• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.1-9
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• 2009

In this paper, we propose the efficient processing technique for unavailable data in hardware implementation of motion estimator in H.264/AVC with parallel processing architecture. Motion estimation processing in the hardware is generally based on pipe-lining, some MV data of neighbor blocks are not available, whereas all MV data are valid in software processing where the data are sequentially processed. In this paper, we solve the problem of data being unavailable in MVp computation. To minimize the quality degradation caused by unavailable MVs, in the proposed method, the unavailable MV of a neighboring block is replaced with an integer pel unit MV, an MVp of neighboring blocks, or an MVcol (MV of co-located block). Comparing to the conventional method [7], our method outperformed maximally 0.832dB and 0.179dB for QCIF and CIF, respectively, in terms of BDPSNR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1707-1714
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• 2015

The neural bases underlying within or between-language picture naming was investigated by using event-related fMRI. The present suudy explorered the following two goals: The first is to compare cortical activation areas relevant to naming process in native and foreign language, and to decide whether the activation pattern of the foreign word will be the same as native words or not. The next is to find the cerebral areas involved only in alternating language switching between native and foreign language condition. Differential activation patterns were observed for language switching against one-language. Both naming tasks all activated the left inferior frontal gyrus (LIFG) as expected. However the differences in naming between languages were reflected in the activation amount of the LIFG, namely more activation in naming the native language than the foreign language. Especially, naming of the foreign word from English showed the similar area and size in activation with native language suggesting that the process of borrowed noun resembles that of native common noun. And the language switching between languages newly activated the right middle frontal gyrus as well as the left inferior frontal areas. The right middle frontal gyrus engagement in switching conditions obviously identified that right hemisphere is recruited in code switching possibly with respect to meta-cognition controlling language index at a subconscious level.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.754-757
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• 2007

In this paper, we present an implementation and it's real-sea test of an underwater acoustic data communication system, which allows the system to reduce complexity and increase robustness in time variant underwater environments. For easy adaptation to complicated and time-varying environments of the ocean, all-digital transmitter and receiver systems were implemented. For frame synchronization the CAZAC sequence was used, and QPSK modulation/ demodulation method with carrier frequency of 25kHz and a bandwidth of 5kHz were applied to generate 10kbps transmission rate including overhead. To improve transmission quality, we used several techniques and algorithms such as adaptive beamforming, adaptive equalizer, and convolution coding/Viterbi decoding. for the verification of the system performance, measurement of BER has been done in a very shallow water with depth of 8m at JangMok, Geoje. During the experiment, image data were successfully transmitted up to about 7.4km.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3C
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• pp.256-262
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• 2002

This paper presents a novel radix-4 modular multiplication algorithm based on the sign estimation technique (3). The sign estimation technique detects the sign of a number represented in the form of a carry-sum pair. It can be implemented with 5-bit carry look-ahead adder. The hardware speed of the cryptosystem is dependent on the performance modular multiplication of large numbers. Our algorithm requires only (n/2+3) clock cycle for n bit modulus in performing modular multiplication. Our algorithm out-performs existing algorithm in terms of required clock cycles by a half, It is efficient for modular exponentiation with large modulus used in RSA cryptosystem. Also, we use high-speed adder (7) instead of CPA (Carry Propagation Adder) for modular multiplication hardware performance in fecal stage of CSA (Carry Save Adder) output. We apply RL (Right-and-Left) binary method for modular exponentiation because the number of clock cycles required to complete the modular exponentiation takes n cycles. Thus, One 1024-bit RSA operation can be done after n(n/2+3) clock cycles.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.2
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• pp.1-13
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• 1999

As the complexity of DSP (Digital Signal Processing) applications increases, the need for new architectures supporting efficient high-level language compilers also grows. By combining several DSP processor specific features, such as single cycle MAC (Multiply-and-ACcumulate), direct memory access, automatic address generation, and hardware looping, with a RISC core having many general purpose registers and orthogonal instructions, a high-performance and compiler-friendly RISC-based DSP processors can be designed. In this study, we develop a code-converter that can exploit these DSP architectural features by post-processing compiler-generated assembly code, and evaluate the performance effects of each feature using seven DSP-kernel benchmarks and a QCELP vocoder program. Finally, we also compare the performances with several existing DSP processors, such as TMS320C3x, TMS320C54x, and TMS320C5x.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.17-23
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• 2015

