• The Korean Journal of Applied Statistics
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• v.23 no.2
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• pp.285-293
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• 2010

The traditional methods for evaluating response surface designs are alphabetic optimality criteria. These single-number criteria such as D-, A-, G- and V-optimality do not completely reflect the prediction variance characteristics of the design in question. Alternatives to single-numbers summaries include graphical displays of the prediction variance across the design regions. We can suggest the animated quantile plots as the animation of the quantile plots and use these animated quantile plots for comparing and evaluating response surface designs.

• Proceedings of the Korean Society for Quality Management Conference
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• 2010.04a
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• pp.115-120
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• 2010

반응표면실험계획들을 평가하기 위한 방법으로서 전형적인 방법이 알파벳최적화이다. 그러나 이러한 알파벳최적화(D-, A-, G-, V-최적화 등)는 하나의 수치이므로 그 유용성에도 불구하고 반응표면실험 계획들이 갖는 추정반응값분산의 분포에 대한 정보에 한계를 갖는다. 이를 극복하고자 하는 대안으로서 그래픽 방법들이 있는데 우리는 그 중에 분위수그림을 애니메이션화한 동적분위수그림을 제안할 수 있고 이 동적분위수그림을 이용하여 반응표면실험계획들이 갖는 추정반응값분산의 분포를 서로 비교, 평가 할 수 있다.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.739-746
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• 2008

The aim of this study is finding the optimal design parameters and the optimal operation variables of a reactive distillation column. Different from steady state optimization, dynamic optimization makes it possible considering operation ability as well as design problems at process design step. For performing dynamic optimization, dynamic simulation should be done first. If dynamic simulation is already finished, dynamic optimization can be performed with less effort than that of dynamic simulation.Reactive distillation systems involving reaction and separation in a single unit have the potential to reduce capital and operating costs, particularly when reaction have conversion constraint or when azeotropes exist making conventional separation difficult and expensive. This study here present work on the continuous distillation process, the homogeneous catalyzed esterification of methanol and acetic acid, the synthesis of methyl acetate. Based on an equilibrium stage model of a reactive distillation column a dynamic optimization problem was formulated and solved. And the results were verified by performing dynamic simulation and showing the variation of conversion and purity as the variation of the operation variables. As the results of dynamic optimization, this study found optimal feed ratio, reflux ratio and reboiler duty of this system. And as this study applied it to dynamic simulations the dynamic characteristics of a reactive distillation column are showed under optimal operating condition.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.81-88
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• 1993

A direct treatment of the min-max type objective function of the dynamic response optimization problem is proposed. Previously, the min-max type objective function was transformed to an artificial design variable and an additional point-wise state variable constraint function was imposed, which increased the complexity of the optimization problem. Especially, the design sensitivity analysis for the augmented Lagrangian functional with the suggested treatment is established by using the adjoint variable method and a computer program to implement the proposed algorithm is developed. The optimization result of the proposed treatment are obtained for three typical problems and compared with those of the previous treatment. It is concluded that the suggested treatment in much more efficient in the computational effort than the previous treatment with giving the similar optimal solutions.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.1
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• pp.32-39
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• 2004

Biological neurons generally have chaotic characteristics for permanent or transient period. The effects of chaotic response of biological neuron have not yet been verified by using analytical methods. Even though the transient chaos of neuron could be beneficial to overcoming the local minimum problem, the permanent chaotic response gives adverse effect on optimization problems in general. To solve optimization problems, which are needed in almost all neural network applications such as pattern recognition, identification or prediction, and control, the neuron should have one stable fixed point. In this paper, the dynamic characteristics of the chaotic dynamic neuron and the condition that produces the chaotic response are analyzed, and the convergence conditions are presented.

• KIISE Transactions on Computing Practices
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• v.21 no.5
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• pp.379-386
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• 2015

We propose a novel user-perceived performance optimization framework for the Android platform that takes advantage of the user-centric response time analysis. To this end, we propose a new definition of response time, which we call the user-centric response time, as a metric for the quality of user-perceived performance of the smartphone application. In this paper, we describe the design and implementation of an on-line user-centric response time analyzer for Android-based smartphones, which provides smartphone application developers with valuable insight for user-perceived performance optimization. We implemented the user-centric response time analyzer on the Android platform, version 4.0.4 (ICS) running on a Galaxy Nexus smartphone. From our experimental results, the proposed user-centric response time analyzer accurately estimates user-centric response times with an accuracy of 92.0% compared to manually measured times with less than 1% performance penalty. In order to evaluate the efficiency of the proposed framework, we were able to reduce the user-centric response time of the target application by up to 16.4% based on the evaluation results by the proposed framework.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.87-93
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• 2007

Generally, the analysis using Computational Fluid Dynamics(CFD) is necessary for aircraft design. However, the analysis using CFD, it requires a lot of computational time and cost. But we can reduce grid reconstruction time of analyzing the various models if we use dynamic mesh. In addition, dynamic mesh can be an efficient technique in aeroelastic analysis and design optimization problem because these problems need grid reconstruction process frequently.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.105-111
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• 2013

The spindle is the main component in machine tools. The static and dynamic characteristics of the spindle directly affect the machining accuracy of workpieces. The characteristics of the spindle depend on the shaft size, bearing span, built-in motor location, and so on. Therefore, the appropriate selection of these parameters is important to improve the spindle characteristics. This paper presents the analysis of the static and dynamic characteristics and optimization design of a 40,000-rpm high-speed spindle. Statistical analysis for optimization and finite element analysis were performed. This study uses the response surface method to optimize the objective function and design factors. The targets are the natural frequency and displacement. The design factors are the shaft length, shaft diameter, bearing span, and motor location. The optimized design provides better results than the initial model, and these results are expected to improve the static and dynamic characteristics of the spindle.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.439-452
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• 1994

A method to optimize the cost of R/C frames and an algorithm of the optimal limit state design for R/C frames subjected to dynamic loads are presented. The modal superposition method was used to find the dynamic responses of the frames. Each member of R/C frame is made up of more than two elements and the stiffness matrix and consistent mass matrix of three d.o.f in the node of each element was used to include axial, shear and flexural effects. The objective function to be minimized formulated the cost of materials, steel and concrete, and optimised to satisfy the behaviors of R/C frame and each constraint imposed by the limit state requirements. Both objective function and each constraint are derived in terms of design variables which include the effective depth, beam width, compression and tension steel area, and column shear steel area. A few applications are presented which demonstrate the feasibility, the validity and efficiency of the algorithm for automated optimum design of R/C frames where dynamic behavior is to be considered.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1327-1334
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• 2012

This study shows the conformance-based design results of a fourth-order dynamic actuator showing a performance variation caused by variation in the components as well as aero-induced disturbances. The actuator comprises a BLDC motor, spur gear and worm gear assembly, and canard. The actuator performance was evaluated by using time-variant angle information of the canard. Based on the response surface models, critical system variables were screened using F-tests, and then, the performance was approximated as a function of the variables because it is difficult to determine the performance of a high-order dynamic system as a function of system variables through analytical approaches. In this study, the conformance of uncertain performance to the specification was defined as a probability measure. The design variables obtained by optimizing the measure can provide actuator performance conforming to the specifications considered, even though there is a variation in both the components and the aero-induced disturbances.