• Journal of computational fluids engineering
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• v.11 no.1 s.32
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• pp.57-66
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• 2006

An optimal shape design approach is presented for a subsonic S-shaped intake using aerodynamic sensitivity analysis. Two-equation turbulence model is employed to capture strong counter vortices in the S-shaped duct more precisely. Sensitivity analysis is performed for the three-dimensional Navier-Stokes equations coupled with two-equation turbulence models using a discrete adjoint method For code validation, the result of the flow solver is compared with experiment data and other computational results of bench marking test. To study the influence oj turbulence models and grid refinement on the duct flow analysis, the results from several turbulence models are compared with one another and the minimum number of grid points, which can yield an accurate solution is investigated The adjoint variable code is validated by comparing the complex step derivative results. To realize a sufficient and flexible design space, NURBS equations are introduced as a geometric representation and a new grid modification technique, Least Square NURBS Grid Approximation is applied With the verified flow solver, the sensitivity analysis code and the geometric modification technique, the optimization of S-shaped intake is carried out and the enhancement of overall intake performance is achieved The designed S-shaped duct is tested in several off-design conditions to confirm the robustness of the current design approach. As a result, the capability and the efficiency of the present design tools are successfully demonstrated in three-dimensional highly turbulent internal flow design and off-design conditions.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.92-98
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• 2010

The design of press bonding tool in LCD module equipment is a very complex and difficult task because many design able variables are involved while their effects are not known. It takes longtime experiments and much expenses to verify the effects of these design variables. However the optimization of bonding tool using OLB(outer lead bonding) and PCB Bonding is a very important problem in LCD manufacturing process, so much design efforts have been made for improving the bonding tool performance. In this paper, a reasonable and fast process which gives optimized solution under the design requirements has been presented. Both analytical and statistical methods are employed in this process. A reliable analytic model using experiment-oriented FE analysis can be obtained, in which the regression equations that predict the tool efficiency from various DOE method are found. Improvement of tool efficiency could be estimated by the regression equations using meaningful factors converged by RSM(Response Surface Method). With this process a reasonable optimized solution that meets a variety of design requirements can be easily obtained.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1120-1122
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• 1995

This paper presents a 2-stage, simple, power-efficient 3V CMOS operational amplifier and its equation based design optimization. Because of its simple structure, it is very suitable as a VLSI library cell in analog/digital mixed-mode systems. The op-amp, which contains a constant-$g_m$ rail-to-rail input stage and a simple feedforward class-AB rail-to-rail output stage, is analyzed and the results are presented in the form of design equations and procedures, which provide an insight into the trade-offs among performance requirements. The results of SPICE simulations are shown to agree very welt with the use of design equations.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.223-224
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• 2011

This paper presents the method to design the inductor and capacitor value considering the ripple component that may be generated by three operating states of the Quasi Z source inverter at the impedance network. Based on the analysis of each operation mode, the equations of the capacitor voltage and inductor current are derived. In order to simplify the design processing, design equations of the impedance network are derived where the capacitor voltage and inductor current are lineared. The validity of the design method is verified with the simulation result using PSIM.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.302-305
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• 2006

The temperature difference of deck and girder is one of the major factors that affect the stress distribution of a section, and therefore, the design of a composite girder bridge. However, domestic design codes of highway and railway bridges, respectively, present different shapes of design equations regarding the temperature difference, which may induce some confusion to the designers. In this study, each design equation is investigated on a theoretical basis and compared together. Some other methodologies such as finite element method and other equations from a different point of view are also taken into account for further comparison. An example of a railway bridge is presented to verify the result of each scheme.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.4
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• pp.307-313
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• 2003

A technique for the design of cooling tower fans with sweep is presented. This technique is developed using the equations for the one dimensional inviscid flow through the fan blade, the empirical equations, and the experimental correlations. A parabolic function is used to generate a sweep of the fan. Design data for the fan and the balde can be obtained for a given flow rate and a pressure rise. Also, the present method is used to construct the three dimensional model for the designed fan. Design data and the model show general characteristics of the axial propeller fan.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.1
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• pp.63-68
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• 2016

This research investigates the deployment time of an active hood lift system(AHLS) activated a gunpowder actuator for the passenger vehicle. The deployment time of the system is investigated by changing the principal design parameters of the system. In order to achieve this goal, after introducing the geometric structure and operating principle of the AHLS, the dynamic equations of the system are formulated for deploying motion. Subsequently, using the dynamic equations, the deployment time of the system is determined by changing several geometric design parameters such as location of actuator. It is then identified which design parameters are main factors to affect the deployment time of AHLS.

• Proceedings of the Korean Association for Survey Research Conference
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• 2001.06a
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• pp.45-56
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• 2001

In this paper, we conducted an empirical study to investigate the design and weighting effects on descriptive and analytic statistics. We compared the regression models using the design-based approach and the generalized estimating equations(GEEs) approach with the model-based approach through the design and weighting effects analysis.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.887-892
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• 2003

A front-end cooling fan is designed and tested in the present study. The design technique is developed using the one-dimensional inviscid flow through the fan blade, the empirical equations, and the experimental correlations. Design data for the blade can be obtained for a given flow rate and a pressure rise. A parabolic function is used to generate a sweep of the fan. Characteristics of the blade geometry are discussed between the huh and the tip. The fan is tested in the fan test unit. The measured volume flow rate at the operating point is in good agreement with that of the design specifications. Sound pressure levels of the noise are predicted with the Ffowcs Williams-Hawkings equations. Calculation results of the sound pressure level(SPL) 1m away from the fan are obtained and cpmpared with the measured data.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.300-305
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• 2004

In this paper, new design equations based on the pole-zero analysis for multi-layered interdigital stripline linear group delay bandpass filter with tap input ports are presented. As a design example, a four-pole group delay filter with center frequency of 2.14GHz, bandwidth of 160MHz, and group delay variation of $\pm$0.1nS for LTCC technology or multilayered PCB technology is designed. In the design process, it is not necessary to simulate the entire structure, as the simulation of half structures is sufficient. Good results can be attained after the optimizing process was performed three times using the proposed equations and a commercial EM simulator.