• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.411-414
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• 2006

This paper describes a recent development on the divergence free basis function based on a hermite stream function. The well-known cavity problem has been used to compare the accuracy and the convergence of the present method with those of a modified residual method known as one of the stabilized finite e1ement methods. The comparison showed the present method performs better in the accuracy and convergence.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.311-319
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• 2007

A Meshfree is a method used to establish algebraic equations of system for the whole problem domain without the use of a predefined mesh for the domain discretization. A point interpolation method is based on combining radial and polynomial basis functions. Involvement of radial basis functions overcomes possible singularity Furthermore, the interpolation function passes through all scattered points in an influence domain and thus shape functions are of delta function property. This makes the implementation of essential boundary conditions much easier than the meshfree methods based on the moving least-squares approximation. This study aims to investigate a stress analysis of structural element between a meshfree method and the finite element method. Examples on cantilever type plate, hollow cylinder and stress concentration problems show that the accuracy and convergence rate of the meshfree methods are high.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.6B
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• pp.693-700
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• 2001

본 논문에서는 유전체 덮개층을 갖는 일축성 매질에서 마이크로스트립 패치 안테나의 공진 주파수와 입력 임피던스, 방사패턴에 대해 연구하였다. 제안된 구조의 구성관계식으로부터 파수영역 다이애딕 그린 함수를 유도하여 전계 적분 방정식을 계산해 낸 후에 갤러킨 모멘트법으로 이산화하여 행렬형태로 표현하였다. 수치 해석적 수렴을 고려하여 사용된 기저 함수는 패치 위의 실제 전류밀도와 가장 유사한 형태인 정현적 기저함수를 선택하였다. 수치해석 결과로 기판의 유전율 변화와 덮개층의 두께 변화와 공진 주파수와 입력 임피던스 그리고 방사 패턴에 미치는 영향에 대해 논의하였다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.2
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• pp.16-26
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• 2001

This paper develops the fast dynamic programming technique to construct the subband structure yielding the maximum coding gain for given filter bases and a given limit of implementation complexity. We first derive the unified coding gain which can be applied to non-orthogonal filter basis as well as orthogonal filter basis and to arbitrary subband decompositions. Then, we verify that the unified coding gains in real systems are monotonically increasing function for the implementation complexities which are proportional to the number of subbands. By using this phenomenon, the implementation complexity and the coding gain are treated in the same way as the rate and distortion function. This makes it possible to use the Lagrangian multiplier method for finding the optimal subband decomposition producing the maximum coding gain [or a given limit of implementation complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.214-223
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• 1996

Noise effects on image profiles reconstructed by the spectral inverse scattering technique is studied based on moment method with series-expanded basis function. It is found that the Fourier series expansion to the field distribution and the averaging of the reconstructed profile in each enlarged cell provides an effective tool for the reduction of noise effects.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.827-832
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• 2001

A multi-level optimum design algorithm for prestressed concrete (PSC) box girders is proposed in this paper. To save the numerical efforts, a multi-level optimization technique using model coordination method that separately utilizes both tendon profile design and section design is incorporated. And also, a reduced basis technique for the efficient tendon profile optimization is proposed in this paper. From the numerical investigations, it may be positively stated that the optimum design of PSC box girder based on the new approach proposed in this study will lead to more rational and economical design compared with the currently available designs.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.336-339
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• 2012

본 논문에서는 비선형 MLCA(Maximum Length Cellular Automata)와 1D CAT(One-Dimensional Cellular Automata Transform)를 이용하여 의료 영상 암호화 방법을 제안한다. 암호화 방법은 먼저, Wolfram Rule 행렬에 의해 전이행렬 T를 생성한다. 그 후, 암호화하려는 원 영상에 생성된 전이 행렬 T를 곱하여 원 영상의 픽셀 값을 변환한다. 또한 변환된 원 영상을 여원 벡터 F와 XOR 연산하여 비선형 MLCA가 적용된 영상으로 변환한다. 다음, 게이트웨이 값을 설정하여 1D CAT 기저함수를 생성한다. 그리고, 비선형 MLCA가 적용된 영상에 생성된 1D CAT 기저함수를 곱하여 암호화를 한다. 마지막으로 키 공간 분석을 통하여 제안한 방법이 높은 암호화 수준의 성질을 가졌음을 검증한다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1363-1364
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• 2015

본 논문은 지문을 이용하여 방사형 기저함수 신경회로망(RBFNN: Radial Basis Function Neural Network)을 기반으로 지문을 식별하고 확인할 수 있는 방법을 제시한다. 지문 데이터로는 공인데이터인 FVC2002의 지문 데이터를 사용하였다. 지문 이미지의 개선을 위해 여러 단계의 전처리를 한 후 특징점을 추출하여 데이터베이스를 구축하였다. 이렇게 구축된 데이터베이스를 방사형 기저함수 신경회로망을 통해 학습을 시키고 지문의 패턴을 분류하여 지문의 대상자와 일치하는 패턴의 지문들을 선정한다. 선정된 지문들과 입력된 지문의 특징점을 이용하여 지문의 대상자를 식별한다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.235-242
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• 2001

An optimization algoriam for the optimum design of prestressed concrete (PSC) box girder bridges is proposed in this paper. In order to optimize the tendon profile efficiently, a reduced basis technique is introduced. The optimization algorithm which includes the tendon profile, tendon size and concrete dimensions optimization problem of the PSC box girder bridges is verified on the Genetic algorikhm (GA) from the numerical examples. it may be positively stated that the optimum design of the PSC box girder bridges based on the new approach proposed in this study will lead to more rational and economical design compared with the currently available designs.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.2
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• pp.48-54
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• 2014

For the element ${\alpha}{\in}GF(p^n)$, two kinds of bases are known. One is a conventional polynomial basis of the form $\{1,{\alpha},{\alpha}^2,{\cdots},{\alpha}^{n-1}\}$, and the other is a normal basis of the form $\{{\alpha},{\alpha}^p,{\alpha}^{p^2},{\cdots},{\alpha}^{p^{n-1}}\}$. In this paper we consider the method of generating normal bases which construct the finite field $GF(p^n)$, as an n-dimensional extension of the finite field GF(p). And we analyze the code sequence generating algorithm and derive the implementation functions of code sequence generator based on the normal bases. We find the normal polynomials of degrees, n=5 and n=7, which can generate normal bases respectively, design, and construct the code sequence generators based on these normal bases. Finally, we produce two code sequence groups(n=5, n=7) by using Simulink, and analyze the characteristics of the autocorrelation function, $R_{i,i}(\tau)$, and crosscorrelation function, $R_{i,j}(\tau)$, $i{\neq}j$ between two different code sequences. Based on these results, we confirm that the analysis of generating algorithms and the design and implementation of the code sequence generators based on normal bases are correct.