• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1719-1726
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• 2002

Design variables and design parameters are rarely deterministic in practice. Robust optimal design takes into consideration of the uncertainties in the design variables and parameters. Robust optimization methodology with probability constraints requires a lot of system analyses fer calculating failure probability of each constraint. By introducing an envelope function to reduce the number of constraints, efficiency of robust optimization techniques can be considerably improved. Through four illustrative examples, it is shown that the number of system analyses is greatly decreased while little differences in the optimum results are observed.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.847-853
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• 2013

Micro-dimples on sliding surfaces have been investigated to reduce the frictional forces on metal bearing surfaces; however, for an elastomer, such as thermoplastic polyurethane (TPU), this has not been studied. The material properties of an elastomer are affected by temperature, and this can shorten the life of the elastomer. In this paper, micro-dimples were applied on the surface of an elastomer in order to reduce the frictional heating, which was experimentally investigated using pin-on-disk apparatus while the surface temperature was measured. To obtain optimal design parameters, the design of the experiment was applied, and the shape of the section, size, depth and density of micro-dimples were selected as the design parameters. The results show that the size of the dimple is the most important design parameter.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.58-63
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• 2007

Lots of needs are being paid for how to design HVAC system in large-scale buildings. Increasing awareness of energy use is main point of this research. HVAC systems' energy characteristics are not clearly identified and understood, so the optimal design of HVAC system is very important. The energy parameters of HVAC design that are system input energy, water/air moving equipments (pumps/fans) energy and outdoor air conditioning energy for IAQ are important. The purpose of this study is to provide the basic data for energy conservational HVAC design strategies.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.1
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• pp.62-74
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• 2002

The tracking of a reference temperature trajectory in a polymerization batch reactor is a common problem and has critical importance because the quality control of a batch reactor is usually achieved by implementing the trajectory precisely. In this study, only energy balances around a reactor are considered as a design model for control synthesis, and material balances describing concentration variations of involved components are treated as unknown disturbances, of which the effects appear as time-varying parameters in the design model. For the synthesis of a tracking controller, a method combining the input-output linearization of a time-variant system with the parameter estimation is proposed. The parameter estimation method provides parameter estimates such that the estimated outputs asymptotically follow the measured outputs in a specified way. Since other unknown external disturbances or uncertainties can be lumped into existing parameters or considered as another separate parameters, the method is useful in practices exposed to diverse uncertainties and disturbances, and the designed controller becomes robust. And the design procedure and setting of tuning parameters are simple and clear due to the resulted linear design equations. The performances and the effectiveness of the proposed method are demonstrated via simulation studies.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.142-154
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• 1998

A stirling engine is a mechanism used to convert heat to power and operates on a closed regenerative thermodynamic cycle with compression and expansion of the working fluid at different temperature. The performance of a stilting cycle machine is a function of six independent parameters, namely; (1) speed N(r.p.m), (2) pressure of the working fluid p(Pa), (3) ratio of the temperature in the compression and expansion space ${\tau}(=T_C/T_E)$ , (4) ratio of the swept volumes in these two spaces K, (5) phase angle $\alpha$ and (6) dead volume ratio X. This paper describes the procedure and presents the results of computations carried out to establish the optimum combinations of these six parameters for maximum engine output for the machine acting as a prime mover, over a combined temperature range from $300^{\circ}K$ to $1000^{\circ}K$ and dead volume ratio X ranging from 0.1 to 2.0. The output of a stilting cycle machine can be expressed in terms of nondimensional power in several different ways. Four methods were studied in detail, the parameters optimized and design charts and engine power charts prepared. The results of this paper may be useful as a guide to the likely effects on the performance of some of the important design parameters and regenerator design.

• Magazine of the Korea Concrete Institute
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• v.9 no.1
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• pp.133-141
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• 1997

This work presents a method of optimum design for reinforced concrete building frames with rectangular cross sections. To overcome difficulties arising from the presence of two materials in one element(concrete and steel) , the principle of divided parameters is adopted. The design variable parameters are divided into two groups - external and internal. The optimization is also divided into external and internal procedure. Several scarxh algorithms are tested to verify their accuracy for the external optimization. This work proposes a new search method, a modified pattern search, and sample problems prove its accuracy and uscf'ulness. The design obtained by this method is an optimum and in full accord with ACI Building Code Ftequirements(ACI'318-89).

