• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.5
• /
• pp.128-135
• /
• 2021

Thin-walled tubes have been widely used as energy absorbing devices because they are light and have high energy-absorption efficiency. However, the downside is that conventional thin-walled tubes usually exhibit an excessive initial peak crushing force (IPCF) and a large fluctuation in the load-displacement curve, and thus lack stability as energy absorbing devices. Corrugated tubes were introduced to reduce IPCF and to increase the stability of collision energy-absorbing devices. Since the performance of corrugated tubes is highly influence by geometry, design optimization methods can be utilized to optimize the performance of corrugated tubes. In this paper, we utilize shape design optimization based on an adaptive surrogate model for crashworthiness analysis. The amplitude and wavelength of the corrugation, as well as curvature changes in the features, are the design variables. A morphing methodology is adopted to perform shape design parameterization. Through numerical examples, we compare optimal design results based on the adaptive surrogate model, with optimal results based on conventional surrogate models, and we show that direct optimal design methods produce more efficient results.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.1
• /
• pp.1-7
• /
• 2011

In this paper, based on an isogeometric approach, we have developed a shape design optimization method for plane elasticity problems subjected to design-dependent loads. The conventional shape optimization using the finite element method has some difficulties in the parameterization of geometry. In an isogeometric analysis, however, the geometric properties are already embedded in the B-spline basis functions and control points so that it has potential capability to overcome the aforementioned difficulties. The solution space for the response analysis can be represented in terms of the same NURBS basis functions to represent the geometry, which yields a precise analysis model that exactly represents the normal and curvature depending on the applied loads. A continuum-based isogeometric adjoint sensitivity is extensively derived for the plane elasticity problems under the design-dependent loads. Through some numerical examples, the developed isogeometric sensitivity analysis method is verified to show excellent agreement with finite difference sensitivity.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.26 no.4
• /
• pp.255-262
• /
• 2013

In this paper, a shape design sensitivity analysis(DSA) method is presented for Mindlin plates using an isogeometric approach. The isogeometric method possesses desirable advantages; the representation of exact geometry and the higher order inter-element continuity, which lead to the fast convergence of solution as well as accurate sensitivity results. Unlike the finite element methods using linear shape functions, the isogeometric method considers the exact normal vector and curvature of the CAD geometry, taking advantages of higher order NURBS basis functions. A selective reduced integration(SRI) technique is incorporated to overcome the difficulty of 'shear locking' phenomenon. This simple technique is surprisingly helpful for the accuracy of the isogeometric shape sensitivity without complicated formulation. Through the numerical examples of plate bending problems, the accuracy of the proposed isogeometric analysis method is compared with that of finite element one. Also, the isogeometric shape sensitivity turns out to be very accurate when compared with finite difference sensitivity.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.9
• /
• pp.825-834
• /
• 2008

Nose chine shape optimization study has been performed to maximize the directional stability at high angle of attack supersonic flow. Various chine shapes are generated using super ellipse equation. By numerically investigating the directional stability characteristics of those shapes, the baseline configuration for the shape optimization has been selected using the three-dimensional Navier-Stokes equations. The configuration is represented by the NURBS curves which can adjust the surface geometry by the control points. The response surfaces are constructed to obtain optimum shape which has high directional stability characteristics and lift-to-drag ratio. From this study, an efficient configuration design and optimization process which utilizes the parameter-based configuration generation techniques and approximation method has been established, then 29% improvement of the directional stability by strong vortexes from chine nose is accomplished.

• Journal of the Korea Society for Simulation
• /
• v.26 no.2
• /
• pp.41-49
• /
• 2017

In the acquisition program, the conceptual design is the most important step toward specifying the military objectives, establishing requirements and determining future developmental directions, of a target system. However, if both the requirements and directions are incorrectly set due to the lack of development experiences and literature backgrounds in the target systems, such as future ground combat vehicles, it may become a major risk in the future design phases and the entire acquisition program. In order to correct these errors in the future phases, time, effort and cost are required. Therefore, it is necessary to reduce the errors that occur in the initial stages to effectively acquire the future ground combat vehicles. This paper describes the initial design method for verifying the requirements and the developmental directions and estimating the system performance at the conceptual design through the system-level physical modeling and simulation (M&S) and the target system performance analysis. The system-level physical M&S use cutting-edge design tools, model-based designs and geometric-based designs. The system performance estimation is driven from the results of the system-level physical M&S and the specialized system analysis software.

