• Title/Summary/Keyword: 가역과정

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Reversible Watermarking Algorithm using Difference of Quantized Coefficients in JPEG image (JPEG 영상의 양자화 계수 차이값을 이용한 가역 워터마킹 알고리즘)

  • Jo, Hyun-Wu;Lee, Hae-Yeoun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2012.04a
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    • pp.665-668
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    • 2012
  • 멀티미디어 콘텐츠는 디지털 데이터의 특성상 수정과 복제가 쉽고, 이에 따라 불법 유통과 위 변조 등의 문제가 발생할 수 있으므로 콘텐츠 보안의 중요성이 높아지고 있고 가역 워터마킹 방법은 하나의 솔루션이다. 본 논문에서는 JPEG 압축 표준에서 사용할 수 있는 가역 워터마킹 기법을 제안한다. JPEG 압축 과정 중 비손실 과정에서 유지되는 양자화 DCT 블록 데이터에 대하여 인접 블록의 계수간 차이값의 히스토그램을 계산하고, 히스토그램 쉬프팅을 통하여 가역 워터마크를 삽입한다. 디코딩 과정에서 영상에 삽입된 워터마크를 추출함과 동시에 원본 JPEG 표준 영상의 품질을 복원한다. 제안 알고리즘의 성능 평가를 위해 다양한 영상을 대상으로 영상 품질과 압축률을 평가하였다. 삽입된 영상의 PSNR과 압축률은 32.33dB과 89.69%로, 표준 JPEG 압축된 영상 대비 각 3.24dB의 PSNR 차이와 2.58%의 압축률 차이를 보였다.

Reversible Image Watermarking with Differential Histogram Shifting and Error Prediction Compensation (차이값 히스토그램 쉬프팅과 오류 예측 보정을 이용한 가역 영상 워터마킹)

  • Yeo, Dong-Gyu;Lee, Hae-Yeoun;Kim, Byeong-Man;Kim, Kyung-Su
    • Journal of KIISE:Software and Applications
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    • v.37 no.6
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    • pp.417-429
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    • 2010
  • Reversible watermarking inserts watermark into digital media in such a way that visual transparency is preserved and then enables to restore the original media from the marked one without any loss of media quality. This watermarking can be applied to quality-sensitive imaging such as medical imaging, military imaging, remote-sensing imaging, and precious artwork, where the original media should be preserved during image processing and analysis. In this paper, a reversible image watermarking technique that embeds message bits by modifying the differential histogram of adjacent pixels is presented. In order to satisfy both high embedding capacity and visual quality, the proposed technique exploits the fact that adjacent pixels in the image have highly spatial correlation. Also, we prevent overflow/underflow problem and salt-and-pepper artifacts by employing a predicted error compensation scheme. Through experiments using various test images, we prove that the presented technique provides perfect reversibility and high embedding capacity, while maintaining the induced-distortion low.

An Analysis On Students' Misconceptions of the Reversibility of Irrational Functions (무리함수의 가역성에 대한 학생들의 오개념 분석)

  • Lee, Ki-Suk;Lee, Du-Ho
    • Communications of Mathematical Education
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    • v.24 no.3
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    • pp.709-730
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    • 2010
  • The inverse function of a one-to-one correspondence is explained with a graph, a numerical formula or other useful expressions. The purpose of this paper is to know how low achieving students understand the learning contents needed reversible thinking about irrational functions. Low achieving students in this study took paper-pencil test and their written answers were collected. They made various mistakes in solving problems. Their error types were grouped into several classes and identified in this analysis. Most students did not connected concepts that they learned in the lower achieving students to think in reverse order in case of and to visualize concepts of functions. This paper implies that it is very important to take into account students' accommodation and reversible thinking activity.

