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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 30, Issue 12C - Dec 2005
Volume 30, Issue 12B - Dec 2005
Volume 30, Issue 12A - Dec 2005
Volume 30, Issue 11C - Nov 2005
Volume 30, Issue 11B - Nov 2005
Volume 30, Issue 11A - Nov 2005
Volume 30, Issue 10C - Oct 2005
Volume 30, Issue 10B - Oct 2005
Volume 30, Issue 10A - Oct 2005
Volume 30, Issue 9C - Sep 2005
Volume 30, Issue 9B - Sep 2005
Volume 30, Issue 9A - Sep 2005
Volume 30, Issue 8C - Aug 2005
Volume 30, Issue 8B - Aug 2005
Volume 30, Issue 8A - Aug 2005
Volume 30, Issue 7C - Jul 2005
Volume 30, Issue 7B - Jul 2005
Volume 30, Issue 7A - Jul 2005
Volume 30, Issue 6C - Jun 2005
Volume 30, Issue 6B - Jun 2005
Volume 30, Issue 6A - Jun 2005
Volume 30, Issue 5C - May 2005
Volume 30, Issue 5B - May 2005
Volume 30, Issue 5A - May 2005
Volume 30, Issue 4C - Apr 2005
Volume 30, Issue 4B - Apr 2005
Volume 30, Issue 4A - Apr 2005
Volume 30, Issue 3C - Mar 2005
Volume 30, Issue 3B - Mar 2005
Volume 30, Issue 3A - Mar 2005
Volume 30, Issue 2C - Feb 2005
Volume 30, Issue 2B - Feb 2005
Volume 30, Issue 2A - Feb 2005
Volume 30, Issue 1C - Jan 2005
Volume 30, Issue 1B - Jan 2005
Volume 30, Issue 1A - Jan 2005
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Optimization of coding and PRML detection scheme for perpendicular magnetic recording systems
Lee Joo hyun ; Lee Jae jin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 59~63
We propose non-DC-free generalized PRML (GPRML) that are suppressed DC contents for matching to the response of perpendicular magnetic recording channel with a ring-head. In addition, DC-free encoding is considered to prevent low-frequency disturbances. The SNR performance is obtained by combining the various PRML channels with DC-free and non-DC-free codes during the normalized recording density increases from 2.5 to 3.5. The GPRML detections without using DC-free code get SNR gains more than 1dB compared to the conventional PRML systems at 10/sup -5/BER. We confirmed that the rate 127/136 DC-free coded GPRML systems show good performances compared with the 16/17 non-DC-free coded GPRML systems. In results, DC-free coded GPRML detections get gains about 1.4dB and 2.0dB at the density of 3.3 and 3.5, respectively.
Complexity Analysis of a VHDL Implementation of the Bit-Serial Reed-Solomon Encoder
Back Seung hun ; Song Iick ho ; Bae Jin soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 64~68
Reed-Solomon code is one of the most versatile channel codes. The encoder can be implemented with two famous structures: ordinary and bit-serial. The ordinary encoder is generally known to be complex and fast, while the bit-serial encoder is simple and not so fast. However, it may not be true for a longer codeword length at least in VHDL implementation. In this letter, it is shown that, when the encoder is implemented with VHDL, the number of logic gates of the bit-serial encoder might be larger than that of the ordinary encoder if the dual basis conversion table has to be used. It is also shown that the encoding speeds of the two VHDL implemented encoders are exactly same.
Constant-Amplitude Biorthogonal Multi-Code Modulation
Hong Dae ki ; Kang Sung jin ; Ju Min chul ; Kim Young sung ; Seo Kyeung hak ; Cho Jin woong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 69~76
In this paper, we propose a biorthogonal modulation employing a constant-amplitude transmission of multi-code signals by introducing a simple constant-amplitude coding scheme with redundant bits. The proposed constant-amplitude biorthogonal multi-code (CABM) modulation can provide high spectral efficiency compared with a conventional direct sequence/spread spectrum (DS/SS) modulation. Nevertheless the proposed CABM modulation can keep up a constant-amplitude signal. Additionally, we propose various types of demodulation structures for the CABM modulation. Simulation results show that bit error rate (BER) performance and hardware complexity of the proposed CABM modulation are highly improved in comparison with those of a constant-amplitude orthogonal multi-code (CAOM) modulation.
