• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1457-1460
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• 2003

자바는 플랫폼에 독립적인 실행을 위해서 바이트코드를 사용하며, 자바가상머신에서 바이트코드를 해석하여 실행시키는 인터프리터 방식을 취하고 있으므로 느린 실행 시간을 갖는다. 이와 같은 느린 실행 시간에 영향을 주는 요인 중의 하나로써 다차원 배열(Multi-dimension Array)에 접근(Acess)할 때 비효율적인 방법으로 실행되는 것을 개선할 필요가 있다. 자바가상머신에서 오브젝트와 배열은 레퍼런스에 의해서 접근되어지고, 특히 다차원 배열은 배열 안에 또 다른 배열이 들어있는 자료구조를 취하기 때문에 다차원 배열의 크기가 커질수록 하나의 원소에 접근할 때 발생되는 레퍼런스(Reference)의 횟수가 많아질수록 성능 저하를 유발한다. 본 논문에서는 다차원 배열에 효율적으로 접근하기 위한 새로운 배열의 자료 구조를 제시하고, 다차원 배열에 접근하는 여러 개의 바이트코드 대신 이런 자료구조에 접근할 수 있는 새로운 바이트코드를 정의 및 구현하였다. 그리고 이를 실제 클래스파일에 적용하고, 간단한 성능 평가를 통해서 성능 개선 효과를 확인할 수 있다.

• The Journal of the Acoustical Society of Korea
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• v.29 no.7
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• pp.431-438
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• 2010

The radiation pattern of conformal transducers installed on a curved surface is likely to be complicated depending on the array pattern on the curved surface. In this research, the acoustic sources constituting a conformal transducer are arrayed in equi-angle, equi-interval, and geodesic dome forms, and the radiation pattern function of each of the array geometries has been derived, and therewith the radiation pattern has been analyzed for each array geometry. Based on the analysis result, we have determined the equi-interval array geometry that provides the widest beam width with the lowest side lobe level among the three array geometries. Results of the present work are expected to be utilized to the design of conformal transducer structures.

• 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 the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1199-1206
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• 2018

The hybrid phase shifting device is consist of general phase shifter in sub-array and the true time delay inter sub-array. This configuration for phased shifting can efficiently improve the beam squint according to frequencies. However, when an appropriate array configuration is not selected, a gain variation of main lobe for a phased array antenna is occurred. In order to solve these problems, a simplified formula for constructing efficient array based on the system design requirements, such as the fractional bandwidth, the maximum beam steering angle, and limit criterion of the gain variation, was presented.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.33-36
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• 2002

폴리비닐알코올 (poly(vinyl alcohol), PVA)은 의류 및 산업용 섬유, 막, 약물전달, 암세포 괴사용 색전제등에 널리 사용되고 있다[1,2]. 이런 PVA와 같은 비닐계 고분자는 분자량 이외에도 입체규칙성에 따라 그 물리적 성질이 변화하는데 그 입체규칙성에 따라 혼성배열, 동일배열 및 교대배열 고분자로 분류할 수 있다. PVA는 일반적으로 55% 이상의 교대배열 다이애드기 함량을 가질 때 교대배열 PVA라고 불린다. (중략)

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.95-97
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• 2000

배열 안테나에서 안테나 소자의 개수의 증가는 안테나의 이득을 증가시킬 수 있으므로 열악한 채널 환경에서도 채널이 필요로 하는 링크 마진을 얻을 수 있다. 그러나, 기존 빔 형성기에서 사용되는 배열 안테나 기법은 많은 계산량과 소모 메모리량 때문에 배열 소자의 개수에 제한이 따르게 된다. 이러한 문제를 해결하기 위하여 본 논문에서는 배열 안테나의 구조에 따른 위상차이를 보상하여 적은 계산량과 메모리를 갖는 배열 위상 차이 보상을 이용한 평행 구조 빔 형성기를 제안한다 배열 위상 차이를 보상하는 기법으로 적은 계산량과 메모리로 개수가 많은 긴 배열 안테나에서 얻을 수 있는 분해능과 안테나 이득을 얻을 수 있다. 제안된 기법의 성능을 비교하기 위해 기존의 빔 형성기법으로delay-sum 빔 형성기와 공분산 행렬의 고유치 해석을 통한 고유벡터 기법의 빔 스펙트럼과 연산량을 비교하였다. 제안된 기법으로 빔 형성을 하면, 배열 안테나의 소자의 개수가 늘어나도 기존의 방법보다 최소 30%의 연산량으로 스펙트럼 상 비슷한 성능을 얻을 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1419-1424
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• 1998

In phased array antennas that scan elevation, the number of radiator rows is one of the important factors to minimizing both cost and weitht. Therefore, the antenna tilt angles having relation with element spacing are among the improtant design parameters. The exact optimum tilt angles for several types of uniformly and nonuniformly excited arrays are obtained theoretically. Four types of uniform linear arrays and Chebyshev array factors as a nonuniformly excited arrav are considered.

• The Korean Journal of Applied Statistics
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• v.18 no.3
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• pp.617-625
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• 2005

We usually use orthogonal designs-orthogonal array of strength 2 as orthogonal arrays. It was shown that fractional factorial plaits represented by orthogonal arrays of strength 3 are universally optimal under the additive motels that includes the mean, all main effects and all two-factor interactions. Therefore, we need the measure for evaluating the orthogonal array of strength 3. We can extend this measure as the measure for evaluating the orthogonal array of strength t($\ge$ 2).

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.6
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• pp.268-278
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• 2005

We consider constructing the generalized suffix way of strings A and B when the suffix arrays of A and B are given, j.e., merging two suffix arrays of A and B. There are efficient algorithms to merge some special suffix arrays such as the odd array and the even array. However, for the general case that A and B are arbitrary strings, no efficient merging algorithms have been developed. Thus, one had to construct the generalized suffix arrays of A and B by constructing the suffix array of A$\#$B$\$$ from scratch, even though the suffix ways of A and B are given. In this paper, we Present efficient merging algorithms for the suffix arrays of two arbitrary strings A and B drawn from constant and integer alphabets. The experimental results show that merging two suffix ways of A and B are about 5 times faster than constructing the suffix way of A$\#$B$\$$ from scratch for constant alphabets. Our algorithms include searching all suffixes of string B in the suffix array of A. To do this, we use suffix links in suffix ways and we developed efficient algorithms for computing the suffix links. Efficient computation of suffix links is another contribution of this paper because it can be used to solve other problems occurred in bioinformatics that should search all suffixes of a given string in the suffix array of another string such as computing matching statistics, finding longest common substrings, and so on. The experimental results show that our methods for computing suffix links is about 3-4 times faster than the previous fastest methods.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.2
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• pp.46-54
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• 1994

In this paper, an analysis and design method is proposed, which is to improve the directivity of microstrip array antennas conformed to a cylindrical surface. In the case of forming an arc-array in the circumferential direction on a circula-cylinder surface, the circular-cylinder can be approximated to a polygonal-pillar and on each pillar-planes the sub-arrays, Dolph-Tschebyscheff array and uniform array with a beam steered in the desired direction, would make a sharp directivity for the total cylin- drical array antenna. And the radiation pattern according to the type of its sub arrays is analyzed and compared using the cylindrical-cavity codel. A cylindrical microstrip array antenna, with 12 elements and uniform arra as a sub-array which have an equal distance$\lambda_0$/2between the elements, is manufactured and conformed to a cylinder with radius of 6 The measured data of side lobe level, HPBW and FNBW are - 13dB, $9^{\circ}$, and $15{\circ}$, ,respectively. This result shows a good improvement on the directivity comparing with a linear array.