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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Communications and Information Sciences
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The Korean Institute of Communications and Information Sciences
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Volume & Issues
Volume 28, Issue 12C - Dec 2003
Volume 28, Issue 12B - Dec 2003
Volume 28, Issue 12A - Dec 2003
Volume 28, Issue 11C - Nov 2003
Volume 28, Issue 11B - Nov 2003
Volume 28, Issue 11A - Nov 2003
Volume 28, Issue 10C - Oct 2003
Volume 28, Issue 10B - Oct 2003
Volume 28, Issue 10A - Oct 2003
Volume 28, Issue 9C - Sep 2003
Volume 28, Issue 9B - Sep 2003
Volume 28, Issue 9A - Sep 2003
Volume 28, Issue 8C - Aug 2003
Volume 28, Issue 8B - Aug 2003
Volume 28, Issue 8A - Aug 2003
Volume 28, Issue 7C - Jul 2003
Volume 28, Issue 7B - Jul 2003
Volume 28, Issue 7A - Jul 2003
Volume 28, Issue 6C - Jun 2003
Volume 28, Issue 6B - Jun 2003
Volume 28, Issue 6A - Jun 2003
Volume 28, Issue 5C - May 2003
Volume 28, Issue 5B - May 2003
Volume 28, Issue 5A - May 2003
Volume 28, Issue 4C - Apr 2003
Volume 28, Issue 4B - Apr 2003
Volume 28, Issue 4A - Apr 2003
Volume 28, Issue 3C - Mar 2003
Volume 28, Issue 3B - Mar 2003
Volume 28, Issue 3A - Mar 2003
Volume 28, Issue 2C - Feb 2003
Volume 28, Issue 2B - Feb 2003
Volume 28, Issue 2A - Feb 2003
Volume 28, Issue 1C - Jan 2003
Volume 28, Issue 1B - Jan 2003
Volume 28, Issue 1A - Jan 2003
Volume 28, Issue 9 - 00 2003
Volume 28, Issue 8 - 00 2003
Volume 28, Issue 7 - 00 2003
Volume 28, Issue 6 - 00 2003
Volume 28, Issue 5 - 00 2003
Volume 28, Issue 3 - 00 2003
Volume 28, Issue 2 - 00 2003
Volume 28, Issue 1 - 00 2003
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Efficient Implementation of SOVA for Turbo Codes
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1045~1051
The SOVA, which produces the soft decision value, can be used as a sub-optimum solution for concatenated codes such as turbo codes, since it is computationally efficient compared with the optimum MAP algorithm. In this paper, we propose an efficient implementation of the SOVA used for decoding turbo codes, by reducing the number of calculations for soft decision values and trace-back operations. In order to utilize the memory efficiently, the whole block of turbo codes is divided into several sub-blocks in the proposed algorithm. It is demonstrated that the proposed algorithm requires less computation than the conventional algorithm, while providing the same overall performance.
Design of the Normalization Unit for a Low-Power and Area-Efficient Turbo Decoders
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1052~1061
This paper proposes a novel normalization scheme in the state metric calculation unit for the Block-wise MAP Turbo decoder. The proposed scheme subtracts one of four metrics from the state metrics in a trellis stage and shifts, if necessary, those metrics for normalization. The proposed architecture can reduce power consumption and memory requirement by reducing the number of the state metrics by one in a trellis stage in the Block-wise MAP decoder which requires an intensive state metric calculations. Simulation results show that dynamic power has been reduced by 17.9% and area has been reduced by 6.6% in the Turbo decoder employing the proposed normalization scheme, when compared to the conventional Block-wise MAP Turbo decoders.
A New Loop Shaping Method for Design of Robust Optimal PID Controller
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1062~1069
This paper presents a new loop shaping technique for design of robust optimal PID controllers in order to satisfy the performance requirements. PID controller can be designed by selecting the suitable weighting factors Q and R. This technique is developed by pushing all two zeros formed by PID controller closely to a larger pole of the second order plant. As a result, a good loop shaping is achieved in the high frequencies region on the Bode plot. For the robust optimal tuning of PID controller for second order system, a new loop shaping procedure is developed via LQR approach.