PRML detection using the patterns of run-length limited codes
Lee Joo hyun ; Lee Jae jin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 77~82
Partial response maximum likelihood (PRML) detection using the Viterbi algorithm involves the calculation of likelihood metrics that determine the most likely sequence of decoded data. In general, it is assumed that branches at each node in the trellis diagram have same probabilities. If modulation code with minimum and maximum run-length constraints is used, the occurrence ratio (Ro) of each particular pattern is different, and therefore the assumption is not true. We present a calculation scheme of the likelihood metrics for the PRML detection using the occurrence ratio. In simulation, we have tested the two (1,7) run-length-limited codes and calculated the occurrence ratios as the orders of PR targets are changed. We can identify that the PRML detections using the occurrence ratio provide more than about 0.5dB gain compared to conventional PRML detections at 10/sup -5/ BER in high-density magnetic recording and optical recording channels.
Performance Analysis of an Adaptive Hybrid Search Code Acquisition Algorithm for DS-CDMA Systems
Park Hyung rae ; Yang Yeon sil ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 83~91
We analyze the performance of an adaptive hybrid search code acquisition algorithm for direct-sequence code division multiple access (DS-CDMA) systems under slowly-moving mobile environments. The code acquisition algorithm is designed to provide the desired feature of constant false alarm rate (CFAR) to cope with nonstationarity of the interference in CDMA forward links. An analytical expression for the mean acquisition time is first derived and the probabilities of detection, miss, and false alarm are then obtained for frequency-selective Rayleigh fading environments. The fading envelope of a received signal is assumed to be constant over the duration of post-detection integration (PDI), considering slow fading environments. Finally, the performance of the designed code acquisition algorithm shall be evaluated numerically to examine the effect of some design parameters such as the sub-window size, size of the PDI, decision threshold, and so on, considering cdma2000 environments.
Motion Detection using Adaptive Background Image and A Net Model Pixel Space of Boundary Detection
Lee Chang soo ; Jun Moon seog ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 92~101
It is difficult to detect the accurate detection which leads the camera it moves follows in change of the noise or illumination and Also, it could be recognized with backgound if the object doesn't move during hours. In this paper, the proposed method is updating changed background image as much as N＊M pixel mask as time goes on after get a difference between imput image and first background image. And checking image pixel can efficiently detect moving by computing fixed distance pixel instead of operate all pixel. Also, set up minimum area of object to use boundary point of object abstracted through checking image pixel and motion detect of object. Therefore motion detection is available as is fast and correct without doing checking image pixel every Dame. From experiment, the designed and implemented system showed high precision ratio in performance assessment more than 90 percents.
Hardware Implementation of a Fast Inter Prediction Engine for MPEG-4 AVC
Lim Young hun ; Lee Dae joon ; Jeong Yong jin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 102~111
In this paper, we propose an advanced hardware architecture for the fast inter prediction engine of the video coding standard MPEG-4 AVC. We describe the algorithm and derive the hardware architecture emphasizing and real time operation of the quarter_pel based motion estimation. The fast inter prediction engine is composed of block segmentation, motion estimation, motion compensation, and the fast quarter_pel calculator. The proposed architecture has been verified by ARM-interfaced emulation board using Excalibur & Virtex2 FPGA, and also by synthesis on Samsung 0.18 um CMOS technology. The synthesis result shows that the proposed hardware can operate at 62.5MHz. In this case, it can process about 88 QCIF video frames per second. The hardware is being used as a core module when implementing a complete MPEG-4 AVC video encoder chip for real-time multimedia application.
