• Journal of the Institute of Convergence Signal Processing
• /
• v.13 no.4
• /
• pp.194-200
• /
• 2012

In this paper we analyze the code sequence generating algorism defined on $GF(2^n)$ proposed by S.Bostas and V.Kumar[7] and derive the implementation functions of code sequence generator using Boolean functions which can map the vector space $F_2^n$ of all binary vectors of length n, to the finite field with two elements $F_2$. We find the code sequence generating boolean functions based on two kinds of the primitive polynomials of degree, n=5 and n=7 from trace function. We then design and implement the code sequence generators using these functions, and produce two code sequence groups. The two groups have the period 31 and 127 and the magnitudes of out of phase(${\tau}{\neq}0$) autocorrelation and crosscorrelation functions {-9, -1, 7} and {-17, -1, 15}, satisfying the period $L=2^n-1$ and the correlation functions $R_{ij}({\tau})=\{-2^{(n+1)/2}-1,-1,2^{(n+l)/2}-1\}$ respectively. Through these results, we confirm that the code sequence generators using boolean functions are designed and implemented correctly.

• ETRI Journal
• /
• v.28 no.1
• /
• pp.95-98
• /
• 2006

In this letter, a novel M-ary code-selected direct sequence (DS) ultra-wideband (UWB) communication system is presented. Our purpose is to achieve a high data rate by an M-ary code-selected direct sequence bipolar pulse amplitude modulation (MCSDS-BPAM) scheme. In this system, a particular DS code sequence is selected by the $log_2M$/2 bits from the DS gold code set. This scheme can accomplish both a high data rate without increasing the system bandwidth or changing the pulse shape and improve the BER with an increase of modulation level M even at a lower signal-to-noise ratio (SNR). The receiver signal processing algorithm is given for an MCSDS-BPAM UWB system over an ideal AWGN channel and correlation receivers.

• Journal of Ginseng Research
• /
• v.41 no.3
• /
• pp.339-346
• /
• 2017

Background: In this study, we investigated how to convert the Panax ginseng DNA sequence code and chemical fingerprints into a two-dimensional code. In order to improve the compression efficiency, GATC2Bytes and digital merger compression algorithms are proposed. Methods: HPLC chemical fingerprint data of 10 groups of P. ginseng from Northeast China and the internal transcribed spacer 2 (ITS2) sequence code as the DNA sequence code were ready for conversion. In order to convert such data into a two-dimensional code, the following six steps were performed: First, the chemical fingerprint characteristic data sets were obtained through the inflection filtering algorithm. Second, precompression processing of such data sets is undertaken. Third, precompression processing was undertaken with the P. ginseng DNA (ITS2) sequence codes. Fourth, the precompressed chemical fingerprint data and the DNA (ITS2) sequence code were combined in accordance with the set data format. Such combined data can be compressed by Zlib, an open source data compression algorithm. Finally, the compressed data generated a two-dimensional code called a quick response code (QR code). Results: Through the abovementioned converting process, it can be found that the number of bytes needed for storing P. ginseng chemical fingerprints and its DNA (ITS2) sequence code can be greatly reduced. After GTCA2Bytes algorithm processing, the ITS2 compression rate reaches 75% and the chemical fingerprint compression rate exceeds 99.65% via filtration and digital merger compression algorithm processing. Therefore, the overall compression ratio even exceeds 99.36%. The capacity of the formed QR code is around 0.5k, which can easily and successfully be read and identified by any smartphone. Conclusion: P. ginseng chemical fingerprints and its DNA (ITS2) sequence code can form a QR code after data processing, and therefore the QR code can be a perfect carrier of the authenticity and quality of P. ginseng information. This study provides a theoretical basis for the development of a quality traceability system of traditional Chinese medicine based on a two-dimensional code.

• IEIE Transactions on Smart Processing and Computing
• /
• v.3 no.5
• /
• pp.319-324
• /
• 2014

Web applications make life more convenient. Many web applications have several kinds of user input (e.g. personal information, a user's comment of commercial goods, etc.) for the activities. On the other hand, there are a range of vulnerabilities in the input functions of Web applications. Malicious actions can be attempted using the free accessibility of many web applications. Attacks by the exploitation of these input vulnerabilities can be achieved by injecting malicious web code; it enables one to perform a variety of illegal actions, such as SQL Injection Attacks (SQLIAs) and Cross Site Scripting (XSS). These actions come down to theft, replacing personal information, or phishing. The existing solutions use a parser for the code, are limited to fixed and very small patterns, and are difficult to adapt to variations. A machine learning method can give leverage to cover a far broader range of malicious web code and is easy to adapt to variations and changes. Therefore, this paper suggests the adaptable classification of malicious web code by machine learning approaches for detecting the exploitation user inputs. The approach usually identifies the "looks-like malicious" code for real malicious code. More detailed classification using sequence information is also introduced. The precision for the "looks-like malicious code" is 99% and for the precise classification with sequence is 90%.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.12 no.2
• /
• pp.1-10
• /
• 1975

