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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 34, Issue 12C - Dec 2009
Volume 34, Issue 12B - Dec 2009
Volume 34, Issue 12A - Dec 2009
Volume 34, Issue 11C - Nov 2009
Volume 34, Issue 11B - Nov 2009
Volume 34, Issue 11A - Nov 2009
Volume 34, Issue 10C - Oct 2009
Volume 34, Issue 10B - Oct 2009
Volume 34, Issue 10A - Oct 2009
Volume 34, Issue 9C - Sep 2009
Volume 34, Issue 9B - Sep 2009
Volume 34, Issue 9A - Sep 2009
Volume 34, Issue 8C - Aug 2009
Volume 34, Issue 8B - Aug 2009
Volume 34, Issue 8A - Aug 2009
Volume 34, Issue 7C - Jul 2009
Volume 34, Issue 7B - Jul 2009
Volume 34, Issue 7A - Jul 2009
Volume 34, Issue 6C - Jun 2009
Volume 34, Issue 6B - Jun 2009
Volume 34, Issue 6A - Jun 2009
Volume 34, Issue 5C - May 2009
Volume 34, Issue 5B - May 2009
Volume 34, Issue 5A - May 2009
Volume 34, Issue 4C - Apr 2009
Volume 34, Issue 4B - Apr 2009
Volume 34, Issue 4A - Apr 2009
Volume 34, Issue 3C - Mar 2009
Volume 34, Issue 3B - Mar 2009
Volume 34, Issue 3A - Mar 2009
Volume 34, Issue 2C - Feb 2009
Volume 34, Issue 2B - Feb 2009
Volume 34, Issue 2A - Feb 2009
Volume 34, Issue 1C - Jan 2009
Volume 34, Issue 1B - Jan 2009
Volume 34, Issue 1A - Jan 2009
Selecting the target year
Time-reversal Channel Capacity in Rayleigh and Ricean Environment
Koh, Il-Suek ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 243~250
In this paper, a closed-form expression of the ergodic channel capacity for a narrow-band time-reversal communication scheme is analytically formulated. In the time-reversal communication scenario, a transmitter sends a signal and a so-called time-reversal array receives the signal. Then, the received signal is reversed in the time do main and resent to the original transmitter. Here, one transmitter and an antenna array for the time-reversal array are assumed. Since the spacing between the array elements is large, the signals received by each antenna element can be considered independent. For simplicity, the communication channel is assumed stationary, whose properties are not changed for the time-reversal process. Based on the obtained formulation, the channel capacities for the time-reversal and the conventional channels are compared.
Overlap and Add Sinusoidal Synthesis Method of Speech Signal Lising the Damping Harmonic Magnitude Parameter
Park, Jong-Bae ; Kim, Young-Joon ; Lee, In-Sung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 251~256
In this paper, we propose a new method with the improved continuity performance of overlap and add speech signal synthesis method using damping harmonic amplitude parameter. The existing method uses the average value of past and current parameters for the sinusoidal amplitude used as the weight of phase error function. But, the proposed method extracts the more accurate sinusoidal amplitude by using a correlation between the original signals and the synthesized signals for the sinusodal amplitude used as the weights. To verify the performance of the proposed method, we observed the average differential error value between the synthesized signals.
Training Method and Speaker Verification Measures for Recurrent Neural Network based Speaker Verification System
Kim, Tae-Hyung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 257~267
This paper presents a training method for neural networks and the employment of MSE (mean scare error) values as the basis of a decision regarding the identity claim of a speaker in a recurrent neural networks based speaker verification system. Recurrent neural networks (RNNs) are employed to capture temporally dynamic characteristics of speech signal. In the process of supervised learning for RNNs, target outputs are automatically generated and the generated target outputs are made to represent the temporal variation of input speech sounds. To increase the capability of discriminating between the true speaker and an impostor, a discriminative training method for RNNs is presented. This paper shows the use and the effectiveness of the MSE value, which is obtained from the Euclidean distance between the target outputs and the outputs of networks for test speech sounds of a speaker, as the basis of speaker verification. In terms of equal error rates, results of experiments, which have been performed using the Korean speech database, show that the proposed speaker verification system exhibits better performance than a conventional hidden Markov model based speaker verification system.
