• 제어로봇시스템학회논문지
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• 제4권5호
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• pp.630-635
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• 1998

The objective of this paper is to propose a new efficient technique for the estimation of time-delay parameters using wavelet theory and third-order cumulants, yielding good performance even in the case of low SNR. In particular, band-limited non-Gaussian signals with non-zero skewness and spatially correlated Gaussian noises are considered here. The approach is based on the fact that the effects of spatially correlated Gaussian noises on time-delay estimation can be reduced by using the projection sequences (based on the redundant wavelet decomposition) of given measurements in the higher-order cumulant domain. Finally, the performance of the proposed approach is demonstrated using simulations.

• 융합신호처리학회논문지
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• 제5권3호
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• pp.173-180
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• 2004

이 논문에서는 중복된 웨이블렛 변환영역에서 다중척도 정칙화를 이용한 새로운 영상복원방법을 제시하였다. 제안된 방법은 중복된 웨이블렛 변환을 이용하여 단일척도 영상복원문제를 다중척도의 영상복원문제로 변환한 후에, 각 척도에 의존하는 정칙화 방법을 이용하여 각 척도별로 영상복원을 하고 그 결과를 중복 웨이블렛 역변환을 통해 최종적인 영상복원을 얻는 방법이다. 제안된 방법은 웨이블렛 관련 복원부분에서는 다소 적은 정칙화 계수를 적용하여 뚜렷한 경계를 복원하는 반면, 적은 정칙화 계수에 적용한 것에 의해 발생하는 잡음은 웨이블렛 축소법을 이용하여 제거하였다. 제안된 방법의 향상된 영상복원 성능은 전통적인 Wiener 필터링과의 비교실험을 통해 검증하였다.

• International journal of advanced smart convergence
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• 제12권3호
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• pp.211-220
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• 2023

Surface electromyography (sEMG) is a noninvasive method used to capture electrically muscle activity, which can be easily measured even during exercise. The basic unit of muscle activity is the motor unit, and because an sEMG signal is a superposition of motor unit action potentials, analysis of muscle activity using sEMG should ideally be done from the perspective of motor unit activity. However, conventional techniques can only evaluate sEMG signals based on abstract signal features, such as root-mean-square (RMS) and mean-power-frequency (MPF), and cannot detect individual motor unit activities from an sEMG signal. On the other hand, needle EMG can only capture the activity of a few local motor units, making it extremely difficult to grasp the activity of the entire muscle. Therefore, in this study, a method to visualize the activities of motor units in a single-channel sEMG signal by relocating wavelet coefficients obtained by redundant discrete wavelet analysis is proposed. The information obtained through this method resides in between the information obtained through needle EMG and the information obtained through sEMG using conventional techniques.

• 디지털산업정보학회논문지
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• 제7권4호
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• pp.119-131
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• 2011

In this paper, we explore the application of 2-D dual-tree discrete wavelet transform (DDWT), which is a directional and redundant transform, for image coding. DDWT main property is a more computationally efficient approach to shift invariance. Also, the DDWT gives much better directional selectivity when filtering multidimensional signals. The dual-tree DWT of a signal is implemented using two critically-sampled DWTs in parallel on the same data. The transform is 2-times expansive because for an N-point signal it gives 2N DWT coefficients. If the filters are designed is a specific way, then the sub-band signals of the upper DWT can be interpreted as the real part of a complex wavelet transform, and sub-band signals of the lower DWT can be interpreted as the imaginary part. The quincunx lattice is a sampling method in image processing. It treats the different directions more homogeneously than the separable two dimensional schemes. Quincunx lattice yields a non separable 2D-wavelet transform, which is also symmetric in both horizontal and vertical direction. And non-separable wavelet transformation can generate sub-images of multiple degrees rotated versions. Therefore, non-separable image processing using DDWT services good performance.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2015년도 추계학술대회
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• pp.173-175
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• 2015

We proposed a blind watermarking scheme using singular vectors based on Discrete Wavelet Transform (DWT) and Redundant Discrete Wavelet Transform (RDWT) combined with Singular Value Decomposition (SVD) for copyright protection application. We replaced the 1st left and right singular vectors decomposed from cover image with the corresponding ones from watermark image to overcome the false-positive problem in current watermark systems using SVD. The proposed scheme realizes the watermarking system without a false positive problem, and shows high fidelity and robustness.