Nonlinear matching measure for the analysis of on-off type microarray image
Ryu Mun ho ; Kim Jong dae ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 112~118
In this paper, we propose a new nonlinear matching measure for automatic analysis of the on-off type DNA microarray images in which the hybridized spots are detected by the template matching method. The proposed measure is obtained by binary-thresholding over the whole template region and taking the number of white pixels inside the spotted area. This measure is compared with the normalized covariance in terms of the classification ability of the successfulness of the locating markers. The proposed measure is evaluated for the scanned images of HPV DNA microarrays where the marker locating is a critical issue because of the small number of spots. The targeting spots of HPV DNA chips are designed for genotyping 22 types of the human papilloma virus(HPV). The proposed measure is proven to give more discriminative response reducing the miss cases of the successful marker locating.
Wavelet Denoising Using Region Merging
Eom Il kyu ; Kim Yoo shin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 119~124
In this paper, we propose a novel algorithm for determining the variable size of locally adaptive window using region-merging method. A region including a denoising point is partitioned to disjoint sub-regions. Locally adaptive window for denoising is obtained by selecting Proper sub-lesions. In our method, nearly arbitrarily shaped window is achieved. Experimental results show that our method outperforms other critically sampled wavelet denoising scheme.
Real Time Gaze Discrimination for Human Computer Interaction
Park Ho sik ; Bae Cheol soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 125~132
This paper describes a computer vision system based on active IR illumination for real-time gaze discrimination system. Unlike most of the existing gaze discrimination techniques, which often require assuming a static head to work well and require a cumbersome calibration process for each person, our gaze discrimination system can perform robust and accurate gaze estimation without calibration and under rather significant head movement. This is made possible by a new gaze calibration procedure that identifies the mapping from pupil parameters to screen coordinates using generalized regression neural networks (GRNNs). With GRNNs, the mapping does not have to be an analytical function and head movement is explicitly accounted for by the gaze mapping function. Futhermore, the mapping function can generalize to other individuals not used in the training. To further improve the gaze estimation accuracy, we employ a reclassification scheme that deals with the classes that tend to be misclassified. This leads to a 10% improvement in classification error. The angular gaze accuracy is about 5°horizontally and 8°vertically. The effectiveness of our gaze tracker is demonstrated by experiments that involve gaze-contingent interactive graphic display.
A Spatial Error Concealment Technique Using Edge-Oriented Interpolation
Yoo Hyun sun ; Kim Won ki ; Jeong Je chang ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 133~140
This paper introduces a spatial error concealment technique using directional interpolation in block-based compression. The first step involves finding the spatial direction vectors represented an edge-direction in the lost block using spatial boundary matching algorithm. Then, the error blocks are recovered by directional interpolation through these vectors and concealed by using the recovered blocks which have lower directional boundary matching error out of them relatively. This proposed method is able to deal with errors on macroblock or slice level adaptively. And it has lower complexity and maintains better performance compared to the conventional methods.
An Adaptive Radial Basis Function Network algorithm for nonlinear channel equalization
Kim Nam yong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 141~146
The authors investigate the convergence speed problem of nonlinear adaptive equalization. Convergence constraints and time constant of radial basis function network using stochastic gradient (RBF-SG) algorithm is analyzed and a method of making time constant independent of hidden-node output power by using sample-by-sample node output power estimation is derived. The method for estimating the node power is to use a single-pole low-pass filter. It is shown by simulation that the proposed algorithm gives faster convergence and lower minimum MSE than the RBF-SG algorithm.
Target bit allocation algorithm for generation of high quality static test stream
Lee Gwang soon ; Han Chan ho ; Jang Soo wook ; Kim Eun su ; Sohng Kyu ik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 147~152
In this paper, we proposed a method for compressing the static video test patterns in high quality to test the picture quality in DTV. In our method, we use the fact that the generated bits and average quantization value have almost identical distribution characteristics per each GOP and we propose a new target bit allocation method suitable for compressing the static test pattern while the target bit allocation method in MPEG-2 TM5 is suitable for the moving picture. The proposed target bit allocation method is to maintain the high quality video continuously by using the normalized complexities which are updated or maintained by means of picture qualities at each GOP. Experiment result showed that the test pattern stream encoded by MPEG-2 software with the proposed algorithm had a stable bit rate and good video quality during the decoding process.
