Kum Won Cho

e-AIRS: an e-science collaboration portal for aerospace applications

Computational simulation in fluid dynamics often requires high performance and massive data intensive process. In addition, advanced expertise to manage complicated simulation processes with various environmental conditions in order to obtain reasonable results is essential but not easy to achieve. This paper presents an e-Science Aerospace Integrated Research System (e-AIRS) that aims to use Grid technology to establish an integrated and collaborative environment to enable distributed computational simulation and remote experiments for remote scientists in aerospace area. e-AIRS provides easy-to-use portal services to manage workflow-based experiment process from application design, execution, monitoring, and visualization for Grid applications.

Development of cactus driver for CFD analyses in the grid computing environment

The Grid Computing[1] has been paid much attention from researchers as an alternative to parallel computing for its unlimited number of potential resources available and as an easier way to build collaborative environments among multiple disciplines. However, the difficulty in establishing the environments and accessing and utilizing the resources has prevented application scientists from using Grid computing. Thus, the present study focuses on building PSE(Problem Solving Environment) which assists application researchers to easily access and utilize the Grid. The Cactus toolkit, originally developed by astrophysicists, is used as a base frame for Grid PSE. Some modules are newly developed and modified for CFD(Computational Fluid Dynamics) analysis. Simultaneously, a web portal, Grid-One portal, is built for remote monitoring/control and job migration. Cactus frame through the web portal service has been applied to various CFD problems, demonstrating that the developed PSE is valuable for large-scaled applications on the Grid.

X-SIGMA: XML Based Simple Data Integration System for Gathering, Managing, and Accessing Scientific Experimental Data in Grid Environments

Effective scientific data management is crucial for e-Science applications. Scientific data management raises challenging requirements: (1) support for not only experimental data but also context data, (2) both schema evolution and integration, (3) and compatibility with legacy data management conventions or environments. In this paper, we present a scientific data management system (called XSIGMA) which is designed to address those issues. X-SIGMA is a Grid-based integrated system for managing, integrating, and accessing scientific experimental data. A prototype system is implemented and has been being used to develop the scientific data management system for the national cyberinfrastructure project called KOCED in Korea.

Systematic probing of an atomic charge set of sialic acid disaccharides for the rational molecular modeling of avian influenza virus based on molecular dynamics simulations

A systematic searching approach for an atomic charge set through molecular dynamics simulations is introduced to calculate a reasonable sialic acid carbohydrate conformation with respect to the experimentally observed structures. The present molecular dynamics simulation study demonstrated that B3LYP/6-31G is the most suitable basis set for the sialic acid disaccharides, attaining good agreement with experimental data.

An Efficient Multigrid Method for Overlapped Grid System to Integrated System Analysis

A technique for the generation of overlapped grid using a simple shooting method, that is a cut-paste algorithm, is presented. It makes possible to generate overlapping grids with moderate mesh interface region. To generate overlapped grids with minimal amount of user inputs, the advancing-front technique using the fringe points as facets is used. To remove hole points initially, fronts using solid bodies and the zones of interference algorithm are used. The overlapped grids are generated for several cases using present algorithms and Euler equations are solved for two/three-dimensional steady state flow fields. To demonstrate the capability of present method, the two dimensional store separation with trajectory mode of three-DOF is computed in an unsteady flow field.

Toward a grid-based simulation of multiphase fluid flow in porous media

Summary form only given. Modeling fluid flow in a porous medium is a challenging computational problem. It involves closely coupled systems of flow transport process consisted of highly heterogeneous distributions of porous medium property, various fluid flow characteristics including injection or production well assemblies, and surface separation and storage facilities. For the design of better flow management scheme, high performance computing tools have been applied as a useful and essential technique in a cost-effective manner. In recent years, grid computing architectures have been emerging as a new computing environment. It allows a powerful computing capability for accurate simulation of complex fluid flow phenomena that occur in porous media. In this paper, grid-enabled simulation approach is presented for modeling a three dimensional, multiphase fluid flow in the grid computing environment Extensive test results of the code are presented in this paper. The preliminary result shows a significant parallel performance. Based on this preliminary study, we further discuss a future plan for the design of multipurpose porous media flow simulator, which allows multiphysical simulation capability in grid computing environment.

