• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.5
• /
• pp.629-635
• /
• 2010

An SGBEM (symmetric Galerkin boundary element method)-FEM alternating method has been proposed by Nikishkov, Park and Atluri. This method can be used to obtain mixed-mode stress intensity factors for planar and nonplanar three-dimensional cracks having an arbitrary shape. For field applications, however, it is necessary to verify the accuracy and consistency of this method. Therefore, in this study, we investigate the effects of several factors on the accuracy of the stress intensity factors obtained using the abovementioned alternating method. The obtained stress intensity factors are compared with the known values provided in handbooks, especially in the case of internal and external circumferential semi-elliptical surface cracks. The results show that the SGBEM-FEM alternating method yields accurate stress intensity factors for three-dimensional cracks, including internal and external circumferential surface cracks and that the method can be used as a robust crack analysis tool for solving field problems.

• Journal of Elementary Mathematics Education in Korea
• /
• v.15 no.1
• /
• pp.77-93
• /
• 2011

Jisuguimundo(地數龜文圖) is a magic hexagon created by Suk-Jung Choi in his book about three hundreds years ago in Korea. Recently attention is focused on jisuguimundo, and it is known that jisuguimundos exist when magic number is from 77 to 108, however a general method making jisuguimundos is not known so far. Up to now, methods of making jisuguimundos using computers are known. In this study, a method making jisuguimundos is suggested using pairs of two numbers with sum p and q ($p{\neq}q$) alternately when magic number is from 88 to 92, and from 94 to 98, without using computer in elementary math class as a task for problem solving. Mathematical theory is introduced for this method, and jisuguimundos are presented which are found out through this method. Elementary students are expected to make their own jisuguimundo using this method.

• The Korean Journal of Applied Statistics
• /
• v.7 no.2
• /
• pp.201-211
• /
• 1994

Ignoring interaction effects has been pointed out to be one of serious drawbacks in analysis of the parameter designs which are constructed by using orthogonal arrays. In this paper a detecting procedure of influential 2-factor inteactions with minimum expeimental runs is described, when each contrl factor has two levels. The presented method is based on the near orthogonal arrays which are very similar to orthogonal arrays in the statistical structure. And those arrarys are the same as trace-optimal balanced saturated two-level fractional factorial designs of resolution V.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.124-129
• /
• 2004

Finite element alternating method have been suggested and used for assessing the integrity of cracked structures. In the paper, in order to analyze arbitrarily shaped three dimensional cracks, the finite element alternating method is extended. The cracks are modeled as a distribution of displacement discontinuities by the displacement discontinuity method and the symmetric Galerkin boundary element method. Applied the proposed method to three dimensional crack included in the elbow, the efficiency and applicability of the method were demonstrated.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.278-283
• /
• 2004

Many analysis methods, including finite element method, have been suggested and used for assessing the integrity of cracked structures. In the paper, in order to analyze arbitrarily shaped three dimensional cracks in an infinite body, the finite element alternating method is extended. The cracks are modeled as a distribution of displacement discontinuities by the displacement discontinuity method and the symmetric Galerkin boundary element method. Applied the proposed method to several example problems for planner cracks in finite bodies, the accuracy and efficiency of the method were demonstrated.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.12
• /
• pp.3838-3846
• /
• 1996

A method is proposed to obtain the stress intensity factors of multiple cracks lying on many straight llnes in an infinite isotropic plate. In this mehtod, analytical solutions for collinear multiple cracks subject to surface point forces are obrained and used as Green functions. For the multiple cracks lying onmany straight lines, the equivalent crack surface tractions are obtained by using the alternating method and the stress intensity factors are calculated. By using the proposed method several useful problems are solved and discussed.

• Communications for Statistical Applications and Methods
• /
• v.5 no.3
• /
• pp.633-644
• /
• 1998

혼합설계의 교호작용에 대한 F 검정이 유효하려면 다표본 구형성(multisample sphericity) 가정과 다변량 정규분포 가정이 만족되어야 한다. F 검정을 실시하기 위한 가정들이 위반된 조건하에서 혼합설계의 교호작용에 대한 검정법들의 1종오류가 비교되었다. 비교된 검정법들은 (1) F 검정(F), (2) 절사평균을 사용한 F 검정($F_T$)(3)$\varepsilon$-수정 F 검정($\varepsilon)$(4) 절사평균을 사용한 $\varepsilon$-수정 F 검정$(\varepsilon_T$) (5) CIGA검정(CIGA), (6) 절사평균을 사용한 CIGA검정($CIGA_T$)이었다. 결과는 CIGA와 $CIGA_T$는 1종오류를 대체로 잘 관리하나, F검정들과 ($\varepsilon$)검정들은 일부 조건에서 아주 작은 1종오류나 아주 큰 1종오류를 갖는 것으로 나타났다.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2004.04a
• /
• pp.387-392
• /
• 2004

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.10
• /
• pp.1009-1016
• /
• 2007

Finite element alternating method has been suggested and used effectively to obtain the fracture parameters in assessing the integrity of cracked structures. The method obtains the solution from alternating independently between the FEM solution for an uncracked body and the crack solution in an infinite body. In the paper, the finite element alternating method is extended in order to obtain the elastic-plastic stress fields of a three dimensional inner crack. The three dimensional crack solutions for an infinite body were obtained using symmetric Galerkin boundary element method. As an example of a three dimensional inner crack, a penny-shaped crack in a finite body was analyzed and the obtained elastc-plastic stress fields were compared with the solution obtained from the finite element analysis with fine mesh. It is noted that in the region ahead of the crack front the stress values from FEAM are close to the values from FEM. But large discrepancy between two values is observed near the crack surfaces.

• Korean Journal of Environment and Ecology
• /
• v.13 no.3
• /
• pp.220-233
• /
• 1999

본 연구는 서열법(교호평균법)과 ZM학파의 식물사회학적 연구방법에 의해 대구, 구미, 김천 근처의 팔공산, 금오산, 황악산 일대의 참나무류 삼림을 분류하고 그 환경조건을 해석할 목적으로 실시되었다 교호평균법에서 추출된 stand의 제 1축상의 종의 배열은 식물사회학적 군락분류의 표징종이나 식별종의 후보 종군을 추출하는데 매우 효과적이었다. 이결과와 타지역과 본 연구지역의 낙엽수림의 조성을 비교 검토한 결과 이하의 2군집, 1군락, 2아군집을 식별하였다. 너도밤나무군강(Fagetea crenatae Miyawaki et al. 1968) ; 당단풍-신갈나무목(Acero-Quercetalia mongolicae Song 1988); 조록싸리-졸참나무군단(Lespedezo-Quercion ser-1-1 때죽나무아군집(Styracetosum japonicae subassoc. nov) 1-2 전형아군집(typicum subassoc. ) (Ainsliaeo-Quercetum mongolicae assoc. nov.) 3. 신갈나무-시닥나무군락(Quercus mongolica-Acer teschonoskii var, rubripes community) 본연구에서 식별된 군단은 우리나라의 냉온대 낙엽활엽수림의 북부형과 남부형에 대응하는 것으로 해석되었다. 서열법에 의해 계산된 제 1축과 제2축상에의 stand의 배열은 인위와 해발과 같은 환경경도상의 계열을 나타내었다. 이상의 연구와 함께 본 연구와 관련되는 사항으로 우리나라의 냉온대림의 군락분류학적 문제점을 종조성론의 입장에서 논하였다.