Earticle

PDF417은 2차원 바코드로서 사용범위가 넓고 방대한량을 압축하여 저장하는 능력을 가지고 있다. 이러한 특성을 가진 PDF417은 현재 중요한 문서의 위조나 변조를 막기 위한 다양한 용도로 쓰이고 있다. 한편 기존의 PDF417 바코드의 디코딩 기술은 단순히 기본 표준규격서인 AIM에서 제시한 디코딩하므로 비효율적이라 할 수 있다. 따라서 본 논문에서는 PDF417 바코드를 보다 빠르고 효율적인 디코딩 알고리즘을 제시하고자 한다. 결과적으로 제안하는 디코딩 알고리즘은 기존 방법과 비교하여 불필요한 디코딩 과정을 제거함으로서 빠르고 효율적인 디코딩 알고리즘이 될 것이다.

Two-dimensional PDF417 bar code has a wide range of use and has a storage capacity to compress a large amount of data. With these characteristics, PDF417 has been used in various ways to prevent the forgery and alteration of important information in documents. On the other hand, previous decoding methods in PDF417 barcode are slow and inefficient because they simply employ the standard specifications of AIM (Association for Automatic Identification and Mobility). Therefore, this paper propose an efficient and fast algorithm of decoding PDF417 bar code. As a result, the proposed decoding algorithm will be more faster and efficient than previous methods.

In quantum communication systems, quantum error-correcting codes (QECCs) are known to exhibit improved performance with the use of error-free entanglement bits (ebits). In practical situations, ebits inevitably suffer from errors, and as a result, the error-correcting capability of the code is diminished. Previous studies have proposed two different schemes as a solution. One study uses only one QECC to correct errors on the receiver side (i.e., Bob) and sender side (i.e., Alice). The other uses different QECCs on each side. In this paper, we present a method to correct errors on both sides by using single nonadditive entanglement-assisted codeword stabilized quantum error-correcting code (EACWS QECC). We use the property that the number of effective error patterns decreases as much as the number of ebits. This property results in a greater number of logical codewords using the same number of physical qubits.

2차원 QR Code는 1차원 바코드의 용량, 크기, 방향에 대한 한계를 개선하였으며, 방대한량의 데이터를 압축하여 저장할 수 있는 능력을 갖추고 많은 응용분야에서 사용되고 있다. 최근에는 QR Code를 인식할 수 있는 스마트 폰의 도입과 사용의 증대로 QR Code의 도입이 급속도로 확산되었다. 하지만 다양한 정보를 저장할 수 있는 QR Code의 디코딩 기술에 대한 구체적인 문서화가 없는 상태이다. 따라서 본 논문에서는 QR code의 인코딩에 따른 디코딩 과정에 대해 구체적인 처리 절차와 알고리즘을 제시하고 예를 통해 디코딩 과정을 상세히 이해시키는 데 연구목적이 있다.

Two-dimensional QR Code has improved greatly the limits on the capacity, size, direction of the one-dimensional bar code. And it has the capacity of compressing and storing the massive amount of data and is widely used in many applications. Recently, the two-dimensional QR Code has been spread rapidly because of introducing the smart phones and increasing the amount of using them. However, there is little documentations about decoding the QR Code in which can store the large amount of information. In this paper, therefore, we present specific processing procedures and algorithms on decoding the two-dimensional QR Code and then make us understand their decoding process by explaining some examples.

본 논문에서는 공간-시간 블록 부호디자인(Space-Time Block Code) 관점에서 직교-디자인(Orthogonal-design) 즉, 최소거리가 5이면서 완전-계수(Full-Rank)인 디자인을 비교대상으로 완전-계수(Full-Rank)가 아니면서 최소거리가 5와7인 두 부호에 관하여 연구되어졌다.

In this paper we present a barcode reader to decode two-dimensional symbology PDF-417 and propose a novel method to extract the bar-space patterns directly from the gray-level barcode image, which employs the location and the distance between extreme points of each row of the barcode image. This algorithm proves to be very robust from the high convolution distortion environments such as defocussing and warping, even under badly illuminating condition. If the scanned barcode image is a result of the convolution of a Gaussian-shaped point spread function with a bi-level image, popular image segmentation methods such as image thresholding can not distinguish between very narrow bar-space patterns with a couple of pixels wide. The proposed algorithm shows improved performance over current barcode readers.

