• Design & Manufacturing
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• v.16 no.4
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• pp.7-16
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• 2022

A helmet is essential for safety when operating personal mobility. However, user's actual helmet wear rate is low due to the inconvenience of wearing and poor ventilation. In this study, a new helmet structure with improved ventilation for personal mobility devices was designed. To design a new structure with improved breathability compared to the existing helmet while satisfying the safety regulations for the helmet, a generative design method was applied to the shock-absorbing liner of the helmet. In addition, other materials were applied to create a structure with improved ventilation while maintaining safety. The generated design result was verified for shock absorption through simulation. As a result of the study, EPS, the current material was replaced with CFRP and Kevlar, and the structure was changed. This design was judged to satisfy safety regulations against impact. The new helmet structure is expected to improve the helmet usability for personal mobility and increase the helmet wear rate of users.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.23-32
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• 1998

A shape estimation is needed to control actively a smart structure. A method is, hence, proposed to predict the deformed shape of the structure subjected to unknown external load using the signal from sensors attached to the structure. The shape estimation is based on the relationship between the deformation of the structure and the signal from the sensors. The matrix containing the relationship between the deformation and signal is obtained using fictitious force or eigenvector of global stiffness matrix. Then the deformed shape can be predicted using the linear matrix and signal from sensors attached to the structure. To verify this method, experiment and FEM were performed and it was shown that the shape estimation method based on the fictitious force predicts deflections well and more accurately than that based on eigenvector.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1018-1023
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• 1993

In mechanical structure design area, many FEM (Finite Element Method) packages are used. But the design using FEM packages depends on an iterative trial and error manner and general CAD systems cannot cope with the change of parameters. This paper presents a methodology for building a designing system of a mechanical structure. This system can generate the drawing for a designed structure automatically. It consists of three steps: generation of a structure by selection of the parameters, stress analysis, and generation of a drawing using CAD system. FEM module and parametric CAD module are developed for this system. Inference engine module generates the parameters with a rule base and a model base, and also evaluates the current structure. The parametric design module generates geometric shapes automatically with given dimension. Parametric design is implemented with the artificial intelligent technique. In older to the demonstrate the effectiveness of the developed system, a frame set of bicycle was designed. The system was implemented on an SUN workstation using C language under OpenWindows environment.

• Wind and Structures
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• v.34 no.3
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• pp.291-301
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• 2022

Although mostly used in wind turbine market, single rotor wind turbines have problems with transportation and installation costs due to their large size. In order to solve such problems, multi-rotor wind turbine is being proposed; however, light weight design of multi-rotor wind turbine is required considering the installation at offshore or deep sea. This study proposes the systematic design process of the multi-rotor wind turbine focused on its supporting structure with simultaneous consideration of static and dynamic behaviors in an ideal situation. 2D and successive 3D topology optimization process based on the density method were applied to minimize the compliance of supporting structure. To realize the conceptual design obtained by topology optimization for manufacturing feasibility, the derived 3D structure was modified to have shell structures and optimized again through parametric design using the design of experiments and the response surface method for detail design of their thicknesses and radii. The resultant structure was determined to satisfy the stress and the buckling load constraint as well as to minimize the weight and the resultant supporting structure were verified numerically.

• Multiscale and Multiphysics Mechanics
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• v.1 no.3
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• pp.225-231
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• 2016

The formation of silicon-on-nothing (SON) structure during an annealing process from the silicon substrate including the trench structures has been considered as an effective technique to construct the structure that has an empty space under the closed flat surface. Previous studies have demonstrated the mechanism of the formation of SON structure, which is based on the surface diffusion driven by the minimization of their surface energy. Also, it has been fragmentarily shown that the morphology of SON structure can be affected by the initial design of trench (e.g., size, number) and the annealing conditions (e.g., temperature, pressure). Based on the previous studies, here, we report a comprehensive study for the design of the cavity-embedded structure (i.e., SON structure). To do this, a dynamic model has been developed with the phase field approach. The simulation results represent that the morphology of SON structures could be detailedly designed, for example the position and thickness of cavity, the thickness of top and bottom layer, according to the design parameters. This study will give us an advantage in the effective design of SON structures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04a
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• pp.559-564
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• 1995

Feature based design approach is widely studied for the application of mechanical part design and process planning. Mechanical parts are associated with volumetric form features in nature. Therfore, one of the important characteristics that reside in the form feature research until now is that features have been studied in connection with CAPP for material removal. We studied the application of feature based design for ship structure design. Ship structure has interesting nature that tis distinct from mechanical parts. Among these are multiple cell structure, non-volumetric part and production by welding or assembling. An idea of applying feature based design paradigm for design, process planning, cost analysis and engineering calculation was shown. Non-manifold geometric modeler ACIS was adopted to fully benefit from the non-manifold nature of ship structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2179-2182
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• 2009

Recently, the development of new structural model in optical mechanical system is required to be started from the conceptual design with low cost, high performance and quality. In this point, a structural-topological shape of system concerned with conceptual design of mechanical structure has a great effect on performance of the system such as the structural rigidities and weight reduction. In this paper, the optimization design methodologies are presented in the design stages of large optical structure. First, using topology optimization, we obtain the optimal layout and the reinforcement of structure, and then carry out the detail designs using size optimization and multidisciplinary optimization technique. As an example, these methods were applied to the design of large mirror structure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.3
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• pp.872-881
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• 1996

The concept of homology design has been devised for the application to large telescope structure by S.v.Hoerner. It is defined that the deformation of a structure shall be called homologous, if a given geometrical relation holds, for a given number of structural points, before, during, and after the deformation. Recently, the need of homology design in the structural design has been increase due to the required precision in the structure. Some researchers have utilized the theory on the structural design with finite element method in the late 1980s In the present investigation, a simple method using geometrical equality constraints is suggested to gain homologous deformation. The previous method is improved in that the decomposition of FEM eqation, which is very expensive, is not necessary. The basic formulations of the homology design with the optimization concept are described and several practical examples are solved to verify the usefulness and validity. Especially, a back-up structure of a satellite antenna is designed by the suggested method. The results are compared with those of existing researches.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.3
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• pp.240-249
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• 2009

HRSG(Heat Recovery Steam Generator) building is large enclosed structure included various heat sources. This building needs to appropriately keep internal air temperature for worker's safety and operability of control devices. In this study, ventilation analysis is performed to find proper ventilation method for temperature control. Ventilation analysis is applied to entire internal space of the building with standard $k-{\varepsilon}$ model and enhanced wall treatment because of large size of the structure. And the ventilation method is considered natural and forced convection with two louver structures which has damper or not. Louver structure affect directly air circulation in near HRSG and lower region of the building. Forced ventilation provides strong inertial force which cause upward airflow. From the analysis, it is found that design requirement for internal air temperature can be satisfied by forced ventilation method with louver structure without damper.

• Journal of Magnetics
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• v.20 no.1
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• pp.69-78
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• 2015

This paper focuses on the design of a flux-biased rotary electromagnetic actuator with compact structure for fast steering mirror (FSM). The actuator has high force density and its torque output shows linear dependence on both excitation current and rotation angle. Benefiting from a new electromagnetic topology, no additional axial force is generated and an armature with small moment of inertia is achieved. To improve modeling accuracy, the actuator is modeled with flux leakage taken into account. In order to achieve an FSM with good performance, a design methodology is presented. The methodology aims to achieve a balance between torque output, torque density and required coil magnetomotive force. By using the design methodology, the actuator which will be used to drive our FSM is achieved. The finite element simulation results validate the design results, along with the concept design, magnetic analysis and torque output model.