• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.269-270
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• 2007

In previous work[1], each codeblock is coded using a context which is adaptively selected from three kinds of scanning directions after 3D DWT. But some subbands still have correlations among the coefficients in horizontal, vertical or temporal direction. In this paper, we propose a new 3D DWT-based video compression technique in which the difference of coefficients is calculated in one of three directions for every codeblocks and coded by a context adaptively selected for each codeblock. Experimental results show that the proposed compression technique outperforms measurably and visually compared to the conventional DWT-based techniques.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.4 s.334
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• pp.19-28
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• 2005

In this paper, we proposed a parallel fast 2-D discrete wavelet transform hardware architecture based on lifting scheme. The proposed architecture improved the 2-D processing speed, and reduced internal memory buffer size. The previous lifting scheme based parallel 2-D wavelet transform architectures were consisted with row direction and column direction modules, which were pair of prediction and update filter module. In 2-D wavelet transform, column direction processing used the row direction results, which were not generated in column direction order but in row direction order, so most hardware architecture need internal buffer memory. The proposed architecture focused on the reducing of the internal memory buffer size and the total calculation time. Reducing the total calculation time, we proposed a 4-way data flow scheduling and memory based parallel hardware architecture. The 4-way data flow scheduling can increase the row direction parallel performance, and reduced the initial latency of starting of the row direction calculation. In this hardware architecture, the internal buffer memory didn't used to store the results of the row direction calculation, while it contained intermediate values of column direction calculation. This method is very effective in column direction processing, because the input data of column direction were not generated in column direction order The proposed architecture was implemented with VHDL and Altera Stratix device. The implementation results showed overall calculation time reduced from $N^2/2+\alpha$ to $N^2/4+\beta$, and internal buffer memory size reduced by around $50\%$ of previous works.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.176-179
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• 2015

본 논문에서는 3D 디지털 영상 컨텐츠의 저작권 보호를 위해 DWT(Discrete Wavelet Transform)를 이용하여 강인성(robustness), 비가시성(invisibility), 보안성(security)을 만족하는 블라인드(Blind) 워터마킹 방법을 제안한다. 이 방법은 깊이 영상 기반 랜더링(DIBR, Depth Image Based Rendering)에 효과적으로 대처하기위해 고안된 알고리즘으로, 랜더링시 발생하는 왜곡에 영향이 적은 1-Level DWT LH 부대역에 워터마크를 삽입하는 방법이다. 이 방법에서 저작권에 대한 판단은 추출한 워터마크 정보를 통합 판단하는 방법을 사용한다. 이 방법은 저작권 보호를 위해 원본 영상을 보관할 필요가 없으며, 깊이 영상 기반 랜더링 baseline distance 5% 공격에 좌,우시점 영상 모두 효율적으로 적은 에러율을 보이며 워터마크로서 충분한 강인성을 보여준다.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.358-361
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• 1997

This paper describes a multichannel epileptic seizure detection algorithm based on wavelet transform(WT), artificial neural network(ANN) and expert system. First, through the WT, a small number of wavelet coefficients is used to represent the single channel epileptic spike. Next, 3-layer feed-forward network employing the error back propagation algorithm is trained and tested using parameters obtained above. Finally, 16 channel expert system which is based on clinical experience is introduced as a artifact rejection and reliable detection. The suggested algorithm was implemented on personal computer(PC). Two main events i.e., epileptiform and normal activities, were selected from 32 person's EEGs(normal: 20, seizure disorder: 12) in consensus among experts. The result was that WT reduced data input size and ANN detected 97 of the 100 EEGs containing definite spike - sensitivity of 97%. Expert rule system was capable of rejecting a wide variety of artifacts commonly found in EEG recordings. It also reduced false positive detections of ANN.

• Journal of Korea Multimedia Society
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• v.9 no.5
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• pp.542-553
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• 2006

Because Y and C signals in a composite video signal are piled one on another in the same frequency, it is impossible to separate them completely. Therefore, it is necessary to develop efficient separation technique in order to minimize degradation of video quality. In this paper, we propose wavelet-based 3D comb filter algorithm and architecture for separating Y and C signals from a composite video signal. The proposed algorithm uses wavelet transform and thresholding of compared lines for acquiring the maximum video quality. Simulation results show that the proposed algorithm has better image quality and better PSNR than previous algorithms. For real application of the proposed algorithm, we developed a hardware architecture and the architecture was implemented by using VHDL. Finally, a VLSI layout of the proposed architecture was generated by using 0.25 micrometer CMOS process.