e-AIRS: Aerospace integrated research systems

While developing information technology and improving engineering environment, modern aerospace technology requires even larger scale computing and data management. However, the technology faces difficulty to use isolated resources. Therefore, needs arise to construct network based and integrated design and analysis system. In order to provide a uniform aerospace development infrastructure, three perspectives are required (i.e., integration and management of aerospace resources located in multiple organizations and areas; facilitating human collaboration in aerospace fields; and remote access and operation of aerospace facilities and instruments). National e-Science project has been developing by the Ministry of Science and Technology and the Ministry of Information and Communication in Korea. Many worldwide organizations and institutes have conducted research on the development of e-Science paradigm. USA NASA has focused on information power grid (IPG), which is designed for environment of real time design, manufacturing, and maintenance of aircraft in grid base. In the United Kingdom, grid based researches is classified into mainly two systems: grid based aircraft multi-discipline optimal design system (GEODISE) and grid based real-time aircraft operation and maintenance system (DAME). In Japan, grid based supersonic aircraft design focused on a sort of integrated aerospace, full cell, materials design, and regional environment. The national e-Science of Korea is commonly contributing to construct of aerospace e-Science (called e-AIRS project). In e-AIRS project, design/ analysis network for aerospace vehicle based on national grid system has been constructed. It also provides collaborative use of aerospace test facilities and equipments dispersed in organizations, institute, industry, and academia. In addition, this project also aims to construct infrastructure for collaborative use of information and database for aerospace vehicle design/analysis. This presentation will address an overview of e-AIRS research activities and a concept demonstration about e-Science portal interface, integrated mesh generation and CFD computation services, and parametric study service for high throughput computing. The parametric study service, which is working on Grid environment, has flexibility to be extended to design optimization. A remote request service for wind tunnel experiments and a collaboration service consisting of video/audio conferences are also introduced.

Separation Analysis of Strap-ons in the Multi-stage Launch Vehicle Using the Grid Computing Technique

A numerical technique for simulating the separation dynamics of strap-on boosters is presented. Six degree of freedom rigid body equations of motion are integrated into the three-dimensional unsteady Navier-Stokes solution procedure to determine the dynamic motions of strap-ons. An automated Chimera overset mesh technique is introduced to achieve maximum efficiency for the relative motion of multiple bodies and each mesh is constructed as multi-block mesh for the representation of the after-body flow. Additionally, a new computing concept, called ‘the Grid computing technique’[1,2], is adopted to guarantee sufficient computing resources and a simple load balancing technique is proposed for an efficient computation in the Grid. As a validation of Chimera mesh technique implementation, computed results around the Titan IV launch vehicle is compared with experimental data and, as a validation of base flow analysis, the aerodynamic coefficients of a strap-on booster of KSR-Ⅲ is analyzed numerically. The complete analysis process is then applied to the KSR-Ⅲ, a three-stage sounding rocket researched in Korea. From the analyses, the base flow effect on separation motions of strap-on boosters are investigated and the different aerodynamic characteristics of inviscid and viscous flows at every time interval are examined. In addition, a guidance map of the jettisoning forces and moments for a safe separation is presented from various simulations of separation phenomena with different jettisoning conditions. Keyword : Separation Motion of Strap-on Boosters, Chimera Overset Mesh, The Grid, Base Flow

Modeling and Prediction of the Crossflow Transition Using Transition Transport Equations

In this paper, the Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with transition transport equations to predict the natural transition. The present γ-Reθ transition model has been developed without using boundary layer integral parameters and this model is based on two additional transport equations, one for the intermittency and one for the transition-onset momentum thickness Reynolds number. An engineering transition model for crossflow instability is proposed based on the philosophy of the local-correlation transition transport. The present transition model is applied to a variety of different complex applications. The main goal of the present paper is to validate the prediction capability for aeronautical flows over three-dimensional configurations using the γ-Reθ transition transport model considering crossflow effect. Validations of the transition model are conducted for an infinite NLF(2)-0415 swept wing, a finite ONERA M6 wing, and 6:1 inclined prolate spheroid configuration. In all cases numerical results considering the crossflow effect are in good agreement with the available experimental data and prove that the proposed crossflow transition model is well validated.

Development of a simulation result management and prediction system using machine learning techniques

Simulations are widely used in various fields of computational science and engineering. As IT technology advances, the complexity and accuracy requirements of the simulations are increasingly rising up, accordingly escalating their execution cost as well. Nevertheless, it appears that the community has not yet paid much attention to the reuse of previously obtained simulation results to improve the performance of the execution of later requested simulations. In this regard, we propose a novel simulation service system that can utilise the results of previously executed simulations and thus improve the performance of later simulations. The proposed system can not only convert completed simulation results into a standard form and then store them into a NoSQL database for efficient retrieval, but also predict the result of a requested simulation using machine learning techniques without actual simulations. We demonstrate that the proposed system achieved very low error prediction rates only up to 7.4% from 0.9%.