• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.11
• /
• pp.1757-1763
• /
• 2010

Flywheel energy storage system (FESS) is defined as a high speed rotating flywheel system that can save surplus electric power. The FESS is proposed as an efficient energy storage system because it can accumulate a large amount of energy when it is operated at a high rotating speed and no mechanical problems are encountered. The FESS consists of a shaft, flywheel, motor/generator, bearings, and case. It is difficult to simulate rotor dynamics using common structure simulation programs because these programs are based on the 3D model and complex input rotating conditions. Therefore, in this paper, a program for the FESS based on the 2D FEM was developed. The 2D FEM can model easier than 3D, and it can present the multi-layer rotor with different material each other. Stiffness changing of the shaft caused by shrink fitting of the hub can be inputted to get clear solving results. The results obtained using the program were compared with those obtained using the common programs to determine any errors.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.410-413
• /
• 2001

This paper is to model a 3D-shape product applying mathematically the data acquired from a 3D scanner and using an Automatic Design Program. The research studied in the reverse engineering up to now has been developed continuously and surprisingly. However, forming 3D-shape solid models in CAE and CAM, based on the research, the study leaves much to be desired. Especially, analyses and studies reverse-designing automatically using measured data after manufacturing. Consequently, we are going to acquire geometric data using an 3D scanner in this study with which we will open a new field of reverse engineering by a program whic hcan design a 3D-shape solid model in a CAD-based program automatically.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.10
• /
• pp.55-62
• /
• 2012

In this research, the algorithm for simulating specific grain size distribution(GSD) with large diameter granular material was developed using the distinct element analysis program $PFC^{3D}$(Particle Flow Code). This modeling approach can generate the initial distinct elements without clump logic or cluster logic and prevent distinct element from escaping through the confining walls during the process. Finally the proposed distinct element model is used to simulate large triaxial compression test of the rockfill material and we compared the simulation output with lab test results. Simulation results of Assembly showed very well agreement with the GSD of the test sample and numerical modeling of granular material would be possible for various stress conditions using this application through the calibration.

• Proceedings of the Korean Society of Disaster Information Conference
• /
• 2022.10a
• /
• pp.309-310
• /
• 2022

본 논문은 3차원 ELS 모델과 건설 프로젝트 관리 프로그램을 이용한 해체 공정을 기계식공법으로 해체하는 구조물에 적용한 사례이다. 해체 공정 설계를 위한 3차원 ELS 모델은 도면 및 현장 조사 통해 부재별 크기와 배근 정보를 확인하여 모델링하였다. 완성된 3차원 모델을 건설 프로젝트 관리 프로그램인 Bexel manager에 적용하여 부재 별 해체 공정을 설계하였다. 설계된 해체 공정은 기계식공법으로 해체하는 구조물에 적용하였고, 해체결과 작업 별 작업동선을 효과적으로 관리할 수 있었으며, 안전하게 해체를 완료하였다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.1
• /
• pp.158-166
• /
• 2018

The application of the BIM for architectural and structural work accompanied many trials-and-errors on project based on BIM by this time Ten years have passed since BIM issued, but it is not activated. This study suggests ways to activate BIM for architectural and structural work. The reason for choosing the structure construction is as follows. Construction cost is a high proportion of structural construction cost. On the other hand, the number of related materials is small, and the first in the 3D modeling process is structure modeling. And build BIM-based Structural Database by quantity take-off. This study shows the applicability of BIM through practical cases. This study is expected to provide suggestion for the successful implementation of BIM-based projects.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.984-990
• /
• 2017

Mesh screen modeling and liquid propellant discharge simulation of surface tension tank were performed using commercial CFD software Flow-3d. $350{\times}2600$, $400{\times}3000$ and $510{\times}3600$ DTW mesh screen were modeled using macroscopic porous media model. Porosity, capillary pressure, and drag coefficient were assigned for each mesh screen model, and bubble point simulations were performed. The mesh screen model was validated with the experimental data. Based on the screen modeling, liquid propellant discharge simulation from PMD tank was performed. NTO was assigned as the liquid propellant, and void was set to flow into the tank inlet to achieve an initial volume flow rate of liquid propellant in $3{\times}10^{-3}g$ acceleration condition. The intial flow pressure drop through the mesh screen was approximately 270 Pa, and the pressure drop increased with time. Liquid propellant discharge was sustained until the flow pressure drop reached approximately 630 Pa, which was near the estimated bubble point value of the screen model.

