• ETRI Journal
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• 제31권5호
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• pp.518-524
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• 2009

Single parity check (SPC) product codes are simple yet powerful codes that are used to correct errors and/or recover erasures. The focus of this paper is to evaluate the performance of such codes under erasure scenarios and to develop a closed-form tight upper bound for the post-decoding erasure rate. Closed-form exact expressions are derived for up to seven erasures. Previously published closed-form bounds assumed that all unrecoverable patterns should contain four erasures in a square. Additional non-square patterns are accounted for in the proposed expressions. The derived expressions are verified using exhaustive search. Eight or more erasures are accounted for by using a bound. The developed expressions improve the evaluation of the recoverability of SPC product codes without the need for simulation or search algorithms, whether exhaustive or novel.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.5-8
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• 2000

In this paper, we present a new cぉnet coding method, so called MLC (Multi-Level Codes), for error detection and correction in digital wireless communication. MLC coding method we the same coding procedure wed in the convolutional coding but it is distinguished from the existing convolutional coding in point of generating the code word by using multi-level information data (M-ary signal) and in point of speed of coding procedure Through computer simulation, we analyze the performance of the coding method suggested here compared to convolutional coding method in case of modulo-operation and in case of non-binary coding Procedure respectively under various channel environments.

• 대한수학회보
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• 제60권2호
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• pp.443-460
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• 2023

A binary linear code is said to be a ℤ₂-double cyclic code if its coordinates can be partitioned into two subsets such that any simultaneous cyclic shift of the coordinates of the subsets leaves the code invariant. These codes were introduced in [6]. A ℤ₂-double cyclic code is called reversible if reversing the order of the coordinates of the two subsets leaves the code invariant. In this note, we give necessary and sufficient conditions for a ℤ₂-double cyclic code to be reversible. We also give a relation between reversible ℤ₂-double cyclic code and LCD ℤ₂-double cyclic code for the separable case and we present a few examples to show that such a relation doesn't hold in the non-separable case. Furthermore, we list examples of reversible ℤ₂-double cyclic codes of length ≤ 10.

• Journal of Communications and Networks
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• 제18권1호
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• pp.40-49
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• 2016

In this paper, we present a symbol-level iterative source-channel decoding (ISCD) algorithm for reliable transmission of variable-length codes (VLCs). Firstly, an improved source a posteriori probability (APP) decoding approach is proposed for packetized variable-length encoded Markov sources. Also proposed is a recursive implementation based on a three-dimensional joint trellis for symbol decoding of binary convolutional codes. APP channel decoding on this joint trellis is realized by modification of the Bahl-Cocke-Jelinek-Raviv algorithm and adaptation to the non-stationary VLC trellis. Simulation results indicate that the proposed ISCD scheme allows to exchange between its constituent decoders the symbol-level extrinsic information and achieves high robustness against channel noises.

• Journal of Communications and Networks
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• 제17권4호
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• pp.339-345
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• 2015

In this paper, we present an iterative reliability-based modified majority-logic decoding algorithm for two classes of structured low-density parity-check codes. Different from the conventional modified one-step majority-logic decoding algorithms, we design a turbo-like iterative strategy to recover the performance degradation caused by the simply flipping operation. The main computational loads of the presented algorithm include only binary logic and integer operations, resulting in low decoding complexity. Furthermore, by introducing the iterative set, a very small proportion (less than 6%) of variable nodes are involved in the reliability updating process, which can further reduce the computational complexity. Simulation results show that, combined with the factor correction technique and a well-designed non-uniform quantization scheme, the presented algorithm can achieve a significant performance improvement and a fast decoding speed, even with very small quantization levels (3-4 bits resolution). The presented algorithm provides a candidate for trade-offs between performance and complexity.

• 전자공학회논문지
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• 제53권4호
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• pp.48-58
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• 2016

본 논문은 GF(64) (160,80) 정규 (2,4) 비이진 LDPC 코드 복호기를 위한 높은 처리량의 병렬 아키텍처를 제안한다. 복호기의 복잡도를 낮추기 위해 체크 노드와 변수 노드의 차수가 작은 코드를 사용하며 뛰어난 에러 정정 성능을 위해 높은 위수의 유한체에서 정의된 코드를 사용한다. 본 논문은 Fully-parallel 아키텍처를 설계하고 체크 노드와 변수 노드를 interleaving하여 복호기의 데이터 처리량을 향상시켰다. 또한 체크 노드의 초기화 지연을 단축시킬 수 있는 조기 분류 기법을 제안하여 데이터 처리량을 추가로 향상시켰다. 제안된 복호기는 1 iteration에 37사이클이 소요되며 625MHz 동작주파수에서 1402Mbps의 데이터 처리량을 갖는다.

