• 호남수학학술지
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• 제37권3호
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• pp.299-315
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• 2015

In this paper, we study the first-order system least-squares (FOSLS) spectral method for parabolic partial differential equations. There were lots of least-squares approaches to solve elliptic partial differential equations using finite element approximation. Also, some approaches using spectral methods have been studied in recent. In order to solve the parabolic partial differential equations in parallel, we consider a parallel numerical method based on a hybrid method of the frequency-domain method and first-order system least-squares method. First, we transform the parabolic problem in the space-time domain to the elliptic problems in the space-frequency domain. Second, we solve each elliptic problem in parallel for some frequencies using the first-order system least-squares method. And then we take the discrete inverse Fourier transforms in order to obtain the approximate solution in the space-time domain. We will introduce such a hybrid method and then present a numerical experiment.

• Journal of applied mathematics & informatics
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• 제7권2호
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• pp.453-465
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• 2000

In this paper, a new method for finding the approximate solution of a second order nonlinear partial differential equation is introduced. In this method the problem is transformed to an equivalent optimization problem. them , by considering it as a distributed parameter control system the theory of measure is used for obtaining the approximate solution of the original problem.

• 대한조선학회논문집
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• 제32권1호
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• pp.37-41
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• 1995

불규칙 해상에서의 선체의 횡동요운동을 해석하기 위하여 통계적 부분선형화 방법을 사용하였다. 선형 1자유도계인 횡동요 운동 모델에 2차의 비선형 감쇠항과 3차 및 5차, 7차, 9차, 11차의 비선형 복원모멘트를 추가하였으며 불규칙 기진모멘트는 가우스 백색잡음으로 가정하였다. 이 해석 결과를 등가선형화 방법으로 구한결과와 비교한 결과 부분선형화 방법이 반드시 더 정확한 결과를 주는 것은 아니란 점을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 추계학술대회 논문집
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• pp.134-138
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• 1994

According to request of insulating materials for high-voltage, recently we make effort not only to develop diagnostic skills of aging state but also to discover defects in insulating material in the early. Especially, partial discharge has been actively studied as a non-destructive diagnosis technique and very useful method. Because the method of partial discharge measurement has damages less than other conventional diagnosis technique. In this paper, the characteristics of partial discharge was investigated and studied on many samples with voids. In order to adapt as a practical diagnosis technique, it is studied on the characteristics of partial discharge and insulation breakdown in the high voltage. We suggest that partial discharge measurement can be used in order to diagnose defects in high-voltage insulation materials.

• 호남수학학술지
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• 제37권4호
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• pp.411-421
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• 2015

This paper investigates the issue of analytic travelling wave solutions for some important coupled models of fractional order. Analytic travelling wave solutions of the considered model are found by means of the Q-function method. The results give us that the Q-function method is very simple, reliable and effective for searching analytic exact solutions of complex nonlinear partial differential equations.

• Ocean Systems Engineering
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• 제1권4호
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• pp.337-353
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• 2011

In the present study, an offshore platform having large partial porous cylindrical members, which are composed of permeable and impermeable cylinders, is suggested. In order to calculate the wave force on large partial porous cylindrical members, the fluid domain is divided into three regions: a single exterior region, N inner regions and N beneath regions, and the scattering wave in each fluid region is expressed by an Eigen-function expansion method. Applying Darcy's law to the porous boundary condition, the effect of porosity is simplified. Wave excitation forces and wave run up on the structures are presented for various wave conditions. For the idealized three-dimensional platform having large partial porous cylindrical members, the dynamic response evaluations of the platform due to wave forces are carried out through the modal analysis. In order to examine the effects of soil-structure interaction, the substructure method is also applied. The displacement and bending stress at the selective nodal points of the structure are computed using various input parameters, such as the shear-wave velocity of soil, the wave height and the wave period. Applying the Monte Carlo Simulation (MCS) method, the reliability evaluations at critical structure members, which contained uncertainties caused by dynamic forces and structural properties, are examined by the reliability index with the results obtained from MCS.

• 대한전기학회논문지
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• 제35권10호
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• pp.427-437
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• 1986

Identification of the plants is not easy task especially in the fields of process control. From this point of view, Kitamori developed a method of control system design based on partial knowledge about controlled processes. However, it is difficult to control the oscillatory plant by kitamori's method. In this paper, we develope a method of partial model matching control system design, which have desirable pole-placements in order to improve the above defects. Design examples are given to illustrate the effectiveness of the method.

• E2M - 전기 전자와 첨단 소재
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• 제7권1호
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• pp.42-48
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• 1994

The preventive diagnosis technique for power system is being highlighted as a research area for deterioration of insulation in machinery because of high-voltage power system. We make efforts to develop not only diagnosis of aging state but also detection of defects in the initial stage from preventive diagnosis technique. Especially, partial discharge is actively studied as a non-destructive diagnosis technique and very useful because partial discharge measurement reduces damage than conventional diagnosis technique. The loaded stress during this test is smaller than that of other diagnosis techniques. But the continuous research for various complicated analysis method is required because partial discharge has very small signals and its signals have complex forms. In this paper, the measurement of partial discharge was investigated and studied on many specimens with void. We made samples having artificial voids and measured partial discharge. In order to use as a practical diagnosis technique, we studied ways of measurement, measured illustrations and types of partial discharge which could be used in order to diagnose defects of power machinery.

• 대한수학회지
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• 제51권6호
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• pp.1123-1139
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• 2014

In this work, we investigate the existence of the extremal solutions for a class of fractional partial differential equations with order 1 < ${\alpha}$ < 2 by upper and lower solution method. Using the theory of Hausdorff measure of noncompactness, a series of results about the solutions to such differential equations is obtained.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 2006년도 하계학술대회
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• pp.251-257
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• 2006

The performance of face recognition methods using subspace projection is directly related to the characteristics of their basis images, especially in the cases of local distortion or partial occlusion. In order for a subspace projection method to be robust to local distortion and partial occlusion, the basis images generated by the method should exhibit a part-based local representation. We propose an effective part-based local representation method named locally salient ICA (LS-ICA) method for face recognition that is robust to local distortion and partial occlusion. The LS-ICA method only employs locally salient information from important facial parts in order to maximize the benefit of applying the idea of 'recognition by parts.' It creates part-based local basis images by imposing additional localization constraint in the process of computing ICA architecture I basis images. We have contrasted the LS-ICA method with other part-based representations such as LNMF (Localized Non-negative Matrix Factorization)and LFA (Local Feature Analysis). Experimental results show that the LS-ICA method performs better than PCA, ICA architecture I, ICA architecture II, LFA, and LNMF methods, especially in the cases of partial occlusions and local distortion