Explicit Simulation of Roll Forming Process with EAS Solid-shell Elements

L.M. Lia,Y.H. Peng,D.Y. Li 한국소성가공학회 2010 기타자료 Vol.2010 No.6

Solid-shell elements can be seen as a class of typical double-surface shell elements with no rational degrees of freedom, which are more suitable for analyzing double-sided contact problems than conventional shell elements. In this study, an EAS-based solid-shell element is implemented into the explicit finite element formulation to simulate roll forming process. A twelve-parameter enhanced assumed strain (EAS) method is adopted to solve for the locking pathologies. Accuracy of the explicit solid-shell finite element model is excised through two NUMISHEET benchmark tests. Afterwards, a U-channel forming is simulated with the present explicit model. Numerical results of longitudinal strains and final geometries are compared with experiment as well as calculated by the commercial software ABAQUS. The solid-shell element is found more applicable in dealing with roll-forming process than ABAQUS inherent elements. Potential of the explicit solid-shell model in analyzing cold roll forming process is confirmed.

New Solid-Shell Finite Element Based on EAS and ANS Concepts for Sheet Metal Forming

A. Ben Bettaieb,L. Duchene,L. Zhang,A.M. Habraken 한국소성가공학회 2011 기타자료 Vol.2011 No.8

We present in this paper a new eight node solid-shell finite element called SSH3D (Three Dimensional Solid-Shell). This element is currently implemented in the frame of the in-house research code called LAGAMINE. Here the Enhanced Assumed Strain (EAS) technique based on the Hu-Washizu variational principle, described in [1] and [2], is used to cure the volumetric locking occurring when the material shows nearly incompressible behavior and Poisson’s thickness locking caused by the high aspect ratio of the finite element. In the proposed element, the EAS technique can be combined with the Assumed Natural Strain (ANS) [3-5] concept to treat shear locking caused by the transverse shear strain and curvature thickness locking caused by the transverse normal strain. Different schemes for the ANS concept are implemented while the number of integration points and the number of EAS modes are element parameters (the element uses four integration points in the plane of the element and at least two integration points through the thickness direction in a single element layer). These features must be adjusted by the user according to the studied process (geometry and loading) so as to avoid locking and limit the calculation time. This element was successfully tested and the numerical remedies were verified using several kinds of patch tests. A double sided contact problem is modeled in order to investigate the performance and accuracy of the developed element and to validate the suggested approach.