Blind MOE-PIC Multiuser Detector for Multicarrier DS-CDMA Systems
Woo Dae ho ; Lee Seung yong ; Byun Youn shik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 153~157
Frequency selective fading occurs due to the Doppler Effect in mobile communication systems. The performances of the systems are rapidly reduced due to effect of multiuser interference under frequency selective channels at DS-CDMA systems. To overcome these problems, we adopted the multi-carrier modulation techniques, and it is able to solve the frequency selective channel effects by means of these modulation techniques, and interference problems due to multiuser access are solved by means of multiuser detection techniques. In this paper, we proposed the blind MOE/PIC multiuser detection method which is composed of both the blind multiuser detection technique and parallel interference canceller. Thus, simulation results show that the proposed method performs better than conventional methods.
DCT Domain Post-Processing Based on POCS
Yim Chang hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 158~166
Even though post-processing methods based on projections onto convex sets (POCS) have shown good performance for blocking artifact reduction, it is infeasible to implement POCS for real-time practical applications. This paper proposes DCT domain post-processing method based on POCS. The proposed method shows very similar performance compared to the conventional POCS method, while it reduces tremendously the computational complexity. DCT domain POCS performs the lowpass filtering in the DCT domain, and it removes the inverse DCT and forward DCT modules. Through the investigation of lowpass filtering in the iterative POCS method, we define kth order lowpass filtering which is equivalent to the lowpass filtering in the kth iteration, and the corresponding kth order DCT domain POCS. Simulation results show that the kth order DCT domain POCS without iteration gives very similar performance compared to the conventional POCS with k iterations, while it requires much less computations. Hence the proposed DCT domain POCS method can be used efficiently in the practical post-processing applications with real-time constraints.
Privacy Control Using GRBAC In An Extended Role-Based Access Control Model
Park Chong hwa ; Kim Ji hong ; Kim Dong kyoo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 167~175
Privacy enforcement has been one of the most important problems in IT area. Privacy protection can be achieved by enforcing privacy policies within an organization's online and offline data processing systems. Traditional security models are more or less inappropriate for enforcing basic privacy requirements, such as purpose binding. This paper proposes a new approach in which a privacy control model is derived from integration of an existing security model. To this, we use an extended role-based access control model for existing security mechanism, in which this model provides context-based access control by combining RBAC and domain-type enforcement. For implementation of privacy control model we use GRBAC(Generalized Role-Based Access Control), which is expressive enough to deal with privacy preference. And small hospital model is considered for application of this model.
Design of a ECC arithmetic engine for Digital Transmission Contents Protection (DTCP)
Kim Eui seek ; Jeong Yong jin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 3C, 2005, Pages 176~184
In this paper, we implemented an Elliptic Curve Cryptography(ECC) processor for Digital Transmission Contents Protection (DTCP), which is a standard for protecting various digital contents in the network. Unlikely to other applications, DTCP uses ECC algorithm which is defined over GF(p), where p is a 160-bit prime integer. The core arithmetic operation of ECC is a scalar multiplication, and it involves large amount of very long integer modular multiplications and additions. In this paper, the modular multiplier was designed using the well-known Montgomery algorithm which was implemented with CSA(Carry-save Adder) and 4-level CLA(Carry-lookahead Adder). Our new ECC processor has been synthesized using Samsung 0.18 m CMOS standard cell library, and the maximum operation frequency was estimated 98 MHz, with the size about 65,000 gates. The resulting performance was 29.6 kbps, that is, it took 5.4 msec to process a 160-bit data frame. We assure that this performance is enough to be used for digital signature, encryption and decryption, and key exchanges in real time environments.