• Transactions of Materials Processing
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• v.30 no.1
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• pp.27-34
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• 2021

In this study, response surface method (RSM) was used in modeling and multi-objective optimization of the parameters of AA5052-H32 in incremental sheet forming (ISF). The goals of optimization were the maximum forming angle, minimum thickness reduction, and minimum surface roughness, with varying values in response to changes in production process parameters, such as tool diameter, tool spindle speed, step depth, and tool feed rate. A Box-Behnken experimental design (BBD) was used to develop an RSM model for modeling the variations in the forming angle, thickness reduction, and surface roughness in response to variations in process parameters. Subsequently, the RSM model was used as the fitness function for multi-objective optimization of the ISF process based on experimental design. The results showed that RSM can be effectively used to control the forming angle, thickness reduction, and surface roughness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.116-121
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• 2016

The purpose of this study was to ensure the safety of a scooter frame through a structure and vibration analysis according to the tube thickness and weight of the frame of the electric scooter, which is currently being commercialized. According to the results of this study, the largest displacement value of 0.13238mm appeared in the 3-mm thickness when applying the 100-kg load according to the thickness, and 0.026591mm and 0.019062mm appeared in the 4-mm and 5-mm thicknesses, respectively. The difference between the 4-mm and 5-mm values was 0.007529mm, and it showed low displacement. Thus, the frame of more than 4-mm thickness was considered safe. In addition, the experimental result for the natural frequency from Mode 1 to Mode 6 in the vibration analysis was within 601.88Hz. In the 5-mm frame, the durability regarding the vibration was recognized as the best due to the appearance of the critical frequency (341.03Hz).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.4
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• pp.321-328
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• 2021

This paper derives numerically new buckling Knockdown factors for the lightweight design of the composite propellant tanks for space launch vehicles. A nonlinear finite element analysis code, ABAQUS, is used for the present postbuckling analysis of composite cylinders under compressive loads. Various thickness ratios (R/t) and slenderness ratios (L/R) are considered and Single Perturbation Load Approach is applied to represent the geometric initial imperfection of the composite cylinder. For the composite cylinder with thickness ratio of 500 and slenderness ratio of 2.04, the buckling Knockdown factor derived in this work is higher by 84.38% than NASA's previous buckling design criteria. Therefore, it is investigated that a lightweight design is possible when the present Knockdown factors are used for the design of composite propellant tanks. In addition, it is shown that global buckling loads and buckling Knockdown factors decrease as the thickness ratio or slenderness ratio of composite cylinders increases.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.3
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• pp.242-249
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• 2017

A design system for doubler reinforcement of the ship plate members subjected to in-plane shear and biaxial compressive loads was developed. This design system of doubler reinforcement on ship plate members established by design supporting system and this system was based on the buckling evaluation process of ship plate members for these in-plane loads. Each design parameters were suggested by equations as the form of influence coefficients for the doubler reinforcement subjected to the various in-plane loads including shear load. Strength of doubler plate member reinforced on the plate member could be suggested by the equivalent flat plate thickness after the consideration of corelation equations in the design system of doubler reinforcement. Level of strength recovery of ship plate members for these in-plane loads according to the local reinforcement by doubler could be suggested by use of this design system in the initial repair design stage of shipyards.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.4
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• pp.398-402
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• 2014

This paper presents the results of a study on the optimal footpad design for vertical climbing on acrylic surfaces with various curvatures used Taguchi methods. For a climbing robot, the adhesion system plays an important role in the climbing process. Only an appropriate adhesion strength will prevent the robot from falling and allow it to climb normally. Therefore, the footpad is a significant parameter for a climbing robot and should be studied. Taguchi methods were used to obtain a robust optimal design, where the design variables were the flat tacky elastomeric shape, area, thickness, and foam thickness of the footpad. Experiments were conducted using acrylic surfaces with various curvatures. An optimized footpad was selected based on the results of the experiments and analysis, and the stability of the wall-climbing robot was verified.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.57-62
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• 2011