조선시대 한글 서체의 微加減法에 관한 고찰

정복동(Jeong, Bokdong) 한국서예학회 2015 서예학연구 Vol.27 No.-

본고는 조선시대 한글서체가 생성․변천한 원인을 규명하는 기초적인 토대를 마련하는 연구이다. 한글서체가 생성․발전․변화해온 근저에는 훈민정음의 제자원리인 ‘倣’과 밀접한 관련이 있다. 정인지는 ‘훈민정음해례’ 후서에서 “세종대왕께서 창제한 ‘훈민정음’ 28 자는 ‘象形而字倣古篆’이라”고 밝혔다. 이는 문자의 기능과 예술적 감각 그리고 백성 의 편의성을 고려한 과학적이며 독창적인 자형이 상형성과 고전모방설에 있다는 것을 의미한다. 심층적으로는 철학적인 태극, 음양오행, 사계절이 循環無斷하는 원리 가 제자원리에 적용되었음을 밝힌 것이기도 하다. 이와 같이 문자의 제자가 象形性, 古篆模倣性, 자연과 철학적 이치 등이 복합적으로 제시되어 있는데, 이에 대한 서체의 조형적 근거를 ‘因文成象圖’에 제시된 ‘한자 의 전서를 만드는 방법 중에서 加와 微加減法이 훈민정음 제자와 관련된다’는 새로운 학설이 발표되었다. 서체의 임모와 창작에서 자형이 만들어진 원리와 변화된 이치는 한글 서예 미학의 중요한 준칙이 된다. 이에 자음의 기본자에 가획을 하여 만든 ‘ㄹ ㅂ ㅍ ㅊ ㅎ’의 자형이 세로획 미가법을 적용한 것을 근거 자료로 선별하여, 조선시대 한글 서체인 판본류와 필사류의 자형에 ‘미가감법’이 구체적으로 어떻게 반영되었는지에 대한 원인을 규명하였다. 연구방법은 조선시대 한글 문헌인 판본류 28종과 필사류 38종을 시기별로 선별하여 훈민정음 자형과 비교하였다. 분석 방법으로 미가법이 적용된 것은 ‘미’, 미가 법에 가까운 것은 근취의 ‘근’, 미가법에서 먼 것은 원취의 ‘원’으로 규정하여, 초성 의 좌측과 상측, 종성을 각각 분석하였다. 아울러 자형이 변화된 것은 ‘변’으로 규정하여 한글 변천의 특징을 파악하였다. 이에 시기별로 구분하고 이를 백분율로 통계한 결과 한글 자형의 변천을 통시적으로 파악할 수 있었다. 15세기 중엽 훈민정음 창제 이후 한글 자형의 모습은 판본 류와 필사류에 따라 변별성이 있으며, 정자, 흘림, 진흘림으로 다양하게 변화하였다. 판본 문헌은 가독성과 시각적 명확성에 충실하여 필사류의 표준 자형의 기능이 있다. 필사류는 필사의 효율성에 따라 실용성에서 점차 예술적 미감이 더해져 하나의 통일된 양식의 궁체가 생성되었다. 따라서 궁체의 생성은 하루아침에 이루어진것이 아니라 선인들이 15세기부터 판본 문헌의 정형적 자형을 토대로 삼아, 16세기 이후 필사자의 개인별 미적경험에 따라 점선면의 분간포백에 대한 변화 혹은 통일에 의한 결과이다. 흘림 자형은 각각 독립적으로 나타난 변화의 과정에서 나타난 것이기보다는 음절 구조를 풀어쓰면 속도가 느리기 때문에 한글자 내에서 서로 긴밀하게 연관되어 필 획의 연결성을 효율적으로 이용하면서 미적 발전을 도모한 결과이다. 이는 당시 필사자들이 단순히 내용을 기록하기 위한 한글 사용에서 탈피하여 자소․점획의 형태와 크기․위치 등을 다양하게 변형시키면서 새로운 자형과 서체를 개발하기 위해 끊임없 이 노력한 것을 알 수 있다. 만물이 각각 그 마땅한 곳에서 자신만의 색채를 띠는 것과 같이 한글 편지의 자 형은 각각 成於自然을 본받은 듯하다. 특히 궁체 형성의 토대를 훈민정음 창제 당시 의 ‘미가법’에 의한 공간 변화로써 응용한 것은 마치 사계절이 끊임없이 순환하는 [物極必反] 이치와 같은 원리를 담으려는 노력이 배어있다. 본 연구의 활용성은 조선시대 5백여 년간 서예사적으로 변천된 자료를 토대로 분석한 것이므로 한글 서체의 조형적 근거와 ‘變’과 ‘化’의 규칙을 파악하여 예술성을 높일 수 있는 근거를 제시할 뿐만 아니라 한글 서예 창작의 영감을 얻을 수 있는 자료가 될 것이다. 그리고 ‘미가법’의 변화를 파악하여 한글 서예가 취상한 자연의 법칙을 관찰하는 것은 훈민정음 자형이나 한글 서체를 시각․조형적인 면에서 실용화하 는 중요한 방안일 뿐 아니라 한글의 예술화 방안을 모색하는 중요한 밑거름이 될 것이다. 나아가 한글서예의 우수성과 아름다운 조형을 제시함으로써 교과서의 참고 자료와 미술대학, 서예대학의 임모자료 및 대학원생의 미학 연구의 대상 자료로 활 용될 수 있을 것이다. This study fundamentally investigated the cause how Hangul chirography in Joseon was created and has been changed. The foundation that Hangul chirography was created, developed and changed is closely related to the creating principle of Hunminjeongeum. Jeong, Inji specified that 28 letters of Hunminjeongeum, King Sejong created, were ‘ 象形而字倣古篆 (It assumed the form, and the letters emulated the old seal script.)’ in the second epistle of ‘Hunminjeongeum Haerye’. It shows that the scientific and creative shape of characters, which considers the function of characters, the artistic sense and the public convenience, is based on the pictogram and the theory of emulation of the old seal script. On the other hand, it was recorded in the creating principle that the constant circulating principle of the Great Ultimate as a philosophical principle, Yinyang and the five elements and four seasons was applied in Hunminjeongeum. As above, the creation of letters is based on the pictogram, the theory of emulation of the old seal script, the nature and the philosophical principle. Therefore, a new theory has been released that the creating principle of Hunminjeongeum was related to and based on Ga( 加 , adding) and Miga·gam method(method with slightly adding or subtracting), one of the creating method of the seal script in Chinese characters, which was suggested in ‘Yīnwénchéngxiàngtú( 因文成象圖 , a figure which shows that an image is completed by a pattern)’. The basis that the shape of characters was created and the principle that it has been changed in the process of