• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.929-931
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• 1993

The design sensitivity analysis based on the finite element method is presented for the eddy current problem with a voltage source. Since, in this problem, the complex variable is used as the state variable, new approach to the sensitivity calculation for the complex variable system is required. Its result is applied to the design of the rotor slot shape of squirrel cage induction motor. As a analysis model, only one slot pitch of rotor is analyzed by using a Periodic boundary condition. The use of this minimal modelling method leads to much saving of calculation time. The design objective is to obtain the desired slip-torque characteristic. Because the shape of rotor slot has much influence on the slip torque characteristic, the design variables are taken on the interface shape between rotor core and rotor bar. The initial shape of rotor slot is the trapezoidal type with rounding corners. The obtained final shape is quite similar to the double squirrel cage type.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.38-43
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• 2021

Permanent magnet linear synchronous motor (PMLSM) is suitable for use in cleanroom environments and have advantages such as high speed, high thrust, and high precision. If the stators are arranged in the entire moving path of the mover, there is a problem in that the installation cost increases. To solve this problem, discontinuous armature arrangement PMLSM has been proposed. In this case, the mover receives a greater detent force in the section where the stator is not arranged. When a large detent force occurs, it appears as a ripple component of the thrust during PMLSM operation. If the shape of the stator is changed to reduce the detent force, the characteristics of the back EMF are changed. Therefore, in this paper, the detent force and the harmonic components of back EMF were reduced through multi-purpose shape optimization. To this end, the FEA model was constructed and main effect analysis was performed on the major shape variables affecting each objective function. Then, the optimal shape that minimizes the objective function was derived through the response surface analysis method.

• Communications for Statistical Applications and Methods
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• v.19 no.1
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• pp.97-105
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• 2012

The generalized canonical correlation biplot is a 2-dimensional plot to graphically investigate the relationship between more than three sets of variables and the relationship between observations and variables. Recently, Choi and Choi (2010) investigated the relationship physique, physical fitness and basic skill factors of Korea Tennis Association(KTA) players of using this biplot; however we consider the set of covariate variables affecting the linearly on two sets of variables. In this case, if we apply the generalized canonical correlation biplot, we cannot clearly interpret the other two sets of variables due to the effect of the set of covariate variables. Moreover, Yeom and Choi (2011) provided partial canonical correlation analysis that removed the linear effect of the set of covariate variables on two sets of variables. In addition, Procrustes analysis is a useful tool for comparing shape between configurations. In this study, we will investigate the relationship between physical fitness and basic skill factors of KTA players of using a partial canonical correlation biplot and Procrustes analysis. We compare shapes and shape variabilities for the generalized, partial and simple canonical correlation biplots.

• Journal of Bio-Environment Control
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• v.7 no.4
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• pp.290-297
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• 1998

In this study an optimization of greenhouse roof shape was performed to maximize solar light transmission which is one of the most important elements in greenhouse environment. To determine roof shape that maximize the total light transmissivity, a computer model for analysing light transmissivity was composed and the Genetic Algorithms was applied for solving optimization problems. By setting composite model as objective function(fitness function), the optimum combination of design variables(roof inclination angle, width ratio) was searched using Genetic Algorithms. The optimum combination of input variables for the maximum light transmissivity at Suwon in winter was found 40 degree root angle , 0.5 width ratio, for two span greenhouses and 37 $_。 / roof angle, 0.7 width ratio, for single span greenhouses.es.

• Fashion & Textile Research Journal
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• v.25 no.4
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• pp.497-507
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• 2023

This study measured the effect 3D printing products comprised of different materials and shapes on heat transfer in clothing to derive fundamental data on thermal comfort among clothing comfort. The variables were three types of material (EVA foam, TPU-10%, TPU-10%+EVA), two types of shape (without holes, with holes), and two types of covers(without cover, with cover). All samples (12 types) prepared by combining these variables were placed on the hot plate set at 36℃, and the surface temperature was measured at three points for 10 minutes. The surface temperature change was dependent on the material, shape, and cover of the sample. The sample printed with TPU exhibited higher temperature transfer compared to the EVA foam sample after 10 mins. In addition, the temperature transfer was better when there were holes, and rate decreased when the sample was covered with fabric. We confirmed that material selection of the pad and thermal conductivity of the cover are extremely important in solving thermal stress to the human body caused by functional clothing with protectors. Additionally, as the protector, it is recommended to design the outer shell with a passage, such as a hole, to allow the rapid transfer of heat to the external environment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.176-179
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• 2003

