• Journal of Korea Society of Industrial Information Systems
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• v.21 no.3
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• pp.7-12
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• 2016

In a hostile Internet environment, steganography has focused to hide a secret message inside the cover medium for increasing the security. That is the complement of the encryption. This paper presents a text steganography techniques using the Hangul text. To enhance the security level, secret messages have been encrypted first through the genetic algorithm operator crossover. And then embedded into an cover text to form the stego text without changing its noticeable properties and structures. To maintain the capacity in the cover media to 3.69%, the experiments show that the size of the stego text was increased up to 14%.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.38-39
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• 2015

최근 고 해상도의 콘텐츠의 보급이 늘어나는데 이에 따라 암호화를 위한 계산 량과 시간이 증가하였다. 본 논문은 고 해상도의 콘텐츠에서 많은 양의 암호화 계산과 시간을 줄이기 위해 프레넬 변환을 이용한 암호화 방법을 제안하였다. 프레넬 변환을 통하여 획득한 회절 영상은 거리에 따라 가운데로 집중되는 특성을 가지는데, 고 해상도의 영상을 먼 거리에서의 회절 영상을 획득하여 가운데의 집중된 영역에 암호화를 수행하여 암호화 영역을 줄여 계산 량을 줄일 수 있다. 본 논문에서 제안하는 암호화 알고리즘을 구현하여 10m의 거리일 때 0.004%의 데이터만 암호화 하여 모든 데이터를 숨길 수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.225-226
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• 2018

홀로그램 콘텐츠의 정보보안을 위한 암호화 방법을 제안한다. 제안하는 암호화 기법은 실시간 처리를 위해 부분 홀로그램에 대하여 편향치를 더하고, 이중 프레넬 변환을 수행하여 에너지가 집중된 DC 영역을 획득한다. 이때 집중된 영역이 암호화 영역으로 적은 데이터롤 이용하여 고효율의 암호화를 수행한다. 제안한 기법은 기존 연구보다 변환하는 크기를 줄이기 때문에 같은 효율로 고속의 암호화를 수행할 수 있다. $1,024{\times}1,024$ 크기의 홀로그램을 $32{\times}32$ 부분홀로그램으로 구성하여 적용할 경우 약 18배 빠르게 처리할 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.326-329
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• 2017

Most modern computer communications and storage media support encryption technology. Many of the Ping Pong algorithms are stream ciphers that generate random numbers in the LFSR core structure. The LFSR has a structure that guarantees the maximum period of a given size, but it has a linear structure and can be predicted. Therefore, the Ping Pong algorithm has a feature of making the linearity of the LFSR into a nonlinear structure through variable clocks and functions. In this paper, we try to improve the existing linearity by replacing the linear disadvantages of LFSR with logistic maps.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.196-201
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• 2016

Digital watermarking is a technique used to hide information within digital media. Digital watermarking techniques can be classified as either robust watermarking or fragile watermarking. Robust watermarking techniques are generally used for the purpose of copyright protection. In addition, fragile watermarking techniques are used for the authentication and integrity verification of a digital image. Therefore, fragile watermarks should be easily breakable for trivial tampering of a watermarked image. This paper proposes an efficient fragile watermarking method for image tamper detection in the spatial domain. In the proposed method, a hash code and symmetric key encryption algorithm are used. The proposed method of inserting a watermark by dividing the original image into many blocks of small sizes is not weak against attacks, such as cut and paste. The proposed method can detect the manipulated parts of a watermarked image without testing the entire block of the image.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.3
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• pp.482-491
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• 2011

The purpose of this study is to design and implement a 2-level secret information transmission system which can be used for information hiding of images transmitted over various IT communication media. To increase the robustness of the hiding power, we combined the steganography method which inserts secret object into cover object to hide the very fact of information hiding itself, and the preprocessing stage to encrypt the secret object before the stego-insertion stage. As a result, even when the stego-image is broken by an attacker, the secret image is protected by encryption. We implemented the 2-level image insertion and extraction algorithm by using C++ programming language. Experiment shows that the PSNR values of stego-images of ours exceed 30.00db which is the threshold of human recognition. The methodology of this study can be applied broadly to the information hiding and protection of the military secret images.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.4
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• pp.163-176
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• 2013

Cloud-based streaming game service has numerous merits, but it may suffer from presentation latency in a thin-client. It is an important issue especially for game service which needs instantaneous response to user inputs. This research proposes the methods for reducing the presentation latency between the server unit and the thin-client unit. The approaches proposed to be employed with server unit include the source/sync video format equalization, encoding format configuration according to the media type, and the S/W implementation for transmitting clock periodically. The methods for the thin-client unit include the decreasing the number of instructions, use of light encryption algorithm, and improvement on H/W decoding. The proposed schemes are tested with a commercialized streaming service platform, which reveals the reduction of presentation latency as large as a few hundred milliseconds and reaches the acceptable level (about 100 milliseconds).