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Adaptive Digital Watermarking for Copyright Protection of CAD Data
권기룡,구본호,김지홍 한국멀티미디어학회 2006 멀티미디어학회논문지 Vol.9 No.6
To protect against unlawful reproductions and distribution, the current paper proposes a digital watermarking technique for architectural drawings produced using a CAD system. First, the POLYLINEs are extracted from the drawing; then, an adaptive algorithm is used to embed a watermark in the characteristics of each POLYLINE. Next, the CIRCLEs are embedded using an adaptive watermarking algorithm related to the radius of circle from drawing. The proposed watermarking scheme is robust to various attacks, such as the geometrical transformation. Additionally, the proposed method satisfies the requirement of transparency for CAD program. It used AutoCAD 2002, which is commonly used as a CAD program for experiments. Experimental results confirmed the robustness and invisibility of the embedded watermarks in several conversions of an architectural drawing.
적응 능동소음제어를 위한 오차경로 인식 방법을 통한 filtered-X LMS 알고리듬
권기룡,송규익,김덕규,이건일 한국통신학회 1994 韓國通信學會論文誌 Vol.19 No.8
본 논문에서는 적응 능동소음제어를 위한 새로운 오차경로 인식 방법을 통한 filtered-X LMS(least mean square) 알고리듬을 제안하였다. 제안한 알고리듬에서는 3개의 마이크로폰과 이중루프제어를 이용하여 오차경로의 전달 특성을 온라인으로 정확히 인식하도록 하였다. 덕트를 통한 소음이 정형파인 경우와 실제 공조기의 소음에 대하여 컴퓨터 시뮬레이션을 각각 수행한 결과, 제안한 방식은 입력소음에 비하여 각각 평균 29.1dB 및 10.4dB 정도의 소음레벨이 감쇠됨을 확인하였다. 이는 Eriksson의 방법보다 각각 평균 0.5dB 및 2.5dB 정도 개선된 것이다. In this paper, a filtered-X LMS algorithm by new error path identification method is proposed for active noise control system. The proposed algorithm identifies accurately the error path transfer function using three microphones and the control of error signal through double loop scheme with on-line. In the computer simulation using the sinusoidal and the practical duct noise, the proposed algorithm reduces noise level about 29.1dB and 10.4dB, respectively. We can observe the improvement of about 0.5dB and 2.5dB in noise level compared with that obtained using the filtered-X LMS algorithm of Eriksson model.
자동차 엔진 소음제거를 위한 시간지연 특성을 갖는 새로운 적응 능동소음제어 모델
권기룡 부산 외국어 대학교 1999 外大論叢 Vol.19 No.3
In this paper, a new adaptive active noise control model is proposed for car engine noise reduction with time delay characteristics. The proposed model identifies transfer characteristic of the louspeaker and error path with time delay. Adaptive filter identifying acoustic plant characteristic uses leaky filtered-X LMS algorithm. The proposed leaky delay LMS algorithm for acoustic time delay model estimates the loudspeaker characteristic and the acoustic time delay of error path in the car. This algorithm is used estimating gain and acoustic time delay to reduce the computational burden. The input signal of filter to estimate gain and acoustic time delay is the same as the filtered-X LMS algorithm. The leaky delay algorithm is employed to counteract parameter drift when noise in nonstationary environment is controlled. To confirm the validity of the proposed methods, for car engine room noise, the proposed leaky delay LMS algorithm reduces about 15.0 and 29.9 dB at 750 and 2000 rpm, respectively.
권기룡,허관,송규익,이건일,Kwon, Ki-Lyong,Heo, Kwan,Sohng, Kyu-Ik,Lee Kuhn-Il 한국음향학회 1993 韓國音響學會誌 Vol.12 No.5
능동소음제어를 위하여 수렴속도가 빠르면서 정상상태오차를 최소화하는 오차보상 NLMS 알고리듬인 CNLMS 알고리듬을 제안하였다. 이 CNLMS 알고리듬에서는 수렴속도를 빠르게 하기 위하여 입력소음과 오차소음의 전력에 따라 수렴인자를 가변시킨 NLMS 알고리듬을 사용하였다. 도한 정상상태오차를 최소화하기 위하여 소음발생기를 사용하지 않고 오차경로에서 발생하는 소음오차를 더욱 작아지도록 보상하는 보조시스템을 사용하여 안정된 능동소음제어가 되도록 하였다. 이와 같은 시스템의 성능을 기존의 적응디지틀필터인 LMS 및 NLMS 알고리듬을 이용한 필터의 그 성능과 비교하였다. 각 알고리듬에 대한 시뮬레이션을 행한 결과, 제안한 CNLMS 알고리듬의 소음레벨은 LMS 및 NLMS 알고리듬의 것보다 각각 평균 14dB 및 6dB 정도 더 큰 감쇄효과가 있음을 확인하였다.
멀티웨이브릿 변환 기반에서 통계적 추정 이론을 이용한 적응 워터마킹 기술에 관한 연구
권기룡,강균호 부산 외국어 대학교 2003 外大論叢 Vol.26 No.-
We propose adaptive watermarking using stochastic estimation theory based on multiwavelet transform in this paper. To embed watermark, the original image is decomposed into 4 levels using a discrete multiwavelet transform, then a watermark is embedded into the perceptual significant coefficients, PSCs larger than the JND (just noticeable differences) threshold of the each subband. We use DGHM multiwavelet that has approximation order 2. The JND threshold is to achieve watermark transparency and it determine the length of watermark signal. The experimental results of computer simulation of the proposed adaptive watermarking method were found to be excellent invisibility and robustness.
권기룡,이석환,정태일,박승섭 한국멀티미디어학회 2006 멀티미디어학회논문지 Vol.9 No.12
There has been more increased the development of 3D technique since many 3D contents of 3D graphic model, 3D mobile/computer game, and3D CAD have been serviced in Web or industry fields. Therefore, the watermarking system is more required to protect the copyright for 3D contents. Currently there has been researched about the watermarking for 3D graphic model of mesh or NURBS. However, watermarking technique based on CAD design drawing leaves something to be desired yet. This paper proposed the watermarking technique for 3D CAD design drawing using Line and Arc components. After drawing out Line and Arc components from designed drawing, we embed the watermark into both the length of Line component and the radius of Arc component. Experimental results verified that the proposed algorithm satisfies the transparency about watermarked drawing and also has the robustness against several attacks by using public CAD tool.