• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.12
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• pp.549-554
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• 2006

Available transfer capability(ATC) is an important indicator of the usable amount of transmission capacity accessible by several parties for commercial trading in power transaction activities. This paper deals with an application of optimization technique for available transfer capability(ATC) calculation and analyzes the results of ATC by considering several constraints. Especially several optimization techniques are used to solve the ATC problem with state-steady security constraints. The results are compared with that of repeat power flow(RPF), sequential quadratic programming(SQP) and linear programming(LP). The proposed method is applied to 10 machines 39 buses model systems to show its effectiveness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.188-191
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• 2005

In this paper, a design optimization technique is presented for determining the stiffness and the damping coefficient of the shock absorber that is used in the Gullwing door system of passenger car. The contact force between the shock absorber and stopper link, when the door is opened, is set up as objective function, and the stiffness and the damping coefficient are set up as design variables. ADAMS optimization module (SQP method) is applied in the design optimization process. This study shows that the stiffness and the damping coefficient of the shock absorber can be effectively determined in initial design stage of the Gullwing door.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.114-120
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• 2010

Optimization of the turning process has been concentrated on the selection of the optimal cutting parameters, such as cutting speed, feed rate and depth of cut. However, optimization of the cutting parameters does not necessarily guarantee the maximum profit. For the maximization of the profit, parameters other than cutting parameters have to be taken care of. In this study, 8 price-related parameters were considered to maximize the profit of the product. Regression equations obtained from RSM technique to relate the cutting parameters and maximum cutting volume with a given insert were used. The experiments with four combinations of cutting inserts and material were executed to compare the results that made the profit and cutting volume maximized. The results showed that the cutting parameters for volume and profit maximization were totally different. Contrary to our intuition, global optimization was achieved when the number of inserts change was larger than those for volume maximization. It is attributed to the faster cutting velocity, which decreases processing time and increasing the number of tool used and the total tool changing time.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1590-1603
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• 2004

In this study the optimization of plate-fin type heat sink with vortex generator for the thermal stability is performed numerically. The optimum solutions in the heat sink are obtained when the temperature rise and the pressure drop are minimized simultaneously. Thermal performance of heat sink is influenced by the heat sink shape such as the base-part fin width, lower-part fin width, and basement thickness. To acquire the optimal design variables automatically, CFD and mathematical optimization are integrated. The flow and thermal fields are predicted using the finite volume method. The optimization is carried out by means of the sequential quadratic programming (SQP) method which is widely used for the constrained nonlinear optimization problem. The results show that the optimal design variables are as follows; B$_1$=2.584 mm, B$_2$=1.741 mm, and t=7.914 mm when the temperature rise is less than 40 K. Comparing with the initial design, the temperature rise is reduced by 4.2 K, while the pressure drop is increased by 9.43 Pa. The relationship between the pressure drop and the temperature rise is also presented to select the heat sink shape for the designers.

• Journal of Ship and Ocean Technology
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• v.9 no.3
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• pp.1-13
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• 2005

A design procedure for a ship with minimum total resistance has been developed using a numerical optimization method called SQP (Sequential Quadratic Programming) to search for optimized hull form and CFD(Computational Fluid Dynamics) technique. The friction resistance is estimated using the ITTC 1957 model-ship correlation line formula and the wave making resistance is evaluated using a potential-flow panel method based on Rankine sources with nonlinear free surface boundary conditions. The geometry of hull surface is represented and modified using B-spline surface patches during the optimization process. Using the Series 60 hull ($C_B$ =0.60) as a base hull, the optimization procedure is applied to obtain an optimal hull that produces the minimum total resistance for the given constraints. To verify the validity of the result, the original model and the optimized model obtained by the optimization process have been built and tested in a towing tank. It is shown that the optimal hull obtained around $13\%$ reduction in the total resistance and around $40\%$ reduction in the residual resistance at a speed tested compared with that of the original one, demonstrating that the present optimization tool can be effectively used for efficient hull form designs.

