• Proceedings of the Korean Society of Laser Processing Conference
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• 2004.10a
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• pp.35-39
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• 2004

• Steel and Composite Structures
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• v.35 no.6
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• pp.789-798
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• 2020

The effect of Chitosan (CS), Carbon Nanotube (CNT) and hybrid (CS-CNT) fillers on the natural frequency of drilled composite plate is investigated by experimentally in this study. The numerical validation is also made with a program based on Finite Element Method (SolidWorks). Nine types filled and one neat composite plates are used in the study. The fillers ratios are 1% CS, 2% CS, 3% CS, 0.1% CNT, 0.2% CNT, 0.3% CNT, 1% CS+0.3% CNT, 2% CS+0.3% CNT, 3% CS+0.3% CNT. The specimens cut to certain sizes by water jet from the plates 400 mm × 400 mm in dimensions. Some of them are drilled in certain dimensions with drill. The natural frequency of each specimen is measured by the vibration test set up to determine the vibration characteristic. The vibration test set up includes an accelerometer, a current source power unit, a data acquisition card and a computer. A code is written in Matlab^® program for the signal processing. The study are investigated and discussed in four main points to understand the effect of the fillers on the natural frequency of the composite plate. These are the effect of fillers contents and amounts, orientation angles of fibers, holes numbers and holes sizes. As results, the natural frequency of the plate with 1% CS and 0.1% CNT hybrid filler is lower than those of the plates with other fillers ratios for 45° orientation angle. Besides, in the composite plate with 0° orientation angle, the natural frequency increases with increasing the filler ratio. Moreover, the natural frequency increases until a certain hole number and then it decreases. Furthermore, the natural frequency is not affected until a certain hole diameter but then it decreases.

• Steel and Composite Structures
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• v.45 no.2
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• pp.159-173
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• 2022

This paper proposes a hybrid machine-learning model, which is called DANN-IP, that combines a deep artificial neural network (DANN) and an interior-point (IP) algorithm in order to improve the prediction capacity on the patch loading resistance of steel plate girders. For this purpose, 394 steel plate girders that were subjected to patch loading were tested in order to construct the DANN-IP model. Firstly, several DANN models were developed in order to establish the relationship between the patch loading resistance and the web panel length, the web height, the web thickness, the flange width, the flange thickness, the applied load length, the web yield strength, and the flange yield strength of steel plate girders. Accordingly, the best DANN model was chosen based on three performance indices, which included the R^2, RMSE, and a20-index. The IP algorithm was then adopted to optimize the weights and biases of the DANN model in order to establish the hybrid DANN-IP model. The results obtained from the proposed DANN-IP model were compared with of the results from the DANN model and the existing empirical formulas. The comparison showed that the proposed DANN-IP model achieved the best accuracy with an R^2 of 0.996, an RMSE of 23.260 kN, and an a20-index of 0.891. Finally, a Graphical User Interface (GUI) tool was developed in order to effectively use the proposed DANN-IP model for practical applications.

• Journal of Korean Association for Spatial Structures
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• v.18 no.4
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• pp.123-130
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• 2018

U-flanged truss beam is composed of u-shaped upper steel flange, lower steel plate of 8mm or more thickness, and connecting lattice bars welded on the upper and lower sides. The hybrid beam with U-flanged steel truss is made in the construction site through pouring the concrete, and designated as U-flanged truss hybrid beam. In this study the structural experiments on the 4 hybrid beams with the proposed basic shapes were performed, and the flexural capacities from the tests were compared with those from the theoretical approach. The failure modes of each specimen were quite similar. The peak load was reached with the ductile behavior after yielding, and the failure occurred through the concrete crushing. The considerable increasement of deformation was observed up to the concrete crushing. The composite action of concrete and steel member was considered to be reliable from the behavior of specimens. The flexural strength of hybrid beam has been evaluated exactly using the calculation method applied in the boubly reinforced concrete beam. The placement of additional rebars in the bottom instead of upper side is proposed for the efficient design of U-flanged truss hybrid beam.

• Korean Journal of Optics and Photonics
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• v.27 no.2
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• pp.73-80
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• 2016

In this paper, we report the results of a study on the design and fabrication of a light-guiding plate (LGP) using a hybrid light-emitting diode (LED) and sunlight source that can be applied to a photobioreactor. LGP patterns for the LED source were designed and engraved on an LGP, together with previously reported patterns for a sunlight source. A control system for the hybrid LGP was designed to maintain the output photon flux density (PFD) from the LGP at a constant value. When the target value of the output PFD was set to $70{\mu}E/(m^2{\cdot}s)$, the error range of the output PFD was found to be within ${\pm}2%$.

