• 대한기계학회논문집A
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• 제25권12호
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• pp.1960-1965
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• 2001

In the practical design, it is important to extract the design space information of a complex system in order to optimize the design because the design contains huge amount of design conflicts in general. In this research FEA (finite element analysis) has been successfully implemented and integrated with a statistical approach such as DOE (design of experiments) based RSM (response surface model) to optimize the thermal deformation of an automotive disk brake. The DOE is used for exploring the engineer's design space and for building the RSM in order to facilitate the effective solution of multi-objective optimization problems. The RSM is utilized as an efficient means to rapidly model the trade-off among many conflicting goals existed in the FEA applications. To reduce the computational burden associated with the FEA, the second-order regression models are generated to derive the objective functions and constraints. In this approach, the multiple objective functions and constraints represented by RSM are solved using the sequential quadratic programming to archive the optimal design of disk brake.

• Journal of Magnetics
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• 제21권1호
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• pp.94-101
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• 2016

This paper shows a new magnetic field analysis of an interior permanent magnet (IPM) machines with an axial overhang structure wherein the rotor axial length exceeds that of the stator. The rotor overhang used to increase torque density of the radial flux machine is difficult to analyze because of extra consideration of axial direction, and thus it is general for machine designer to take 3-D finite element analysis (FEA) capable of considering both radial and axial complicated geometry in the machine. However, it requires too much computing time for preliminary design especially for optimization process. Therefore, in this paper a 2-D analytic method using a lumped magnetic circuit model (LMCM) is proposed to overcome the problem. For the analysis of overhang effect, the magnetic circuit is separated and solved from overhang and non-overhang regions respectively. For the validation of proposed concept, 3-D finite element analysis (FEA) is performed. From the analysis results, it is shown that our new proposed method presents good performance in terms of calculating electromotive force (EMF) and torque within a short time. Therefore, the proposed model can be useful in design of IPM with an overhang structure.

• Advances in aircraft and spacecraft science
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• 제3권3호
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• pp.331-349
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• 2016

Stiff and light fibre reinforced composites as used in air- and space-craft applications tend to high sound emission. Therefore, the damping properties are essential for the entire structural and acoustic engineering. Viscous damping is an established and reasonably linear model of the dissipation behaviour. Commonly, it is assumed to be isotropic and constant over all modes. For anisotropic materials it depends on the fibre orientation as well as the elastic and thermal material properties. To portray the orthogonal anisotropic behaviour, a model for unidirectional fibre reinforced plastics (frp) has been developed based on the classical laminate theory by ADAMS and BACON starting in 1973. Their approach includes three damping coefficients - for longitudinal damping in fibre direction, damping transversal to the fibres and shear based dissipation. The damping of a laminate is then accumulated layer wise including the anisotropic stiffness. So far, the model has been applied mainly to thermoset matrix materials. In this study, an experimental parameter estimation for different thermoplastic frp with angle ply and cross ply layups was carried out by measuring free vibrations of cantilever beams. The results show potential and limits of the ADAMS/BACON damping criterion. In addition, a possibility of modelling the anisotropic damping is shown. The implementation in standard FEA software is used to study the influence of boundary conditions on the damping properties and numerically estimate the radiated sound power of thin-walled frp parts.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.354-366
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• 2020

This work mainly focuses on determination of the fully plastic J-integral solutions for welded center cracked plates subjected to remote tension loading. Detailed three-dimensional elasticeplastic Finite Element Analyses (FEA) were implemented to compute the fully plastic J-integral along the crack front for a wide range of crack geometries, material properties and weld strength mismatch ratios for 900 cases. According to the database generated from FEA, Back-propagation Neural Network (BPNN) model was proposed to predict the values and distributions of fully plastic J-integral along crack front based on the variables used in FEA. The determination coefficient R2 is greater than 0.99, indicating the robustness and goodness of fit of the developed BPNN model. The network model can accurately and efficiently predict the elastic-plastic J-integral for weld centerline crack, which can be used to perform fracture analyses and safety assessment for welded center cracked plates with varying strength mismatch conditions under uniaxial loading.

• 한국해양공학회지
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• 제36권3호
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• pp.161-167
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• 2022

Three-dimensional finite element analysis (3D-FEA) models have been used to evaluate the shock-resistance responses of various equipments, including armaments mounted on a warship caused by underwater explosion (UNDEX). This paper aims to check the possibility of using one-dimensional (1D) FEA models for the shock-resistance responses. A frigate was chosen for the evaluation of the shock-resistance responses by the UNDEX. The frigate was divided into the thirteen discrete segments along the length of the ship. The 1D Timoshenko beam elements were used to model the frigate. The explosive charge mass and the stand-off distance were determined based on the ship length and the keel shock factor (KSF), respectively. The UNDEX pressure fields were generated using the Geers-Hunter doubly asymptotic model. The pseudo-velocity shock response spectrum (PVSS) for the 1D-FEA model (1D-PVSS) was calculated using the acceleration history at a concerned equipment position where the digital recursive filtering algorithm was used. The 1D-PVSS was compared with the 3D-PVSS that was taken from a reference, and a relatively good agreement was found. In addition, the 1D-PVSS was compared with the design criteria specified by the German Federal Armed forces, which is called the BV043. The 1D-PVSS was proven to be relatively reasonable, reducing the computing cost dramatically.

