• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.763-765
• /
• 2000

Detent force is produced in a permanent magnet linear machine. It is generally an undesired effect that contributes to the output ripple of machine, vibration and noise. This paper analyzes detent force in a Permanent Magnet Linear Synchronous Motor (PMLSM) by using various detent force minimization techniques. A two-dimensional Finite Element Method(FEM) is used to predict detent forces due to structural factors and non-linearity. And moving node technique for the drawing models is used to reduce modeling time and efforts.

• Steel and Composite Structures
• /
• v.20 no.1
• /
• pp.185-203
• /
• 2016

Shear connectors are key components to ensure the efficient composite action and satisfactory transfer of shear forces at the steel-concrete interface in composite beams. Under hazardous circumstances, such as fire in a building, the performance of a composite beam significantly relies on the performance of shear connectors. Studies on the behavior of shear connectors subjected to elevated temperatures performed in the last decade are reviewed in this paper. The experimental testing of push-out specimens, the design approaches provided by researchers and different codes, the major failure modes, and the finite element modeling of shear connectors are highlighted. The critical research review showed that the strength of a shear connector decreases proportionally with the increase in temperature. Compared with the volume of work published on shear connectors at ambient temperatures, a few studies on the behavior of shear connectors under fire have been conducted. Several areas where additional research is needed are also identified in this paper.

• Interaction and multiscale mechanics
• /
• v.1 no.3
• /
• pp.329-337
• /
• 2008

This paper presents the derivation of the generalized governing equations in theory of elasticity, their weak forms and the some applications in the numerical analysis of structural mechanics. Unlike the differential equations in classical elasticity theory, the generalized equations of the equilibrium and compatibility equations presented here take the form of integral equations, and the generalized equilibrium equations contain the classical differential equations and the boundary conditions in a single equation. By using appropriate test functions, the weak forms of these generalized governing equations can be established. It can be shown that various variational principles in structural analysis are merely the special cases of these weak forms of generalized governing equations in elasticity. The present weak forms of elasticity equations extend greatly the choices of the trial functions for approximate solutions in the numerical analysis of various engineering problems. Therefore, the weak forms of generalized governing equations in elasticity provide a powerful modeling tool in the computational structural mechanics.

• Steel and Composite Structures
• /
• v.27 no.2
• /
• pp.135-147
• /
• 2018

Quasi-static three-point bending tests on sandwich beams with expanded metal sheets as core were conducted. Relationships between the force and displacement at the mid-span of the sandwich beams were obtained from the experiments. Numerical simulations were carried out using ABAQUS/EXPLCIT and the results were thoroughly compared with the experimental results. A parametric analysis was performed using a Box-Behnken design (BBD) for the design of experiments (DOE) techniques and a finite element modeling. Then, the influence of the core layers number, size of the cell and, thickness of the substrates was investigated. The results showed that the increase in the size of the expanded metal cell in a reasonable range was required to improve the performance of the structure under bending collapse. It was found that core layers number and size of the cell was key factors governing the quasi-static response of the sandwich beams with lattice cores.

• Smart Structures and Systems
• /
• v.22 no.4
• /
• pp.369-382
• /
• 2018

Novel design of interdigitated electrodes capable of increasing the performance of piezoelectric transducers are proposed. The new electrodes' geometry improve the electromechanical coupling by offering an enhanced adaptation of the electric field to the interdigitated electrode configuration. The proposed analysis is based on finite element modeling and takes into account local polarization effect. It is shown that the proposed electrodes considerably increase the strain generation compared to flat electrode arrangement used for Macro Fiber Composite (MFC) and Active Fiber Composite (AFC) actuators. Also, electric field singularities are reduced allowing better reliability of the transducer against electric failure.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1029-1034
• /
• 2004

Recent engineering process requires fast development and manufacturing of the products. This paper mainly discusses the process of rapid product development (RPD) from the reverse engineering to the optimal design. A laser scanning system scans a product and the efficient data processing method reduces the scanned point data. The reduced (scanned) points model is transformed to a finite element model without the construction of a CAD model. Since CAD modeling is a time-consuming work, skipping this step can save much time. This FE model is updated from the result based on the structural characteristics from modal test of the real model. For FE model updating, Response Surface Method is adopted. Finally, the updated FE model is optimized using the reliability-based topology optimization, which is developed recently. All these processes are applied to the design of an upper part model of a cellular phone.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.7
• /
• pp.820-830
• /
• 1999

The coupled turbulent flow and solidification is considered in a typical slab continuous easting process using commercial program FIDAP. Standard $k-{\varepsilon}$ turbulence model is modified to decay turbulent viscosity in the mushy zone and laminar viscosity is set to a sufficiently large value at the solid region. This coupled turbulent flow and solidification model also contains thermal contact resistance due to the mold powder and air gap between the strand and mold using an effective thermal conductivity. From the computed flow pattern, the trajectory of inclusion particles was calculated. The comparison between the predicted and experimental solidified shell thickness shows a good agreement.

• Proceedings of the KSR Conference
• /
• 2002.05a
• /
• pp.303-311
• /
• 2002

A first evaluation of the possibilities of high speed trains in conventional railway in Korea have been investigated. The radius of curvature was considered the major problem with high-speed trains in Korea. If KNR(Korea National railway) likes to increase the speed, is then whether KNR shall construct straigthen the track or develop a train that can reduce travel time in curves The research concerns structural design of train car-body is to reduce heavy stress concentration. Using 3D solid modeling, Finite Element analysis and shape optimization combined with powerful postprocessing, graphical display and animation to achieve complete and accurate design and performance will be carried out further project Main purpose of this project is to provide korean tilting train car body's conceptional design. Based on first year research results, the design of car-body will be performed by train manufacture.

• Computational Structural Engineering
• /
• v.7 no.4
• /
• pp.137-144
• /
• 1994

As for the safety evaluation of existing large-scale structures, methods for the estimation of structural and dynamic properties are studied. Sequential prediction error method in time domain and frequency response function estimators in frequency domain are examined. For this purpose, impact tests are performed on a steel frame structure with 2 bays and 3 floors. Results from both methods are found to be consistent to each others. However those from the finite-element analysis are slightly different from the experimental results. The discrepancies may be caused by the improper modeling of the complex behavior at the connection joints of the model structure.

• International Journal of CAD/CAM
• /
• v.2 no.1
• /
• pp.1-12
• /
• 2002

Computer-Aided Reliable and Optimal Design (CAROD) system is an efficient tool defining the best compromise between cost and safety. Using the concurrent engineering concept, it can supply the designer with all numerical information in the design process. This system integrates several fields such as multidisciplinary optimization, reliability analysis, finite element analysis, geometrical modeling, sensitivity analysis and concurrent engineering. When integrating these disciplines, many difficulties are found such as model coupling and computational time. In this paper, we propose a new concurrent methodology satisfying the reliability requirement, allowing the coupling of different models and reducing the computational time. Two applications (rotating disk and hook structures) demonstrate that CAROD system can be a practical concurrent engineering application for designers.