PERFORMANCE ENHANCEMENT OF PARALLEL MULTIFRONTAL SOLVER ON BLOCK LANCZOS METHOD

Wanil BYUN,Seung Jo KIM 한국산업응용수학회 2009 Journal of the Korean Society for Industrial and A Vol.13 No.1

The IPSAP which is a finite element analysis program has been developed for high parallel performance computing. This program consists of various analysis modules ? stress, vibration and thermal analysis module, etc. The M orthogonal block Lanczos algorithm with shiftinvert transformation is used for solving eigenvalue problems in the vibration module. And the multifrontal algorithm which is one of the most efficient direct linear equation solvers is applied to factorization and triangular system solving phases in this block Lanczos iteration routine. In this study, the performance enhancement procedures of the IPSAP are composed of the following stages: 1) communication volume minimization of the factorization phase by modifying parallel matrix subroutines. 2) idling time minimization in triangular system solving phase by partial inverse of the frontal matrix and the LCM (least common multiple) concept.

Buckling analysis and optimal structural design of supercavitating vehicles using finite element technology

Wanil Byun,김민기,박국진,김승조,Minho Chung,Jin Yeon Cho,Sung-Han Park 대한조선학회 2011 International Journal of Naval Architecture and Oc Vol.3 No.4

The supercavitating vehicle is an underwater vehicle that is surrounded almost completely by a supercavity to reduce hydrodynamic drag substantially. Since the cruise speed of the vehicle is much higher than that of conventional submarines, the drag force is huge and a buckling may occur. The buckling phenomenon is analyzed in this study through static and dynamic approaches. Critical buckling load and pressure as well as buckling mode shapes are calculated using static buckling analysis and a stability map is obtained from dynamic buckling analysis. When the finite element method (FEM) is used for the buckling analysis, the solver requires a linear static solver and an eigenvalue solver. In this study, these two solvers are integrated and a consolidated buckling analysis module is constructed. Furthermore, Particle Swarm Optimization (PSO) algorithm is combined in the buckling analysis module to perform a design optimization computation of a simplified supercavitating vehicle. The simplified configuration includes cylindrical shell structure with three stiffeners. The target for the design optimization process is to minimize total weight while maintaining the given structure buckling-free.

성층권 태양광 무인기 개발 동향

변완일(Byun, Wanil),김종범(Kim, Jong-bum),황진영(Hwang, Chin-young) 한국항공우주연구원 2015 항공우주산업기술동향 Vol.13 No.2

2000년대 접어들면서 복합재료, 태양전지판, 배터리 기술의 발전으로 인하여 성층권 영역에서 태양에너지를 동력원으로 장기간 체공하면서 정찰 · 감시, 통신 등의 임무를 수행하는 개념의 초경량 무인기 연구들이 진행되었고, 영국의 QinetiQ는 2010년 최대 고도, 체공 시간에 관한 최고기록을 수립하며 실현 가능성을 입증하였다. 이를 계기로 거대 인터넷 기업인 구글과 페이스북 또한 미래의 먹거리로 범지구적 무선인터넷 인프라를 구축하는 계획을 발표하였고, 이 계획의 핵심인 성층권 영역에는 태양광 무인기를 활용하기 위하여 적극적인 연구개발을 수행하고 있다. 이 계획의 핵심인 성층권 영역에는 태양광 무인기를 활용하기 위하여 적극적인 연구개발을 수행하고 있다. 본 논문에서는 무선인터넷을 중심으로 향후 활용 가능성이 높은 성층권 장기체공 태양광 무인기의 개발 동향을 조사하여 보았다. Since the 2000s, due to the advancement of composite materials, solar panel and battery, the ultra-light solar powered UAV with long endurance which has missions such as R&S(reconnaissance & surveillance) and communication in the Stratosphere have been studied. And UK’s QinetiQ showed the feasibility by establishing the world records about the absolute altitude and duration in 2010. It triggered that Google and Facebook announced projects to construct global wireless internet infrastructure. And these projects are also including researches of the UAV for the Stratosphere flight. In this paper, we thus surveyed these UAVs which are expected in the foreseeable future.

