• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.80-83
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• 2002

A 3D shape optimization algorithm integrates the geometric parameterizationi 3D F.E. performance analysis, steepest descent method with design sensitivity and mesh relocation method. The design sensitivity of the surface nodal points is also systematically converted into that of the design variables for the application to parameterized optimization. The proposed algorithm is applied to the optimum design of tank shield model of transformer and the effectiveness is proved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.239-240
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• 2009

• Journal of the korean Society of Automotive Engineers
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• v.12 no.4
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• pp.47-55
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• 1990

This study is the first step for the grasp of transfer path to the vibration generated from the automotive engine and consideration of counterplan for optimal design and low vibration, low noise of the exhaust system. In this study, by applying the theory of modal analysis and experiment, vibrational reduction effect is evaluated according to the attachment of flexible coupling to the exhaust system. And data for the design is suggested to improve the characteristics of vibration. The vibration isolation and damping characteristics are improved due to the attachment of flexible coupling to the exhaust system. As a result, it is identified that flexible coupling which has good flexibility is more effective for the improvement of vibrational characteristics. By the estimation of modeshape of vibration, the location of optimal damping hanger is determined in the viewpoint of vibration isolation. Also it is confirmed that the characteristics of vibration is improved due to the attachment of damping hanger.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1373-1392
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• 2017

WiFi Direct (WD) is a state of the art technology for a Device-to-Device (D2D) communication in 802.11 networks. The performance of the WD system can be significantly affected by some key factors such as the type of application, specifications of MAC and PHY layer parameters, and surrounding environment etc. It is, therefore, important to develop a system model that takes these factors into account. In this paper, we focus on investigating the design parameters of the PHY layer that could maximize the efficiency of the WD 802.11 system. For this purpose, a basic theoretical model is formulated for a WD network under a 2x2 Multiple In Multiple Out (MIMO) TGn channel B model. The design level parameters such as input symbol rate and antenna spacing, as well as the effects of the environment, are thoroughly examined in terms of path gain, spectral density, outage probability and Packet Error Rate (PER). Thereafter, a novel adaptive algorithm is proposed to choose optimal parameters in accordance with the Quality of Experience (QoE) for a targeted application. The simulation results show that the proposed method outperforms the standard method thereby achieving an optimal performance in an adaptive manner.

• Steel and Composite Structures
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• v.15 no.5
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• pp.519-538
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• 2013

The design optimization of a cold-formed steel portal frame building is considered in this paper. The proposed genetic algorithm (GA) optimizer considers both topology (i.e., frame spacing and pitch) and cross-sectional sizes of the main structural members as the decision variables. Previous GAs in the literature were characterized by poor convergence, including slow progress, that usually results in excessive computation times and/or frequent failure to achieve an optimal or near-optimal solution. This is the main issue addressed in this paper. In an effort to improve the performance of the conventional GA, a niching strategy is presented that is shown to be an effective means of enhancing the dissimilarity of the solutions in each generation of the GA. Thus, population diversity is maintained and premature convergence is reduced significantly. Through benchmark examples, it is shown that the efficient GA proposed generates optimal solutions more consistently. A parametric study was carried out, and the results included. They show significant variation in the optimal topology in terms of pitch and frame spacing for a range of typical column heights. They also show that the optimized design achieved large savings based on the cost of the main structural elements; the inclusion of knee braces at the eaves yield further savings in cost, that are significant.

• Journal of the Korean Geotechnical Society
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• v.27 no.8
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• pp.51-61
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• 2011

Spatial estimation of the thickness and depth of the geological profile has been regarded as an important procedure for the design of soft ground. A minimum variance criterion, which has often been used in traditional kriging techniques, does not always guarantee the optima1 estimates for the decision-making process in geotechnical engineering. In this study, a geostatistica; framework is used to determine the optimal thickness of the consolidation layer and the optimal area that needs the adoption of prefabricated vertical drains via indicator kriging and loss function. From the exemplary problem, different optimal estimates can be obtained depending on the loss function chosen. The design procedure and method considering the minimum expected loss presented in this paper can be used in the decision-making process for geotechnical engineering design.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.325-327
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• 1998

Disk type single-phase switched reluctance motor which has an advantage of simple robust construction, simple control circuity, and low manufacturing cost has a specific property of axial flux machine and radial flux machine simultaneously. So, this DSPSRM has a complicated magnetic circuit and it is difficult to analyze characteristics of DSPSRM for design. In this paper, we used to analyze the effects of radial flux and axial flux simultaneously by 3D-finite element method. From the results of 3-D FEM, we obtained the approximated torque characteristics of DSPSRM. It's analysis results can be used in optimal design of DSPSRM considering the saturation.

• Korean Journal of Human Ecology
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• v.14 no.3
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• pp.467-473
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• 2005

The integrative Internet program was developed for the selection of optimal brassiere components according to the breast types of middle-aged women. In this program, a customer is classified into a certain group through three steps of a discriminant analysis. Three variables used in the analysis include breast volume, radii of curvature of under-breast curve, and a distance between inner breast points. Using individual data of three variables, the optimal brassiere components, i.e. brassiere cup size, curvature of front panel and wire, distance between cups, are suggested for each customer. Discrimination of breast types using only 2D measurements is also included for those who do not have easy access to a 3D measurement device.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.61-67
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• 2002

The present work is investigated optimal design for the injection molding process of a hand brake cover. The viscoelastic flow through a hand brake cover shape in the mold were calculated and compared with the experimental data. Numerical analysis reasonably predicted the general performance i.e hold pressure, cooling time and hold pressure time. In order to determine optimal process parameters, Numerical analysis and experiments have been performed for various process conditions. In this study, we obtained to increase in the productivity by $160\%$ by optimal process conditions.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.221-227
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• 2017

A new approach to designing a broadband and highly efficient class-E power amplifier based on nonlinear shunt capacitance analysis is proposed. The nonlinear shunt capacitance method accurately extracts optimum class-E power amplifier parameters, including an external shunt capacitance and an output impedance, at different frequencies. The dependence of the former parameter on the frequency is considered to select an optimal value of external shunt capacitor. Then, upon determining the latter parameter, an output matching network is optimized to obtain the highest efficiency across the bandwidth of interest. An analytical approach is presented to design the broadband class-E power amplifier of a MOSFET transistor. The proposed method is experimentally verified by a 140-170 MHz class-E power amplifier design with maximum added power efficiency of 82% and output power of 34 dBm.