• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.486-489
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• 2002

This paper proposes a tabu search (TS) algorithm to optimal weight selection in design of robust H$_{\infty}$ power system stabilize. (PSS), In H$_{\infty}$ control design, the weight selection and the representation of system uncertainties are the major difficulties. To cope with these problems, TS is employed to automatically search for the optimal weights. On the other hand, the normalized coprime factorization (NCF) is used. The H$_{\infty}$ controller can be directly developed without ${\gamma}$-iteration. Also, the pole-zero cancellation phenomena are prevented. The performance and robustness of the proposed PSS under different loading conditions are investigated in comparison with a robust tuned PSS by examining the case of a single machine infinite bus (SMIB) system. The simulation results illustrate the effectiveness and robustness of the proposed PSS.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.127-136
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• 2006

Metallic sandwich plates with inner dimpled shell subject to 3-point bending have been analyzed and then optimized for minimum weight. Inner dimpled shells can be easily fabricated by press or roll with high precision and bonded with same material skin sheets by resistance welding or adhesive bonding. Metallic sandwich plates with inner dimpled shell structure can be optimally designed for minimum weight subject to prescribed combination of bending and transverse shear loads. Fundamental findings for lightweight design are presented through constrained optimization. Failure responses of sandwich plates are predicted and formulated with an assumption of narrow sandwich beam theory. Failure is attributed to four kinds of mechanisms: face yielding, face buckling, dimple buckling and dimple collapse. Optimized shape of inner dimpled shell structure is a hemispherical shell to minimize weight without failure. It is demonstrated that bending stiffness of sandwich plate is 2 or 3 times larger than solid plates with the same strength. Failure mode boundaries and iso-strength lines dependent upon the geometry and yield strain of the material are plotted with respect to geometric parameters on the failure map. Because optimal parameters of maximum strength for given material weight can be selected from the map, analytic solutions for maximum strength are expressed as a function of only material property and proposed strength. These optimal parameters match well with numerical optimal parameters.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.14-20
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• 2020

Currently, the automotive market is intensively researching eco-friendly vehicles such as EV vehicles and hydrogen vehicles. Further, research and developments for the future markets such as autonomous vehicles and the connective cars are coped up continuously along with the rising fuel economy regulations and the emission regulations. In this development, various sensors, batteries, and control devices are fused in order to decrease the weight of the vehicle. Moreover, since the fuel economy regulation is an issue, research on the weight reduction of body parts is underway. Therefore, in this work, a study is conducted to obtain the optimal design of the Dash part that separates the engine room and the passenger seat of the vehicle body by combining lightweight materials with high rigidity materials. The optimal design was obtained using the Finite Element Analysis. Further, AL5083 was used as the lightweight material and ASBC1470 was used for high strength materials. The parts made with this combination of materials had strength equivalent to that of the existing steel and the weight was reduced by 10%.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.35-42
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• 2008

Most of tasks for vertical surface work in shipyard have been accomplished by human workers. However, such manual work often causes injury to workers, also the production cost becomes high due to increasing individual wage. To cope with the circumstance, shipbuilding companies try to introduce wall-climbing robots for carrying out such kind of tasks. In designing a wall-climbing robot, it is essential to minimize its own weight to improve the performance such as moving speed and power saving. For such purpose. this study proposes a method of optimal design for a wall-climbing robot using a genetic algorithm with multi-objective function. Specifically, the thickness of the robot base is minimized to reduce the weight while maintaining the allowable strength and avoiding the resonance frequencies. The proposed method is applied to the design of a wall-climbing robot, and the result shows that the method is useful at an early design stage.

• Journal of the Korean Society of Industry Convergence
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• v.16 no.4
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• pp.133-140
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• 2013

This paper presents an overview of the concepts of optimal feeder design in relation to the loading of bulk solids for Automatic filling system that should be control the amount of goods and packaging to seal. Feeder modular device, important parts of the package, so in order to perform a conceptual design optimization techniques are applied in two steps. First of all derive the problems through structural analysis for the conceptual model of vibrating feeder. Secondly derive reasonable design model based on the results of the structural analysis of modified boundary shape and then verify it. The proposed system has the following goal that is satisfies the dynamic stability with minimum weight and optimization of the shape. As a result, the weight reduction of feeder is 2.1% and 7% increase in the natural frequency.

