• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.9-15
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• 2011

Zero-watermarking is a digital watermarking technique that can escape from data distortion and quality degradation by no watermark insertion into digital images to be watermarked. This paper proposes DCT0CRT, a CRT-based zero-watermarking technique in the domain of DCT. One of the DC and low-frequency AC coefficients of each DCT block chosen in chaotic way from an image is selected by testing whether it satisfies the CRT-based condition matching with the watermark bit to be embedded. Such selection information forms a key to extract the watermark from the watermarked image. Experimental results show that the image quality watermarked by DCT0CRT is better than that watermarked by any other CRT-based watermarking techniques and the inserted watermark is robust against some common attacks such as sharpening, blurring, and JPEG lossy compression.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.61-61
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• 1999

저항이 5$\Omega$-cm인 n-type Si(100) 웨이퍼를 실리콘 식각시 마스크로 사용하기 위하여 습식 열산화법을 이용하여 100$0^{\circ}C$에서 SiO2을 2400$\AA$ 성장시킨 후, OPCVD 공정을 통해 785$^{\circ}C$서 SiH2Cl2 가스 30sccm과 NH3가스 100sccm을 이용하여 Si3N4를 3000$\AA$ 증착시켰다. 이 웨이퍼를 포토-리쏘그라피 공정을 거쳐 지름 2$\mu\textrm{m}$의 포토레지스트 패턴을 제작한 후 600W의 RF power하에서 CF4 가스 10sccm, CHF3 가스 15sccm, O2가스 8sccm 및 Ar가스 10sccm을 이용하여 MERIE 방법으로 Si3N4를 식각한 다음, 7:1 BHF 용액내에서 30초간의 습식식각을 통해 40wt.%의 KOH 용액내에 8$0^{\circ}C$에서 30초간의 이방성 식각을 통해 피라미드 모양의 Si FEA(field emitter array)를 제작하였다. 본 실험은 다음과 같이 완성된 Si FEA를 샤프닝 산화 후 산화막 식각을 통해 마스크를 제거한 다음, tip의 열화학적 내구성을 증가시키고 장시간 구동시 안정성과 전계방출 전류밀도를 높이기 위해 tip의 표면에 Ti를 sputter 방법으로 약 300$\AA$ 증착시킨 후, RTA 장비를 이용하여 2단계 열처리 (first annealing:$600^{\circ}C$/30sec, second annealing : 85$0^{\circ}C$/15sec)를 통해 Si FEA의 경우보다 낮은 turn-on 전압과 높은 전계방출 특성을 나타낼 것으로 기대된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.361-363
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• 2013

비파괴 검사란 재료나 제품을 원형과 기능에 변화를 주지 않고 실시하여 원하는 정보를 획득할 수 있는 검사를 의미한다. 비파괴검사는 점검자의 육안 조사를 통한 수작업으로 이루어지고 있기 때문에 점검자의 주관이 개입되며, 점검자에 따라 검사 결과의 차이가 있을 수 있으므로 신뢰도의 차이가 발생하게 된다. 그러므로 본 논문에서는 비파괴 검사를 이용하여 획득한 세라믹 소재 영상에서 효율적으로 결함을 검출하는 방법을 제안한다. 제안된 방법은 세라믹 소재 영상에 가우시안 필터링 기법을 적용하여 잡음을 제거하고, Ends-in Search Stretching 기법을 적용하여 명암 대비를 강조한다. 명암 대비가 강조된 영상에 샤프닝 기법을 적용하여 윤곽선을 강조한다. 윤곽선이 강조된 영상에 $3{\times}3 $ Roberts 마스크를 적용하여 강조된 윤곽선을 추출하고, Glassfire 기법을 적용하여 라벨링한 후, 시그마 퍼지 이진화 기법과 형태학적 정보를 이용하여 잡음을 제거하고 결함 영역을 검출한다. 제안된 방법을 세라믹 소재 영상을 대상으로 실험한 결과, 효율적으로 결함을 검출하는 것을 확인할 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.477-479
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• 2016

본 논문에서는 초음파 영상에서 어깨 부위를 분석하여 어깨 힘줄(Tendon) 영역에서 인대 손상영역을 추출하는 방법을 제안한다. 제안된 방법은 초음파 영상에서 ROI(Region of Interest)을 추출하고 샤프닝 기법을 적용하여 ROI 영역을 뚜렷한 후에 퍼지 스트레칭 기법을 적용하여 명암 대비를 높인 후, 평균 이진화 기법을 적용하여 ROI 영역을 이진화 한다. 이진화된 ROI 영역에 침식, 팽창기법과 라벨링 기법을 적용하여 전체 ROI의 면적 영역에서 0.4%이하인 객체 영역들을 잡음으로 간주하여 제거한 후, ROI 영역에서 수평 너비가 가장 큰 영역의 상단 경계에 스플라인 곡선을 적용한다. 스플라인 곡선이 적용된 영역에서 곡선이 가장 높은 지점을 구한 후, 구한 지점으로부터 ROI 영역의 세로 길이의 1/5를 갖는 상단부분을 제거한 후에 양자화할 영역을 추출하고 FCM을 적용하여 양자화를 한다. 양자화된 영역에서 어깨 힘줄 영역 안에 있는 인대 손상의 후보 영역을 추출하고 면적의 크기가 0.14%이상이거나 3%이하인 영역을 어깨 힘줄의 인대 손상 영역으로 추출한다. 제안된 방법을 어깨 힘줄이 있는 초음파 영상을 대상으로 실험한 결과, 제안된 방법이 어깨 힘줄의 인대 손상 영역이 비교적 정확히 추출되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1C
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• pp.62-67
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• 2008

