• 대한전자공학회논문지SD
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• 제40권3호
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• pp.33-42
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• 2003

본 논문에서는 NST (new Svoboda-Tung) 알고리즘을 이용한 비동기식 제산기의 효율적 설계에 관해 기술한다. 본 제산기설계에서는 비동기 설계방식을 사용하여 제산연산이 필요할 때에만 동작함으로써 전력소모를 줄이도록 설계한다. 제산기는 비동기식 파이프라인 구조를 이용한 per-scale부, iteration step부, on-the-fly converter부의 세부분으로 구성된다. Per-scale부에서는 새로운 전용 감산기를 이용하여 적은 면적과 고성능을 갖도록 설계한다. Iteration step부에서는 4개의 division step을 갖는 비동기식 링 구조로 설계하고, 아울러 크리티컬 패스(critical path)에 해당하는 부분만을 2선식으로, 나머지 부분은 단선식으로 구성하는 구현방법을 채택하여 하드웨어의 오버헤드를 줄인다. On-the-fly converter부는 iteration step부와 병렬연산이 가능한 on-the-fly 알고리즘을 이용하여 고속연산이 되도록 설계한다. 0.6㎛ CMOS 공정을 이용하여 설계한 결과, 1,480 ×1,200㎛²의 면적에 12,956개의 트랜지스터가 사용되었고, 41.7㎱의 평균지연시간을 가졌다.

• 대한수학회보
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• 제38권2호
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• pp.369-378
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• 2001

In this paper, we obtain the following results: Let f be a transcendental entire function with log M(r,f)=$O(log r)^\beta (e^{log r}^\alpha)\; (0\leq\alpha<1,\beta>1$). Then every component of N(f) is bounded. This result generalizes the result of Baker.

• Journal of the Korean Data and Information Science Society
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• 제19권4호
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• pp.1371-1377
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• 2008

In this paper, we have employed the variational iteration method to solve the boundary value problems. Numerical results reveal that it is a very effective method compared with the results obtained by using the Adomian decomposition method in Wazwaz, A. M. (2000).

• 대한조선학회논문집
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• 제46권3호
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• pp.232-248
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• 2009

Numerical methodology to solve ship springing problem, which is basically fluid-structure interaction problem, was explored in this study. Solution of this hydroelasticity problem was sought by coupling higher order B-spline Rankine panel method and finite element method in time domain, each of which is introduced for fluid and structure domain respectively. Even though varieties of different combinations in terms of numerical scheme are possible and have been tried by many researchers to solve the problem, no systematic study regarding the characteristics of each scheme has been done so far. Here, extensive case studies have been done on the numerical schemes especially focusing on the iteration method, FE analysis of beam-like structure, handling of forward speed problem and so on. Two different iteration scheme, Newton style one and fixed point iteration, were tried in this study and results were compared between the two. For the solution of the FE-based equation of motion, direct integration and modal superposition method were compared with each other from the viewpoint of its efficiency and accuracy. Finally, calculation of second derivative of basis potential, which is difficult to obtain with accuracy within grid-based method like BEM was discussed.

• Communications for Statistical Applications and Methods
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• 제7권2호
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• pp.574-574
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• 2000

Consider the problem of estimating regression function from a set of data which is contaminated by a long-tailed error distribution. The linear smoother is a kind of a local weighted average of response, so it is not robust against outliers. The kernel M-smoother and the lowess attain robustness against outliers by down-weighting outliers. However, the kernel M-smoother and the lowess requires the iteration for computing the robustness weights, and as Wang and Scott(1994) pointed out, the requirement of iteration is not a desirable property. In this article, we propose the robust nonparametic regression method which does not require the iteration. Robustness can be achieved not only by down-weighting outliers but also by transforming outliers. The rank transformation is a simple procedure where the data are replaced by their corresponding ranks. Iman and Conover(1979) showed the fact that the rank transformation is a robust and powerful procedure in the linear regression. In this paper, we show that we can also use the rank transformation to nonparametric regression to achieve the robustness.

• Communications for Statistical Applications and Methods
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• 제7권2호
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• pp.575-583
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• 2000

Consider the problem of estimating regression function from a set of data which is contaminated by a long-tailed error distribution. The linear smoother is a kind of a local weighted average of response, so it is not robust against outliers. The kernel M-smoother and the lowess attain robustness against outliers by down-weighting outliers. However, the kernel M-smoother and the lowess requires the iteration for computing the robustness weights, and as Wang and Scott(1994) pointed out, the requirement of iteration is not a desirable property. In this article, we propose the robust nonparametic regression method which does not require the iteration. Robustness can be achieved not only by down-weighting outliers but also by transforming outliers. The rank transformation is a simple procedure where the data are replaced by their corresponding ranks. Iman and Conover(1979) showed the fact that the rank transformation is a robust and powerful procedure in the linear regression. In this paper, we show that we can also use the rank transformation to nonparametric regression to achieve the robustness.

• Journal of applied mathematics & informatics
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• 제29권5_6호
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• pp.1167-1178
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• 2011

In this paper, we further investigate the local Hermitian and skew-Hermitian splitting (LHSS) iteration method and the modified LHSS (MLHSS) iteration method for solving generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. When A is non-symmetric positive definite, the convergence conditions are obtained, which generalize some results of Jiang and Cao [M.-Q. Jiang and Y. Cao, On local Hermitian and Skew-Hermitian splitting iteration methods for generalized saddle point problems, J. Comput. Appl. Math., 2009(231): 973-982] for the generalized saddle point problems to generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. Numerical experiments show the effectiveness of the iterative methods.

• East Asian mathematical journal
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• 제24권1호
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• pp.105-110
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• 2008

The aim of this paper is to prove convergence of implicit iteration process to a common fixed point for a finite family of strong successive $\Phi$-pseudocontractive mappings. The results presented in this paper extend and improve the corresponding results of S. S. Chang [On the convergence of implicit iteration process with error for a finite family of asymptotically nonexpansive mappings, J. Math. Anal. Appl. 313(2006), 273-283], M. O. Osilike[Implicit iteration process for common fixed points of a finite finite family of strictly pseudocontractive maps, Appl. Math. Comput. 189(2) (2007), 1058-1065].

• 대한수학회보
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• 제39권3호
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• pp.389-399
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• 2002

We prove that the results of Chang, Park and Cho in ［1］ concerning the iterative approximation of asymptotically pseudocontractive maps with bounded ranges can be extended to a certain class of asymptotically pseudocontractive maps whose ranges need not be bounded.

• 천문학회지
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• 제42권3호
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• pp.47-54
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• 2009

In this paper we present an independent FORTRAN code for calculating LTE-plane-parallel model atmospheres. The transfer equation has been solved using Avrett and Loeser method. It is shown that, using an approximate non-gray temperature distribution together with the iteration factors method (Simonneau and Crivellari) for correcting the temperature distribution reduce the number of iteration required to achieve the condition of radiative equilibrium. Preliminary results for pure helium model atmospheres are presented.