This paper proposes a novel reversible data hiding scheme based on a Vector Quantization (VQ) codebook. The proposed scheme uses the principle component analysis (PCA) algorithm to sort the codebook and to find two similar codewords of an image block. According to the secret to be embedded and the difference between those two similar codewords, the original image block is transformed into a difference number table. Finally, this table is compressed by entropy coding and sent to the receiver. The experimental results demonstrate that the proposed scheme can achieve greater hiding capacity, about five bits per index, with an acceptable bit rate. At the receiver end, after the compressed code has been decoded, the image can be recovered to a VQ compressed image.

Several code-division multiple access (CDMA)-based interconnect schemes have been recently proposed as alternatives to the conventional time-division multiplexing bus in multicore systems-on-chip. CDMA systems with a dynamic assignment of spreading codewords are particularly attractive because of their potential for higher bandwidth efficiency compared with the systems in which the codewords are statically assigned to processing elements. In this paper, we propose a novel distributed arbitration scheme for dynamic CDMA-bus-based systems, which solves the complexity and scalability issues associated with commonly used centralized arbitration schemes. The proposed arbitration unit is decomposed into multiple simple arbitration elements, which are connected in a ring. The arbitration ring implements a token-passing algorithm, which both resolves destination conflicts and assigns the codewords to processing elements. Simulation results show that the throughput reduction in an optimally configured dynamic CDMA bus due to arbitration-related overheads does not exceed 5%.

We find the generalized Hamming weights of cyclic linear q-ary codes which are generated by a codeword of weight 2, and of any length.

This paper presents a new method for Huffman decoding specially designed for the MPEG-2 AAC audio. The method significantly enhances the processing efficiency of the conventional Huffman decoding realized with the ordinary binary tree search method. A data structure is newly designed based on the numerical interpretation of the incoming bit stream and its utilization for the offset oriented nodes allocation. The experimental results show the average performance enhancement of 54% and 665%, compared to those of the conventional binary tree search method and the sequential search method, respectively.

Vector quantization (VQ) is widely used in many high-quality and high-rate data compression applications such as speech coding, audio coding, image coding and video coding. When the size of a VQ codebook is large, the computational complexity for the full codeword search method is a significant problem for many applications. A number of complexity reduction algorithms have been proposed and investigated using such properties of the codebook as the triangle inequality. This paper proposes a new structured VQ search algorithm that is based on a multi-stage structure for searching for the best codeword. Even using only two stages, a significant complexity reduction can be obtained without any loss of quality.

In tis paper, sthe new data model for the hardware implementation of lempel-ziv compression algorithm was proposed. Traditional model generates the codeword which consists of 3 bytes, the last symbol, the position and the matched length. MSB (most significant bit) of the last symbol is the comparession flag and the remaining seven bits represent the character. We confined the value of the matched length to 128 instead of 256, which can be coded with seven bits only. In the proposed model, the codeword consists of 2 bytes, the merged symbol and the position. MSB of the merged symbol is the comression flag. The remaining seven bits represent the character or the matched length according to the value of the compression flag. The proposed model reduces the compression ratio by 5% compared with the traditional model. The proposed model can be adopted to the existing hardware architectures. The incremental factors of the compression ratio are also analyzed in this paper.

본 논문에서는 DC 억압능력이 없거나 부족한 코드에 만족할 만한 DC 억압능력을 갖도록 하기 위한 멀티모드코드 방식을 제안한다. 제안한 멀티모드코드는 데이터열의 다중화를 위해 Pseudo Scrambling Technique를 사용하며, 다중화 된 데이터열의 변조를 위해 DC-free RLL(d, k) Code를 사용하는 특징을 가진다. 제안한 방법에서는 Sync 코드워드의 패리티를 다중화 정보로 사용하여 입력데이터를 2개의 데이터 열로 다중화하고, 2개로 다중화 된 데이터 열에 대해 DC-free RLL(d, k) Code를 사용하여 코드워드로 변환하며, 코드워드로 변환된 2 개의 코드워드 열에 대해 DC 성분이 적은 코드워드 열 하나를 선택하여 변조 스트림으로 출력한다. 본 논문에서는 Sync 코드워드의 패리티를 다중화 정보로 사용하여 별도의 Redundancy를 부가하지 않고 DC 억압성능을 향상시킬 수 있었다.