• Journal of the Society of Naval Architects of Korea
• /
• v.36 no.1
• /
• pp.99-108
• /
• 1999

The solid modelling program was developed for the 3-D representation and analysis of VEry High-rise Steel Artificial Reefs(VEHSAR) using Visual C++ on the Microsoft's Windows 95(or Windows NT) based on MFC(Microsoft Foundation Class). Importing oriented-object program and CAD/CAM technique, this integrated design system which aims at low cost and high efficiency makes it possible to predict problems and to establish counterplans through visualizing the construction of Very High-rise Steel Artificial Reefs in advance. Also it is useful in enhancing productivity. Introduction of OpenGL makes it display high quality 3D graphics more faster.

• Geophysics and Geophysical Exploration
• /
• v.4 no.3
• /
• pp.70-79
• /
• 2001

The integral equation method is a powerful tool for numerical electromagnetic modeling. But the difficulty of this technique is the size of the linear equations, which demands excessive memory and calculation time to invert. This limitation of the integral equation method becomes critical in inverse problem. The conventional Born approximation, where the electric field in the anomalous body is approximated by the background field, is very rapid and easy to compute. However, the technique is inaccurate when the conductivity contrast between the body and the background medium is large. Quasi-linear, quasi-analytical and extended Born approximations are novel approaches to 3-D EM modeling based on the linearization of the integral equations for scattered EM field. These approximation methods are much less time consuming than full integral equation method and more accurate than conventional Born approximation. They we, however, still approximate methods for 3-D EM modeling. Iterative series methods such as modified Born, quasi-linear and quasi-analytical can be used to increase the accuracy of various approximation methods. Comparisons of numerical performance against a full integral equation and various approximation codes show that the iterative series methods are very accurate and almost always converge. Furthermore, they are very fast and easy to implement on a computer. In this study, extended Born series method is developed and it shows more accurate result than that of other series methods. Therefore, Iterative series methods, including extended Born series, open principally new possibilities for fast and accurate 3-D EM modeling and inversion.

• Journal of Korean Society for Geospatial Information Science
• /
• v.5 no.2 s.10
• /
• pp.77-85
• /
• 1997

Researches in the field of Computer Graphics and Geographical Information Systems(GIS) have extensively studied the method of photo-realistic landscape modelling, because it have become a commom requirement in applications such as flight simulators, mission rehearsal, and construction planning. A common approach to the display of terrain uses a Digital Elevation Model(DEM). DEM is an evenly spaced array of the terrain elevation data and can be obtained from stereo satellite data. With the DEM data, the process of 3D terrain modelling consists of three steps. The first step is to extract the meaningful data (such as peak, pit, passes...) from DEM data based on LOD(Level Of Detail) criteria. The second is to construct the 3D surface by TIN, which represents a surface as a set of non-overlapping continuous triangular facets of irregular size and shape. The third is a rendering of 3D terrain model. The goal of this research is a construction of 3D terrain with TIN. To do this, we are going to app]y Radial Sweep Algorithm. Radial Sweep Algorithm for generating TIN works quickly and efficiently. However, it does not solve the problem caused by the approximated nature of triangulated surface. To solve this problem, this research derive improved radial sweep algorithms with the optimal triangle definition.

• Journal of the Korean earth science society
• /
• v.38 no.1
• /
• pp.80-90
• /
• 2017

To build tetrahedra mesh for FEM numerical analysis, Boundary Representation (B-Rep) model is required, which provides the efficient volume description of an object. In engineering, the parametric solid modeling method is used for building B-Rep model. However, a geological modeling generally adopts discrete modeling based on the triangulated surface, called a Sealed Geological Model, which defines geological domain by using geological interfaces such as horizons, faults, intrusives and modeling boundaries. Discrete B-Rep model is incompatible with mesh generation softwares in engineering because of discrepancies between discrete and parametric technique. In this research we have developed a converting program from Sealed Geological Model to Gmsh and COMSOL software. The developed program can convert complex geological model built by geomodeling software to user-friendly FEM software and it can be applied to geoscience simulation such as geothermal, mechanical rock simulation etc.