Availability of Energy and Reconstruction of Thermodynamics(I) Thermodydamics of the Reversible World (에너지의 가용성과 열역학의 재구성 (I) 가역세계 열역학)

  • 정평석;노승탁
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.5
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    • pp.1227-1236
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    • 1993
  • In conventional thermodynamics, energy is regarded as a physical quantity transferring from one system to another, but in present study, the real energy is regarded as a physical quantity coming out from one interaction and absorbing into another interaction between two systems. To reconstruct thermodynamics with such a point of view, available work is distinguished from half work in conventional work concepts, and a special space named reversible world is proposed in which every process is reversible and the only measurable quantity is available work and just the equality between the intensities of two systems can be verified. As results, thermodynamic laws are arranged into two principles in the reversible world-conservations of energy elements and conservation of available energy. It means the exsistences of state properties corresponding to transferring energy elements and the available work. The former are extensive properties and the later is named potential work which is a property of the composite system and a kind of mathematical distance. The conventional available energy (exergy) and internal energy can be explained as the special cases of potential work, and the conventional first law of thermodynamics can be derived from the principle of the conservation of available energy. With these new concepts, the description of thermodynamic processes is more comprehensive. The second law of thermodynamics is no longer needed in the reversible world.

Electrochemical Behaviors of Copper-1-(2-Thiazolylazo)-2-naphthol Complex in Acetonitrile (아세토니트릴 용매 중에서 Copper-1-(2-Thiazolylazo)-2-naphthol 착물의 전기화학적 거동)

  • Bae Zun Ung;Lee Heung Lark;Park Tae Myung;Seo Moo Lyong
    • Journal of the Korean Chemical Society
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    • v.35 no.4
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    • pp.405-409
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    • 1991
  • The electrochemical behaviors of copper-1-(2-thiazolylazo)-2-naphthol [Cu(II)-TAN] complex in acetonitrile (AN) solution have been investigated by the use of polarography, controlled potential coulometry and UV-Vis spectroscopy. Cu(II)-TAN complex exhibit three reduction waves at -0.91 V, -1.34 V and -1.65 V vs. S.C.E. in acetonitrile solution containing 5.0 ${\times}\;10^{-3}$M tetraethylammonium perchlorate. Every reduction wave is diffusion controlled. The first reduction wave is considerably reversible and this process is attributed to the formation of anion radical. The second reduction process to the dianion is followed by a chemical reaction producing a complex of hydrazo complex. The third reduction process produce Cu(Hg) amalgam and amine compound.

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Integrity Authentication Algorithm of JPEG Compressed Images through Reversible Watermarking (가역 워터마킹 기술을 통한 JPEG 압축 영상의 무결성 인증 알고리즘)

  • Jo, Hyun-Wu;Yeo, Dong-Gyu;Lee, Hae-Yeoun
    • The KIPS Transactions:PartB
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    • v.19B no.2
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    • pp.83-92
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    • 2012
  • Multimedia contents can be copied and manipulated without quality degradation. Therefore, they are vulnerable to digital forgery and illegal distribution. In these days, with increasing the importance of multimedia security, various multimedia security techniques are studied. In this paper, we propose a content authentication algorithm based on reversible watermarking which supports JPEG compression commonly used for multimedia contents. After splitting image blocks, a specific authentication code for each block is extracted and embedded into the quantized coefficients on JPEG compression which are preserved against lossy processing. At a decoding process, the watermarked JPEG image is authenticated by extracting the embedded code and restored to have the original image quality. To evaluate the performance of the proposed algorithm, we analyzed image quality and compression ratio on various test images. The average PSNR value and compression ratio of the watermarked JPEG image were 33.13dB and 90.65%, respectively, whose difference with the standard JPEG compression were 2.44dB and 1.63%.

