• Journal of information and communication convergence engineering
• /
• 제8권3호
• /
• pp.317-322
• /
• 2010

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. An inverse computing method of an element over GF($3^m$) which corresponds to a polynomial over GF($3^m$) with order less than equal to m-1. Here, the computation is based on multiplication, square and cube method derived from the mathematics properties over finite fields.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 학술대회지
• /
• pp.514-518
• /
• 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
• /
• 한국해양정보통신학회 2008년도 추계종합학술대회 B
• /
• pp.768-771
• /
• 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.

• 소성∙가공
• /
• 제16권8호
• /
• pp.590-595
• /
• 2007

This paper introduces a new approach to take account of bending history in finite element inverse analysis during sheet metal forming process. A modified membrane element was adopted for finite element inverse analysis so that bending-unbending energy was additionally imposed in the total plastic energy, predicting bending-unbending regions using the geometry of the final shape and tools. An algorithm was applied to a cylindrical cup deep drawing process. The blank shape and the distribution of the thickness strain were compared with those obtained from the incremental finite element analysis in order to evaluate the effect of the bending history. The algorithm reduced the difference between the results of the inverse analysis from those of the incremental analysis due to bending history. The analysis was also carried out with the variation of the thickness of the initial blank to investigate the effect of bending deformation. The results showed that the difference was remarkably reduced as the thickness of the initial blank increased. This indicates that the finite element inverse analysis cooperated with the suggested scheme is useful to obtain more accurate results, especially when bending effects are significant.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2001년도 추계학술대회 논문집
• /
• pp.81-84
• /
• 2001

An inverse finite element approach is employed for more capability to design the optimum blank shape from the desired final shape with small amount of computation time and effort. In some drawing or stamping simulation with inverse method, it is difficult to apply inverse scheme due to the large aspect ratio or steep vertical angle of inclination. The reason is that initial guesses are hard to make out with present method for those cases. In this paper, a direct mesh marring scheme to generate initial guess on the sliding constraint surface described by finite element patches is suggested for one step inverse analysis to calculate initial blank shape. Radial type mapping is adopted for the simulation of rectangular cup drawing process with large aspect ratio and parallel type mapping for the simulation of S-Rail forming process with steep vertical angle of inclination.

• 소성∙가공
• /
• 제9권3호
• /
• pp.304-312
• /
• 2000

An inverse finite element approach is employed to efficiently design the optimum blank shape and intermediate shapes from the desired final shape in multi-stage elliptic cup drawing processes. The multi-stage deep-drawing process is difficult to design with the conventional finite element analysis since the process is very complicate with the conventional finite element analysis since the process is very complicated with intermediate shapes and the numerical analysis undergoes the convergence problem even with tremendous computing time. The elliptic cup drawing process needs much effort to design sine it requires full three-dimensional analysis. The inverse analysis is able to omit all complicated and tedious analysis procedures for the optimum process design. In this paper, the finite element inverse analysis provides the thickness strain distribution of each intermediate shape through the multi-stage analysis. The multi-stage analysis deals with the convergence among intermediate shapes and the corresponding sliding constraint surfaces that are described by the analytic function of merged-arc type surfaces.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2007년도 춘계학술대회 논문집
• /
• pp.340-343
• /
• 2007

This paper introduces a new approach to consider the bending history in finite element inverse analysis of the cylindrical cup drawing. A modified membrane element is adopted to add the bending-unbending energy to the total plastic energy on the bending-unbending region predicted from the geometry of the final shape and tools. The algorithm suggested was applied to a cylindrical cup deep drawing process. The blank shape and the distribution of the thickness strain are compared with those obtained from incremental finite element analysis. The comparison demonstrates the algorithm proposed reduces the difference between the results from inverse analysis and those from incremental analysis when the bending history is considered.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2009년도 IWAIT
• /
• pp.684-688
• /
• 2009

In this paper, it proposes the technique to restore from a binary image in the color image. The color image is composed of three element images of red, green and blue. Therefore, the color image is first divided into a red, green, and blue element, and the Inverse Halftoning[2]$\sim$[4] is processed to each element images. Finally, each element images is collectively displayed. In that case, the Kalman filter was applied to the Inverse Halftoning for the restoration accuracy improvement of the image. As a result, it was possible to restore it in the color image as well as the time of a monochrome image. Moreover, the result that the restoration accuracy had improved even when which combining with the technique by using the Kalman filter for the Inverse Halftoning so far came out.

• 소성∙가공
• /
• 제11권5호
• /
• pp.457-464
• /
• 2002

A finite element inverse analysis is utilized to consider forming effects of an S-rail on the assessment of the crashworthiness with small amount of computation time. A crash analysis can be directly performed after the inverse simulation of a forming process without a smoothing or remeshing scheme. The direct mesh mapping method is used to calculate an initial guess from a sliding constraint surface that is extracted from the die and punch set. Analysis results demonstrate that energy absorption of structures is increased when simulation considers forming effects of thickness variation and work hardening. The finite element inverse analysis is proved to be an effective tool in consideration of forming effects for the crash analysis.

• Structural Engineering and Mechanics
• /
• 제88권1호
• /
• pp.83-94
• /
• 2023

An accurate and highly efficient inverse element labelled iPCB is developed based on the inverse finite element method (iFEM) for real-time shape estimation of plane-curved structures (such as arch bridges) utilizing onboard strain data. This inverse problem, named shape sensing, is vital for the design of smart structures and structural health monitoring (SHM) procedures. The iPCB formulation is defined based on a least-squares variational principle that employs curved Timoshenko beam theory as its baseline. The accurate strain-displacement relationship considering tension-bending coupling is used to establish theoretical and measured section strains. The displacement fields of the isoparametric element iPCB are interpolated utilizing nonuniform rational B-spline (NURBS) basis functions, enabling exact geometric modelling even with a very coarse mesh density. The present formulation is completely free from membrane and shear locking. Numerical validation examples for different curved structures subjected to different loading conditions have been performed and have demonstrated the excellent prediction capability of iPCBs. The present formulation has also been shown to be practical and robust since relatively accurate predictions can be obtained even omitting the shear deformation contributions and considering polluted strain measures. The current element offers a promising tool for real-time shape estimation of plane-curved structures.