• International Journal of Precision Engineering and Manufacturing
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• 제1권1호
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• pp.62-70
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• 2000

The design of gear train is a kind of mixed problems which have to determine various types of design variables; i,e., continuous, discrete, and integer variables. Therefore, the most common practice of optimum design using the derivative of objective function has difficulty in solving those kinds of problems and the optimum solution also depends on initial guess because there are many sophisticated constrains. In this study, the Genetic Algorithm is introduced for the optimum design of gear trains to solve such problems and we propose a genetic algorithm based gear design system. This system is applied for the geometrical volume(size) minimization problem of the two-stage gear train and the simple planetary gear train to show that genetic algorithm is better than the conventional algorithm solving the problems that have continuous, discrete, and integer variables. In this system, each design factor such as strength, durability, interference, contact ratio, etc. is considered on the basis of AGMA standards to satisfy the required design specification and the performance with minimizing the geometrical volume(size) of gear trains

• International Journal of CAD/CAM
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• 제8권1호
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• pp.1-10
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• 2009

This paper presents a topology optimization approach using element-free Galerkin method (EFGM) for the optimal design of compliant mechanisms with geometrically non-linearity. Meshless method has an advantage over the finite element method(FEM) because it is more capable of handling large deformation resulted from geometrical nonlinearity. Therefore, in this paper, EFGM is employed to discretize the governing equations and the bulk density field. The sensitivity analysis of the optimization problem is performed by incorporating the adjoint approach with the meshless method. The Lagrange multipliers method adjusted for imposition of both the concentrated and continuous essential boundary conditions in the EFGM is proposed in details. The optimization mathematical formulation is developed to convert the multi-criteria problem to an equivalent single-objective problem. The popularly applied interpolation scheme, solid isotropic material with penalization (SIMP), is used to indicate the dependence of material property upon on pseudo densities discretized to the integration points. A well studied numerical example has been applied to demonstrate the proposed approach works very well and the non-linear EFGM can obtain the better topologies than the linear EFGM to design large-displacement compliant mechanisms.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권3호
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• pp.93-100
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• 2003

Switched reluctance motor(SRM) has some advantages such as low cost, high torque density but SRM has essentially high torque ripple due to its salient structure. In order to apply SRM to industrial field, torque ripple has to be reduced. This paper introduces optimal design process of SRM using an optimization algorithm of Progressive Quadratic Response Surface Modeling(PQRSM) and two-dimensional(2D) Finite Element Method(FEM). The electrical and geometrical design parameters have been adopted as 2D design variables. From this work, it can be obtained both the optimal design minimized torque ripple and the optima1 design maximized the average torque, respectively. Finally, this Paper Presents Performance comparison of two optimal designs and consider influence of the selected design variables in torque characteristics.

• 한국가시화정보학회지
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• 제16권3호
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• pp.35-39
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• 2018

In multiphase systems, surface wettability is one of dominant design parameters to enhance system performance. Since surface wettability can be maximized and minimized with micro-textured surfaces, therefore micro-textured surfaces are widely countered in various research and engineering fields. In this study, for better understanding of micrometer scaled surface wettability, spreading phenomena is experimentally investigated on the hydrophilic micro-textured surfaces. By photolithography and conventional dry etching method, there are prepared the surfaces with uniformly arrayed micro-pillars. The interfacial motions of a water droplet on the test sections are visualized by high speed camera in top view. On the basis of visualization data, it is analyzed the relation between dynamic coefficient and geometrical features on micro-textured surfaces.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.72-77
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• 2008

Stability is a very important part which we must consider in structural design. In this paper, we take advantage of finite element method, and study about parametrical instability of star-dome structures, which is subjected to harmonically pulsating load. When calculating stiffness matrix, we consider elastic stiffness and geometrical stiffness simultaneously. In equation of motion, we represent displacements and accelerations by trigonometric series expansions, and then obtain Hill's infinite determinants. After first order approximation, we can get first and second order dynamic instability region finally.