MRC Diversity Analysis for Square M-QAM in Nakagkmi-m Fading Channels
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1070~1076
This paper presents and analyses the exact and general closed-form expression for the average bit error probability of M-ary square quadrature amplitude modulation (QAM) for maximal ratio combining (MRC) diversity reception in frequency-nonselective Nakagami-m fading. An L-branch Maximal ratio combining diversity technique with independent or correlated fading cases is considered. Numerical results demonstrate the error performance improvement by employing with the use of MRC diversity reception. The new expressions presented here can offer a convenient way to evaluate the performance of an arbitrary square M-W square QAM with an MRC diversity combiner for various cases of practical interest.
Design of Multimode Block Cryptosystem for Network Security
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1077~1087
In this paper, we proposed an architecture of a cryptosystem with various operating modes for the network security and implemented in hardware using the ASIC library. For configuring a cryptosystem, the standard block ciphers such as AES, SEED and 3DES were included. And the implemented cryptosystem can encrypt and decrypt the data in real time through the wired/wireless network with the minimum latency time (minimum 64 clocks, maximum 256 clocks). It can support CTR mode which is widely used recently as well as the conventional block cipher modes such as ECB, CBC and OFB, and operates in the multi-bit mode (64, 128, 192, and 256 bits). The implemented hardware has the expansion possibility for the other algorithms according to the network security protocol such as IPsec and the included ciphering blocks can be operated simultaneously. The self-ciphering mode and various ciphering mode can be supported by the hardware sharing and the programmable data-path. The global operation is programmed by the serial communication port and the operation is decided by the control signals decoded from the instruction by the host. The designed hardware using VHDL was synthesized with Hynix 0.25
CMOS technology and it used the about 100,000 gates. Also we could assure the stable operation in the timing simulation over 100㎒ using NC-verilog.
A New Snakes Algorithm Combined with Disparity Information in the Stereo Images
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1088~1097
In this paper, we propose a method that improves the snakes algorithm well known as previously active contour model. Generally, the previous snakes algorithm applied to the 2-D images doesn't get the good results due to the influences about other objects adjacent to contour of object to be extracted. Users directly set the initial snakes points near to the contour of the object to get better results. In this paper, using the disparity information of the stereo images, a new algorithm of the object segmentation is proposed to reduce the influences adjacent to the contour of object. Users can establish initial snakes points automatically from the setting of the interested regions.
Reduction of Speckle Noise in Images Using Homomorphic Wavelet-Based MMSE Filter with Edge Detection
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1098~1110
In this paper, we propose a homomorphic wavelet-based MMSE filter with edge detection to restore images degraded by speckle noise. In the proposed method, a noisy image is first transformed into logarithmic domain. Each pixel in the transformed image is then classified into flat and edge regions by applying DIP operator to the image restored by homomorphic directional MMSE filter. Each pixel in flat region is restored by homomorphic wavelet-based MMSE filter. Each pixel in edge region is restored by the weighted sum of the output of homomorphic wavelet-based MMSE filtering and that of homomorphic directional MMSE filtering. The restored image in spatial domain is finally obtained by applying the exponential function to the restored image in logarithmic domain. Experimental results show that the restored images by the proposed method have ISNR improvement of 3.3-4.0 ㏈ and
, a measurement parameter on edge preservation, improvement of 0.0103-0.0126 and superior subjective image quality over those by conventional methods.
Decision Feedback Doppler Adaptive Band-Limit Algorithm for Maximum Doppler frequency Estimation
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1111~1117
The maximum Doppler frequency, or equivalently, the mobile speed is very useful information to optimize the performance of many wireless communication systems. However, the performance of a maximum Doppler frequency estimator is limited since it requires an estimate of the signal-to-noise ratio (SNR) of the channel environment. In this paper, the improved method for the maximum Doppler frequency estimations based on the decision feedback Doppler adaptive band-limit (DF-DABL) method is proposed. To reduce the effect of additive noise, the proposed algorithm uses a novel Doppler adaptive band-limit (DABL) technique. The distortion due to the additive noise is drastically removed by the proposed DF-DABL method. Especially, the DF-DABL method does not need any other channel information such as SNR.
An invisible watermarking scheme using the SVD
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1118~1122
In this paper, we propose a new invisible digital watermarking scheme based on wavelet transform using singular value decomposition. Embedding process is started by decomposing the lowest frequency band image with 3
3 block among which we define the watermark block chosen by a key set; entropy and condition number of the block. A watermark is embedded in the singular values of each watermark blocks. This provides a robust watermarking in lowest possible time-frequency domain. To detect the watermark, we are locally modeling an attack as 3
3 matrices on the watermark blocks. Combining with the SVD and the attack matrices, we estimate watermark set corresponding to the watermark blocks. In each watermark block, we determine an optimal watermark which is justified by the T-testing. A numerical experiment shows that the proposed watermarking scheme efficiently detects the watermarks from several JPEG attacks.
