• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.299-304
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• 2018

An improved genetic algorithm was proposed for pattern synthesis of an adaptive beam forming system using phased array antennas. The proposed genetic algorithm is an algorithm that adds acquired characteristics procedure to solve local optimization using the diversity. The performance of the proposed genetic algorithm is verified through the problem of finding a suitable chromosome for a picture composed of binary. And it is confirmed that it is suitable for the adaptive beam forming system based on the performance problem of combining main beam and two pattern nulls.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.237-246
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• 2013

This paper proposes a hydrophone array design optimization technique for cavitation tunnel noise measurements. The optimization technique comprises of design parameters, an objective function and an optimization algorithm. The design parameters are defined for circular, spiral and multi-spiral arrays. The objective function is defined so as to consider the mainlobe beamwidth and the maximum sidelobe level simultaneously. A global optimization scheme is applied to the array design using very fast simulated reannealing (VFSR). After applying the optimization technique to arrays respectively, the peak sidelobe level and the mainlobe beamwidth of optimum arrays are analyzed. Finally the array patterns considering multiple reflections in the cavitation tunnel are evaluated to validate the proposed method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.187-195
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• 2012

In this paper, we propose the optimization of subarray configurations for linear array to minimize the side lobe level (SLL) in sum beam pattern based on the genetic algorithm. The operations of genetic algorithm are modified to be applied to subarray configurations. Using the proposed method, we construct subarray structure with 16 irregular subarray elements from 40 linear array elements to minimize the SLL in sum beam pattern in case of applying the adaptive beamforming(ABF) to suppress the jamming power, whose the SLL is 10 dB lower than that of regular subarray configuration.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.665-675
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• 2016

With the development of active phased array radar technology in recent years, active phased array antennas, which digitally combine signals received from subarray units using dozens of digital receiver, have been developed. The beam characteristics are greatly affected by the shape of the subarray structure as well as the weight of subarray in digital beamforming. So in this paper, the method to generate subarray structures by using recursive element exchanging method and the method to optimize subarray structures that can minimize sidelobes of operating beams are proposed. Additionally it presents the result to find the optimized subarray structure to minimize the maximum sidelobe of monopulse beam and pencil multi-beam respectively or simultaneously which are commonly used for digital beamforming by applying the algorithm propsed in this paper.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.1068-1074
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• 2008

In this paper, we propose the algorithm for generating the array of elemental image by using look-up table (L UT) in a computer generated integral imaging system. It makes the LUT independently for the projection point of x and y. The algorithm using LUT to the existing ones needs less computing time to generate the array of elemental image. By comparing the computing time of proposed algorithm with that of the existing algorithms e xperimently, we proved the efficiency of proposed algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.690-697
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• 2010

In this paper we propose an opposite-sign phase method to implement a nulling antenna using genetic algorithm. In the opposite-sign phase method the phase value of each antenna element in the linear phased array antenna is symmetrical to the center of the array and the sign of the phases of the neighboring elements is alternating. Compared to the conventional genetic algorithm our genetic algorithm shows the capability of synthesizing nulls faster and sharper.

• The KIPS Transactions:PartA
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• v.17A no.5
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• pp.221-228
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• 2010

Since string operations were applied to computational biology, security and search for Internet, various data structures and algorithms for computing efficient string operations have been studied. The all-pairs suffix-prefix matching is to find the longest suffix and prefix among given strings. The matching algorithm is importantly used for fast approximation algorithm to find the shortest superstring, as well as for bio-informatics and data compressions. In this paper, we propose an algorithm to find all-pairs suffix-prefix matching using the suffix array, which takes O($k{\cdot}m$)�� time complexity. The suffix array algorithm is proven to be better than the suffix tree algorithm by showing it takes less time and memory through experiments.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.5
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• pp.236-244
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• 2001

디스크배열 또는 RAID 시스템은 저렴한 비용으로 대용량 저장공간을 제공할 수 있으나, VOD 서비스와 같은 대규모 멀티미디어 서비스에 대해서는 아직 충분한 입출력 속도를 지원하지 못하고 있다. 보다 높은 대역폭을 지원하기 위해 다수의 디스크 컨트롤러를 채용한 다중 디스크배열에서 스트라이프를 전체 디스크에 효과적으로 분산시키기 위한 수직 스트라이핑 모델이 이용되고 있다. VOD 서비스 이용자가 고품질의 동영상을 감상하기 위해서는, 응용프로그램이 요청한 마감시간까지 저장장치에 기록되어 있는 데이터를 읽어와야 한다. 본 논문에서는 효과적이 VOD 서비스 지원을 위해, 다중 디스크배열에서 각 디스크 컨트롤러의 지역 요청큐로 분산된 입출력 요청들을 스케쥴링하여 마감시간 초과율(deadline miss rate)을 줄이기 위한 알고리즘을 제안한다. 이 알고리즘은 VOD 서버와 같이 데이터 읽기 작업이 많은 멀티미디어 서비스에 적합하도록 설계되었다. 시뮬레이션 결과, 제안된 알고리즘이 마감시간 초과율을 평균 41.5% 감소시킴을 알 수 있었다.

• 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.

• Investigative Magnetic Resonance Imaging
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• v.9 no.1
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• pp.36-42
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• 2005

Purpose : To develop a novel approach to calculate the sensitivity profiles of the phased array coil for use in non-uniform intensity correction. Materials and Methods : The proposed intensity correction method estimates the sensitivity profile of the coil to extract intensity variations that represent the scanned image. The sensitivity profile is estimated by fitting a non-linear curve to various angles of projections through the imaged object in order to eliminate the high-frequency image content. Filtered back projection is then used to compute the estimates of the sensitivity profile of each coil. The method was applied both to phantom and brain images from 8-channel phased-array coil and 4-channel phased-array coil, respectively. Results : Intensity-corrected images from the proposed method have more uniform intensity than those from the commonly used 'sum-of-squares' approach. By using the proposed correction method, the intensity variation was reduced to $6.1\%$ from $13.1\%$, acquired from the 'sum-of-squares'. Conclusion : The proposed method is more effective at correcting the intensity non-uniformity of the phased-array surface-coil images than the conventional 'sum-of-squares' method.