있어서 적절한 족저압력분포를 고려하여야 한다.

• 소성∙가공
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• 제12권7호
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• pp.640-646
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• 2003

The nanoprobe based on lithography, mainly represented by SPM based technologies, has been recognized as potential application to fabricate the surface nanostructures because of its operational versatility and simplicity. The objective of the work is to suggest new mastless pattern fabrication technique using the combination of machining by nanoindenter and KOH wet etching. The scratch option of the nanoindenter is a very promising method for obtaining nanometer scale features on a large size specimen because it has a very wide working area and load range. Sample line patterns were machined on a silicon surface, which has a native oxide on it, by constant load scratch (CLS) of the Nanoindenter with a Berkovich diamond tip, and they were etched in KOH solutions to investigate chemical characteristics of the machined silicon surface. After the etching process, the convex structure was made because of masking effect of the affected layer generated by nano-scratch. On the basis of this fact, some line patterns with convex structures were fabricated. Achieved patterns can be used as a mold that will be used for mass production processes such as nanoimprint or PDMS molding process. All morphological data of scratch traces were scanned using atomic force microscope (AFM).

• 한국측량학회지
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• 제37권5호
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• pp.351-357
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• 2019

UAV (Unmanned Aerial Vehicle) images can be exploited for rapid forest fire damage assessment by virtue of UAV systems' advantages. In 2019, catastrophic forest fire occurred in Goseong and Sokcho, Korea and burned 1,757 hectares of forests. We visited the town in Goseong where suffered the most severe damage and conducted UAV flights for forest fire damage assessment. In this study, economic and rapid damage assessment method for forest fire has been proposed using UAV systems equipped with only a RGB sensor. First, forest masking was performed using automatic elevation thresholding to extract forest area. Then ExG (Excess Green) vegetation index which can be calculated without near-infrared band was adopted to extract damaged forests. In addition, entropy filtering was applied to ExG for better differentiation between damaged and non-damaged forest. We could confirm that the proposed forest masking can screen out non-forest land covers such as bare soil, agriculture lands, and artificial objects. In addition, entropy filtering enhanced the ExG homogeneity difference between damaged and non-damaged forests. The automatically detected damaged forests of the proposed method showed high accuracy of 87%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권8호
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• pp.2298-2315
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• 2024

This paper introduces a method aimed at diagnosing the presence or absence of lesions by detecting anomalies in Chest X-ray images. The proposed approach is based on the PatchCore anomaly detection method, which extracts a feature vector containing location information of an image patch from normal image data and calculates the anomaly distance from the normal vector. However, applying PatchCore directly to medical image processing presents challenges due to the possibility of diseases occurring only in specific organs and the presence of image noise unrelated to lesions. In this study, we present an image alignment method that utilizes affine transformation parameter prediction to standardize already captured X-ray images into a specific composition. Additionally, we introduce a region-specific abnormality detection method that requires affine-transformed chest X-ray images. Furthermore, we propose a method to enhance application efficiency and performance through feature map hard masking. The experimental results demonstrate that our proposed approach achieved a maximum AUROC (Area Under the Receiver Operating Characteristic) of 0.774. Compared to a previous study conducted on the same dataset, our method shows a 6.9% higher performance and improved accuracy.

• 지능정보연구
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• 제9권2호
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• pp.1-18
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• 2003

The automatic recognition of transport containers using image processing is very hard because of the irregular size and position of identifiers, diverse colors of background and identifiers, and the impaired shapes of identifiers caused by container damages and the bent surface of container, etc. We proposed and evaluated the novel recognition algorithm of container identifiers that overcomes effectively the hardness and recognizes identifiers from container images captured in the various environments. The proposed algorithm, first, extracts the area including only all identifiers from container images by using CANNY masking and bi-directional histogram method. The extracted identifier area is binarized by the fuzzy binarization method newly proposed in this paper and by applying contour tracking method to the binarized area, container identifiers which are targets of recognition are extracted. We proposed and applied the ART2-based RBF network for recognition of container identifiers. The results of experiment for performance evaluation on the real container images showed that the proposed algorithm has more improved performance in the extraction and recognition of container identifiers than the previous algorithms.

• 대한원격탐사학회지
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• 제8권2호
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• pp.105-123
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• 1992

A study was made on the feature extraction for non-metallic one deposits and their related geology using the Remote Sensing and Airborne Radiometric data. The area chosen is around the Haenam area, where dickite and Quarzite mines are distributed in. The geology of the area consists mainly of Cretaceous volcanics and PreCambrian metamorphic. The methods applied are study on the reflectance characteristics of minerals and rocks sampled in the study area, and the feature extraction extraction of histogram normalized images for Landsat TM and Airborne Radiometric data, and finally evaluation of applicability of some useful pattern recognition techniques for regional lithological mapping. As a result, reflectances of non-metallic minerals are much higher than rock samples in the area. However, low grade dickites are slightly higher than rock samples, probably due to their greyish colour and also their textural features which may scatter the reflectance and may be capable of capturing much hychoryl ions. The reflectances of rock samples may depend on the degree of whiteness of samples. The outcrops or mine dumps in the study area were most effectively extracted on the histogram normalized image of TM Band 1, 2 and 3, due to their high reflectivity. The Masking technique using the above bands may be the most effective and the natural colour composite may provide some success as well. The colour composite image of PCA may also be effective in extracting geological features, and airborne radiometric data may be useful to some degree as an complementary tool.