Parallel Finite Element Analysis System Based on Domain Decomposition Method Bridges

이준성,염곡 강이,이은철,이양창,Lee, Joon-Seong,Shioya, Ryuji,Lee, Eun-Chul,Lee, Yang-Chang Computational Structural Engineering Institute of 2009 한국전산구조공학회논문집 Vol.22 No.1

본 논문에서는 대규모 3차원 구조해석에 필요한 병렬 유한요소해석을 위한 영역분할법의 적용에 대해 묘사하였다. 영역분할법을 사용한 병렬 유한요소법 시스템을 개발하였다. 절점 생성시, 절점들간의 거리가 특정절점에서의 공간함수와 같아지면 절점이 생성되어 진다. 이 절점공간함수는 퍼지지식처리에 의해 조절되어 진다. 기본적인 요소생성은 데로우니 삼각화 기법을 적용하였다. 자동요소생성 시스템을 이용한 영역분할법은 3차원 해석에 큰 도움이 된다. 공간함수와 유사하게 절점들간의 유한요소해석을 위한 병렬 수치 알고리즘으로서 영역분할법을 전체의 해석영역을 완전히 여러 개의 작은 영역으로 겹치지 않게 나누는 공역구배인 반복적 솔버와 결합시켰다. 개발된 시스템의 효용성에 대한 성능을 몇 가지 예를 통해 제시하였다. This paper describes an application of domain decomposition method for parallel finite element analysis which is required to large scale 3D structural analysis. A parallel finite element method system which adopts a domain decomposition method is developed. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay triangulation method is introduced as a basic tool for element generation. Domain decomposition method using automatic mesh generation system holds great benefits for 3D analyses. Aa parallel numerical algorithm for the finite element analyses, domain decomposition method was combined with an iterative solver, i.e. the conjugate gradient(CG) method where a whole analysis domain is fictitiously divided into a number of subdomains without overlapping. Practical performance of the present system are demonstrated through several examples.

기능성 위장관 질환은 사라지는 진단명인가?

이준성 ( Joon Seong Lee ) 대한소화기학회 2006 대한소화기학회지 Vol.47 No.4

3차원 균열을 갖는 구조물에 대한 건전성 평가(II)

이준성(Lee, Joon-Seong) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.1

3차원 균열은 항공기나 압력용기 계통에서 흔히 발견되는 결함중의 하나이다. 균열을 갖는 구조물에 대한 정확한 응력확대계수 해석과 균열성장속도는 파괴강도와 피로수명을 평가하는데 필요로 한다. 3차원 유한요소법은 구 조물에 존재하는 표면균열의 응력확대계수를 구하는데 이용되어 진다. 기하모델, 즉 균열을 포함하는 솔리드모델을 정의한 후, 절점이 버켓법에 의해 생성되어 진다. 요소생성은 사변형 솔리드요소를 데라우니 삼각화 기술에 의해 생 성하도록 하였다. 시스템의 정확도와 효용성을 체크하기 위해 내압을 받는 원통형용기에 균열이 존재하는 경우의 응 력확대계수 해석을 수행하였다. 개발된 시스템을 이용한 해석결과는 ASME 식과 Raju-Newnam식과 비교하여 5%이내의 차이를 보였다. Three Surface cracks are among the more common flaws in aircraft and pressure vessel components. Accurate stress intensity analyses and crack growth rate data of surface-cracked components are needed for reliable prediction of their fatigue life and fracture strengths. Three Dimensional finite element method (FEM) was used to obtain the stress intensity factor for surface cracks existing in structures. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Nodes are generated by bucket method, and quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in cylindrical structures subjected to pressure is calculated. Analysis results by present system showed good agreement with those by ASME equation and Raju-Newman’s equation.

몬테카를로 시뮬레이션을 이용한 확률론적 파괴역학 수법의 적용성 검토

이준성(Joon-Seong Lee),곽상록(Sang-Log Kwak),김영진(Young-Jin Kim) Korean Society for Precision Engineering 2001 한국정밀공학회지 Vol.18 No.10

과민성 장증후군 / 새로운 약물치료

이준성 ( Joon Seong Lee ) 대한소화관운동학회 2002 대한소화관운동학회 춘계학술대회 Vol.14 No.-

비만과 위장관 운동

이준성 ( Joon Seong Lee ) 대한소화기학회 2006 대한소화기학회지 Vol.48 No.2

Gastrointestinal (GI) motility has a crucial role in the food consumption, digestion and absorption, and also controls the appetite and satiety. In obese patients, various alterations of GI motility have been investigated. The prevalence of GERD and esophageal motor disorders in obese patients are higher than those of general population. Gastric emptying of solid food is generally accelerated and fasting gastric volume especially in distal stomach is larger in obese patients without change in accommodation. Contractile activity of small intestine in fasting period is more prominent, but orocecal transit is delayed. Autonomic dysfunction is frequently demonstrated in obese patients. These findings correspond with increased appetite and delayed satiety in obese patients, but causes or results have not been confirmed. Therapeutic interventions of these altered GI motility have been developed using botulinum toxin, gastric electrical stimulation in obese patients. Novel agents targeted for GI hormone modulation (such as ghrelin and leptin) need to be developed in the near future. (Korean J Gastroenterol 2006; 48:89-96)

적합한 Epoxy 선정을 위한 EMC 모듈의 유한요소해석

이준성(Lee, Joon-Seong),홍희록(Hong, Hee-Rok),조계현(Jo, Gye-Hyeon),박동근(Park, Dong-Keun) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.11