Robust-to-rotation Iris Recognition Using Local Gradient Orientation Histogram
Choi, Chang-Soo ; Jun, Byoung-Min ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 268~273
Iris recognition is a biometric technology which can identify a person using the iris pattern. It is important for the iris recognition system to extract the feature which is invariant to changes in iris patterns. Those changes can be occurred by the influence of lights, changes in the size of the pupil, and head tilting. In this paper, we propose a novel method based on local gradient orientation histogram which is robust to variations in illumination and rotations of iris patterns. The proposed method enables high-speed feature extraction and feature comparison because it requires no additional processing to obtain the rotation invariance, and shows comparable performance to the well-known previous methods.
Object Recognition and Tracking using Histogram Through Successive Frames
Park, Ho-Sik ; Bae, Cheol-Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 274~278
Recently, the research which concerns the object class recognition has been done. Although an object tracking based on most of histograms employs a colored model to improve robustness, the system is not reliable enough yet. In this paper, we presents a method to express and track an object by using the histograms which are composed with visual features through successive frames. The experimental results shows that this method is reliable to track a car within 80m distance from camera.
Hierarchical Stereo Matching with Color Information
Kim, Tae-June ; Yoo, Ji-Sang ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 279~287
In this paper, a hierarchical stereo matching with color information is proposed. To generate an initial disparity map, feature based stereo matching is carried out and to generate a final disparity map, hierarchical stereo matching is carried out. The boundary (edge) region is obtained by segmenting a given image into R, G, B and White components. From the obtained boundary, disparity is extracted. The initial disparity map is generated when the extracted disparity is spread to the surrounding regions by evaluating autocorrelation from each color region. The initial disparity map is used as an initial value for generating the final disparity map. The final disparity map is generated from each color region by changing the size of a block and the search range. 4 test images that are provided by Middlebury stereo vision are used to evaluate the performance of the proposed algorithm objectively. The experiment results show better performance compared to the Graph-cuts and Dynamic Programming methods. In the final disparity map, about 11% of the disparities for the entire image were inaccurate. It was verified that the boundary for the non-contiguous point was clear in the disparity map.
Reconstruction of High Resolution Images by ARPS Motion Estimation and POCS Restoration
Song, Hee-Keun ; Kim, Yong-Cheol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 288~296
In POCS (projection onto convex sets)-based reconstruction of HR (high resolution) image, the quality of reconstructed image is gradually improved through iterative motion estimation and image restoration. The amount of computation, however, increases because of the repeated inter-frame motion estimation. In this paper, an HR reconstruction algorithm is proposed where modified ARPS (adaptive rood pattern search) and POCS are simultaneously performed. In the modified ARPS, the motion estimates obtained from phase correlation or from the previous steps in POCS restoration are utilized as the initial reference in the motion estimation. Moreover, estimated motion is regularized with reference to the neighboring blocks' motion to enhance the reliability. Computer simulation results show that, when compared to conventional methods which are composed of full search block matching and POCS restoration, the proposed method is about 30 times faster and yet produces HR images of almost equal or better quality.
Compression of Elemental Images Using Block Division in 3D Integral Imaging
Kang, Ho-Hyun ; Shin, Dong-Hak ; Kim, Eun-Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 297~303
Integral imaging is a well-known 3D image recording and display technique. The huge size of integral imaging data requires a compression scheme to store and transmit 3D scenes. In the conventional compression scheme, the data amount of elemental images depends on the various recording condition such as the positional location of a 3D object, the illumination and specification of the lenslet array even if an identical pickup system is used. In this paper, to reduce the dependence of the image characteristics of elemental images on the pickup conditions, a compression scheme using block division on the elemental image of integral imaging is proposed. The proposed scheme provides an improved compression ratio by considering the local similarity of elemental images picked up from three-dimensional objects according to a positional location. To test the proposed scheme, various elemental images are picked up and a compression process is then carried out u sing a standard MPEG-4. Based on compression ratio results, the proposed compression scheme is improved by approximately 9% compared with the conventional compression method.