• Steel and Composite Structures
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• v.33 no.4
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• pp.489-507
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• 2019

In order to obtain high bearing capacity and good ductility simultaneously, a structural column with hybrid normal and high strength steel (HNHSS) welded box section has been developed. Residual stress is an important factor that can influence the behaviour of a structural member in steel structures. Accordingly, the magnitudes and distributions of residual stresses in HNHSS welded box sections were investigated experimentally using the sectioning method. In this study, the following four box sections were tested: one normal strength steel (NSS) section, one high strength steel (HSS) section, and two HNHSS sections. Based on the experimental data from previous studies and the test results of this study, the effects of the width-to-thickness ratio of plate, yield strength of plate, and the plate thickness of the residual stresses of welded box sections were investigated in detail. A unified residual stress model for NSS, HSS and HNHSS welded box sections was proposed, and the corresponding simplified prediction equations for the maximum tensile residual stress ratio (${\sigma}_{rt}/f_y$) and average compressive residual stress ratio (${\sigma}_{rc}/f_y$) in the model were quantitatively established. The predicted magnitudes and distributions of residual stresses for four tested sections in this study by using the proposed residual stress model were compared with the experimental results, and the feasibility of this proposed model was shown to be in good agreement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.9
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• pp.814-821
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• 2007

A hybrid method is presented for efficient computation of turbulent flow noise at low Mach numbers. In this method, the turbulent flow field is computed by incompressible large eddy simulation (LES), while the acoustic field is computed with the linearized perturbed compressible equations (LPCE) derived in this study. Since LPCE is computed on the rather coarse acoustic grid with the flow variables and source term obtained by the incompressible LES, the computational efficiency of calculation is greatly enhanced. Furthermore, LPCE suppress the instability of perturbed vortical mode and therefore secure consistent and stable acoustic solutions. The proposed LES/LPCE hybrid method is applied to three low Mach number turbulent flow noise problems: i) circular cylinder, ii) isolated flat plate, and iii) interaction between cylinder wake and airfoil. The computed results are closely compared with the experimental measurements.

• Steel and Composite Structures
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• v.27 no.5
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• pp.633-646
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• 2018

This study investigated the seismic performance of a hybrid damper composed of a steel slit plate and friction pads, and an optimum retrofit scheme was developed based on life cycle cost. A sample hybrid damper was tested under cyclic loading to confirm its validity as a damping device and to construct its nonlinear analysis model. The effectiveness of the optimum damper distribution schemes was investigated by comparing the seismic fragility and the life cycle costs of the model structure before and after the retrofit. The test results showed that the damper behaved stably throughout the loading history. Numerical analysis results showed that the slit-friction hybrid dampers optimally distributed based on life cycle cost proved to be effective in minimizing the failure probability and the repair cost after earthquakes.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.510-519
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• 2015

Concerning the issue of high-dimensions, hybrid uncertainties of randomness and intervals including implicit and highly nonlinear limit state function, reliability analysis based on the hybrid uncertainty reliability mode combining with back propagation neural network (HU-BP neural network) is proposed in this paper. Random variables and interval variables are as input layer of the neural network, after the training and approximation of the neural network, the response variables are obtained through the output layer. Reliability index is calculated by solving the optimization model of the most probable point (MPP) searching in the limit state band. Two numerical cases are used to demonstrate the method proposed in this paper, and finally the method is employed to solving an engineering problem of the aerospace friction plate. For this high nonlinear, small failure probability problem with interval variables, this method could achieve a good analysis result.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.272-279
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• 1998

The purpose of this study is to show how to gain the morphology of the Hybrid Spatial Structures and to get the geometrical data such as node coordinates, member relationships and graphic images. To form spatial structures, we have developed morphological aspects of general spatial structures, programming process and techniques. Structural design has many processes. Especially, it is very important to consider the determination of structural configuration. Regular Hybrid Spatial Structures have complex configuration, so we need to make use of automated computer process to determine structural shape in Hybrid Spatial Structures. We have applied morphological aspects to double layer plate, single layer dome, double layer dome and tensegrity structure.