• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.823-826
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• 2001

A shape optimization of a rib of a bolster of a bogie frame is attempted and a dimension optimization on upper and lower plates is also carried out for the reduction of the weight of bogie frame. In addition, the dynamic characteristics of the weight reduced model are investigated by an analysis of a natural frequency and a transient analysis. The results show that the first natural frequency of an optimized model is larger than that of the lowest design value. And the results of transit analysis based on the experimental stress also show smaller value than the yield stress. Thus the optimized model attempted in this study is considered to be structurally stable and useful for the improvement of railway carriages.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.121-124
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• 2004

The purpose of this study is to define the optimized layer pattern of composite wind turbine blade by using a commercial FEM program and to perform the fatigue test of T-Bolt. FEM analysis is done by using a PATRAN and ABAQUS to get a information about stress distribution ,critical deformation shape and get a critical load factor in local buckling analysis. As a result of the linear and nonlinear structural analysis, layer pattern of blade was optimized. T-Bolt is a connecting part of wind turbine blade and rotor hub, therefore T-bolt is cirtical part of wind turbine blade. T-bolt fatigue test is conducted to get a information of life cycle of T-bolt. The test is done by using a hydraulic actuator system

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.99-106
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• 2011

In this study, the analysis technique, which can estimate the temperature rise and thermal deformation of the ventilated disc considering the vehicle information, braking condition and properties of the disc and pad, is developed. The analytical process of the braking power generation during braking is mathematically derived. The thermal energy, which is applied to the surface of a disc as heat flux, is calculated. Then, the temperature rise and thermal deformation of a disc are estimated using FE software, SAMCEF. Shape of the cross section of the disc is optimized according to the response surface analysis method in order to minimize the temperature rise and thermal deformation. The hot judder analysis is done using the optimized disc, and the analysis results are discussed.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.178-182
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• 2007

In this study, we evaluated current raingauge network of Soyanggang dam region applying spatial-correlation analysis and Entropy theory to recommend an optimized raingauge network. In the process of analysis, correlation distance of raingauge stations is estimated and evaluated via spatial-correlation method and entropy method. From this correlation distances, respective influencing radii of each dataset and each methods is assessed. The result of correlation and entropy analysis has estimated correlation distance of 25.546km and influence radius of 7.206km, deducing a decrease of network density from $224.53km^2$ to $122.47km^2$ which satisfy the recommended minimum densities of $250km^2$ in mountainous regions(WMO, 1994) and an increase of basin coverage from 59.3% to 86.8%. As for the elevation analysis the relative evaluation ratio increased from 0.59(current) to 0.92(optimized) resulting an obvious improvement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1915-1933
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• 2013

In this study, the virtual fixed point analysis and 3D fully modeling analysis for bent pile structures are conducted by considering various influencing factors and the applicability of the virtual fixed point theory is discussed. Also, the optimized column-pile length ratio is analyzed for supplementing virtual fixed point design and examining a more exact behavior of bent pile structures by taking into account the major influencing parameters such as pile length, column and pile diameter, reinforcement ratio and soil conditions. To obtain the detailed information, the settlement and lateral deflection of the virtual fixed point theory are smaller than those of 3D fully modeling analysis. On the other hand, the virtual fixed point analysis overestimates the axial force and bending moment compared with 3D fully modeling analysis. It is shown that the virtual fixed point analysis cannot adequately predict the real behavior of bent pile structures. Therefore, it is necessary that 3D fully modeling analysis is considered for the exact design of bent pile structures. In this study, the emphasis is on quantifying an improved design method (optimized column-pile length ratio) of bent pile structures developed by considering the relation between the column-pile length ratio and allowable lateral deflection criteria. It can be effectively used to perform a more economical and improved design of bent pile structures.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.735-740
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• 2012

In this paper, we introduce design methodologies of polynomial radial basis function neural network classifier with the aid of Principal Component Analysis(PCA) and Linear Discriminant Analysis(LDA). By minimizing the information loss of given data, Feature data is obtained through preprocessing of PCA and LDA and then this data is used as input data of RBFNNs. The hidden layer of RBFNNs is built up by Fuzzy C-Mean(FCM) clustering algorithm instead of receptive fields and linear polynomial function is used as connection weights between hidden and output layer. In order to design optimized classifier, the structural and parametric values such as the number of eigenvectors of PCA and LDA, and fuzzification coefficient of FCM algorithm are optimized by Artificial Bee Colony(ABC) optimization algorithm. The proposed classifier is applied to some machine learning datasets and its result is compared with some other classifiers.