• Smart Structures and Systems
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• v.26 no.5
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• pp.545-558
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• 2020

A design method of a Multiple Tuned Mass Damper (MTMD) system is presented for wind induced vibration control of a cable-supported roof structure. Modal contribution analysis is carried out to determine the dominating modes of the structure for the MTMD design. Two MTMD systems are developed for two most dominating modes. Each MTMD system is composed of multiple TMDs with small masses spread at multiple locations with large responses in the corresponding mode. Frequencies of TMDs are distributed uniformly within a range around the dominating frequencies of the roof structure to enhance the robustness of the MTMD system against uncertainties of structural frequencies. Parameter optimizations are carried out by minimizing objective functions regarding the structural responses, TMD strokes, robustness and mass cost. Two optimization approaches are used: Single Objective Approach (SOA) using Sequential Quadratic Programming (SQP) with multi-start method and Multi-Objective Approach (MOA) using Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The computation efficiency of the MOA is found to be superior to the SOA with consistent optimization results. A Pareto optimal front is obtained regarding the control performance and the total weight of the TMDs, from which several specific design options are proposed. The final design may be selected based on the Pareto optimal front and other engineering factors.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1418-1423
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• 2004

Optimization of a heat exchanger with internally finned circular tubes has been performed for three-dimensional periodically fully developed turbulent flow and heat transfer. The design variables of fin number N, fin width ($d_1,d_2$) and fin height(H), are numerically optimized for the limiting conditions of $N=22{\sim}37$, $d_1=0.5{\sim}1.5$ mm, $d_2=0.5{\sim}1.5$ mm, $H=0.1{\sim}1.5$. Due to the periodic boundary conditions along main flow direction, the three layers of meshes are considered. The CFD and the mathematical optimization are coupled to optimize the heat exchanger. The flow and thermal fields are predicted using the finite volume method and the optimization is carried out by using the sequential quadratic programming (SQP) method which is widely used in the constrained nonlinear optimization problem.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.103-108
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• 2012

In this paper, the optimal design of a spring-type gravity compensation system for an articulated robot is presented. Sequential quadratic programming (SQP) is adopted to resolve various nonlinear constraints in spring design such as stress, buckling, and fatigue constraints, and to reduce computation time. In addition, continuous relaxation method is used to explain the integer-valued design variables. The simulation results show that the gravity compensation system designed by proposed method improves the performance effectively without additional weight gain in the main workspace.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.4 s.235
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• pp.460-468
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• 2005

Analyses of flow and heat transfer characteristics and shape optimization of internally finned circular tubes have been performed for three-dimensional periodically fully developed turbulent flow and heat transfer. CFD and mathematical optimization are coupled in order to optimize the shape of heat exchanger. The design variables such as fin widths $(d_{1},\;d_{2})$ and fin height (h) are numerically optimized by minimizing the pressure loss and maximizing the heat transfer rate for limiting conditions of $d_{1}=0.2\~1.5\;mm,\;d_{2}=0.2\~1.5\;mm,$ and $h=0.2\~1.5mm$. Due to the periodic boundary conditions along main flow direction, the three layers of meshes are considered. The flow and thermal fields are predicted using the finite volume method and the optimization is carried out by means of the sequential quadratic programming (SQP) method which is widely used in the constrained nonlinear optimization problem.

• The Journal of the Acoustical Society of Korea
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• v.27 no.6
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• pp.263-270
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• 2008

The performance of an ultrasonic array sensor is determined by the properties of constituent materials and the effects of many structural parameters. In this study, with the finite element method, variation of the performances of an ultrasonic array sensor was analyzed in relation to its structural variables. Based on the analysis result, the structure of the ultrasonic array sensor was optimized to provide the highest sensitivity while satisfying such requirements as fractional bandwidth, center frequency and -20 dB pulse length. The optimization was carried out with the SQP-PD method for a target function composed of the ultrasonic array sensor performance. The optimized ultrasonic array sensor satisfied all the required specifications to be applicable to medical imaging diagnosis. The design technology in this paper can be utilized for other ultrasonic array sensors of a similar structure.