• Journal of Communications and Networks
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• 제12권6호
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• pp.577-581
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• 2010

We introduce a novel packet retransmission technique which improves the efficiency of automatic retransmission query (ARQ) protocols in the context of satellite broadcast/multicast systems. The proposed coded ARQ technique, similarly to fountain coding, performs transmission of redundant packets, which are made by linear combinations of the packets composing the source block. Differently from fountain codes, the packets for the linear combinations are selected on the basis of the retransmission requests coming from the user terminals. The selection is performed in a way that, at the terminals, the source packets can be recovered iteratively by means of simple back-substitutions. This work aims at providing a simple and efficient alternative to reliable multicast protocols based on erasure correction coding techniques.

• Journal of applied mathematics & informatics
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• 제8권3호
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• pp.773-793
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• 2001

The explicit expressions for the 2n+1 primitive idempotents in R/sub pⁿ/ = F[x]/< x/sup pⁿ/ -1>, where F is the field of prime power order q and the multiplicative order of q modulo pⁿ is ø(pⁿ)/2(n≥1 and p is an odd prime), are obtained. An algorithm for computing the generating polynomials of the minimal QR cyclic codes of length pⁿ, generated by these primitive idempotents, is given and hence some bounds on the minimum distance of some QR codes of prime length over GF(q)(q=2, 3, ...) are obtained.

• 대한전자공학회논문지
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• 제27권2호
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• pp.9-15
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• 1990

本 論文에서는 線刑 2元 블럭 符號에 대한 軟判定 復號 알고리듬을 제안하였다. 이 알고리듬은 블록 誤謬 確率을 最小化하기 위한 것이다. 提案된 알고리듬을 기存의 다른 復號法과 비교하기 위하여(7,4) Hamming 符號와(23,12)Golay 符號에 대한 컴퓨터 시뮬레이션을 수행하였다. 그 결과, 提案된 알고리듬의 乎均 硬判定 復號 回數는 항상 2以下이며 信號對 雜音比가 충분히 클때 1에 접근하였다. 즉, 기存 다른 復號法에 비하여 復號의 複雜度가 減少되었음을 확인하였다.

• 충청수학회지
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• 제26권1호
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• pp.147-159
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• 2013

Hamada ([8]) and Maruta ([17]) proved the minimum length $n_3(6,\;d)=g_3(6,\;d)+1$ for some ternary codes. In this paper we consider such minimum length problem for $q{\geq}4$, and we prove that $n_q(6,\;d)=g_q(6,\;d)+1$ for $d=q^5-q^3-q^2-2q+e$, $1{\leq}e{\leq}q$. Combining this result with Theorem A in [4], we have $n_q(6,\;d)=g-q(6,\;d)+1$ for $q^5-q^3-q^2-2q+1{\leq}d{\leq}q^5-q^3-q^2$ with $q{\geq}4$. Note that $n_q(6,\;d)=g_q(6,\;d)$ for $q^5-q^3-q^2+1{\leq}d{\leq}q^5$ by Theorem 1.2.

• Journal of Communications and Networks
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• 제15권4호
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• pp.411-421
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• 2013

Digital fountain codes are record-breaking codes for erasure channels. They have many potential applications in both wired and wireless communications. Most existing digital fountain codes operate over binary fields using an iterative belief-propagation (BP) decoding algorithm. In this paper, we propose a new iterative decoding algorithm for both binary and nonbinary fields. The basic form of our proposed algorithm considers both degree-1 and degree-2 check nodes (instead of only degree-1 check nodes as in the original BP decoding scheme), and has linear complexity. Extensive simulation demonstrates that it outperforms the original BP decoding scheme, especially for a small number of source packets. The enhanced form of the proposed algorithm combines the basic form of the algorithm and a guess-based algorithm to further improve the decoding performance. Simulation results demonstrate that it can provide better decoding performance than the guess-based algorithm with fewer guesses, and can achieve decoding performance close to that of the maximum likelihood decoder at a much lower decoding complexity. Last, we show that our nonbinary scheme has the potential to outperform the binary scheme when choosing suitable degree distributions, and furthermore it is insensitive to the size of the Galois field.

• East Asian mathematical journal
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• 제12권2호
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• pp.155-162
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• 1996

• East Asian mathematical journal
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• 제12권2호
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• pp.147-153
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• 1996

• Earthquakes and Structures
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• 제16권3호
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• pp.295-310
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• 2019

This study attempts to develop new simplified approximate formulas to predict the fundamental natural periods of vibration (T) for bearing wall systems engaged with special reinforced concrete shear walls (RCSW) under seismic loads. Commonly, seismic codes suggested empirical formulas established by regression analysis of measured T for buildings during earthquake motions. These formulas depend on structure type, building height, number, height and length of SW, and ratio of SW area to base area of structure. In this study, a parametric investigation is performed for T of 110 selected models of bearing RCSW systems with varying structural height, configuration of horizontal plans including building width, number and width of bays, presence of middle corridors and core SWs. For this purpose, a 3D non-linear response time history (TH) analysis is implemented using ETABS v16.2.1. New formulas to estimate T are anticipated and compared with those obtained from formulas of IBC 2012 and ASCE/SEI 7-10. Moreover, the study examines responses of an arbitrarily two selected test model of 60 m and 80 m in height with presence of SWs having middle corridors. It is observed that the performance of the tested buildings is different through arising of considerable errors when using codes' formulas for estimating T. Accordingly, using the present proposed formulas exhibits more reasonable and safer design compared to codes' formulas. The results showed that equitable enhancement is promising to improve T formulas approaching enhanced and accurate estimation of T with reliable analysis, design, and evaluation of bearing RCSW systems.

• 정보처리학회논문지C
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• 제10C권1호
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• pp.27-32
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• 2003

본 논문에서는 선형 블록 부호에 대한 효율적인 연판정 복호법을 제안하였다. 제안된 연판정 복호법은 연판정 복호 과정을 반복하여 실현하는 방식이다. 경판정 복호 결과로부터 후보 부호버들을 효율적으로 탐색할 수 있는 방법을 개발하였다. 이 과정에서 후보 부호어가 선출되지 않는 경우의 발생을 억제할 수 있는 새로운 복호법을 제안하였다. 또한, 복잡도를 줄이는 방안도 개발하여 알고리듬 개선으로 인한 복잡도 증가가 거의 나타나지 않도록 하였다. 2진(63, 36) BCH 부호에 대한 시뮬레이션 결과로 이러한 사실들을 확인할 수 있었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.370-373
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• 2011

The subcommittee 3 (SC3) of Technical Committee 108 (TC 108) covers the calibration of mechanical vibration and shock measuring pickups and instruments. This paper introduces what KS codes are linked to the ISO standards developed by TC108 / SC3. It is shown that the KS codes do not fulfill the full set of ISO codes approved in the field of TC 108/SC3. Series of ISO standards established by the Working Group 6 (WG6) of SC3 are introduced. Main objectives of those WG 6 efforts are shown to replace the old versions of ISO 5347 series into new ISO 16063 series. Their features are briefly summarized in this paper. Finally, challenging technical issues underlying behind ISO TC108 / SC3 are addressed,, such as MEMS typed linear and angular vibration pickups.