Successive MAP Detection with Soft Interference Cancellation for Iterative Receivers in Hierarchical M-ary QAM Systems
Kim, Jong-Kyung ; Seo, Jong-Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 304~310
This paper proposes a successive MAP (maximum a posteriori probability) detection scheme with SoIC(soft interference cancellation) to reduce the receiver complexity of hierarchical M-ary QAM system. For the successive MAP detection, modulation symbols generated from the other data streams are treated as Gaussian noise or eliminated as the soft interference according to their priorities. The log-likelihood ratio of the a posteriori probability (LAPRP) of each bit is calculated by the MAP detector with an adjusted noise variance in order to take the elimination and Gaussian assumption effect into account. By separating the detection process into the successive steps, the detection complexity is reduced to increase linearly with the number of bits per hierarchical M-ary QAM symbol. Simulation results show that the proposed detection provides a small performance degradation as compared to the optimal MAP detection.
Design of Efficient frequency Offset Estimator for MB-OFDM based UWB Systems
Kim, Kil-Hwan ; Jung, Yun-Ho ; Kim, Jae-Seok ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 311~321
This paper proposes an efficient frequency offset estimation algorithm for MB-OFDM based UWB systems. The time-frequency interleaving in MB-OFDM extends the time-interval between two transmitted OFDM symbols in the same sub-band. The extended time-interval causes not only the degradation of the system performance by reducing frequency offset estimation range, but also the increase of the hardware complexity by requiring the larger number of storing samples. The proposed estimation algorithm expands the estimation range by applying the proposed sign detection scheme. Simulation results show that the estimation range is increased above 30 ppm compared with a conventional auto-correlation based scheme. The estimation is performed on only one sub-band, and the frequency offsets of the others are calculated by relation to center frequency. This way reduced the number of the storing samples by about l/3. The frequency offset estimator with the proposed algorithm was designed into the architecture which minimizes hardware overhead by time-sharing operators and memory units, and which was synthesized to gate-level circuits using
CMOS technology, and the total gates were about 47K.
New Simplified Sum-Product Algorithm for Low Complexity LDPC Decoding
Han, Jae-Hee ; SunWoo, Myung-Hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 322~328
This paper proposes new simplified sum-product (SSP) decoding algorithm to improve BER performance for low-density parity-check codes. The proposed SSP algorithm can replace multiplications and divisions with additions and subtractions without extra computations. In addition, the proposed SSP algorithm can simplify both the In[tanh(x)] and tanh-1 [exp(x)] by using two quantization tables which can reduce tremendous computational complexity. Moreover, the simulation results show that the proposed SSP algorithm can improve about
of BER performance compared with the existing modified sum-product algorithms.
A Generalized Advanced Region Correlation (G-ARC) Scheme for BOC(pn,n) Modulated Code Tracking in GNSS
Yoo, Seung-Soo ; Lee, Young-Yoon ; Kim, Yeong-Moon ; Yoon, Seok-Ho ; Kim, Sun-Yong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 34, issue 3C, 2009, Pages 329~340
This paper proposes a novel code tracking scheme to track the fine code synchronization for BOC(pn,n) modulated spreading signals. The correlation function of BOC(pn,n) modulated spreading signals has been several peaks. In this paper, we observe that the correlation function in the advanced offset region remains almost unchanged, due to the multipath signals being received later than a line-of-sight signal. Based on this observation, we propose a novel code tracking scheme which is called the advanced region correlation (ARC) method for BOC(n,n) modulated spreading signals. And, we compare with the code tracking accuracy between the conventional and proposed methods in the static multipath and land mobile satellite system channels through the Monte-Carlo simulation. Then, base on the proposed scheme, we propose the generalized-ARC (ARC) scheme for BOC(pn, n) modulated spreading signals.