• Korean Journal of Computational Design and Engineering
• /
• v.11 no.2
• /
• pp.77-87
• /
• 2006

It is necessary to change the existing design process to cope with a short life-cycle product and various customer's demands. Also a frequent design change may delay the whole design process and it will increase the unit cost of the production. New alternatives or techniques have emerged to solve the existing design problems, such as a knowledge based engineering, an intelligent CAD, a function based design, and so on. In this paper, we propose a hybrid design system with a knowledge based design methodology and a function based design technique. The knowledge based design is good at a frequent design change and the function based design is effective to extract a core design behavior. In an early design process, the system utilizes a core design behavior through the function based design process. On the other hand, the system manages complicated design issues with the knowledge based design technique in the detailed design process. We conclude that the hybrid design system can bring fair effects on implementing an efficient design environment in aspect of time and expense.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.3
• /
• pp.1063-1069
• /
• 2011

Today, tire performance becomes better as vehicle performance increases. Driviability, endurance, comfortability, noise, and antiwear performance is influenced by tire contour. Tire design method is developed by high-tech engineering technology. Among theses studies, tire performance improvement through tire contour optimization is performed by many vehicle investigator. Therefore, in the present study, an optimum contour design system satisfying the tire performance requirements is constructed by regression analysis and genetic algorithm by using design of experiments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2022.06a
• /
• pp.323-324
• /
• 2022

복잡한 항만해역에서 자율운항선박 입출항 지원을 위해서는 항내에서 통항하는 선박에 대한 지속적인 인식이 필요하며, 이를 위해 선박자동식별시스템(AIS)에서 송출된 정보를 기반으로 선박의 운동정보(위치/침로/속도), 식별번호 및 크기 정보를 확인한다. 하지만, AIS 탑재 의무가 있는 선박에 대한 정보만 취득이 가능하기 때문에, 보조적으로 육상레이더를 활용하여 AIS 정보로부터 식별이 안되는 선박을 인식할 수 있는 기술이 필요하다. 본 연구에서는 자율운항선박 입출항 지원을 위해 레이더 이미지를 활용하여 선박의 운동정보와 형상정보를 동시에 추정할 수 있는 알고리즘을 설계하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.9
• /
• pp.11-19
• /
• 2006

Design program was developed to determine the external shape of the supersonic axisymmetric inlet by combining conical flow solver and approximation technique of conical shock with gradient-based optimization algorithm. Inlet designs were carried out under various operation conditions through optimization with respectively two object functions which consist of pressure recovery and cowl drag and with constraints about shock position, cowl shape, and minimum throat area. New object function consisting of pressure recovery and drag of the external cowl was proposed and the optimized shapes from new object function were compared to the ones from the old object function which maximize only the pressure recovery. Through computations of inviscid and turbulent flow, was tested performance of the design program and performance estimated in design program agreed well with computation results for inlets designed under various flight conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.8
• /
• pp.661-669
• /
• 2021

A mechanical stiffener has been mainly applied on a PCB to secure fatigue life of a solder joint of an electronic components in spaceborne electronics by minimizing bending displacement of the PCB. However, it causes an increase of mass and volume of the electronics. The high damping PCB implemented by multi-layered viscoelastic tapes of a previous research was effective for assuring the fatigue life of the solder joint, but it also has a limitation to decrease accommodation efficiency for the components on the PCB. In this study, we proposed high damping PCB with a multi-layered superelastic shape memory alloy stiffener for spatialminimized, light-weighted, high-integrated structure design of the electronics. To investigate the basic characteristics of the proposed PCB, a static load test, a free vibration test were performed. Then, the high damping characteristic and the design effectiveness of the PCB were validated through a random vibration test.