In this paper, wavelet based blind watermarking using self-reference method is proposed. First, we process wavelet transform of original image. Then, we set all domain except for the low-frequency domain to zero and make self-reference image after wavelet reverse transformation. By choosing specific domain according to the pixel value difference between original image and self-reference image, we make random sequence, use as watermark and embed. The experimental results of the watermark embedding and extraction on various images show that the proposed scheme not only has good image quality, but also has stability on JPEG lossy compression, filtering, sharpening, blurring and noise.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.703-710
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• 2001

In this paper, we consider a multiple watermarking for image copyright protection. Multiple watermarking can be defined that two or more watermarks are inserted into the same content. Multiple watermarking using spread spectrum technique is able to extract the correct watermarks from the watermarked content when the orthogonality among keys should be guaranteed only. To keep the orthogonal property between keys, we perform the process of Gram-Schmidt on the random sequences. The orthogonalized sequences are used as keys to embed the watermarks. The proposed method can not only extract correctly the embedded watermarks but also show the robustness against various attacks such as Gaussian noise addition, histogram equalization, gamma correlation, sharpening and brightness/contrast adjustment.

• Journal of Broadcast Engineering
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• v.19 no.5
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• pp.606-615
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• 2014

This paper is to propose an algorithm for digital hologram watermarking by using a characteristic of the Fresnel diffraction model in 2D image. When 2D image is applied Fresnel transform, the result concentrates center region. When applied to a hologram, on the other hand, the result focused diffraction pattern of 2D form. Using this characteristic, to generate diffraction model by applying 2-th Fresnel transform to the hologram. Corner of diffraction model is mark space. This mark space is embedded watermark and extracted watermark. Experimental results showed that all the extracted watermarks after several kinds of attacks (Gaussian blurring, Sharpening, JPEG compression) showed visibilities good enough to be recognized to insist the ownership of the hologram.

• The Journal of the Korea Contents Association
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• v.9 no.7
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• pp.37-44
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• 2009

Digital watermarking is a technology for preventing illegal copying, for protecting intellectual property rights and copyrights, and for suggesting grounds of the ownership by inserting watermarks into digital contents. Generally speaking, watermarking techniques cannot escape from data distortion and quality degradation due to the watermark insertion. In order to overcome the shortcoming, zero-watermarking techniques which do not change the original data have been proposed recently. This paper proposes CSMVQ(Chaotic SMVQ), a zero-watermarking system for SMVQ(Side Match Vector Quantization) which shows better compression ratio and quality and less blocking effect than VQ(Vector Quantization). In SMVQ, compression progresses from left top to right bottom in order to use the information of the two neighbor blocks, so it is impossible to insert watermarks chaotically. In the process of encoding, CSMVQ dynamically considers the information of the (1 to 4) neighbor blocks already encoded. Therefore, watermark can be inserted into digital contents in chaotic way. Experimental results show that the image quality compressed by CSMVQ is better than that of SMVQ and the inserted watermark is robust against some common attacks.

• The Journal of the Korea Contents Association
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• v.15 no.9
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• pp.11-20
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• 2015

Digital watermarking provides electronic means for proving the copyrights of distributed digital media copies. Research on digital watermarking for images is recently directed toward that for color images extensively used in real life, based on the substantial results in digital watermarking for gray-scale images. Color images have multiple channels, each of which corresponds to a gray-scale image. While there are some watermarking techniques for color images that just apply those for gray-scale images to one channel of the color images, the correlation characteristics between the channels are not considered in them. This paper proposes a zero-watermarking technique that makes keys via combining an image dependent watermark, created through comparing two channels of the color image and copyright watermark scrambled. Due to zero-watermarking, it does not change anything of cover(host) images. Watermark images are robust against some common attacks such as sharpening, blurring, JPEG lossy compression, scaling, and cropping.

• Journal of Digital Contents Society
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• v.18 no.1
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• pp.141-147
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• 2017

Scalable extension of High Efficiency Video Coding (SHVC) standard uses the up-sampled residual data from the base layer to make a residual data in the enhancement layer. This paper describes an efficient algorithm for improving coding gain by using the filtered residual signal of base layer in the Scalable extension of High Efficiency Video Coding (SHVC). The proposed adaptive filter selection mechanism uses the smoothing and sharpening filters to enhance the quality of inter-layer prediction. Based on two filters and the existing up-sampling filter, a rate-distortion (RD)-cost fuction-based competitive scheme is proposed to get better quality of video. Experimental results showed that average BD-rate gains of 1.5%, 2.1%, and 1.7% for Y, U and V components, respectively, were achieved, compared with SHVC reference software 5.0, which is based on HEVC reference model (HM) 13.