• Smart Structures and Systems
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• v.19 no.3
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• pp.279-288
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• 2017

Magnetorheological damper has received significant attention in recent years due to the reason that it can offer adaptability of active control devices without requiring the associated large power sources. In this paper, performance tests on a MR damper are carried out under different currents, excitation amplitudes and frequencies, the damping characteristics and energy dissipation capacity of the MR damper are analyzed. Elasto-plastic dynamic analysis on a space frame structure incorporated with MR dampers is conducted, and numerical analysis results show that MR dampers can significantly mitigate the structural vibration responses. Finally, the genetic algorithm with the improved binary crossover and mutation technique is adopted to optimize the arrangement of MR dampers. Numerical results show that dynamic responses of the optimal controlled structure are mitigated more effectively.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.29-34
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• 2003

Genetic algorithm is a optimization technique based on the mechanics of natural selection and natural genetics. Global optimum solution can be obtained efficiently by operations of reproduction, crossover and mutation in genetic algorithm. The authors developed a computer program which can optimize marine propulsion shafting by using binary-coded genetic algorithm and modal analysis method. In order to confirm the effectiveness of the developed computer program, we apply the program to a optimum design problem which is to obtain optimum diameters of intermediate shaft and propeller shaft in marine propulsion shafting. Objective function is to minimize total mass of shafts and constraints are that torsional vibration stresses of shafts in marine propulsion shafting can not exceed the permissible torsional vibration stresses of the ship classification society. The computational results by the program were compared with those of conventional design technique.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.145-152
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• 2003

An optimal design method in cooperated with nonlinear inelastic analysis method is presented. The proposed nonlinear inelastic method overcomes the difficulties due to incompatibility between the elastic global analysis and the limit state member design in the conventional LRFD method. The genetic algorithm uses a procedure based on Darwinian notions of survival of the fittest, where selection, crossover, and mutation operators are used among sections in the database to look for high performance ones. They satisfy the constraint functions and give the lightest weight to the structure. The objective function is set to the total weight of the steel structure and the constraint functions are load-carrying capacities, serviceability, and ductility requirement. Case studies of a three-dimensional frame and a three-dimensional steel arch bridge are presented.

• Structural Engineering and Mechanics
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• v.17 no.5
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• pp.707-725
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• 2004

An optimal design method with nonlinear elastic analysis is presented. The proposed nonlinear elastic method overcomes the drawback of the conventional LRFD method that accounts for nonlinear effect by using the moment amplification factors of $B_1$ and $B_2$. The genetic algorithm used is a procedure based on Darwinian notions of survival of the fittest, where selection, crossover, and mutation operators are employed to look for high performance ones among sections in the database. They are satisfied with the constraint functions and give the lightest weight to the structure. The objective function taken is the total weight of the steel structure and the constraint functions are strength, serviceability, and ductility requirement. Case studies of a planar portal frame, a space two-story frame, and a three-dimensional steel arch bridge are presented.

• Journal of the Korea Society of Computer and Information
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• v.22 no.11
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• pp.143-149
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• 2017

In this paper, we propose efficient management method of liberal education for improving computer literacy. We analyzed the actual conditions and factors affecting education and reflected the analysis results in education. The subject of the study is 'Practice Excel', and tested achievement based on computer literacy. In order to evaluate objectively, we conducted CBT(Computer Based Test) based on Computer Specialist in Spreadsheet & Database Level-2. Analysis of the questionnaire included the use of the popular statistical program, IBM SPSS 24 trial, and frequency, ANOVA, t-test, crossover analysis, and correlation. Evaluation results, An important factor influencing educational performance was active participation. It also proved to be very helpful for understanding excel functions & expression.

• Biomedical Science Letters
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• v.28 no.3
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• pp.178-185
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• 2022

The purpose of this study was to analyze the effect of chewing difficulty on osteoarthritis in Korean adults. Data from the National Health and Nutrition Examination Survey for two years from 2019 to 2020. The collected data were analyzed using the SPSS (21.0) program using composite samples, and the mean crossover analysis and logistic return analysis were performed. An analysis of the effects of chewing difficulty on osteoarthritis in korean adults showed that those with chewing difficulty had a 2.02 fold higher risk of osteoarthritis (95%CI=1.56~2.42) and a statistically significant difference (P<0.05). The association between the chewing difficulty on osteoarthritis could be confirmed, and measures improve of the oral health and preventing osteoarthritis should be prepared.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.559-564
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• 2001

The design of an automobile mirror actuator system needs a systematic optimization due to several variables, constraints, geometric limitations, moving angle, and so on. Therefore, this article provides the procedure of a genetic algorithm(GA) based optimization with finite element analysis for design of a mirror actuator considering design constraints, geometric limitations, moving angle. Local optimum problem in optimization design with sensitivity analysis is overcome by using zero-order overall searching method which is new optimization design method using a genetic algorithm.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.1
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• pp.67-73
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• 1999

This paper presents resizing design optimization method by utilizing genetic algorithm(GA), which consists of three basic operators : reproduction, crossover and mutation. The fitness and penalty function for resizing optimization problem are defined, and the flowchart of the developed computer program along with the descriptions of each modules is presented. Also, modelling for flexible-body dynamic analysis is presented. The model is composed of bodies, joints, and force elements such as translational spring-damper-actuator. The design objects si to determine the wall thickness for minimum weight under dynamic displacement constraint.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.968-970
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• 2001

Recently, the power supply equipments have tendency to take multiple feedback loop paths. In this paper the state space averaging technique is applied for the analysis of flyback type current mode control circuit. We made real converter for the gurantee of stable output characteristic and proper design of feedback circuit. The validity of proposed method is verified from test results. The improvement of stability is confirmed by sinusoidal signal injection method with isolated transformer. It is known that phase margin is sufficient and gain crossover frequency $f_c$ is nearly 1/5 of switching frequency $f_s$, from the experimental result with frequency response analyzer.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.10
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• pp.879-885
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• 2013

By performing interval analysis on the system transfer function, we propose an improved method of control loop design for a DC/DC converter. In conventional design methods, the effect of system parameter change due to the specified range of operating conditions and production tolerances in power components should be checked a posteriori, because this may result in a transfer function shift and performance degradation. In the proposed method, a possible parameter change is considered a priori in the design step in order that the desired crossover frequency and sufficient phase margin can be achieved even in the worst case condition. As an illustrative example, a buck dc/dc converter is designed by two different methods and performance comparisons are performed to verify the feasibility of the proposed scheme.