• Structural Engineering and Mechanics
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• v.71 no.5
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• pp.503-513
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• 2019

Genetic Algorithms (GAs) have found the best design for reinforced concrete frames. The design of the optimum beam sections by GAs has been unified. The process of the optimum-design sections has satisfied axial, flexural, shear and torsion necessities based on the designing code. The frames' function has contained the function of both concrete and reinforced steel besides the function of the frames' formwork. The results have revealed that limiting the dimension of frame-beam with the dimension of frame-column have increased the optimum function of the structure, thereby reducing the reanalysis requirement for checking the optimum-designed structures through GAs.

• Journal of Korean Association for Spatial Structures
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• v.10 no.4
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• pp.59-66
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• 2010

This study presents the topology optimization technique by density method to determine the initial shape of space truss structures. Most initial shape design is performed by designer's previous experiences and trial and error method instead of the application of reasonable optimization method. Thus, the reasonable and economical optimization methods are needed to be introduced for the initial shape design. Therefore, we set design domain for cantilever space truss structure as an example model. And topology optimization is used to obtain optimum layout for them, and then size optimization method is used to find the optimum member size. Therefore, the reasonable initial optimal shapes of spatial truss structures can be obtained through the topology and size optimization using density method.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.5
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• pp.31-48
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• 2012

The purpose of this study is to select indicators by a methodical approach and to establish a functional assessment system as a basic study for planning and constructing green space of forest. The types of green space were divided into 6 classes based on theoretical reviews of literature and the functions of green space were restricted to 'nature-ecological function', 'environment-control function' and 'usage function'. As a result of the selection of indicators, 35 indicators were initially selected by theoretical review and these indicators were reduced to 29 through brainstorming. Also, these indicators were classified into three functions such as 12 indicators (nature-ecological function), 8 indicators (environment-control function), 6 indicators (usage function) by analysis of suitability. According to the result of selection of the optimum indicators using MCB (Multiple Comparisons with the Best treatment) analysis, the optimum indicators of 7, 5, and 4 respectively by each function were selected for forest green space. The results of AHP (Analytic Hierarchy Process) for the establishment of the assessment system in forest, the weight of nature-ecological function was evaluated highest at 0.558, while the weight of environment-control and usage function were calculated at each 0.277, 0.165. 'Naturality (0.189)', 'Carbon sink (0.235)', and 'Accessibility (0.354)' among indicators showed highest by each function. The weight of indicator and assessment system may be used as a valuable guideline in case of assessing synthetically green space within urban planning.

• Journal of Advanced Navigation Technology
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• v.6 no.2
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• pp.130-137
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• 2002

We present Space-Time Trellis Coded Code Division Multiple Access systems, which maintain the full diversity and coding gain of Space-Time Trellis Codes(STTC) and have the immunity to performance degradation caused by multipath fading. These STTC CDMA systems are constructed by adding the spreading and despreading processes of PN codes to STTC systems. In multipath fading channels, delay spreaded signals are detected and combined, then decoded. According to the combining and decoding methods, there are four decoding methods. There are optimum ML decoding without combining, adding multipath signals in each receive antenna before decoding, combining multi path signals in each antenna before decoding, and combining all received signals before decoding. Performance of these methods is proportional to complexity. Besides, all methods are shown to compensate the irreducible error rate which appears in multipath fading channels.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.4
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• pp.275-283
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• 2013

In this paper, the structural optimum design method of composite rotor blade cross-section was investigated with the genetic algorithm. An auto-mesh generation program was developed for iterative calculations of optimum design, and stresses in the blade cross-section were analyzed by VABS (variational asymptotic beam sectional analysis) program. Minimum mass of rotor blade was defined as an object function, and stress failure index, center mass and blade minimum mass per unit length were chosen as constraints. Finally, design parameters such as the thickness and layup angles of a skin, and the thickness, position and width of a torsion box were determined through the structural optimum design method of composite rotor blade cross-section presented in this paper.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.2
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• pp.177-184
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• 2008

In this study, in order to reduce appeals regarding vibration and noise from blasts, the optimum delay-time of the electronic detonator, which can minimize blast vibration, is found through blast-waveform composition and blasting simulation, and we have developed the full-face Sequential Blasting Method based on the studies of damping properties of full-face section blasting. The optimum delay-time of the electronic detonator and Full-face Sequential Blasting Method using electronic detonator was applied to the Gyeongbu high-speed railway construction site to test the feasibility of this method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.825-835
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• 2017

This paper aims to build a drone platform based on an optimum design of its single arm. Its single arm is assumed as a cantilevered beam with a tip mass. Based on the numerical optimization theory, validation and optimization of a new design is conducted by comparing the results with the similar ones obtained by ANSYS. Finally, this design is reflected in the control simulation, and the requirement of an optimum structural design considering the resonance situation is satisfied.

• Nuclear Engineering and Technology
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• v.33 no.3
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• pp.327-338
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• 2001

A computational fluid dynamics (CFD) analysis was performed to propose the optimum design of flow mixing vane on the space grid in a PWR fuel assembly. The flow mixing vanes considered in this study for optimum design are swirl-vane and twisted-vane. A single subchannel of one grid span was modeled using flow symmetry to minimize the computational effort. The CFD predictions are in good agreement with the experimental results for the split- vane, which shows the applicability of the CFD method. The mixing effect by swirling flow and crossflow, and the pressure drop were estimated and compared for the various vane angles. The optimum vane angle is proposed to be 40。 and 35。 from the direction of axial flow for the swirl-vane and the twisted-vane, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.514-521
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• 2007

There has been considerable interest recently in the topic of renewable energy. This is primarily due to concerns about environmental impacts. Moreover, fluctuating and rising oil prices, increases in demand, supply uncertainties and other factors have led to increased calls for alternative energy sources. Small hydropower, especially using water supply system, attracts high attentions because of relatively lower cost and smaller space requirements to construct the plant. Moreover. newly developed positive displacement turbine has high acceptability for the system. Therefore, the purpose of this study is focused on the examination of the performance characteristics and proposition of a optimum design method of the turbine for the improvement of the performance. The results show that newly proposed optimum design method for the turbine has high accuracy of performance prediction and good applicability for the performance improvement of the turbine.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.454-457
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• 2005

Voloxidizer for hot cell demonstration that handle spend fuel of high radiation virulence in limited space should become a small size and not scatter in its exit. This study determine optimum velocity of $U_3O_8$ using Newton-Raphson Method. We have conducted fortran programing on the Newton-Raphson Method, obtained a theory results and, predicted optimum velocity on the particle size distribution of $U_3O_8$. We have conducted experimentation using acrylic experimental device for verification of theory method, sampled and analyzed using the particle size analyzer In the results, we have found maximum $5\~7\%$ error rate in the comparative value of theory and experimentation. Optimum velocity and experimental results of $U_3O_8$ for scatter prevention have applied for design of demonstration voloxidizer, and produced operation condition of voloxidizer.