국내 항공우주산업의 현황과 전망

변완일(Byun, Wanil) 한국항공우주연구원 2014 항공우주산업기술동향 Vol.12 No.1

최근 우리나라는 고부가가치인 항공우주산업의 진흥과 관련된 많은 정책들과 함께 미래 경제 발전을 모색하고 있다. 진입장벽이 다른 산업에 비해 높다는 단점 때문에 정부차원의 산업육성이 요구되는 항공우주산업은 경제 성장뿐만 아니라 국가 방위와 품격과도 관계된 전략적 산업으로서 매우 중요하다. 과거, 군과 정부의 수요에만 거의 의존하였던 국내 항공우주산업은 완제기 수출과 보잉, 에어버스와의 RSP(Risk Sharing Partner)참여로 한계를 극복하고 있다. 또한 고해상도 지구 관측 위성과 정지궤도 통신해양기상위성의 개발경험을 기반으로 인공위성의 해외 수출도 이루어졌으며, 인공위성 운용으로 창출되는 영상 데이터, 기상 정보, 통신 서비스 등으로 많은 매출을 올리고 있다. 이와 관련하여, 본 논문은 먼저 세계 시장에서의 국내 항공 우주산업의 위치를 알아보고, 국내 항공우주의 산업체의 현재 상황을 분석하였다. 그리고 정부 정책 및 시장상황을 고려한 향후 산업체의 발전 방향을 모색하였다. Recently, in South Korea, it is seeking for economic growth with many policies related in the promotion of a high value-added aerospace industry. Because barriers to entry is higher than other industries, the development of this industry is required to support at the government level, and it is important as a strategic industry involved economic growth, as well as national defense and dignity. In the past, domestic aerospace industry depended on demands of military and government. But they have overcome the limitation to participate in RSP with Boeing and Airbus. They also try to export satellites based on their development experience and make profits with image data, meteorological information and communication service through satellite operation. In this paper, at first, we analysed current position of the domestic aerospace industry in the global market, and looked for direction of improvement considered with government policy and market condition.

STRUCTURAL OPTIMIZATION FOR STATIC AND DYNAMIC BUCKLING BEHAVIOR USING PARTICLE SWARM ALGORITHM

Kook-Jin Park,Wanil Byun,Yong-Jin Park,Seung Jo Kim 한국산업응용수학회 2011 한국산업응용수학회 학술대회 논문집 Vol.6 No.2

To design aircraft and rocket, it should be guaranteed that the structures receiving compressive forces are buckling free. Meanwhile, since the cost is deeply related to the total mass of structure system, the minimization of mass is very important issue. In order to achieve best structural design, parametric studies are usually conducted. But it requires tedious efforts. Therefore, we implemented optimization frame-work based on GUI environment so that once initial design was accomplished, it is automatically improved to have better fitness. Critical buckling load calculated using static buckling analysis and stability region obtained by dynamic buckling analysis are used as constraint. These buckling analysis codes are in-house finite element program called IPSAP. Particle swarming optimization algorithm, which is based on the social behavior metaphor, is gaining attention as non-gradient based global optimization method. So, it is suitable for these FE analysis. All of those user interface were implemented with Open-CASCADE which is based on OpenGL library.

초공동 운동체 구조물의 동적 불안정성 연구

김승조(Seung Jo Kim),변완일(Wanil Byun),장채규(Chae Kyu Jang),조진연(Jin Yeon Cho) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.5

초공동 수중 운동체의 구조물은 수중 운동 시에 유동 마찰에 의해 생성되는 높은 축 방향 하중과 추력의 조합에 의해 좌굴 현상이 발생하게 되며, 이는 구조물의 손상과 연결된다. 따라서 운용하고자 하는 수동 운동체의 속도 범위에서 이러한 좌굴이 발생되지 않도록 구조 설계가 요구되며, 이는 유한요소 해석을 이용한 정적 및 동적 좌굴 해석으로 좌굴 예측이 가능하다. 본 연구에서는 이러한 좌굴 해석을 위한 기초적인 소개와 유한요소 좌굴 해석에 필요한 고유치 해법을 소개하고, 좌굴 해석에 앞서 고유치 해법을 통한 고유 진동수 및 모드 형상을 DIAMOND/IPSAP 프로그램을 통해 예측하여 보았다. Supercavitating vehicles which cruise under water undergo high longitudinal force caused by thrust and drag. These combination may cause structural buckling. Static and dynamic buckling analysis method by using FEM can be used to predict this structural failure behavior. In this paper, some principles which include method for solution eigenvalue problem for buckling analysis are introduced. And before buckling analysis, we predicted some mode shape and natural frequency of cylindrical shell by using DIAMOND/IPSAP eigen-solver.

항공 분야 연구개발의 경제사회적 파급 효과 분석

정호진(Hojin Jung),장태진(Taejin Chang),최우영(Woo-young Choi),변완일(Wanil Byun),김종범(Jong-Bum Kim) 한국항공우주학회 2016 한국항공우주학회 학술발표회 논문집 Vol.2016 No.4

Experimental study on dynamic buckling phenomena for supercavitating underwater vehicle

Minho Chung,Hee Jun Lee,Yeon Cheol Kang,Woo-Bin Lim,김정호,조진연,Wanil Byun,Seung Jo Kim,Sung-Han Park 대한조선학회 2012 International Journal of Naval Architecture and Oc Vol.4 No.3

Dynamic buckling, also known as parametric resonance, is one of the dynamic instability phenomena which may lead to catastrophic failure of structures. It occurs when compressive dynamic loading is applied to the structures. Therefore it is essential to establish a reliable procedure to test and evaluate the dynamic buckling behaviors of structures, especially when the structure is designed to be utilized in compressive dynamic loading environment, such as supercavitating underwater vehicle. In the line of thought, a dynamic buckling test system is designed in this work. Using the test system, dynamic buckling tests including beam, plate, and stiffened plate are carried out, and the dynamic buckling characteristics of considered structures are investigated experimentally as well as theoretically and numerically.