• Journal of Broadcast Engineering
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• v.14 no.6
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• pp.742-748
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• 2009

Most commercial digital still cameras use a single sensor array (e.g., CMOS or CCD) with color filter array (CFA) to reduce the cost and size. Since the image obtained with CFA has only one color value per pixel, the demosaicing is needed to acquire missing two color values. Although many demosaicing methods have been proposed, they still have artifacts such as rainbow and zippering artifact. In this paper, we propose the simple demosaicing algorithm using tendency of neighbor pixels with the enhanced weighting function. In the experimental results, our algorithm shows much better subjective qualities of the images than conventional demosaicing algorithm and improves objective qualities.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2902-2912
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• 1994

The ultrasonic array sensor system, consisting of one transmitter and fourreceivers instead of the traditional combination of a transmitter and a receiver is proposed in order to identify the location of objects. From the theoretical analysis and the experimental results, it is found that this new array sensor system could derive the information on the position of objects accurately, while the traditional sensor system could provide only the informatioin on the distance to objects. This sensor system is used to develop a sonar-based local mapping algorithm. The local map is used to find the existence of possible gates, through which the mobile robots can pass, and to select the suitable one in order for the robots to reach the goal safely in the presence of obstacles. The performance of the proposed local map algorithm is demonstrated experimentally in a small working area with several obstacles. It is found that the quality of the resulting local map is sufficient for the avoidance of collisions between the robots and obstacles and for the selection of the suitable gate leading to the goal. It is also shown that the global map of the working area could be obtained by integrating several local maps constructed from different locations and that it matches the actual layout of the working area well.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.2
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• pp.111-116
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• 2014

In this paper, we estimates the direction of arrival of desired a target using linear array antenna in wireless communication. Direction of arrival estimation is to estimate for desired target position among incident signals on receiver array antennas. This paper improved estimation of direction of arrival for target using optimum weight, high resolution adaptive beamforming algorithm, and sparse matrix for driection of arrival estimation. Through simulation, we showed that we are performance the analysis to compare general algorithm with proposed algorithm. We show that propose algorithm more improve for direction of estimation than general beamforming algorithm.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.9
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• pp.49-61
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• 1996

Back-propagation(BP) algorithm needs a lot of time to train the artificial neural network (ANN) to get high accuracy level in classification tasks. So there have been extensive researches to process back-propagation algorithm on parallel processors. This paper prsents a linear systolic array which calculates forward-backward propagation of BP algorithm at the same time using effective space-time transformation and PE structure. First, we analyze data flow of forwared and backward propagations and then, represent the BP algorithm into data dapendency graph (DG) which shows parallelism inherent in the BP algorithm. Next, apply space-time transformation on the DG of ANN is turn with orthogonal direction projection. By doing so, we can get a snakelike systolic array. Also we calculate the interval of input for parallel processing, calculate the indices to make the right datas be used at the right PE when forward and bvackward propagations are processed in the same PE. And then verify the correctness of output when forward and backward propagations are executed at the same time. By doing so, the proposed system maximizes parallelism of BP algorithm, minimizes th enumber of PEs. And it reduces the execution time by 2 times through making idle PEs participate in forward-backward propagation at the same time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2131-2138
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• 2011

GPS is vulnerable to jamming because of extremely low signal power. Many anti-jamming techniques are studied for complement this vulnerability. Anti-jamming techniques using array antenna are most effective technique and these techniques are required the DOA estimates. MUSIC algorithm and Root-MUSIC Algorithm are typical algorithms used in DOA estimation. Two algorithms have different characteristics, so the choice of an algorithm may depends on many factors such as the environment and the system requirements. The analysis and performance comparison of both algorithms is necessary to choose the best method to apply. This paper summarizes the theory of MUSIC and Root-MUSIC algorithms. And this paper extends both algorithm to estimate two-dimensional angles. The software simulator of both algorithms are implemented to evaluate the performance. Root-MUSIC algorithm has the computational advantage on ULA. MUSIC algorithm is applicable to any antenna array. MUSIC shows better estimation performance when number of array element is small while the computational load of MUSIC is much higher than Root-MUSIC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.5
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• pp.592-600
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• 2014

This paper proposes an enhanced adaptive genetic algorithm(EAGA) dedicated to pattern synthesis of array antenna which conforms to a curved surface of rotation with quadratic function. EAGA combines adaptive genetic algorithm(AGA) with invasive weed optimization(IWO) for the faster convergence and the lower cost value of the cost function. The amplitude and phase of each excited weighting factor are optimized to meet the required goals using EAGA. The EAGA results indicate that the proposed algorithm is superior to AGA when applied to the problem of conformal array antenna pattern synthesis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.8
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• pp.758-764
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• 2015

This paper describes the pattern synthesis of array antenna which conforms to a metallic curved surface formed by the rotation of a quadratic function by using EAGA(Enhanced Adaptive Genetic Algorithm). Three rotated-type conformal surfaces are realized by changing the coefficient of the quadratic function and the pattern of each conformal array antenna is synthesized. In order to reduce the overall time of pattern synthesis, the transformed active element pattern obtained by the active element pattern of the 2-dimensional planar array using Euler angles rotation is utilized instead of the active element pattern of the 3-dimensional conformal array antenna itself. To verify validity of the proposed synthesis procedure, the synthesized patterns using EAGA are compared with those obtained by MWS.

• The Journal of the Acoustical Society of Korea
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• v.38 no.6
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• pp.630-636
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• 2019

Passive Ranging Sonar (PRS) is a type of passive sonar consisting of three sub-array on the port and starboard, and has a characteristic of detecting a target and calculating a bearing and a distance. The bearing and distance calculation requires physical sub-array position information, and the bearing and distance accuracy performance are deteriorated when the position information of the sub-array is inaccurate. In particular, it has a greater impact on distance accuracy performance using plus value of two time-delay than a bearing using average value of two time-delay. In order to improve this, a study on sub-array position error estimation and error compensation is needed. In this paper, We estimate the sub-array position error based on enetic algorithm, an optimization search technique, and propose a method to improve the performance of distance accuracy by compensating the time delay error caused by the position error. In addition, we will verify the proposed algorithm and its performance using the sea-going data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1296-1302
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• 2012

In this research, optimization of a dual-band dipole array was performed using genetic algorithm. A non-uniform, aperture-shared linear array was configured with dipoles which resonate at 4 GHz and 9.5 GHz. The excited current distributions on dipoles were computed considering mutual coupling between dipole elements. The current distributions were also computed using method of moment (MoM). The optimization using genetic algorithm was performed to obtain the low sidelobe levels in two operating frequency band. The PSLs of the optimized array for 4 GHz and 9.5 GHz are -15.7 dB and -17 dB, respectively. Comparison between computed and simulated results are also discussed.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1053-1060
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• 2019

The satellite antenna for collecting information is mainly classified into reflector antenna, lens antenna, and phased array antenna. Among them, the phased array antenna with the excellent antenna pattern control performance for a multi-beam system is frequently used. Although the terrestrial signal information collection based on the satellite is not much effected geographically, it requires the accurate angle-of-arrival (AOA) information of the interesting signal. In this paper, we discuss the characteristics and the advantages/disadvantages of the antenna array shape employed in the phased array antenna. In addition, we present the Cascade AOA estimation algorithm based on a square array antenna mounted on the satellite receiver, and show the performance evaluation results through the computer simulation.