The mean temperature prediction of strip is very important in hot strip finishing mill because of affecting on product quality and shape. Also, temperature can be used by basic information in other on-line control models with affecting control accuracy in factory. So, FE based on-line temperature model was developed for predicting strip mean temperature accurately in various process conditions and factory environments. There are many variables in affecting strip mean temperature in on-line states of factory. But some problems are occurred in considering all variables for making temperature model because of the bad efficiency of regression or fitting analysis. In this report, we have adopted dimensional analysis for solving these problems. We have many variables with dimensions affecting strip temperature but we are able to make non-dimensional variables less than dimensional variables from the combination of dimensional variables caused by PI-Theorem in fluid mechanics. The developed models are divided by two parts. The one is interstand temperature prediction model. The other is roll gap temperature model.

• Transactions of Materials Processing
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• v.30 no.6
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• pp.291-300
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• 2021

Currently, starting with electric vehicles, the application of ultra-high-strength steel sheets and light metals has expanded to improve mileage by reducing vehicle weight. At a time when internal combustion engine vehicles are rapidly changing to electric vehicles, the application of ultra-high-strength steel is expanding to satisfy both weight reductions and the performance safety of the chassis parts. There is an urgent need to improve the quality of parts without defects. It is particularly difficult to estimate the part formability through the finite element method (FEM) in the burring operation, so product design has been based on the hole expansion ratio (HER) and experience. In this study, design of experiment (DOE), analysis of variance (ANOVA), and regression analysis were combined to optimize the formability by adjusting the process variables affecting the burring formability of ultra-high-strength steel parts. The optimal variables were derived by analyzing the influence of variables and the correlation between the variables through FE analysis. Finally, the optimized process parameters were verified by comparing experiment with simulation. As for the main influence of each process variable, the initial hole diameter of the piercing process and the shape height of the preforming process had the greatest effects on burring formability, while the effect of a lower round of punching in the burring process was the least. Moreover, as the diameter of the initial hole increased, the thickness reduction rate in the burring part decreased, and the final burring height increased as the shape height during preforming increased.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.125-129
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• 2009

In this paper automatic 3D wing shape modeling program is introduced. The program is developed in Visual Basic based on Net Framework 3.5 environment by using CATIA COM Library, and it is used together with CATIA system to model 3D wings with or without flaps. With this program users can easily construct wing models by specifying geometry parameters which are usually design variables with the aid of easy-to-use GUI environment, and specifying sectional airfoil data is done either by using analytic shape functions such as NACA series airfoils or by providing input files with point data describing the airfoil shape. When all the input parameters are provided, users can either work further with the model in the CATIA system which would be automatically started by the program or save the resultant model in the format of users choice. Unstructured grid generation program is also briefly described which can make grid generation task for a 3D wing easy and efficient one when used together with the wing modeling program by choosing STL format as the model's output format.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.114-117
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• 2004

The isothermal forging design of a Ti-6Al-4V wing shape was performed by 3D FE simulation. The design focuses on near-net shape forming by the single stage. The process variables such as the die design, pre-form shape and size, ram speed and forging temperature were investigated. The minimization of forging load and uniform strain distribution in a given forging condition were considered as main design factors. The FE simulation results fur the final process design were compared with the isothermal forging tests. Finally, the modified process design for producing the uniform Ti-6Al-4V wing product without forming defects was suggested.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.897-903
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• 2010

This paper presents a response surface method(RSM) with Latin Hypercube Sampling strategy, which is employed to optimize a magnet pole shape of large scale BLDC motor to minimize the cogging torque. The proposed LHS algorithm consists of the multi-objective Pareto optimization and (1+1) evolution strategy. The algorithm is compared with the uniform sampling point method in view points of computing time and convergence. In order to verify the developed algorithm, a 6 MW BLDC motor is simulated with 4 design parameters (arc length and 3 variables for magnet) and 4 constraints for minimizing of the cogging torque. The optimization procedure has two stages; the fist is to optimize the arc length of the PM and the second is to optimize the magnet pole shape by using the proposed hybrid algorithm. At the 3rd iteration, an optimal point is obtained, and the cogging torque of the optimized shape is converged to about 14% of the initial one. It means that 3 iterations aregood enough to obtain the optimal design parameters in the program.