• Wind and Structures
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• v.22 no.4
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• pp.503-524
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• 2016

The suitability of Computational Fluid Dynamics (CFD) simulations on the built environment for the purpose of estimating average roughness characteristics and for studying wind flow patterns within the environment is assessed. Urban models of various levels of complexity are considered including an empty domain, array of obstacles arranged in regular and staggered manners, in-homogeneous roughness with multiple patches, a semi-idealized built environment, and finally a real built environment. For each of the test cases, we conducted CFD simulations using RANS turbulence closure and validated the results against appropriate methods: existing empirical formulas for the homogeneous roughness case, empirical wind speed models for the in-homogeneous roughness case, and wind tunnel tests for the semi-idealized built environment case. In general, results obtained from the CFD simulations show good agreement with the corresponding validation methods, thereby, giving further evidence to the suitability of CFD simulations for built environment studies consisting of wide-ranging roughness. This work also provides a comprehensive overview of roughness modeling in CFD-from the simplest approach of modeling roughness implicitly through wall functions to the most elaborate approach of modeling roughness explicitly for the sake of accurate wind flow simulations within the built environment.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.04a
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• pp.78-80
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• 1999

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1995.04a
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• pp.119-120
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• 1995

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2015.10a
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• pp.375-376
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• 2015

• Structural Engineering and Mechanics
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• v.39 no.3
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• pp.361-382
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• 2011

This paper presents the results of an investigation on shear strengthening of RC beams externally reinforced with CFRP composite. A total of six full-scale beams of four CFRP strengthened and two unstrengthened were tested in the absence of internal stirrups in the shear span. The strengthening configurations contained two styles: discrete uniformly spaced strips and customized wide strips over B-regions. The composite systems provided an increase in ultimate strength as compared to the unstrengthened beams. Among the three layouts that had the same area of CFRP, the highest contribution was provided by the customized layout that targeted the B-regions. A comparative study of the experimental results with published empirical equations was conducted in order to evaluate the assumed effective strains. The empirical equations were found to be unconservative. Nonlinear finite element (NLFE) models were developed for the beams. The models agreed with test results that targeting the B-region was more effective than distributing the same CFRP area in a discrete strip style over shear spans. Moreover, the numerical models predicted the contribution of different configurations better than the empirical equations.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.2
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• pp.97-106
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• 2012

The pharmacokinetics/pharmacodynamics analysis software NONMEM$^{(R)}$ output provides model parameter estimates and associated standard errors. However, the standard error of empirical Bayes estimates of inter-subject variability is not available. A simple and direct method for estimating standard error of the empirical Bayes estimates of inter-subject variability using the NONMEM$^{(R)}$ VI internal matrix POSTV is developed and applied to several pharmacokinetic models using intensively or sparsely sampled data for demonstration and to evaluate performance. The computed standard error is in general similar to the results from other post-processing methods and the degree of difference, if any, depends on the employed estimation options.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.9
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• pp.391-396
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• 2005

In this paper the modeling of interrupting characteristics of a high voltage current limiting fuse to be used in a power distribution system is introduced. In order to reduce the level of energy which can be absorbed by equipment during fault current flow, a high voltage current limiting fuse can generate a high voltage at the fuse terminals. Consequently it is necessary to model and analyze precisely the voltage and current variation during a CL fuse action. The characteristics of CL fuse operation modeled by electrical components have been performed with less than 6 [$\%$] errors. So the fuse designer or manufacturer can estimate the characteristics of CL fuse operation by using this modeling. The Electro Magnetic Transient Program (EMTP) is used to develop the modeling.

• Journal of Integrative Natural Science
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• v.13 no.3
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• pp.97-104
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• 2020

This study suggests the emotion space modeling and emotion inference methods suitable for personalized services based on psychological and emotional models. For personalized emotion space modeling taking into account the subjective disposition based on the empirical assessment of the personal emotions felt by the personalization process of emotion space was used as a decision support tool, the Analytic Hierarchy Process. This confirmed that the special learning to perform personalized emotion space modeling without considering the subjective tendencies. In particular to check the possible reasoning based on fuzzy emotion space modeling and sensitivity for the quantification and vague human emotion to it based on the inherent human sensitivity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.4 s.235
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• pp.526-536
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• 2005

A heat dissipation modeling method of EEE parts, or semi-empirical heat dissipation method, is developed for thermal design and analysis an electronic equipment of geostationary satellite. The power consumption measurement value of each functional breadboard is used for the heat dissipation modeling method. For the purpose of conduction heat transfer modeling of EEE parts, surface heat model using very thin ignorable thermal plates is developed instead of conventional lumped capacity nodes. The thermal plates are projected to the printed circuit board and can be modeled and modified easily by numerically preprocessing programs according to design changes. These modeling methods are applied to the thermal design and analysis of CTU (Command and Telemetry Unit) and verified by thermal cycling and vacuum tests.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.106-113
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• 2018

The Intense acoustic wave generated by the jet flame at the lift-off causes the vehicle to vibrate in the form of acoustic loads. The DSM-II(Distributing Source Method-II), which is a representative empirical acoustic loads prediction method, is a method of distributing a noise source along a jet flame axis and has advantages in calculation cost and accuracy. However, due to the limitation of the distributing method, there is a limit to accurately reflect the various launch pad configurations. In this study, acoustic loads prediction method which can freely distribute noise sources is studied. by introducing NURBS(Non-Uniform Rational B-Spline) modeling into empirical prediction method. For the verification of the newly introduced analytical technique of the NURBS, the acoustic loads prediction for the Epsilon rocket's low-noise launch pad shape was performed and the results of the analysis were compared with the existing prediction methods and experimental results.