• Journal of Auto-vehicle Safety Association
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• v.11 no.4
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• pp.57-62
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• 2019

The seat back frame of the vehicle is subjected to load on the passenger behavior. Because of steel material, it is necessary to optimize the frame considering lightweight and safety. In this paper, finite element analysis is used for the optimal design of the seat back frame. First, a lightweight material is applied to reduce the weight of the seat back frame. Secondly, the design position of the pipe part fastened in the seat back frame was selected by considering the strength against the load generated by the occupant. Third, the shape of the side frame was derived by performing the phase optimization analysis for the AFT load condition. And we have compared the initial model with the optimal model to verify the light weighting and safety. As a result, the optimal design model of the seat back frame satisfying the weight reduction and safety has been proposed.

• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.830-835
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• 2018

The tubular link chain conveyor works under very extreme conditions such as high tensile load, friction, and dangerous operating environments. In this study, we propose an optimal design plan for reducing cost and improving performance through weight reduction of tubular link chain conveyors for sludge transport. For light weight of tubular link chain conveyor, the optimization software using SHERPA algorithms, HEEDS was used in conjunction with ANSYS Mechanical V14.5, which is widely used in structural analysis, to achieve optimal tubular link chain. Through the optimization process, 19% light weight was achieved.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.1
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• pp.19-25
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• 2010

A computational study for the optimal design of heat exchangers (HX) used in a high temperature and high pressure system is presented. Two types of air to air HX are considered in this study. One is a single-pass cross-flow type with straight plain tubes and the other is a two-pass cross-counter flow type with plain U-tubes. These two types of HX have the staggered arrangement of tubes. The design models are formulated using the number of transfer units ($\varepsilon$-NTU method) and optimized using a genetic algorithm. In order to design compact light weight HX with the minimum pressure loss and the maximum heat exchange rate, the weight of HX core is chosen as the object function. Dimensions and tube pitch ratio of a HX are used as design variables. Demanded performance such as the pressure loss (${\Delta}P$) and the temperature drop (${\Delta}T$) are used as constraints. The performance of HX is discussed and their optimal designs are presented with an investigation of the effect of design variables and constraints.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_3
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• pp.1279-1288
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• 2023

Recently, domestic leisure boats have been actively researching eco-friendly product development to enter the global market. Since the hulls of existing leisure boats are mainly made of fiber reinforced plastic (FRP) or aluminum, design techniques for securing structural safety by applying related materials have been mainly studied. In this study, an initial structural design safety assessment of a trimaran pontoon leisure boat with a modular hull structure and eco-friendly high-density polyethylene (HDPE) material was conducted, and sensitivity evaluation and optimization analysis for lightweight design were performed. The initial structural design safety assessment was carried out by creating a finite element analysis model and applying the loading conditions specified in the ship classification regulation to check whether the specified allowable stresses are satisfied. For the sensitivity evaluation, the influence of stress and weight of each hull structural member was evaluated using the orthogonal array design of experiments method, and an approximate model based on the response surface method was generated using the results of the design of experiments. The optimization analysis set the thickness of the hull structural members as the design variable and considered the optimal design formulation to minimize the weight while satisfying the allowable stress. The algorithm of the optimization analysis applied the Gradient-population Based Optimizer (GBO) to improve the accuracy of the optimal solution convergence while reducing the numerical cost. Through this study, the optimal design of a newly developed eco-friendly trimaran pontoon leisure boat with a weight reduction of 10% was presented.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.301-309
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• 1995

Shape optimal design of an excavator boom to minimize weight can be formulated as a nonlinear programming problem with an automesh refinement carried out by using the finite element method. The design variables are the radii and the coordinates of the circle to describe the excavator boundary shape. In addition to the displacement and stress constraints, geometric constraints are imposed such that the nodes cannot cross the certain range. The optimum design is obtained by using the PLBA nonlinear programming code. The sensitivity derivatives are calculated using the semi-analytical scheme. Numerical results of an excavator boom show potential for weight reduction of 4.4%(65.6 kgf) when considering the displacement, stress and geometric constraints.