This paper presents an adaptive data compression algorithm for video data. The coling complexity due to the high correlation in the given data sequence is alleviated by coding the difference data, sequence rather than the data sequence itself. The adaptation to the nonstationary statistics of the data is confined within a code set, which consists of two constant length cades and six modified Shannon.Fano codes. lt is assumed that the probability distributions of tile difference data sequence and of the data entropy are Laplacian and Gaussion, respectively. The adaptive coding performance is compared for two code selection criteria: entropy and $P_r$[difference value=0]=$P_0$. It is shown that data compression ratio 2 : 1 is achievable with the adaptive coding. The gain by the adaptive coding over the fixed coding is shown to be about 10% in compression ratio and 15% in code efficiency. In addition, $P_0$ is found to he not only a convenient criterion for code selection, but also such efficient a parameter as to perform almost like entropy.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.14 no.2
• /
• pp.137-145
• /
• 1989

In this paper we consider the design of bent sequence generators employing a modified bent function. Through the experimental results and simulation, we show that the period of sequences is $2^n$-1, the number of sequences in the set is $2n/2$, the largest magnitude of correlation is $2n/2$+1, and the sequence generators easy to randomly initialize into any assigned code and hence can be rapidly hopped from sequence to sequence. And we construct a code synchronization system with bent sequence generator as the local code generator, a sliding correlator and DLL as the acquisition subsystem and the tracking subsystem, respectively for DS-CODA, and verify the experimenta results for accomplishing code synchronism.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
• /
• v.8 no.3
• /
• pp.107-110
• /
• 2009

In this paper, a PN code tracking loop with extended Kalman filter (EKF) is proposed for a direct-sequence spread-spectrum. EKF is used to estimate amplitude and delay in a multipath. fading channel. It is shown that tracking error performance is significantly improved by EKF compared with a conventional tracking loop.

• Journal of IKEEE
• /
• v.16 no.1
• /
• pp.51-55
• /
• 2012

In this paper, we propose to employ a ternary sequence as a cyclic code shift keying (CCSK) modulation sequence. And we simulate the performance in a frequency hopping spread spectrum/time division multiple access (FHSS/TDMA) system with CCSK. Wireless channel is modeled as Rayleigh fading channel. From the simulation results, it is demonstrated that the system adopting the ternary sequence as a CCSK sequence has higher performance than that with a random sequence.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.12
• /
• pp.1910-1917
• /
• 1989

This paper shows the performances of asynchronous binary direct-sequence spread-spectrum multiple access communication systems with Rayleigh fading and White Gaussian noise. The performance measures considered are worst-case bit error probability and average SNR depending on code sequences and chip waveforms. The code sequences used are m-sequence and Gold sequence with period 31.The chip waveforms employed are rectangular, sinusoidal and something other chip waveforms.

• Journal of the Institute of Convergence Signal Processing
• /
• v.15 no.2
• /
• pp.48-54
• /
• 2014

For the element ${\alpha}{\in}GF(p^n)$, two kinds of bases are known. One is a conventional polynomial basis of the form $\{1,{\alpha},{\alpha}^2,{\cdots},{\alpha}^{n-1}\}$, and the other is a normal basis of the form $\{{\alpha},{\alpha}^p,{\alpha}^{p^2},{\cdots},{\alpha}^{p^{n-1}}\}$. In this paper we consider the method of generating normal bases which construct the finite field $GF(p^n)$, as an n-dimensional extension of the finite field GF(p). And we analyze the code sequence generating algorithm and derive the implementation functions of code sequence generator based on the normal bases. We find the normal polynomials of degrees, n=5 and n=7, which can generate normal bases respectively, design, and construct the code sequence generators based on these normal bases. Finally, we produce two code sequence groups(n=5, n=7) by using Simulink, and analyze the characteristics of the autocorrelation function, $R_{i,i}(\tau)$, and crosscorrelation function, $R_{i,j}(\tau)$, $i{\neq}j$ between two different code sequences. Based on these results, we confirm that the analysis of generating algorithms and the design and implementation of the code sequence generators based on normal bases are correct.