• Journal of the Korea Safety Management & Science
• /
• v.6 no.1
• /
• pp.311-323
• /
• 2004

This paper is to study the energy absorption characteristics of CF/Epoxy(Carbon Fiber/Epoxy Resin) laminated shell with the various curvatures subjected to transverse impact loadings under the low impact velocity in consideration of design of structural members for use of transportation machine, which are consisted of the characteristics of high stiffness, strength and lightweight. The curvature radius are associated with the energy absorption characteristics of CF/Epoxy laminated shell which is brittleness material. In all tests, maximum load of CF/Epoxy laminated plate is higher than that of laminated shell with curvature, but maximum deflection is lower. And then absorbed energy of laminated shell with curvature is higher than laminated plate(curvature radius is unlimited), As curvature radius is increased, the absorbed energy is increased in laminated shell with curvature.

• Journal of Korean Association for Spatial Structures
• /
• v.16 no.3
• /
• pp.67-78
• /
• 2016

Determining of the shape in the process of design for natural draught cooling tower is very important, because the shape of hyperbolic shell is respond sensitively to dynamic behavior of the whole cooling tower against wind load. In engineering practice, the geometric parameters have been determining based on the natural frequency. This study analyses influence of the tower shell geometric parameters on the structural behavior. For three representative models were selected, they were analyzed based on evaluation of damage by means of nonlinear FE-method. As a result, a hyperbolic rotational shell with the small radius overall was the lowest damage index induced by sufficient capacity of the stress redistribution and thus a wind-insensitive structure.

• Current Optics and Photonics
• /
• v.7 no.5
• /
• pp.496-503
• /
• 2023

We present a detailed analysis of the light extraction efficiency (LEE) of a core-shell nanorod light emitting diode (LED) using finite-difference time-domain (FDTD) simulations. We found that the LEE has a deep dependence on source positions and polarization directions based on the calculated LEE results for every x and z position inside the core-shell nanorod structure. The LEEs are different for the upper part (pyramid) and the lower part (sidewall) of the core-shell nanorod owing to total internal reflection (TIR) and the generated optical modes in the structure. As a result, the LEE of sidewall is much larger than that of pyramid. The averaged LEE of the core-shell nanorod LED is also investigated with variable p-GaN thickness, n-GaN thickness, and height for the design guidelines for the optimized LEE of core-shell nanorod LEDs.

• Journal of Korean Institute of Industrial Engineers
• /
• v.19 no.2
• /
• pp.83-93
• /
• 1993

Conventional computer programs developed and used by practicing engineers can be considered to contain expert knowledge and design experience. If these conventional programs are converted into expert systems, the difficult and time consuming process of knowledge acquisition can be simplified. Also the constructed knowledge-base can have higher confidence level than that constructed by the usual knowledge acquisition method of interviews. An existing computer program which is being used by ship structural designers has been reformulated as a design expert system by applying an expert system development shell-Nexpert. Utilizing the callable interface provided by the development shell, external design tools have also been integrated. The interfaced external functions are a graphical user interface (GUI) for the design process control, and graphics functions for the visualization of design results. It is observed that the developed system for design support is useful in two aspects. The trace-back function shows what portion of design rules are applied in arriving at certain design decisions. Also the knowledge-base can be conveniently updated as design rules of the classification societies are updated.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.138-143
• /
• 2007

The leading-cab (high energy absorption area) of rolling stock directly is impacted on the frontal crash unlike other cabs. Thus, leading-cab has a structurally complex shape to solve getting concentrated loads. However, in order to enhance structural performance and to achieve the weight reduction of cab, changing the sizes and adjusting the distance of members do not take an effective result. Therefore, in design phase, to find the material arrangement which helps structural capacity be better should be done. This research applies the topology optimization to concept design of protective shell frame on strategy of crush energy absorption with considering pressure and vertical loads acting on the principal part of leading-cab. In this research, topology optimization method focuses on structural design, and which yields optimal material arrangement under given loads and boundary conditions using density method which has the density of material as design variables. Finally, this research presents optimal material arrangement and structure of protective shell frame on given loads with applying topology optimization.

• Proceeding of EDISON Challenge
• /
• 2015.03a
• /
• pp.541-542
• /
• 2015

Recently, a popularity of the smartphone is on the rise. And also related services are being created. The growth of the smart technology makes advanced equipment for smartphone accessories. Selfie-rod is one of them. Selfie-rod satisfies people who want to take their own picture at long distance. However, the weight of recent selfie-rods is too heavy that has nice functions. So, we have re-designed new selfie-rod that has light-weight body. First, we observed a selfie-rod and check the reason of the selfie-rod's high weight. The new selfie-rod has a shell and inside, there is a space that it can be light-weight. The shell and space make the selfie-rod lighter. In FreeCAD, we designed shell with a rotation function. Finally, we designed light-weight body selfie-rod with FreeCAD. FreeCAD can be used easily for beginners of CAD. FreeCAD is suitable 3D-design tool for era of 3D-printing.

• Transactions of Materials Processing
• /
• v.8 no.4
• /
• pp.356-363
• /
• 1999

This paper discusses some techniques for the determination of optimum blank size and pre-form design for multi-stepped deep drawing of oval shell. The deep drawing process of oval shape has been regarded as more difficult than that of cylindrical shell because of its complicated behavior of plastic deformation. But there is insufficient information in this area to carry out successful deep drawing work of irregular products such as oval, rectangular, and square shapes. In order to find the optimum conditions, the drawing apparatus for two kinds of pre-form design are built, a series of drawing experiments performed, and thickness stain distributions measured. From the results of thess suggested experiments, various optimum process variables are observed and discussed.

• Structural Engineering and Mechanics
• /
• v.68 no.1
• /
• pp.81-94
• /
• 2018

This paper uses the finite element method (FEM) considering geometrically nonlinear strains to study the first ply failure of laminated composite skewed hypar shell roofs through well-established failure criteria along with the serviceability criterion of deflection. Apart from validating the approach through solution of benchmark problems, skewed hypars with different practical parametric variations are studied for failure loads and tendencies. First ply failure zones are also identified to suggest design and non-destructive monitoring guidelines to the practising engineers. Recommendation tables regarding the design approaches to be adopted in specific cases and factor of safety values needed to be imposed on first ply failure load values for varying shell curvatures are also suggested in this paper. Providing practical inputs to design engineers is the main achievement of the present study.

• Korean Journal of Computational Design and Engineering
• /
• v.6 no.2
• /
• pp.111-124
• /
• 2001

In this paper, we propose rounding operations on shell meshes, which give a constant or variable radius of rounding directly to sharp edges on a shell mesh. The rolling-ball methods for freeform surface rounding are introduced to devise the algorithms for these operations. Our algorithms consists of three steps as follows: detecting sharp edges, generating a rolling-ball surface contacting with two face groups adjacent to the sharp edges, and then replacing the rounding area of the original mesh with the mesh generated on the rolling-ball surface. In addition, this paper shows their application to the area of stamping die design. These operations enable CAE engineers to directly change the meshes of stamping tools without modification of CAD models for dies and regeneration of their meshes.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1328-1333
• /
• 2003

In the present study, an integrated framework of geometric modeling, analysis, and design optimization is proposed. Geometric modeling is based on B-spline surface representation. Geometrically-exact shell finite element is implemented in analysis module. Control points of the surface are selected as design variables for optimization, which can make the interaction easier between analysis and surface representation. Sequential linear programming(SLP) is adopted for the shape optimization of surfaces. For the computation of shape sensitivities, semi-analytical method is used. The developed integrated framework should serve as a powerful tool for the geometric modeling, analysis, and shape design of surfaces.