• JOURNAL OF ELECTRICAL WORLD
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• s.431
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• pp.68-72
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• 2012

• 한국전산유체공학회:학술대회논문집
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• 1999.05a
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• pp.11-22
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• 1999

A numerical prediction method has been proposed to predict non-linear free surface oscillation in a three-dimensional container. The fluid motions are numerically predicted with Navier-Stokes equations discretized in a Lagrangian scheme with sufficient numerical accuracy. The profile of a free surface is precisely represented with three-dimensional body-fitted coordinates (BFC), which are regenerated in each computational step on the basis of the arbitrary Lagrangian-Eulerian (ALE) formulation. In order to confirm the reliability of the computational method, it was firstly applied to three-dimensional flows within complicated-shaped rigid boundaries, such as curved pipes and ducts. Than it was applied to benchmark computations related to free surface oscillations. Following these basic verifications, non-linear sloshings in a cylindrical tank and transitions from sloshing to swirling motions were numerically predicted. Throughout these computations, the applicability of the present computational method has been confirmed and some of the predicted free surface motions were visualized as sequential images and animations to understand their dynamic futures.

• Earthquakes and Structures
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• v.17 no.5
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• pp.489-499
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• 2019

Elastic-plastic behavior of nuclear power plant elbow piping under seismic loads has been conducted in this study. Finite element analyses are performed using classical Bilinear kinematic hardening model (BKIN) and Multilinear kinematic hardening model (MKIN) as well as a nonlinear kinematic hardening model (Chaboche model). The influence of internal pressure and seismic loading on ratcheting strain of elbow pipe is studied by means of the three models. The results found that the predicted results of Chaboche model is maximum, closely followed by the predicted results of MKIN model, and the minimum is the predicted results of BKIN model. Moreover, comparisons of analysis results for each plasticity model against predicted results for a equivalent cyclic loading elbow component and for a simplified piping system seismic test are presented in the paper.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.267-278
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• 2020

ESS is an essential requirement for resolving power shortages and power demand management and promoting renewable energy at a time when the energy paradigm changes. In this paper, we propose a cost-effective ESS Peak-Shaving operation plan through load and solar power generation forecast. For the ESS operation plan, electric load and solar power generation were predicted through RMS, which is a statistical measure, and a target load reduction guideline for one hour was set through the predicted electric load and solar power generation amount. The load and solar power generation amount from May 6th to 10th, 2019 was predicted by simulation of load and photovoltaic power generation using real data of the target customer for one year, and an hourly guideline was set. The average error rate for predicting load was 7.12%, and the average error rate for predicting solar power generation amount was 10.57%. Through the ESS operation plan, it was confirmed that the hourly guide-line suggested in this paper contributed to the peak-shaving maximization of customers.Through the results of this paper, it is expected that future energy problems can be reduced by minimizing environmental problems caused by fossil energy in connection with solar power and utilizing new and renewable energy to the maximum.

• Proceedings of the Korea Society of Costume Conference
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• 2003.10a
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• pp.77-77
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• 2003

If we look closely to the power shift of the powerful countries historically. during the 16th century Spain's power came from gold, colony trade, the mercenary force, close relation with the thrown, 17th century Netherlands owes their power to trade, capital market, the marines, 18th century France owes it to population, agriculture, public administration, and the army. Also, England had their industry, political unity, finance and trust, the marines, liberalistic principles, a geographical merit of being an island which can be defended well and the 20th century America has their cosmopolitan culture, supernational communication, the capacity of the economy, science technology, military strength, alliances, liberalism international formation. But in the 21st century culture and art will prevail over the information age where technology and knowledge was the key, and it is predicted that this will be the source of power for a strong country. Rolfe Yesson, the head of The Copenhagen Research Center for future studies said, "Information age has ended and in the future Dream Society will arrive which focuses on making distinctions by delivering dreams and emotions to consumers". As cyberspace gradually substitutes reality, cyberspace has become more than an information search engine and has become a place where people fulfill their desires and exchange culture. And as a medium for diffusing culture, the importance of the digital dress-up avatar is predicted to increase gradually.gradually.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1242-1250
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• 2008

In this paper, we predicted the radiation field strength from the low power radio devices to force the radio interference on the AMPS receiver. The predicted value of 79.13[$dB{\mu}V/m$] is the upper value of radiation against the intermodulation interference emanated from the low power radio devices. To show the validity of the suggested values theoretical analysis on intermodulation and modeling of the AMPS receiver are performed, and also measurements on the AMPS receiver IC are carried out. The resultant numerals show the good match between them within the allowable tolerances.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.89-96
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• 2016

The mechanism for laminar dust flame propagation can only be elucidated from a comprehensive mathematical model which incorporates conduction and radiation, as well as the chemical kinetics of particle devolatilization and gas phase and char reaction. The mathematical model for a flat, laminar, premixed coal-air flame is applied to the atmospheric coal-air mixtures studied by Smoot and co-workers, and comparisons are made with their measurements and predictions. Here the principal parameter for comparison is the laminar burning velocity. The studies of Smoot and co-workers are first reviewed and compared with those predicted by the present model. The effects of inlet temperature and devolatilization rate constants on the burning velocities are studied with the present model, and compared with their measurements and predictions. Their measured burning velocities are approximately predicted with the present model at relatively high coal concentrations, with a somewhat increased inlet temperature. From the comparisons, their model might over-estimate particle temperature and rates of devolatilization. This would enable coal-air mixtures to be burned without any form of preheat and would tend to increase their computed values of burning velocity.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.4
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• pp.234-242
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• 2021

In this study, we introduce the prediction of brake power for low-speed full ships and container carriers using the linear regression and a machine learning approach. The residual resistance coefficient, wake fraction coefficient, and thrust deduction factor are predicted by regression models using the main dimensions of ship and propeller. The brake power of a ship can be calculated by these coefficients according to the 1978 ITTC performance prediction method. The mean absolute error of the predicted power was under 7%. As a result of several validation cases, it was confirmed that the machine learning model showed slightly better results than linear regression.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.426-430
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• 2006

This paper deals with a novel utilization method of the predicted current in the high performance PI current controller with a control time delay. The inevitable error of the predicted current in the linear servo drive using a permanent magnet linear synchronous motor is analyzed and a modified cross-coupling decoupling synchronous frame PI current controller is proposed in order to improve the current control response under both the control time delay and the inevitable current prediction error. Simulation and experimental results show that the proposed current controller has an improved current control performance under both the control time delay and the inevitable current prediction error in the servo drive system.

• Computers and Concrete
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• v.5 no.3
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• pp.261-277
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• 2008

This paper presents methodologies for remaining life prediction of plain concrete structural components considering tension softening effect. Non-linear fracture mechanics principles (NLFM) have been used for crack growth analysis and remaining life prediction. Various tension softening models such as linear, bi-linear, tri-linear, exponential and power curve have been presented with appropriate expressions. A methodology to account for tension softening effects in the computation of SIF and remaining life prediction of concrete structural components has been presented. The tension softening effects has been represented by using any one of the models mentioned above. Numerical studies have been conducted on three point bending concrete structural component under constant amplitude loading. Remaining life has been predicted for different loading cases and for various tension softening models. The predicted values have been compared with the corresponding experimental observations. It is observed that the predicted life using bi-linear model and power curve model is in close agreement with the experimental values. Parametric studies on remaining life prediction have also been conducted by using modified bilinear model. A suitable value for constant of modified bilinear model is suggested based on parametric studies.