imitating and creating chirography were very important regulations in Hangul chirography aesthetics. Thus, this study concentrated on ‘ ㄹ ㅂ ㅍ ㅊ ㅎ ’ which have been changed in shape and aimed to understand how the Miga·gam method of vertical stokes concretely applied the handwritings for block-printing and manuscripts, which are Hangul chirography in Joseon. This study compared the shape of characters of ‘ ㄹ ㅂ ㅍ ㅊ ㅎ ’ sorted according to the times from 28 kinds of block-printed book and 38 kinds of manuscripts, Hangul literature in Joseon, with that of characters in Hunminjeongeum. It analyzed each left and upper part of an initial consonant and a final consonant by defining that Miga method was applied as ‘Mi( 微 , slight)’, close to Miga method as ‘Geun( 近 , close)’ and far from Miga method as ‘Won( 遠 , far)’. In addition, it investigated the features that Hangul has been changed by defining that the shape of characters has been changed as ‘Byeon( 變 , change)’. The block-printed literature is substantial in readability and visual clarity, so it could function as a standard shape of characters of handwritings in manuscripts. Handwritings in manuscripts have been developed to Gungche(the court style of Hangul), which had one unified style, by adding an artistic sense of beauty according to the efficiency of handwritings. Therefore, Gungche was not created in a day. The foregoers have achieved it by changing or unifying the structure and the arrangement of dots, lines and faces according to their individual aesthetic experiences based on the standardized shape of characters in manuscript literature since 15th century. It could be discovered that the shape of characters in cursive style has not been independently changed, but aesthetically developed by efficiently using the connectivity of strokes closely connected to each other in a letter because the writing speed was too slow when writing the structure of syllables separately. The writers have broken away from using Hangul for simply recording contents, and they have constantly tried to develop a new shape of characters and a new handwriting style by variously changing the shape, size and position of consonants, dots and strokes.

GPU-Based ECC Decode Unit for Efficient Massive Data Reception Acceleration

( Jisu Kwon ),( Moon Gi Seok ),( Daejin Park ) 한국정보처리학회 2020 Journal of information processing systems Vol.16 No.6

In transmitting and receiving such a large amount of data, reliable data communication is crucial for normal operation of a device and to prevent abnormal operations caused by errors. Therefore, in this paper, it is assumed that an error correction code (ECC) that can detect and correct errors by itself is used in an environment where massive data is sequentially received. Because an embedded system has limited resources, such as a lowperformance processor or a small memory, it requires efficient operation of applications. In this paper, we propose using an accelerated ECC-decoding technique with a graphics processing unit (GPU) built into the embedded system when receiving a large amount of data. In the matrix-vector multiplication that forms the Hamming code used as a function of the ECC operation, the matrix is expressed in compressed sparse row (CSR) format, and a sparse matrix-vector product is used. The multiplication operation is performed in the kernel of the GPU, and we also accelerate the Hamming code computation so that the ECC operation can be performed in parallel. The proposed technique is implemented with CUDA on a GPU-embedded target board, NVIDIA Jetson TX2, and compared with execution time of the CPU.