• 대한수학회지
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• 제58권1호
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• pp.29-44
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• 2021

The set D of column vectors of a generator matrix of a linear code is called a defining set of the linear code. In this paper we consider the problem of constructing few-weight (mainly two- or three-weight) linear codes from defining sets. It can be easily seen that we obtain an one-weight code when we take a defining set to be the nonzero codewords of a linear code. Therefore we have to choose a defining set from a non-linear code to obtain two- or three-weight codes, and we face the problem that the constructed code contains many weights. To overcome this difficulty, we employ the linear codes of the following form: Let D be a subset of ��2n, and W (resp. V ) be a subspace of ��2 (resp. ��2n). We define the linear code ��D(W; V ) with defining set D and restricted to W, V by $${\mathcal{C}}_D(W;V )=\{(s+u{\cdot}x)_{x{\in}D^{\ast}}|s{\in}W,u{\in}V\}$$. We obtain two- or three-weight codes by taking D to be a Vasil'ev code of length n = 2m - 1(m ≥ 3) and a suitable choices of W. We do the same job for D being the complement of a Vasil'ev code. The constructed few-weight codes share some nice properties. Some of them are optimal in the sense that they attain either the Griesmer bound or the Grey-Rankin bound. Most of them are minimal codes which, in turn, have an application in secret sharing schemes. Finally we obtain an infinite family of minimal codes for which the sufficient condition of Ashikhmin and Barg does not hold.

• 전자공학회논문지B
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• 제33B권10호
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• pp.63-71
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• 1996

This paper proposes a method which analyzes facial shape and extracts positions of eyes regardless of the tilt and the size of input iamge. With the extracted feature parameters of facial element by the method, full human faces are recognized by a neural network which BP algorithm is applied on. Input image is changed into binary codes, and then labelled. Area, circumference, and circular degree of the labelled binary image are obtained by using chain code and defined as feature parameters of face image. We first extract two eyes from the similarity and distance of feature parameter of each facial element, and then input face image is corrected by standardizing on two extracted eyes. After a mask is genrated line historgram is applied to finding the feature points of facial elements. Distances and angles between the feature points are used as parameters to recognize full face. To show the validity learning algorithm. We confirmed that the proposed algorithm shows 100% recognition rate on both learned and non-learned data for 20 persons.

• 융합보안논문지
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• 제15권7호
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• pp.75-84
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• 2015

윈도우즈 NTFS 파일시스템에서 인덱스 레코드에 데이터를 숨기기 위한 기법은 파일명을 이용하여 메시지를 숨기는 방법이다. 윈도우즈 NTFS의 파일명 규칙에서 일부 ASCII 문자는 파일명으로 사용할 수 없는 문제가 있다. 영문과 함께 한글, 기호 문자가 함께 입력이 될 때와 바이너리 형태의 데이터들이 입력될 때 인덱스 레코드에 데이터 숨기기 방법 수행 시에 파일생성 에러 문제가 발생하는 것을 해결하기 위한 방법으로 유니코드의 특정 영역으로 변환하는 방법을 제안한다. 에러가 발생하는 문자들을 한글과 영문 영역이 아닌 유니코드로 변환하고. 바이너리 형태의 데이터인 경우는 확장 유니코드 영역과 아스키 코드의 영역이 아닌 유니코드의 영역으로 256개의 코드 전체를 변환하는 방식을 적용한다. 영문과 함께 한글이 사용된 경우에 제안한 방식이 적용된 사례의 결과를 보이고. 바이너리의 경우는 PNG이미지 파일의 바이너리 코드를 유니코드로 변환한 사례를 통해서 제안한 방법이 타당함을 보인다.

• 한국병원경영학회지
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• 제26권4호
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• pp.29-37
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• 2021

Purpose: The purpose of this study is to identify the characteristics and factors affecting falls among elderly inpatients with chronic diseases based on the data from the discharge damage depth survey of the Korea Disease Control and Prevention Agency(KDCA) from 2014 to 2018. Method: The study selected elderly inpatients aged over 65 who were hospitalized(n=1,173). Their data were analyzed after being assigned to either a fall group(KSCD, W00-W19) or a non-fall group. Frequency analysis, cross-tabulation analysis, and binary logistic regression analysis were conducted, using SPSS 28. Results: According to the analysis on category of fall and non-fall group were statistically significant difference in age and having chronic diseases. Based on the binary logistic regression analysis of factors affecting falls, The risk of falls was 1.058 times higher with age, and E11-E14 and I63 as main diagnostic codes, the risk of falls was 2.049 times and 2.437 times higher. Conclusion: It is necessary to develop customized educational manuals and muscle exercise programs considering the characteristics of chronic diseases and to create a safe hospital room environment, and this result is expected to be used as basic data for fall prevention education and manual development for elderly inpatients with chronic diseases.