Earticle

Genetic algorithm (GA), which has a powerful searching ability and is comparatively easy to use and also to apply, is in the spotlight in the field of the optimization for mechanical systems these days. However, it also contains some problems of slow convergence and low efficiency caused by a huge amount of repetitive computation. To improve the processing efficiency of repetitive computation, some papers have proposed paralleled GA these days. There are some cases that mention the use of gray code or suggest using gray code partially in GA to raise its slow convergence. Gray code is an encoding of numbers so that adjacent numbers have a single digit differing by 1. A binary gray code with n digits corresponds to a hamiltonian path on an n-dimensional hypercube (including direction reversals). The term gray code is open used to refer to a reflected code, or more specifically still, the binary reflected gray code. However, according to proposed reports, gray code GA has lower convergence about 10-20% comparing with binary code GA without presenting any results. This study proposes new Full gray code GA (FGGA) applying a gray code throughout all basic operation fields of GA, which has a good data processing ability to improve the slow convergence of binary code GA.

Quantum dot cellular automata (QCA) are pledging nanotechnology which has been used widely in digital circuits and systems. Conventional lithography based VLSI model encounter acute challenges of tunneling, variation of doping and short channel issue. In a remarkably fast development of VLSI technology, it is the cardinal of the age to reach a stable model with area and low power consumption. QCA is a promising alternative to complementary metal–oxide–semiconductor (CMOS) technology with many enticing features such as high-speed, low power consumption and higher switching frequency than transistor based technology. The code converters are the basic unit for transformation of data to execute arithmetic processes. In this paper, a novel QCA based 2-bit binary-to-gray, 3-bit binary-to-gray, and 4-bit binary-to-gray code converter have been proposed. The proposed design reduces the number of cells, area, and raises switching speed. The energy dissipation by the proposed circuits are evaluated which certifies the prospect of QCA nano-circuit presenting as a substitute level for the attainment of reversible circuits. The consistency of the proposed circuits is tested under thermal randomness that reveal the functioning effectiveness of the circuits. The proposed circuits are simulated using QCADesigner and Microwindlite tool which is widely used for simulation and verification.

In coded-structured light three dimensional measurement system, system calibration plays an important role for the measurement accuracy. Projector calibration is an important part of the system calibration. Therefore, this paper proposes a projector calibration method with simple calibration process and high accuracy. This method combines Zhang’s plane model calibration method with orthogonal Gray code + trapezoid phase shift code. During the calibration process, this paper uses Gray code pattern and trapezoid phase shift code pattern to establish the relation of projector image and camera point coordinates, the corner extraction accuracy of this paper’s method is higher than the traditional orthogonal Gray code. According to the image coordinates in the projector’s perspective, we program and calculate the projector’s internal and external parameters matrix based on the Zhang’s plane model calibration toolbox. The results show that this paper’s method is simple and flexible, the maximum relative error of the calibration parameters is 0.027%, and it meets the requirements of system calibration in engineering or industrial fields.

Distribution Fields (DFs) for tracking achieved a better performance than traditional algorithms due to its special representation that allows smoothing the objective function without destroying information about pixel values. DFs descriptor can satisfy both the specificity and smooth landscape requirements of a good tracking algorithm. In this paper, we evaluate the Gray code in original DFs algorithm by replacing the pixel values using Gray code instead of original binary code. Experimental results show that the Gray code can improve the tracking efficiency in certain way.

The existing structured light measurement technologies mainly focus on the single color objects, especially for measuring white object. Mainly because of in the process of three-dimensional measurement for color objects, color object’s surface has a great influence on color components of structured light, leading to the color of structured light changing, this will cause serious errors in the decoding process. To solve this problem, combined with the actual measurements for colored objects, this paper adopts a color Gray code for encoding and decoding structured light, and presents an obtaining technical for color components of structured light, which first through regression analysis builds a mathematical model, and then uses the least squares method for solving it, at last restores the color of the projected stripes to ensure the correctness of decoding, to achieve the measurement for color object and to improve the measurement accuracy. The experimental results show that this method has a good effect on decoding.

인터넷 환경의 급속한 성장으로 인해 효율적인 디지털 콘텐츠 보급이 가능하게 되었다. 하지만 악의적인 공격자에 의한 저작권 침해 등으로 인해, 이미지 데이터 보호 및 비밀 통신 방법에 관한 요구사항 또한 높아지고 있다. Shamir와 Lin-Tsai는 각각 비밀 공유의 원리를 기반으로 간단한 비밀 이미지 암호화 알고리즘들을 제안하였다. 하지만 Shamir와 Lin-Tsai가 제안한 비밀 공유 기법들은 이미지의 화질을 저하시키는 심각한 문제가 있다. 이로 인해, 제3자가 쉽게 은닉된 정보를 알아챌 수 있다. 본 논문에서 이미지의 화질과 안전성을 향상시킬 수 있는 그레이 코드를 이용한 비밀 공유 기법을 제안한다. 제안한 기법은 Shamir와 Lin-Tsai의 기법들과 비교하여 공유 이미지의 화질이 우수할 뿐만 아니라 보다 강화된 보안성을 제공한다.