• Journal of Power Electronics
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• v.17 no.3
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• pp.835-847
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• 2017

A transmitting coil with an optimal topology and number of turns can effectively improve the performance of the wireless power transfer (WPT) systems for endoscope robots. This study proposes the evaluation parameters of the transmitting coils related to the performance of the WPT system to standardize the design of the transmitting coils. It considers both the quality factor of transmitting coils and the coupling factor between the two sides. Furthermore, an analytical model of transmitting coils with different topologies is built to exactly estimate the evaluation parameters. Several coils with the specified topologies are wound to verify the analytical model and the feasibility of evaluation parameters. In the case of a constant power received, the related evaluation parameters are proportional to the transfer efficiency of the WPT system. Therefore, the applicable frequency ranges of transmitting coils with different topologies are determined theoretically. Then a transmitting coil with a diameter of 69 cm is re-optimized both theoretically and experimentally. The transfer efficiency of the WPT system is increased from 3.58% to 7.37% with the maximum magnetic field intensity permitted by human tissue. Finally, the standardized design of the transmitting coil is achieved by summing-up and facilitating the optimization of the coils in various situations.

• Wind and Structures
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• v.27 no.1
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• pp.41-57
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• 2018

Concentrated Solar Photovoltaic (CPV) is a promising alternative to conventional solar structures. These solar tracking structures need to be optimized to be competitive against other types of energy production. In particular, the selection of the structural parameters needs to be optimized with regards to the dynamic wind response. This study aims to evaluate the effect of the main structural parameters, as selected in the preliminary design phase, on the wind response and then on the weight of the steel support structure. A parametric study has been performed where parameters influencing dynamic wind response are varied. The study is performed using a semi-deterministic time-domain wind analysis method. Unsteady aerodynamic model is applied for the shape of the CPV structure collector at different configurations in conjunction with a consistent mass-spring-damper model with the corresponding degrees of freedom to describe the dynamic response of the system. It is shown that, unlike the static response analysis, the variation of the peak wind response with many structural parameters is highly nonlinear because of the dynamic wind action. A steel structural optimization process reveals that close attention to structural and site wind parameters could lead to optimal design of CPV steel support structure.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.1
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• pp.176-181
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• 2009

The passenger airbag(PAB) designed for standard sized adults may induce unexpected results to children in out-of-position(OOP) postures. In this work, using MADYMO software, simulations of the OOP injury of children have been performed with respect to PAB design parameters and child dummy positions. The attention is focused on some details with respect to the injury of 3 and 6 year old children in two OOP postures. Among the various design parameters of the passenger airbag systems, four parameters are selected for the sensitivity analysis of the injury with the Taguchi method: bag folding pattern, vent hole size, position of the cover tear seam and the type of door tear seam. An optimal combination of the parameters is suggested.

• Structural Engineering and Mechanics
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• v.88 no.6
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• pp.521-533
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• 2023

In the present study, the finite volume method is applied for the thermal performance prediction of the natural ventilation system using vertical solar chimney whereas, design parameters are optimized through the response surface methodology (RSM). The computational simulations are performed for various parameters of the solar chimney such as absorber temperature (40≤T_abs≤70℃), inlet temperature (20≤T₀≤30℃), inlet height of (0.1≤h≤0.2 m) and chimney width (0.1≤d≤0.2 m). Analysis of variance (ANOVA) was carried out to identify the design parameters that influence the average Nusselt number (Nu) and mass flow rate (ṁ). Then, quadratic polynomial regression models were developed to predict of all the response parameters. Consequently, numerical and graphical optimizations were performed to achieve multi-objective optimization for the desired criteria. According to the desirability function approach, it can be seen that the optimum objective functions are Nu=25.67 and ṁ=24.68 kg/h·m, corresponding to design parameters h=0.18 m, d=0.2 m, T_abs=46.81℃ and T₀=20℃. The optimal ventilation flow rate is enhanced by about 96.65% compared to the minimum ventilation rate, while solar energy consumption is reduced by 49.54% compared to the maximum ventilation rate.