• 패션비즈니스
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• 제27권5호
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• pp.135-145
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• 2023

The purpose of this paper is to develop a workwear design framework that can be applied in workwear design. A general explorationstudy was conducted onworkwear concepts and market research to understand the importance and growth potential of workwear. Subsequently, representative brands specializing in workwear are selected, and a case analysis of workwear is conducted with a focus on jackets, pants, and overall items. As a result, four key characteristics of workwear are derived: Ergonomic Pattern-making, Certified Fabric, Specialized Color, and Customized Details. To present a model that considers the functional, expressive,and aesthetic aspects of workwear simultaneously, the 'Function Express Aesthetic' (FEA) model is utilized as the foundation. The 12 derived elements in the newly developed framework combine these four characteristics with three aspects (functional, expressive, and aesthetic), allowing for comprehensive consideration and validation of workwear conditions. The new framework will be used in subsequent research for developing workwear prototypes and is expected to enhanceworkwear production by employing a systematic approach during the design ideation and evaluation stages. By effectively integrating functional aspects with expressive-aesthetic values centered on the functionality of workwear products, this framework will provide.

• 패션비즈니스
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• 제27권6호
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• pp.37-46
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• 2023

This study aims to develop workwear prototypes by applying a systematic approach considering the characteristics of workwear. A case study was conducted before this study to derive workwear's four characteristics: 'Ergonomic Pattern-Making, Certified Fabric, Specialized Color, and Customized Details.' a prior study proposed the integrated framework combining these characteristics with the FEA model. The new framework identified that these characteristics are considered in terms of functionality, expression, and aesthetics; it can increase workers' satisfaction and meet the market demand without concentrating on only particular aspects. Before prototype production, the requirements for each characteristic of workwear were analyzed through theoretical research of previously published related papers. The study primarily gathered workwear requirements data and sources from consumer satisfaction surveys and investigations into the wearing conditions of work clothes. When considering all aspects of pattern-making, fabric, color, and detail in functionality, 'comfort movement, body protection, improved work efficiency' were identified as necessary. Expressive requirements were fundamental, including 'reflecting the wearer's preferences, expressing a sense of belonging and identity. It was clear that incorporating design elements and applying current trends to the aesthetic requirements of work clothes was necessary. Four prototypes comprised two top and bottom sets and two overalls using these requirements. The framework was used throughout the entire process of planning, producing, and evaluating prototypes, and through this, the results fulfilled the requirements. This study is significant because it produced workwear prototypes using an integrated approach that considered functional, expressive, and aesthetic aspects.

• 전기학회논문지
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• 제63권7호
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• pp.956-961
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• 2014

Due to the increasing needs of anti-fall device for elderly, it is required to develop the test rigs for fall simulation. The femoral bone model consists of silicone and steel is used as an effective device to simulate falls. In this work, we propose five different femoral bone models and analyse them by using a commercial FEA tool. It has been shown that two kinds of simplified models exhibit the simulated side falls with an error range of ~1% in the impact load of femoral neck compared with full model. Especially, the upper tissue model is found to provide us with the best efficient test environment, attributable to its simple structure.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 제7회 압연 심포지엄
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• pp.93-96
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• 2009

The high grade thick plate is in great demand in the ship building industry and the construction industry. The main problems to produce the high grade plate are residual stress and flatness of plate. In the previous research, Finite Element Analysis(FEA) was conducted for cold roller leveler to understand the behaviors of cold roller leveler under different conditions of thickness, intermesh, and yield stress. In this study, a numerical model of roller leveler is developed and the calculated results of this model are compared with the FEA results to show the validity of the numerical model. The optimal leveling conditions to improve flatness of plate are suggested using this numerical model.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권3호
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• pp.118-123
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• 1999

This paper describes the finite element procedure including the magnetic hysteresis phenomena. The magnetization-dependent Preisach model is employed to simulate the magnetic hysteresis and applied to each elements. Magnetization is calculated by the Fibonacci search method for the applied field in the implementation of the magnetization-dependent model. This can calculate the magnetization very accurately with small iteration numbers. The magnetic field intensity and the magnetization corresponding to the magnetic flux density obtained by the finite element analysis(FEA) are computed at the same time under the condition that these balues must satisfy the constitutive equation. In order to reduce the total calculation cost, pseudo-permeability is used for the input for the FEA. It is found that the presented method is very useful in combining the hysteresis model with the finite element method.