Due to the rapid growth of the Internet, it is possible to distribute the digital content efficiently. However, the need for image data protection and secret communication technique is also on the rise because of an infringement of the copyright by malicious attackers. Shamir and Lin-Tsai proposed simple secret image encryption algorithms based on the principle of secret sharing, respectively. However, their secret sharing schemes have a serious problem which can be declined the image quality and it is possible for third party to know embed information. In this paper, we propose a new secret sharing scheme using gray code that can be increased the image quality and security. As a result of our experiment, the proposed scheme is not only shown of good image quality and but also provide enhanced security compare with Shamir and Lin-Tasi's schemes.

This paper presents a new type of absolute rotary encoder system based on the affine n-digit N-ary gray code. A brief comparison of the existing encoder systems is carried out in terms of resolution, encoding and decoding principles and number of sensor heads needed. Using the proposed method, two different types of encoder disks are designed, namely, color-coded disk and grayscale coded disk. The designed coded disk pattern is used to manufacture 3 digit 3 ary and 2 digit 5 ary grayscale coded disks respectively. The manufactured disk is used with the light emitter and photodetector assembly to design the entire encode system. Experimental analysis is done on the designed prototype with LabVIEW platform for data acquisition. A comparison of the designed system is done with the traditional binary gray code encoder system in terms of resolution, disk diameter, number of tracks and data acquisition system. The resolution of the manufactured system is 3 times higher than the conventional system. Also, for a 5 digit 5 ary coded encoder system, a resolution approximately 100 times better than the conventional binary system can be achieved. In general, the proposed encoder system gives $(N/2)^n$ times better resolution compared with the traditional gray coded disk. The miniaturization in diameter of the coded disk can be achieved compared to the conventional binary systems.

본 논문에서는 화면 간 차이 신호에 적용하기 위한 적응적인 그레이코드 할당을 갖는 분산 비디오 코덱의 성능 분석을 수행하였다. 즉, 화면 간 차이 신호가 갖는 통계특성에 기초하여 양자화된 값에 대해 최고의 성능을 갖는 그레이코드 할당 방법과 최저의 성능을 갖는 그레이코드 할당 방법에 대해 성능을 비교 분석하였다. 모의실험을 통해 8비트 밝기 해상도를 갖는 영상에서 화면 간 차이 신호는 9비트의 데이터를 발생시키고, 양자화해서 전송되는 비트가 n비트이면, 화면 간 차이 신호에 $256+2^{9-n-1}$를 더함으로써 가상채널잡음의 효과를 최소화할 수 있음을 확인하였다. 영상시퀀스를 이용한 모의실험에서 최고의 성능과 최저의 성능을 갖는 방식간에 동일 비트율에서 약 1.5dB이상의 화질 차이가 발생함을 확인하였다. 본 논문에서 분석된 결과는 화소영역 또는 변환영역의 위너-지브 부호화기법으로 확장하여 적용될 수 있을 것으로 기대된다.

In this paper, we investigated the performances of the distributed video codec with adaptive Gray code to apply for frame-difference signal. That is, the best cases and the worst cases were analyzed and compared by considering the statistical characteristics of the frame difference signal in view of the Gray code allocation. Through computer simulations, if 9-bit data for frame difference signal is generated for luminance signal with 8-bit definition and so n-bit is allocated to the quantized coefficient, we were able to find the best method to reduce the virtual channel noise by adding $256+2^{9-n-1}$ to the frame difference signal. Through computer simulation with test video sequences, it was shown that the performance difference between the best cases and the worst cases is larger than about 1.5dB at same rate. It is expected that the results in this paper are applicable for the transform-domain scheme as well as the pixel-domain scheme.

본 논문에서는 상관 레일레이 페이딩 채널에서 간단히 수정된 터보 부호 구조를 제안하고, 이것과 같이 사용된 16-QAM의 성능을 분석한다. 기존 터보 부호기에 입력되는 2N개의 정보 비트열을 1회의 RSC 부호화 과정을 거쳐 개 비트들로 구성된 단일 패리티 열을 얻는 대신, 제안한 구조에서는 입력 정보 비트열을 2N개의 그룹으로 나누어 독립적으로 RSC 부호화함에 따라 2회에 걸쳐 2개의 N개 비트들로 구성된 2개의 패리티 비트열을 얻도록 한다. 수신기에서 반복 복호를 수행할 때, 두 개의 독립적으로 RSC을 이용하여 부호화하여 송신된 패리티 비트열을 각각 복호한 후 연결시키고 이 결과를 기존 복호기와 마찬가지로 반복 복호에 적용한다. 제안된 구조를 이용할 경우 기존의 터보 부호와 호환성을 유지하면서, 상대적으로 높은 도플러 스펙트럼이 존재하는 경우에 성능이 개선된다.

In this paper, we propose a simply modified Turbo coding structure and investigate its performance in conjunction with Gray coded 16-quadrature amplitude modulation (QAM) over correlated Rayleigh fading channel. Instead of conventional Turbo encoder producing a single parity stream of bits after single operation of a RSC encoder using information bits, the modified Turbo encoder outputs two independent bit parity streams after two times operation of RSC with information bits divided into two streams with bits for each. During iterative decoding at the receiver, the received two independently RSC coded parity streams are independently decoded and apply for this process after constituting these streams to a single stream like the conventional structure. With the proposed structure, we can obtain not only improved decoding performance in moderate/high Doppler spectrum but also compatibility with conventional Turbo code structure.