스마트폰 배터리 사용시간이 짧아지는 문제의 해결방안으로 PMP(Protection Module Package)를 제안한다. PMP란 보호회로가 하나의 반도체로 구성하는 것을 의미한다. 이번 연구에서는 유한요소 해석을 통하여 EMC 모듈의 적합한 Epoxy 재질을 선정하기 위한 기반연구를 수행하였다. 먼저 굽힘강도 해석을 통하여 외부 힘에 대한 응력을 비교하였다. 다음 열해석 에서, 계산한 발열량을 사용하여 EMC 모듈의 내부 부품의 온도 변화를 비교한다. 마지막으로, 충전률은 EMC 모듈 내의 용융된 에폭시를 주입하여 비교하였다. The use of the PMP (Protection Module Package) was proposed as a solution for the shorter battery lifetime. The PMP means that a protection circuit consists of a semiconductor single. In this study, basic research was carried out to select a suitable epoxy material of the EMC module through finite element analysis. First, the stress on the external force was compared by the flexural strength analysis. In the following thermal analysis, the temperature change of the EMC module and the internal part was compared using the calculated heating value. Finally, the filling ratio was compared with the injection of the melting epoxy in the EMC module.

Mesh Generation Methodology for FE Analysis of 3D Structures Using Fuzzy Knowledge and Bubble Method

이준성(Joon-Seong Lee),이은철(Eun-Chul Lee) 한국지능시스템학회 2009 한국지능시스템학회논문지 Vol.19 No.2

본 논문은 3차원구조물의 유한요소해석을 위한 자동 유한요소 생성에 관한 것으로 퍼지이론과 버블요소 생성기법, 상용 솔리드모델러로 구성되어진다. 새로운 요소생성과정은 (a) 해석모델인 형상모델링 정의, (b) 버블생성, 그리고 (c) 요소생성으로 이루어진다. 형상모델링에는 상용 솔리드모델러를 이용하였으며 버블은 각 지점에서의 버블간격함수에 의해 생성되어진다. 버블간격 함수는 지식처리수법에 의해 조절되어 진다. 요소생성을 위해서는 기본적으로 데로우니방법을 도입하였다. 이러한 3차원 구조물에 대한 유한요소의 자동생성은 해석을 위해 큰 잇점이 있다. 실제적인 현 시스템의 효용성을 검증하기 위해 3차원 형상에 대한 예를 제시하였다. This paper describes an automatic finite element mesh generation for finite element analysis of three-dimensional structures. It is consisting of fuzzy knowledge processing, bubble meshing and solid geometry modeler. This novel mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of bubbles, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid structures. Bubble is generated if its distance from existing bubble points is similar to the bubble spacing function at the point. The bubble spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of finite element for three-dimensional solid structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for 3D geometry.

Development of the Fuzzy-Based System for3D FE Analysis

이준성(Joon-Seong Lee),이양창(Yang-Chang Lee),장윤석(Yoon-Suk Chang),최재붕(Jae-Boong Choi),박영재(Young-Jae Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

This paper describes a fuzzy-based mesh generation system for three-dimensional structures. The system allows a geometry model of concern to be automatically converted to different FE models, depending on physical phenomena to be analyzed, i.e. electrostatic analysis, stress analysis, modal analysis and so on. The FE models are then automatically analyzed. One of commercial solid modelers is employed for three-dimensional solid and shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy theory. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional solid and shell structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

중합효소 연쇄반응법 ( Polymerase Chain Reaction ) 을 이용한 Helicobacter pylori 의 검출

이준성(Joon Seong Lee),송동화(Dong Wha Song),박찬욱(Chan Wook Park),이문성(Moon Sung Lee),조성원(Sung Won Cho),심찬섭(Chan Sup Shim),진소영(So Young Jin) 대한내과학회 1995 대한내과학회지 Vol.49 No.3

N/A Objectives: Helicobacter pylri (H. pylori) infection is now known to be the major cause of chronic gastritis, and is strongly associated with peptic ulcer disease and gastric cancer. But no unanimity exists among investigators about which method represents an appropriate gold standard for diagnosing H. pylori infection. Polymerase chain reaction(PCR) has great potential for improving the ability to diagnose infectious diseases caused by fastidious or slow growing bacterias. But its clinical usefulness as a diagnostic tool for H. pylori is uncertain. Methods: We performed endoscopic biopsy of stomach (>3 pieces, at antrum) for the rapid urease test (CLO stain) and PCR in 11 patients with duodenal ulcer, 2 patients with gastric ulcer, 3 patients with combined gastric and duodenal ulcer, 2 patients with gastric cancer, and 12 patients with gastritis. In preliminary study, endoscopic instruments were tested for residual H. pylori using PCR after combined manual and machine-cleaning and ultrasonic washing with disinfection in 5 patients with positive CLO test. Gastric biopsy tissues were digested in proteinase K(F.C.: 500pl/ml) for DNA extraction, and PCR amplification was performed by using 20 base oligonucleotide primers(CAM 2, CAM 4) homologous to a portion of the 1.9-kb fragment. PCR assay amplified a 203 bp product which was analyzed by agarose gel electrophoresis. Results: 1) in preliminary study, H. pylori were detected by PCR in 4 postendoscopic samples of working channels and biopsy forceps of 2 patients, and 1 preendoscopic sample of biopsy forceps, 2) Of the 30 patients, 19(63.3%) were positive for H. pylori by PCR, 17(56.7%) were positive by CLO test and silver staining. 3) The grade of severity of gastritis on H-E stain was well correlated with the grade of H. pylori infection on Warthin-Starrry silver stain(r=0.651, p<0.01). 4) Discordant results between PCR & other diagnostic tools were 3 cases. Repeat PCR tests disclosed the same results. Conclusion: PCR test of H. pylori is the most sensitive and reproducible test and can overcome the disadvantages of other diagnostic techniques showing less sensitivity and specificity, but it must be dealt with caution of instrumental contamination.