An improved H.264 Video Encoding using a New Syntax Element
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1123~1129
In the H.264 video coding standard, the information for the macroblock is encoded by the independent syntax elements, called RUN and MB_type. Through the experimental observation for various test sequences, it is shown that the performance of the video coding is improved by using the combined RUN and MB_type as an entity. Based on this fact, we propose an unified new syntax element composed of the RUN and MB_type in order to improve the compression ratio of H.264 video coding. In the proposed syntax element, an EOF(End-Of-Frame) symbol indicating the end of picture is used for enhancing the performance of video coding. The simulation result shows that the proposed method outperforms maximally 15 % to the conventional method for the bitrate of the macroblock.
Multi-Hypothesis Error Concealment Algorithm for H.26L Video
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1130~1139
In this work, we propose a multi-hypothesis error concealment algorithm, which replaces a lost block with a weighted superposition of more than two reference blocks in previous frames. Three methods are developed to find the set of reference blocks and determine the weighting coefficients. These methods are implemented based on H.26L standard, and their performances are evaluated. It is shown that the proposed multi-hypothesis algorithm provides up to 1.5㏈ better PSNR performance than the conventional single-hypothesis concealment algorithm.
A Study on Face Recognition Based on Modified Otsu's Binarization and Hu Moment
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1140~1151
This paper proposes a face recognition method based on modified Otsu's binarization and Hu moment. Proposed method is robust to brightness, contrast, scale, rotation, and translation changes. As the proposed modified Otsu's binarization computes other thresholds from conventional Otsu's binarization, namely we create two binary images, we can extract higher dimensional feature vector. Here the feature vector has properties of robustness to brightness and contrast changes because the proposed method is based on Otsu's binarization. And our face recognition system is robust to scale, rotation, and translation changes because of using Hu moment. In the perspective of brightness, contrast, scale, rotation, and translation changes, experimental results with Olivetti Research Laboratory (ORL) database and the AR database showed that average recognition rates of conventional well-known principal component analysis (PCA) are 93.2% and 81.4%, respectively. Meanwhile, the proposed method for the same databases has superior performance of the average recognition rates of 93.2% and 81.4%, respectively.
English Digital Signal Processing Circuit in HD Monitor using Synchronization Signal Optimization
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1152~1160
Start The current paper proposes an improved HD(High Definition) monitor that can support a signal input with various resolutions. Due to the inadequate performance of the built-in digital PLL(Phase-locked Loop) of an ADC(Analog to Digital Converter) and poor tolerance of ADC ICs, there are problems in the stable processing of synchronization signals with various input signals. Accordingly, the proposed synchronization signal optimization technique regenerates the horizontal synchronization signal in the vertical blanking interval based on the regularity of the synchronization signal, i.e. the timing of the falling edge signal remains constant, thereby solving the above problem and minimizing the interference of the system. As a result, the proposed system can stabilize various synchronization signals with different resolution modes.
An Improved VAD Algorithm Employing Speech Enhancement Preprocessing and Threshold Updating
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1161~1168
In this paper, we propose an improved statistical model-based voice activity detection algorithm and threshold update method. We first improve signal-to-noise ratio by using speech enhancement preprocessing algorithm combined power subtraction method and matched filter, then apply it to LLR test optimum decision rule for improving the performance even in low SNR conditions. And we propose an adaptive threshold update method that was not concerned in any papers. We also perform extensive computer simulations to demonstrate the performance improvement of the proposed VAD algorithm employing the proposed speech enhancement preprocessing algorithm and adaptive threshold update method under various background noise environments. Finally we verify our results by comparing ITU-T G.729 Annex B.
Blind Watermarking Using HVS and Wavelet Transform
The Journal of Korean Institute of Communications and Information Sciences, volume 28, issue 11C, 2003, Pages 1169~1176
In this paper, we propose a blind watermarking that embeds watermarks into wavelet middle frequency subbands using human visual system. Wavelet middle frequency pairs(MFP) show similar distortion against general image processing attacks such as compression and filtering. So the quantization between MFPs is more robust than conventional methods that directly quantize DWT coefficients. We use a noise visibility function(NVF) to obtain a good visual quality This is able to preserve embedding positions after many attacks. Our experimental results show that the proposed scheme is robust to various image processing such as JPEG, while preserving good visual quality above 44㏈.