• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.216-221
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• 2004

In two dimensional incompressible flaws, a preconditioning technique called Hierarchical Iterative Procedure(HIP) has been implemented on a SUPG finite element formulation. By using the SUPG formulation, one can escape from the LBB constraint and hence achieve an equal order formulation. In this paper, we increased the order of interpolation up to cubic. The conjugate gradient squared(CGS) method is used for the outer iteration, and the HIP for the preconditioning for the incompressible Navier-Stokes equation. The hierarchical elements has been used to achieve a higher order accuracy in fluid flaw analyses, but a proper efficient iterative procedure for higher order finite element formulation has not been available so far. The numerical results by the present HIP for the lid driven cavity flaw showed the present procedure to be stable, very efficient and useful in flaw analyses in conjunction with hierarchical elements.

• 한국해양공학회지
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• 제17권5호
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• pp.11-18
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• 2003

In two-dimensional incompressible flows, a preconditioning technique called Hierarchical Iterative Procedure (HIP) has been implemented on a SUPG finite element formulation. By using the SUPG formulation, one can escape from the LBB constraint hence, achieving an equal order formulation. In this paper, we increased the order of interpolation up to cubic. The conjugate gradient squared (CGS) method is used for the outer iteration, and the HIP for the preconditioning for the incompressible Navier-Stokes equation. The hierarchical elements have been used to achieve a higher order accuracy in fluid flow analyses, but a proper and efficient iterative procedure for higher order finite element formulation has not been available, thus far. The numerical results by the present HIP for the lid driven cavity flow showed the present procedure to be stable, very efficient, and useful in flow analyses, in conjunction with hierarchical elements.

• 한국전산유체공학회지
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• 제9권3호
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• pp.57-65
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• 2004

The incompressible Navier-Stokes equations in two dimensions are stabilized by a modified residual method, and then discretized by hierarchical elements. The stabilization is necessary to escape from the Ladyzhenskaya-Babuska-Brezzi(LBB) constraint and hence to achieve an equal order formulation. To expedite a standard iterative method such as the conjugate gradient squared(CGS) method, a preconditioning technique called the Hierarchical Iterative Procedure(HIP) has been applied. In this paper, we increased the order of interpolation within an element up to cubic. The hierarchical elements have been used to achieve a higher order accuracy in fluid flow analyses, but a proper efficient iterative procedure for higher order finite element formulation has not been available so far The numerical results by the present HIP for the lid driven cavity flow and others showed the present procedure to be stable, very efficient and useful in flow analyses in conjunction with hierarchical elements.

• 대한기계학회논문집
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• 제18권3호
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• pp.624-634
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• 1994

A numerical method which combines equal-order velocity-pressure formulation originated from SIMPLE algorithm and streamline upwinding method has been developed. To verify the proposed numerical method, we considered the lid-driven cavity flow and backward facing step flow. The trend of convergence history is stable up to the error criterion beyond which the maximum value of error is oscillatory due4 to the round-off error. In the present study, all results were obtained with the single precision calculation up to the given error criterion and it was found to be sufficient for our purpose. The present results were then compared with existing experimental results using laser doppler velocimetry and numerical results using finite difference method and mixed interpolation finite element method. It has been shown that the present method gives accurate results with less memories and execution time than the coventional finite element method.

• 한국정밀공학회지
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• 제18권6호
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• pp.182-187
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• 2001

Much research efforts have been made on the equal-channel angular pressing(ECAP)that produces ultra-fine grain size materials. Recently many materials have been tested for ECAP process, and in this paper pure-Zirconium is considered due to its applicability to nuclear reactors. Among many process parameters of ECAP, frictional effects on the deformation behavior of materials and on the stress distribution of die have been investigated. The finite element method has been employed in order to investigate this issue, and experiments have also been made to verify the numerical results.

• Journal of applied mathematics & informatics
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• 제29권5_6호
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• pp.1205-1219
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• 2011

In this work, a stabilized characteristic finite volume method for the time-dependent Navier-Stokes equations is investigated based on the lowest equal-order finite element pair. The temporal differentiation and advection term are dealt with by characteristic scheme. Stability of the numerical solution is derived under some regularity assumptions. Optimal error estimates of the velocity and pressure are obtained by using the relationship between the finite volume and finite element methods.

• 한국분말재료학회지
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• 제15권3호
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• pp.204-209
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• 2008

Aluminum alloys are not only lightweight materials, but also have excellent thermal conductivity, electrical conductivity and workability, hence, they are widely used in industry. It is important to control and enhance the densification behavior of metal powders of aluminum. Investigation on the extrusion processing combined with equal channel angular pressing for densification of aluminum powders was performed in order to develop a continuous production process. The continuous processing achieved high effective strain and full relative density at $200^{\circ}C$. Optimum processing conditions were suggested for good mechanical properties. The results of this simulation helped to understand the distribution of relative density and effective strain.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.409-412
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• 2000

Much research efforts have been made on the structure and properties of metals deformed to severe plastic deformation (SPD). Being deformed to SPD, ultra-fine grains (UFG) are usually formed, and UFG structure exhibits fundamental differences in original physical properties. One method often used to obtain SPD is equal channel angular pressing (ECAP). In order for this technique to be exploited, it is important to understand the deformation behavior during the ECAP processing with respect to friction. The finite element method (FEM) has been used to investigate this issue.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.514-518
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• 2004

This paper presents an algorithm generating inverse element over finite fields $GF(3^{m})$, and constructing method of inverse element generator based on inverse element generating algorithm. A method computing inverse of an element over $GF(3^{m})$ which corresponds to a polynomial over $GF(3^{m})$ with order less than equal to m-l. Here, the computation is based on multiplication, square and cube method derived from the mathematics properties over finite fields.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.768-771
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• 2008

본 논문에서는 유한체 $GF(3^m)$상에서의 역원을 효과적으로 생성할 수 있는 알고리즘을 제안하였으며, 이를 바탕으로 역원생성기를 구성하는 방법에 대해 논의하였다. 제안한 역원 생성기는 승산기, 출력레지스터 군, 승산 및 세제곱 선택 게이트와 순차선택기, 세제곱처리부, 내림차순 생성부 등으로 구성된다. 제안한 역원알고리즘과 역원생성기는 회로설계의 단순성, 규칙성, 확장성 및 모듈화 기능을 갖는다.