In this paper, we propose an efficient joint demodulation and decoding scheme for FTN (Faster than Nyquist) systems. Several previous works have demonstrated that ISI (Inter Symbol Interference) cancellation schemes based on BCJR (Bahl-Cocke-Jelinek-Raviv) algorithm are suitable for FTN systems. Unfortunately, required complexity of the previous ISI cancellation schemes is very high, especially when a multi-level modulation scheme is employed. In this paper, we propose a joint demodulation and decoding scheme for FTN systems with an iteratively decodable channel coding scheme and a multi-level modulation. Compared with the previously proposed schemes, the proposed scheme not only offers reliable performance but also requires relatively low complexity. Also, the proposed scheme can be easily applied to the FTN system with a multi-level modulation with a minor modification.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.4
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• pp.22-32
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• 2001

In this paper, we propose an average acquisition time and hardware design of high speed PN code synchronous acquisition system using DMF(Digital Matched Filter) with new switching method in DS-SS/CDMA(Direct Sequence Spread Spectrum Code Division Multiple Access). In reality, the PN code synchronous acquisition system using DMF has very complicated hardware, high cost and high power consumption. The PN code synchronous acquisition system using proposed switching method DMF can overcome those disadvantages. Therefore, we can make hardware simple and obtain low power and high density by reducing the area by 1/5 against the conventional approaches of using either the matched filters or the serial correlators. The proposed system architecture is also simple and easily controllable since there is no square-term circuit after execution of digital filtering.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.111-116
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• 2018

This paper compare the adaptive equalization performance of RMMA (Region-based MMA) and SCA (Square Contour Algorithm) in order to minimize the intersymbol interference that is occurred in communication channel when transmit the multilevel QAM signal. The RMMA used for improving the performance by translate to 4-level constant modulus and stability in current MMA algorithm, and the SCA used for the improving the performacne by combines the current CMA and RCA algorithm. These algorithms are aimed to improving the equalization peformance by applying the differenct principle each other in multilevel QAM signal, its different performance were compared by computer simulation in the same channel environment. For this, the output signal constellation of equalizer, residual isi, maximum distortion were applied in performance index. As a result, RMMA have more fairly good in every performance index such as signal point clustering capabilities and convergence speed compared to SCA. It is confired that the equalization noise due to misadjumstment was reduced in RMMA than SCA.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.93-99
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• 2014

This paper deals with the FC-MMA (Fast Convergence-Multi Modulus Algorithm) which is improving the convergence characteristics of the MMA (Multiple Modulus Algorithm) adaptive equalization algorithm that is used for the minimization of the intersymbol interference which occurs in the time dispersive communication channel. In the time varying charateristics and the abnormal situation like as outage of the communication channel, the adaptive equalizer needs to adapting the new environment more rapidly. For this problem, the residual isi and the maximum distortion performance index which are meaning the convergence characteristics are widely adapted in the adaptive equalizer. The 16-QAM signal is transmitted and it was confirmed that the proposed algorithm, the FC-MMA has the fast convergence performance such as in the 1.75 times fast in residual isi and 2.5 times fast in the maximum distortion in order to reaching the steady state compare to the MMA algorithm in the same channel environment by the computer simulation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.85-91
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• 2014

This paper relates with the VSDA (Variable stepsize Square contour Decision directed Algorithm) adaptive equalization algorithm that is used for the minimization of the intersymbol interference due to the distortion which occurs in the time dispersive channel for the transmission of 16-QAM signal.. In the conventional SCA, it is possible to compensates the amplitude and phase in the received signal that are mixed with the intersymbol interference by the constellatin dependent constant by using the 2nd order statistics of the transmitted signal. But in the VSDA, it is possible to the increasing the equalization performance by adding the concept of distance adjusted approach for constellation matching and the cost function of decision directed. We compare the performance of VSDA and SCA algorithm by the computer simulation. For this, the equalizer output signal constellation, residual isi, maximum distortion and MSE were used in the performace index. As a result of computer simulation, the VSDA algorithm has better than the SCA in convergence speed, but it gives nearly same equalization performance in other index.