• 융합신호처리학회논문지
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• 제5권2호
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• pp.85-90
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• 2004

본 논문에서는 모폴로지에 의한 중요 클러스터 추출과 적응양자화를 이용한 웨이브릿 영상부호화 방법을 제안한다. 제안한 방법은 기존의 MRWD방법에서의 클러스터 전송시의 부가정보의 비중이 전체 데이터 비트에서 큰 것을 고려하여 모폴로지를 적용하여 중요클러스터를 추출하여 코딩의 효율을 개선하였고 MRWD 양자화기에서 생기는 불필요한 비교연산수를 줄이기 위해 적응 양자화기를 제안하여 양자화 시 발생하는 불필요한 비교연산을 줄일 수 있었다. 본 논문은 양질의 PSNR을 유지하면서 정보량을 줄일 수 있었다.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.65-74
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• 2012

이중 트리 이산 웨이브렛 변환은 이산 웨이브렛 변환 보다 우수하며, 이동 변이(shift variance)의 웨이브렛 보다 적은 계산량을 가진다. 이러한 특성들은 잡음 제거, 텍스쳐 분할 등에서 효율적으로 사용된다. 이중 트리 이산 웨이브렛 변환을 수행하는 과정에 Quincunx 표본화를 적용하였다. 이 방법은 이중 트리 이산 웨이브렛 변환의 주된 특징인 이동 불변성의 성질과 다양한 방향성의 특징 그리고 비분리 영상처리 효과를 증가시킬 수 있다. 본 논문에서는 제안된 방법에 대한 성능을 평가하고 실험결과를 제시하였다. 따라서 비분리 처리특성으로 인위적인 패턴을 갖는 디지털 영상에 대해서 웨이브렛 변환의 특징을 얻을 수 있어 효율적인 영상처리가 가능하다.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2384-2392
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• 2015

The technical development and practical applications of big-data for health is one hot topic under the banner of big-data. Big-data medical image fusion is one of key problems. A new fusion approach with coding based on Spherical Coordinate Domain (SCD) in Wireless Sensor Network (WSN) for big-data medical image is proposed in this paper. In this approach, the three high-frequency coefficients in wavelet domain of medical image are pre-processed. This pre-processing strategy can reduce the redundant ratio of big-data medical image. Firstly, the high-frequency coefficients are transformed to the spherical coordinate domain to reduce the correlation in the same scale. Then, a multi-scale model product (MSMP) is used to control the shrinkage function so as to make the small wavelet coefficients and some noise removed. The high-frequency parts in spherical coordinate domain are coded by improved SPIHT algorithm. Finally, based on the multi-scale edge of medical image, it can be fused and reconstructed. Experimental results indicate the novel approach is effective and very useful for transmission of big-data medical image(especially, in the wireless environment).

• 방송공학회논문지
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• 제21권2호
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• pp.149-156
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• 2016

우리는 컨텐츠 복제방지를 위하여 기존의 SVD와 DWT/RDWT를 결합한 워터마킹 시스템에 특이벡터를 추가로 사용하는 방안을 제안하였다. 우리는 SVD를 사용하는 워터마킹 시스템에 존재하는 오류긍정문제(false-positive problem)를 극복하기 위하여 기존의 SVD기반 알고리즘과 같이 특이값에 워트마크를 임베딩할 뿐만 아니라, 커버이미지의 첫 번째 좌/우 특이벡터를 워터마크 이미지의 첫번째 좌/우 특이벡터와 교체하였다. 제안 방안은 오류긍정문제 (false-positive problem)가 발생하지 않는 워터마킹 시스템을 구현할 수 있었으며, 기존의 오류긍정문제가 없는 시스템과 비교하여 우수한 충실성과 강인성을 보여 주었을 뿐만 아니라, 오류긍정문제가 발생하는 시스템에 비해서도 크게 성능차이가 나지 않음을 보여 주었다.

• Journal of Information Processing Systems
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• 제12권4호
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• pp.681-687
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• 2016

Today's modern world requires a digital watermarking technique that takes the redundancy of an image into consideration for embedding a watermark. The novel algorithm used in this paper takes into consideration the redundancies of spatial domain and wavelet domain for embedding a watermark. Also, the cryptography-based secret key makes the algorithm difficult to hack and help protect ownership. Watermarking is blind, as it does not require the original image. Few coefficient matrices and secret keys are essential to retrieve the original watermark, which makes it redundant to various intentional attacks. The proposed technique resolves the challenge of optimizing transparency and robustness using a Canny-based edge detector technique. Improvements in the transparency of the cover image can be seen in the computed PSNR value, which is 44.20 dB.