• Journal of Korea Multimedia Society
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• v.11 no.11
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• pp.1501-1514
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• 2008

The face shape extracted by the depth values has different appearance as the most important facial information. The face images decomposed into frequency subband are signified personal features in detail. In this paper, we develop a method for recognizing the range face images by multiple frequency domains for each depth image using the modified fuzzy c-mean algorithm. For the proposed approach, the first step tries to find the nose tip that has a protrusion shape on the face from the extracted face area. And the second step takes into consideration of the orientated frontal posture to normalize. Multiple contour line areas which have a different shape for each person are extracted by the depth threshold values from the reference point, nose tip. And then, the frequency component extracted from the wavelet subband can be adopted as feature information for the authentication problems. The third step of approach concerns the application of eigenface to reduce the dimension. And the linear discriminant analysis (LDA) method to improve the classification ability between the similar features is adapted. In the last step, the individual classifiers using the modified fuzzy c-mean method based on the K-NN to initialize the membership degree is explained for extracted coefficient at each resolution level. In the experimental results, using the depth threshold value 60 (DT60) showed the highest recognition rate among the extracted regions, and the proposed classification method achieved 98.3% recognition rate, incase of fuzzy cluster.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.85-99
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• 2022

Rock discontinuities, as weak interfaces in rock, control mechanical properties of rock mass. Presence of discontinuities complicates the engineering properties of rock, which is the root of anisotropy and heterogeneity that have nonnegligible influences on the rock engineering. Morphological characteristics of discontinuities in natural rock are an important factor influencing the mechanical properties, particularly roughness, of discontinuities. Therefore, the accurate measurement and characterization of morphologies of discontinuities are preconditions for studying mechanical properties of discontinuities. Taking discontinuities in red sandstone as research objects, the research obtained three-dimensional (3D) morphologies of discontinuities in natural rock by carrying out 3D morphological scanning tests. The waviness and roughness were separated from 3D morphologies of rock discontinuities through wavelet transform. In addition, the calculation method for the overall slope root mean square (RMS) as well as slope RMSs of waviness and roughness of 3D morphologies of discontinuities considering the shear direction was proposed. The research finally determined an evaluation method for 3D morphologies of discontinuities by quantitatively characterizing 3D morphologies with the mean value of the three slope RMSs.

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.5-13
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• 2001

It is well known that there are two experimental errors on acoustic decay measurements. ,One is due to the influence of the band pass filter the other one is that of an averaging device. In this paper the influence of the filter is investigated in detail. To minimize the influence of the filter, the product of the filter bandwidth B (3dB bandwidth) and the reverberation time T/sub 60/ of the room under test should be at least 16. Moreover, if the initial part of an acoustic decay curve is important, the strong requirement, i. e. BT/sub 60/〉64, must be satisfied. In this paper, the wavelet filter bank instead of the band pass filter bank is applied to obtain an acoustic decay curve. As a result, the influence of filter is reduced and then the value of BT/sub 60/ required for obtaining an acceptable decay curve becomes at least 4. The strong requirement for the initial part of a decay curve is also replaced by the BT/sub 60/〉16 instead of BT/sub 60/〉64.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.1-7
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• 2005

We propose an effective Landsat TM image compression method using the classified bidirectional prediction (CBP), the classified KLT and the SPIHT. The SPIHT is used to exploit the spatial redundancy of feature bands selected in the visible range and the infrared range separately. Regions of the prediction bands are classified into three classes in the wavelet domain, and then the CBP is performed to exploit the spectral redundancy. Residual bands that consist of difference values between the original band and the predicted band are decorrelated by the spectral KLT Finally, the three dimensional (3-D) SPIHT is used to encode the decorrelated coefficients. Experiment results show that the proposed method reconstructs higher quality Landsat TM image than conventional methods at the same bit rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.5
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• pp.1245-1252
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• 2013

As the usage of digital image contents increase, a security problem for the payed image data or the ones requiring confidentiality is raised. This paper propose a depth-map image contents encryption methodology to hide the depth information. This method is performed on the frequency coefficients in the Wavelet domain. This method, by selecting the level and threshold value for the wavelet transform, encryption at various strengths are possible. The experimental results showed that encrypting only 0.048% of the entire data was enough to hide the constants of the depth-map. The encryption algorithm expected to be used effectively on the researches on encryption and others for image processing.