• Korean Journal of Biological Psychiatry
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• v.18 no.4
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• pp.232-238
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• 2011

Objectives Optimized voxel based morphometry (VBM) has been increasingly applied to investigate differences in the brain morphology between a group of patients with mild cognitive impairment (MCI) and control subjects. Optimized VBM permits comparison of gray matter (GM) volume at voxel-level from the entire brain. The purpose of this study was to assess the regional GM volume change measured by optimized VBM in MCI subjects compared to controls. Methods Twenty patients with MCI and 20 control subjects with normal cognition were recruited for this study. We applied the optimized VBM protocol to the image data including study-specific template and the modulation of the data with the Jacobian determinants. GM volume differences between the MCI subjects and the control subjects and their correlations with the neuropsychological performances were investigated. Results Optimized VBM analysis revealed GM volume reduction in hippocampus, precentral gyrus, insula and parietal operculum in the MCI group compared to the control group (family wise error corrected p < 0.05). Korean version of the Consortium to Establish a Registry for Alzheimer's disease (CERAD-K) word list recall scores were significantly correlated with the GM volumes of hippocampus, precuneus and posterior cingulate in the MCI group (FWE corrected p < 0.05). Conclusions The results confirm previous findings of atrophic changes in medial temporal lobe and parietal lobe in the MCI group and suggest that these abnormalities may be related with cognitive decline and prognosis in patients with MCI.

• Journal of the Korea Society for Simulation
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• v.24 no.2
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• pp.1-9
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• 2015

The tactical employment is a critical factor to win the war in the modern battlefield. To apply optimized tactics, it needs analyses related to a battle system. Normally, M&S (Modeling & Simulation) has been studied to analyze data in general problems. However, this method is not suitable for military simulations because there are many variables which make complex interaction in the system. For this reason, we suggested the optimized simulation framework based on the M&S by using DPSO (Discrete binary version of PSO) algorithm. This optimized simulation framework makes the best tactical employment to reduce the searching time compared with the normal M&S used by Monte Carlo search method. This paper shows an example to find the best combination of anti-torpedo scenario in a short searching time. From the simulation example, the optimized simulation framework presents the effectiveness.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.575-580
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• 2017

Because moire artifacts overlap with fine lesions and frequency bands, image processing software that removes moire artifacts can lead to loss of micro lesions. In this study, microscopic lesions such as microcalcification and microfracture were randomly formed on SD (Sprague Dawley) rats and image and optimized grid images were compared and analyzed using reference image and grid suppression software. The images were read by two consecutive radiologists using a McNemar's test. Among the 73 microcalcifications, in the 13 cases after grid suppression, the image of the optimized grid shows the loss of image in 3 cases, and the image after grid suppression shows statistically significant image loss (p=0.021). In all 53 fracture lines, there were 19 cases of image loss after the grid suppression, and only one case of the optimized grid showed no image loss. Therefore, the use of grid suppression software to remove moire artifacts should be carefully considered in the diagnosis of micro lesions.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4134-4145
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• 2022

The collimator is one of the high-heat-flux components used to avoid a series of vacuum and thermal problems. In this paper, the heat load distribution throughout the collimator is first calculated through experimental data, and a transient thermodynamic simulation analysis of the original model is carried out. The error of the pipe outlet temperature between the simulated and experimental values is 1.632%, indicating that the simulation result is reliable. Second, the model is optimized to improve the heat transfer performance of the collimator, including the contact mode between the pipe and the flange, the pipe material and the addition of a twisted tape in the pipe. It is concluded that the convective heat transfer coefficient of the optimized model is increased by 15.381% and the maximum wall temperature is reduced by 16.415%; thus, the heat transfer capacity of the optimized model is effectively improved. Third, to adapt the long-pulse steady-state operation of the experimental advanced superconducting Tokamak (EAST) in the future, steady-state simulations of the original and optimized collimators are carried out. The results show that the maximum temperature of the optimized model is reduced by 37.864% compared with that of the original model. The optimized model was changed as little as possible to obtain a better heat exchange structure on the premise of ensuring the consumption of the same mass flow rate of water so that the collimator can adapt to operational environments with higher heat fluxes and long pulses in the future. These research methods also provide a reference for the future design of components under high-energy and long-pulse operational conditions.