In this study, the optimized design for 130 liter storage fuel tank with 70MPa filling pressure has been investigated using a FEM technique and Taguchi design method. The strength safety of a composite fuel tank in which is fabricated by an aluminum liner of 6061-T6 material and carbon fiber wound composite layers of T800-24K has been analyzed based on the criterion of design safety of US DOT-CFFC and Korean Standard. The FEM computed results on the stress safety of 70MPa hydrogen gas tank were compared with a criterion of a stress ratio, 2.4 of US DOT-CFFC and Korean Standard, and indicated the safety. Thus, the optimized design elements based on the Taguchi's method were recommended as an aluminum liner thickness of 6.4mm, a carbon fiber laminate thickness in hoop direction of 31mm and a carbon fiber laminate thickness in helical direction of 10.2mm, which is represented by a design model of No. 5.

• Journal of Information Display
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• v.9 no.3
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• pp.28-32
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• 2008

Low sustained voltage $(V_s)$ and high luminous efficiency (lumen/Watts) are required for the enhanced performance of an AC PDP. Both are not realized in the same condition, however, because luminous efficiency decreases when the sustained voltage is lowered in most cases. In this study, the three design factors in the front panel of a PDP, i.e., the thickness and position of the bus electrode and the thickness of the dielectric layer, were chosen to investigate how they affect the sustained voltage and the luminous efficiency, and to find a way to optimize them. Two values were given to each of the three design factors, and experiments were done via full factorial design, i.e., with a total of eight conditions, using a 3-in.diagonal test panel. The changes in the sustained voltage and the luminous characteristics were explained in connection with the discharge characteristics of the PDP cells.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.6
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• pp.612-618
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• 2009

This study is concerned about the optimal design of the arm 1 and arm 2 in the SCARA robot. The mass and inertia moment of the arm I and arm 2 in a SCARA robot is greatly affected on the performance such as a cycle time, and torques loaded on $1^{st}$ axis and $2^{nd}$ axis. To reduce the mass and inertia moment, this study carried out optimal design by FEM analysis using parametric variables, which is a width, a height of the rib and a thickness of arm in the arm. The rib is adapted instead of reducing the thickness in the arm. And the simulation by computer was conducted on two given paths in X direction and Y direction. After optimal design, the result showed that maximum torque of $1^{st}$ axis and $2^{nd}$ axis reduced to maximum 9.5% on a given path.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.135-142
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• 2004

The apparent advantages of FRP (fiber reinforced plastics) composites over the conventional structural materials may be attributed to their high specific strength and stiffness. Other affordable properties of FRPs including an excellent durability make them particularly attractive for the structures in severe service conditions. Therefore, the material and sectional properties of a FRP structural component should be designed to meet its specific requirements and service conditions. This paper is performed the material property optimization under optimum design of pultruded FRP bridge deck section. In the problem formulation, an objective function is selected to minimize the maximum R(strength ratio). The thickness of layers, volumes of fibers and matrix fiber orientation, and stacking sequence of FRPs are used as the design variables. Strength ratio in the design code, material failure criteria and pultruded manufacture thickness are selected as the design constraints to enhance the material performance of FRP decks. From the results of the numerical investigation, we obtained the optimum deck section profile for conventional using object.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.26-30
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• 2016

This paper presented an optimum design of a perpendicular PMDSLSM (Permanent Magnet Double-sided Linear Synchronous Motor) to minimize the detent force. As an optimum method, the response surface method was used and 3D finite element method for the calculation. The design variables of the machine were the primary core width and thickness, and magnet width, thickness and length. Object functions were to minimize the detent force and maximize the thrust of the basic model. The results showed that the thrust force of the optimum design increased from 82.1N to 90.2N and detent force decreased from 15.2N to 2.8N, respectively, compared to the basic model.