• 반도체디스플레이기술학회지
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• 제8권4호
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• pp.71-76
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• 2009

The clean non-contact type conveyor system for vertical transfer of large size FPD(Flat Panel Display) glasses has been installed at FPD production line just since a few years ago. The most important part of the conveyor is the 3 axis permanent magnet rollers faced orthogonally in pairs. However, the systematic design method about it has not been proposed yet. In this paper, we studied a design analysis for determining geometrical parameters of the magnetic roller by using a commercial FEM tool of the 3D Maxwell. Through a series of simulation, we obtained the relationship of several geometrical parameters affecting the torque of the conveyor.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.136-142
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• 2014

A major problem in Switched Reluctance Motor (SRM) is torque ripple, which causes undesirable acoustic noise and vibration. This work focuses on reducing the undesirable torque ripple in SRM by modifying stator and rotor geometry. This paper presents a comparative study on torque ripple minimization in SRM with modified pole shapes such as stator pole taper, stator pole face with non-uniform air gap and pole shoe attached to rotor pole. Further this paper presents a detailed sensitivity analysis of the effect of different geometrical parameters that alter the pole face shapes on the performance of SRM. The analysis is performed using finite-element method considering average torque and torque ripple as performance parameters. Based on the analysis, a design combining stator pole taper with non-uniform air gap is proposed to improve the torque characteristics of SRM. The dynamic characteristics of the proposed design are simulated and the results show satisfactory reduction in torque ripple.

• 한국의상디자인학회지
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• 제2권1호
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• pp.21-35
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• 2000

The purpose of this study was to evaluate the preference of image for modern application of Korean traditional patterns. A survey was conducted using the randomly selected 292 undergraduate women students of Taegu city. The degree of interest and preference in Korean traditional style or something like that had measured by 5 scale method. And then they had two groups which are interest/non-interest group, and preference/non-preference group in Korean traditional style. Also, preference of Korean traditional patterns was measured by 5 scale method. The image of Korean traditional patterns consisted of semantic differential scales. Analysis was by frequency, percentage, and mean. For difference of groups analysis was by t-test. The results were as follows:1. For the survey, 53.8% showed the interest and 40.4% did the preference for the traditional patterns. There was the positive correlation(0.782) between the degree of the interest and preference. 2. Among twenty traditional patterns, the patterns of plants and nature were very preferred, but the patterns of geometrical things was not preferred. 3. For the nature pattern, the image seemed to be elegant and feminine(womanly). For the plant pattern, the image seemed to be feminine, neat, weak, light and mild. For the animal pattern, the image seemed to be heavy, gorgeous, deluxe, virile(manly), strong and active. Last, for the geometrical pattern, the image seemed to be elegant, deluxe, rigid and strong. 4. Between the interest／non­interest groups, there was the significant difference in pattern of cloud, mountain, lotus flower, plum blossoms, orchid, dragon, chinese phoenix and bogy. Especially, for the orchid pattern, the preference difference between these groups was large. 5. For the plant pattern, the image difference between these groups was very large as the elegant-rustic image. Especially, the interest group evaluated as the elegant image. 6. Between the preference／non­preference groups, there was the strongly significant difference in the preference for the orchid pattern. 7. For the geometrical pattern, the image difference between these groups was very large as the mild­cold image. Especially, the preference groups evaluated as the cold image.

• 대한기계학회논문집A
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• 제28권4호
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• pp.378-385
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• 2004

Viscous-driven pumping is a very promising type in microscale applications. However, there exist a few disadvantages such as low efficiency and small volume flow rate. In the present study, a pump with tandem rotating cylinders and its optimum synthesis are proposed fur enhancing pumping performance. First, using an unstructured grid CFD method, we investigate the effects of geometrical parameters and then the performance of the pump with tandem cylinders is evaluated. Next, an optimum design synthesis tool is constructed by combining the aforementioned CFD analysis model with the mathematical optimization model, namely, Modified Method of Feasible Directions (MMFD). This technique is used to optimize the geometrical parameters of the pump, fur maximizing pumping efficiency. From the optimization results, it is believed that the present optimum synthesis is robust and has a potential fur other microfluidic device design.

• 한국전기전자재료학회논문지
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• 제26권6호
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• pp.457-461
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• 2013

In this paper, a novel method based on geometrical optics is proposed to calculate the optical characteristics of an electric field driven liquid crystal (ELC) lens. For an optimally designed ELC lens, effective refractive index is calculated and then ray tracing is carried out using Huygens' principle. From the results, the intensity distribution at the optimum viewing distance (OVD) is obtained. To confirm the validity of our work, the result is compared with that calculated by the extended Jones matrix method (EJMM). As a result, it turns out that the novel method provides more simple and rigorous simulation results than the EJMM.