5th Graders' Logical Development through Learning Division with Decimals (5학년 아동의 소수 나눗셈 원리 이해에 관한 연구)

  • Lee, Jong-Euk
    • School Mathematics
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    • v.9 no.1
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    • pp.99-117
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    • 2007
  • In this paper it is discussed how children develop their logical reasoning beyond difficulties in the process of making sense of division with decimals in the classroom setting. When we consider the gap between mathematics at elementary and secondary levels, and given the logical nature of mathematics at the latter levels, it can be seen as important that the aspects of children's logical development in the upper grades in elementary school should be clarified. This study focuses on the teaching and learning of division with decimals in a 5th grade classroom, because it is well known to be difficult for children to understand the meaning of division with decimals. It is suggested that children begin to conceive division as the relationship between the equivalent expressions at the hypothetical-deductive level detached from the concrete one, and that children's explanation based on a reversibility of reciprocity are effective in overcoming the difficulties related to division with decimals. It enables children to conceive multiplication and division as a system of operations.

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A novel Reversible Data Hiding Scheme based on Modulo Operation and Histogram Shifting (모듈러 연산과 히스토그램 이동에 기반한 새로운 가역 정보 은닉 기법)

  • Kim, Dae-Soo;Yoo, Kee-Young
    • Journal of Korea Multimedia Society
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    • v.15 no.5
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    • pp.639-650
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    • 2012
  • In 2009, Tsai et al. proposed reversible image hiding scheme using linear prediction coding and histogram shifting. Tsai et al.'s scheme improved the hiding capacity of Ni et al.'s scheme by using the prediction coding and two histograms. However, Tsai et al.'s scheme has problems. In the prediction coding, the basic pixel is not used from embedding procedure. Many additional communication data are generated because two peak and zero point pairs are generated by each block. To solve the problems, this paper proposes a novel reversible data hiding scheme based on modulo operation and histogram shifting. In experimental results, the hiding capacity was increased by 28% than Tsai et al.'s scheme. However, the additional communication data was decreased by 71%.

The Development of the Unfading Urethane Polymer Based on Reversible Properties for Ceramics and Restoration with This Urethane Product (가역성을 갖는 도자기 복원용 무황변 우레탄 수지의 개발과 이를 이용한 도자기의 복원)

  • Han, Won-Sik;Park, Gi-Jung;Lim, Sung-Jin;Lee, Young-Hoon;Hong, Tae-Kee;Wi, Koang-Chul
    • Journal of Conservation Science
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    • v.26 no.2
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    • pp.183-190
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    • 2010
  • We fabricated urethane material based on properties of reversible and unfading for antic-ceramics restoration. This material with low viscosity was made hardness control possible that user want. And it have very strong adhesion and shear strength properties and is shown the best properties for pigment filling, anti-contractibility, coloring as like epoxy system materials. Particularly, the yellowing and ir-reversibility problem in epoxy restoration material were finally solved. So, there is guarantee in the eternity and stabilization of restoration for antic-celamics. And in order to show the reversible state of the restoration, we successfully dissolve this urethane materials in solvent after perfect restoring subsequently.

The Development of the Unfading Polyvinyl Butyral Gap-filling Material Based on Reversible Properties and Restoration of a Punchong Plate from Sam-cheon Temple Site with This Polyvinyl Butyral Product (가역성을 갖는 무황변 Polyvinyl Butyral 메움제의 개발과 이를 이용한 삼천사지 분청사기접시의 복원)

  • Han, Won-Sik;Wi, Koang-Chul;Park, Gi-Jung;Hong, Tae-Kee
    • Journal of Conservation Science
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    • v.25 no.3
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    • pp.293-298
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    • 2009
  • We fabricated the gap-filling material for antic-ceramics restoration which were made up polyvinyl butyral (butvar) base and silane system additive in iso-propyl solvent. This was made hardness control possible that user want. And it have very strong adhesion and shear strength properties and is shown the best properties for pigment filling, anti-contractibility, coloring as like epoxy system materials. Particularly, the yellowing and ir-reversibility problem in Epoxy restoration material were finally steadiness. So, there is guarantee in the eternity and stabilization of restoration for antic-celamics. And in order to show the reversible state of the restoration, we successfully dissolve this polyvinyl butyral gap-filling materials in solvent after perfect restoring the Punchong plate from sam-chun temple site subsequently.

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