• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.571-576
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• 2007

This study presents stiffness-based optimal design to control quantitatively lateral drift of frame-shear wall structures subject to seismic loads. To this end, lateral drift constraints are established by introducing approximation concept that preserves the generality of the mathematical programming and can efficiently solve large scale problems. Also, the relationships of sectional properties are established to reduce the number of design variables and resizing technique of member is developed under the 'constant-shape' assumption. Specifically, the methodology of dynamic displacement sensitivity analysis is developed to formulate the approximated lateral displacement constraints. The 12 story frame-shear wall structural models is considered to illustrate the features of dynamic stiffness-based optimal design technique proposed in this study.

• Korean Journal of Computational Design and Engineering
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• v.15 no.6
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• pp.467-475
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• 2010

Due to the needs of design optimization and productivity for modernized Korean traditional house, standardization of Korean traditional building components is proceeding by BIM (Building Information Modeling). Currently, most of BIM software support object-based parametric modeling. By means of parameterized Korean traditional building components, the shape and assembly relation can be controlled. Although IFC(ISO/PAS 16739), which is an international standard in the AEC field, has been developed for information exchange among BIM software, IFC and other existing common data formats cannot be exchangeable parametric information. For the exchangeable parametric information within IFC, the authors defined meta-data by using Pset(Property-Set). The authors analyzed results about interoperability test in Revit $Architecture^{TM}$, $ArchiCAD^{TM}$ and Digital $Project^{TM}$. In order to solve found problems, the authors developed a translator to improve interoperability among BIM software.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.64-69
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• 2012

In this paper, the optimal design of notch and barrier was carried out in order to improve characteristics of constant torque with minimizing the cogging torque occurred by teeth and slot structure. Optimized design was carried out by design of experiment and various characteristics including torque were studied by finite element method(FEM). In addition, in order to verify resonance frequency, natural frequency of the stator was analyzed by modal analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.589-595
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• 2008

Detent force of a permanent magnet linear motor(PMLSM) consist of cogging and drag forces, and should be minimized for high precision control purpose applications. This paper shows that the cogging force can be reduced effectively by employing 9 pole 10 slot structure. The drag force is minimized by optimizing the total length and shape of the exterior teeth of armature core simultaneously by using($1+{\lambda}$) evolution strategy coupled with response surface method. After optimization, the optimized PMLSM is proven to reduce 95% and 92.6% of the cogging and total detent forces, respectively, and give 12% and 6.4% higher Back-emf and thrust force, respectively, compared with a conventional 12 pole 9 slot structure under the same condition. Additionally, Simulation results by the proposed optimum design are verified by the experiment results.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.401-409
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• 2014

This research develops tools and strategies for optimizing RC column sections applied in tall buildings. Optimization parameters are concrete strength and section shape, the objective function for which is subject to several predefined constraints drawn from the original structural design. For this purpose, we developed new components for StrAuto, a parametric modeling and optimization tool for building structure. The components receive from external analysis solvers member strengths calculated from the original design model, and output optimized column sections satisfying the minimum cost. Using these components, optimized sections are firstly obtained for each predefined concrete strength applied to the whole floors in the project building. The obtained results for each concrete strength are comparatively examined to determine the fittest sections which will also result in the fittest vertical zoning for concrete strength. The main optimization scenario for this is to search for the vertical levels where the identical optimized sections coincide for the two different concrete strengths in concern, and select those levels for the boundaries where a concrete strength will be changed to another. The optimization process provided in this research is a product of an intensive development designed for a specific member in a specific project. Thus, the algorithm suggested takes on a microscopic and mathematical approach. However, the technique has a lot of potential that it can further be extensively developed and applied for future projects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.9-17
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• 2006

The SNU MAV has been designed through studies on highly efficient aerodynamic shape and propulsion system. The configuration of the vehicle was determined from conventional empirical equations, iterative wind tunnel tests and flight tests. The propeller shape was optimized with the various thrust tests and RSM(Response Surface Method) to obtain the higher efficient propulsion system. It was certified that the MAV could fly for over 17 minutes with a 210mAh battery. In addition, it showed good flight characteristics in both stability and controllability.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.3
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• pp.317-322
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• 2012

The low speed aerodynamic characteristics for a modified sonic arc airfoil which is designed by using the nose shape function of sonic arc, the shape function of NACA four-digit wing sections, and Maple are experimentally investigated. The small rotor blades of a modified sonic arc and NACA0012 airfoil are precisely fabricated with a commercially available light aluminum(Al 6061-T6) and are spin tested over a low speed range (3000rpm-5000rpm). In a consuming power comparison, the consuming powers of NACA0012 are higher than that of modified sonic arcs at each pitch angle. The measured rotor thrust for each pitch angle is used to estimate the rotor thrust coefficient according to momentum theory in the hover state. The value of thrust coefficients for both two airfoils at each pitch angle show almost constant values over the low Mach number range. However, the rotor thrust coefficient of NACA0012 is higher than that of the modified sonic arc at each pitch angle. In conclusion, the aerodynamic performance of NACA0012 is better than that of modified sonic arcs in the low speed regime. This test model will provide a convenient platform for improving the aerodynamic performance of small scale airfoils and for performing design optimization studies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.7
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• pp.509-515
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• 2013

In this study, the real-coded adaptive range multi-objective genetic algorithm code, which represents the global multi-objective optimization algorithm, was developed for an airfoil shape design. In order to achieve the better aerodynamic characteristics than reference airfoil at landing and cruise conditions, maximum lift coefficient and lift-to-drag ratio were chosen as object functions. Futhermore, the PARSEC method reflecting geometrical properties of airfoil was adopted to generate airfoil shapes. Finally, two airfoils, which show better aerodynamic characteristics than a reference airfoil, were chosen. As a result, maximum lift coefficient and lift-to-drag ratio were increased of 4.89% and 5.38% for first candidate airfoil and 7.13% and 4.33% for second candidate airfoil.

• New & Renewable Energy
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• v.8 no.2
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• pp.6-13
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• 2012

Due to global warming, the need to secure an alternative resource has become more important nationally. Having very strong current on the west coast with up to 10 m tidal range, there are many suitable site for the application of TCP (Tidal Current Power) in Korea. On the south west regions between many islands that create strong current in the narrow channels. The rotor is one of the essential components which can convert tidal current energy into rotational energy to generate electricity. The design optimization of rotor is very important to maximize the power production. The performance of rotor can be determined by various parameters including number of blades, shape, sectional size, diameters and etc. This paper introduces the multi-layer vertical axis tidal current power system which can be applied to offshore jetties and piers effectively. Various cases of VAT turbine were designed. Specifically, the number of blades and turbine shape are changed in several cases. Also, performance analysis was carried out by CFD.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.2
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• pp.219-227
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• 2015

A dehumidifier using a thermoelement has many advantages compare to a dehumidifier using compressor systems. However, it is crucial to optimize the performance of heat sink for improving heat dissipation problem on the heat generation part. In this study, we utilized computational fluid dynamics software to compare Nusselt number, temperature and system efficiency based on fin thickness, flow gap between fin and fin length. Moreover, slip flow on the boundary layer was applied for the further analysis. Our objective in this study is to suggest an optimal fin shape to improve heat transfer with the tendency of performance factor depending on change of the shapes. Our results on the optimization of fin shape and analysis of slip flow will be utilized to enhance the heat transfer in the heat sink which is important in the design of dehumidifier using a thermoelement.