• 한국정보컨버전스학회:학술대회논문집
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• 2008.06a
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• pp.93-97
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• 2008

In this letter, a novel wavelet-based semi-fragile watermarking scheme is presented which exploiting the time-frequency feature of chaotic map. We also analyze the robustness to mild modification and fragility to malicious attack of our scheme. Its application includes tamper detection, image verification and copyright protection of multimedia content. Simulation results show the scheme can detect and localize malicious attacks with high peak signal-to-noise ratio(PSNR), while tolerating certain degree of JPEG compression and channel additive white Gaussian noise(AWGN)

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.2073-2076
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• 2003

본 논문에서는 이산코사인변환의 선형성을 이용하여 정지화상의 위변조를 방지하기 위한 semi-fragile 워터마킹 방법을 제안하였다. 제안한 방법에서는 이산코사인변환의 선형특성을 이용하여 공간영역에서 임의의 DCT 계수를 변형시킬 수 있으므로 이산코사인변환을 행하지 않고도 워터마킹 정보를 삽입할 수 있으므로 빠른 워터마킹 삽입이 가능하다 또한 정해진 DCT 계수에만 워터마킹 정보를 삽입할 수 있으므로 비가시성의 향상을 가져올 수 있다. 제안한 방법이 압축에 강인함을 실험을 통하여 입증하였다.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.418-429
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• 2018

This paper studies the decentralized position/force control problem for constrained reconfigurable manipulator without torque sensing. A novel joint torque estimation scheme that exploits the existing structural elasticity of the manipulator joint with harmonic drive model is applied for each joint module. Based on the estimated joint torque and dynamic output feedback technique, a decentralized position/force control strategy is presented. In order to solve the problem of controller parameter perturbation, the non-fragile robust technique is introduced into the dynamic output feedback controller. Subsequently, the stability of the closed-loop system is proved using the Lyapunov theory and linear matrix inequality (LMI) technique. Finally, two 2-DOF constrained reconfigurable manipulators with different configurations are applied to verify the effectiveness of the proposed control scheme in numerical simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11c
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• pp.1823-1826
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• 2003

본 논문에서는 디지털 영상의 인증 및 무결성을 위한 Fragile Watermarking 기법을 제안한다. 이 기법은 원 영상과 워터마크 영상을 각각 랜덤하게 섞고, 랜덤수와 LUT를 이용하여 워터마크를 LSB에 삽입하므로 보안성을 갖는다. 또한, 워터마크 삽입 추출과정에서 두 개의 비밀키와 XOR를 이용하여 간단히 처리할 수 있다. 실험을 통하여 영상의 변형 여부 및 조작 위치를 검출하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.171-178
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• 2017

This paper studies the state estimation problem for static neural networks with time-varying delay. Unlike other studies, the controller scheme, which involves time-varying sampling and uncertainties, is first employed to design the state estimator for delayed static neural networks. Based on Lyapunov functional approach and linear matrix inequality technique, the non-fragile sampled-data estimator is designed such that the resulting estimation error system is globally asymptotically stable with $H_{\infty}$ performance. Finally, the effectiveness of the developed results is demonstrated by a numerical example.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1486-1488
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• 2009

본 논문은 비디오 압축 기술인 H.264/AVC와 H.264/SVC에 적용할 수 있는 인증 목적의 효율적인 프레자일(fragile) 워터마킹 기법을 제안한다. 제안된 워터마킹 기법은 H.264/AVC 비디오 부호화기에서 압축률을 높이기 위해 사용하는 매크로블록(MB) 예측 모드들을 특징 값으로 추출하여 콘텐츠 제공자의 비밀키로 암호화 후 워터마크로 사용하는 인증 기법으로, 이는 공간적, 시간적 그리고 SNR 확장성을 가지는 H.264/SVC에도 확장하여 적용할 수 있다. 워터마크 삽입은 최적의 예측 모드를 찾기 위한 모드 결정과정에서 수행되어 워터마크 후에도 최적화 된 콘텐츠를 얻을 수 있으며, 간단한 연산을 엔코더와 결합시켜 낮은 시간 증가율을 가진다.

• Clinical and Experimental Pediatrics
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• v.46 no.12
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• pp.1186-1193
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• 2003

Purpose : Fragile sites are points on chromosomes which tend to break non-randomly when exposed to specific chemical agents or conditions of tissue culture. The chromosomal break induced by the antineoplastic drug, 1-${\beta}$-D-arabinofuranosyl-cytosine(Ara-c), was investigated to study the laboratory conditions in which the incidence of chromosomal break could be enhanced. Besides, the fragile sites induced by Ara-C were investigated and compared to the already known locations of the specific chromosomal alterations observed in specific neoplasms. Methods : T-lymphocytes from theree normal males and three females were cultured for 48 hours. Cells from each individual were exposed to the Ara-C for an additional 24 hours. After the caffeine was added during the last six hours culture, the metaphase chromosomes were prepared following the conventional method. A site was considered fragile if it was found to break two or more per 100 chromosomal breaks in more than four of six individuals tested. Results : Ara-C induced 252.1 chromosomal breaks per 100 mitotic cells and this result was significantly higher than that of the control, which induced 25.2 breaks(P<0.05). The incidence of the chromosomal break by Ara-C was higher, if cultured in the MEM-FA, which has no folic acid, than in the RPMI 1640 which contains enough folic acid(P<0.05). The most common break site by Ara-C was 3p14.2(FRA3B). There were 20 fragile sites induced by Ara-C. Among these 20 fragile sites, seven coincided with the locations of the mapped oncogenes, JUN, SKI, REL, N-MYC, FHIT, MET, ETS-1, and FOS. Conclusion : S phase specific chemotherapeutic agent, Ara-C, induced the expression of the chromosomal fragile sites effectively using the T-lymphocyte in vitro. Some of the fragile sites by Ara-C highly coincided with the oncogenes and neoplasm specific chromosome breakpoints. In this regard, the fragile sites reported here could provide the unknown neoplasm related chromosomal alternation points.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.623-626
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• 2002

Extreme development in digital multimedia has raised anxiety in the minds of copyrighted content owners. This has resulted in the creation of several watermarking techniques. This paper, proposes a method of embedding a perceptually transparent digital signal, named semi-fragile watermark in the wavelet domain, utilizing the characteristics of the human visual system. So as to detect attacks inflicted on the content and use an algorithm to specify the character of the attack.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.223-226
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• 2001

In this paper, we propose a robust and fragile watermarking technique for tamper proofing of still images. Robust watermarks are embedded by quantization with a robust quantization step-size, and it is imperceptible value for human visual system. Fragile watermarks are embedded by thresholding and quantization with EW(Embedded Zerotree Wavelet) algorithm. The proposed method enables us to distinguish malicious change from non-malicious change. Futhermore this technique enables us to find tampering regions and degrees.

• Proceedings of the Korean Society of Life Science Conference
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• 2006.09a
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• pp.61.1-61.1
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• 2006