• Title/Summary/Keyword: larger embedding rate

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A Modified Product Code Over ℤ4 in Steganography with Large Embedding Rate

  • Zhang, Lingyu;Chen, Deyuan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.7
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    • pp.3353-3370
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    • 2016
  • The way of combination of Product Perfect Codes (PPCs) is based on the theory of short codes constructing long codes. PPCs have larger embedding rate than Hamming codes by expending embedding columns in a coding block, and they have been proven to enhance the performance of the F5 steganographic method. In this paper, the proposed modified product codes called MPCs are introduced as an efficient way to embed more data than PPCs by increasing 2r2-1-r2 embedding columns. Unlike PPC, the generation of the check matrix H in MPC is random, and it is different from PPC. In addition a simple solving way of the linear algebraic equations is applied to figure out the problem of expending embedding columns or compensating cases. Furthermore, the MPCs over ℤ4 have been proposed to further enhance not only the performance but also the computation speed which reaches O(n1+σ). Finally, the proposed ℤ4-MPC intends to maximize the embedding rate with maintaining less distortion , and the performance surpasses the existing improved product perfect codes. The performance of large embedding rate should have the significance in the high-capacity of covert communication.

An Investigation of TEM Specimen Preparation Methods from Powders Using a Centrifuge (원심분리기를 이용한 분말시료의 TEM용 시편 준비법 연구)

  • Jeung, Jong-Man;Lee, Young-Boo;Kim, Youn-Joong
    • Applied Microscopy
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    • v.29 no.1
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    • pp.67-73
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    • 1999
  • It is practically hard to prepare good TEM specimens from powders which are embedded in epoxy materials for ion milling, because the milling rate difference between powders and epoxy is quite large. In order to overcome this problem, we tried to find methods to increase the density of powders in the embedding epoxy without loosing the adhesive strength between them. Powder density was considerably increased by employing a centrifuge for embedding, compared to the result by a conventional vacuum embedding. In addition, mixing powders of different sizes after sieving also enhanced the final density by allowing smaller particles filling in the gaps of larger particles. Ion milling of powders embedded by these methods resulted in thin specimens good enough for normal TEM works. TEM specimens from spherical, platy and fibrous powders of submicron size were successfully prepared by this centrifuging method.

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SSLmTCP Handshake : Embedding the SSL Handshake into the TCP 3-Way Handshake (SSLmTCP 핸드쉐이크 : SSL 핸드쉐이크를 포함하는 TCP 3-단계 핸드쉐이크)

  • Byun, Ki-Seok;Park, Jun-Cheol
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.3
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    • pp.595-603
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    • 2017
  • We propose a scheme to reduce the time for the SSL/TLS handshake by embedding it into the TCP 3-way handshake. The scheme can be selectively applied on the standard TCP for making the SSL/TCP handshake happen within the TCP handshake, rather than performing the TCP handshake and SSL/TLS handshake in sequence. We implemented a prototype of the scheme and did some experiments on its performance. Experimental results showed that, compared to the sequential handshakes of the TCP and the SSL/TLS, the time reduction achieved by the scheme varied in the range of 3.2% and 14%(when the elapsed time by the ping program from the client to the server was 11.6ms). The longer the time measured by the ping program, which would grow as the propagation and queuing delays do, the larger the reduction rate. It accords with the supposition that the reduced time due to the scheme will increase in proportion to the amount of the elapsed time measured by the ping program.