• Water Engineering Research
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• v.5 no.4
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• pp.195-206
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• 2004

This paper deals with oxygen transfer by air entrainment and energy dissipations by flow characteristics at the stepped drop structure. Nappe flow occurred at low flow rates and for relatively large step height. Dominant flow features included an air pocket, a free-falling nappe impact and a subsequent hydraulic jump on the downstream step. Most energy was dissipated by nappe impact and in the downstream hydraulic jump. Skimming flow occurred at larger flow rates with formation of recirculating vortices between the main flow and the step comers. Oxygen transfer was found to be proportional to the flow velocity, the flow discharge, and the Froude number. It was more related to the flow discharge than to the Froude number. Energy dissipations in both cases of nappe flow and skimming flow were proportional to the step height and were inversely proportional to the overflow depth, and were not proportional to the step slope. The stepped drop structure was found to be efficient for water treatment associated with substantial air entrainment and for energy dissipation.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.679-680
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• 2011

This paper is developed to Energy Balance Flow show the flow of total energy resource be used nationally. The Energy Balance Flow is applicable of demand management factor through the analysis of foreign energy model of supply and demand and energy statistic data in the country. This study is based on and developed to Energy system management model is able to appraisal efficient of energy cost cutting, CO2 emission reduction and Energy saving at the national level calculated effect reached amount of primary energy to change of energy flow followed application of demand side management factor is able to appraisal quantitatively at the total energy to model of demand and supply.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.307-314
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• 2016

Energy flow analysis(EFA) is a representative method that can predict the statistical energetics of structures at high frequencies. Generally, as the frequency increases, the shear distortion and rotatory inertia effects in the out-of-plane motion of beams or plates become important. Therefore, to predict the out-of-plane energetics of coupled structures in the high frequency range, the energy flow analyses of Timoshenko beam and Mindlin plate are required. Unlike the energy flow model of Kirchhoff plate, the energy flow model of Mindlin plate is composed of three kinds of energy governing equations(out-of-plane shear wave, bending dominant flexural wave, and shear dominant flexural wave). This paper performed the energy flow finite element analysis(EFFEA) of coplanar coupled Mindlin plates. For EFFEA of coplanar coupled Mindlin plates, the energy flow finite element formulation of out-of-plane energetics in the Mindlin plate was performed. The general EFFEA program was implemented by MATLAB® language. For the verification of EFFEA of Mindlin plate, the various numerical applications were done successfully.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.735-744
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• 2012

In order to quantify the flow distribution characteristics of APR+ reactor, a test was performed on a test facility, ACOP ($\underline{A}$PR+ $\underline{C}$ore Flow & $\underline{P}$ressure Test Facility), having a length scale of 1/5 referring to the prototype plant. The major parameters are core inlet flow and outlet pressure distribution and sectional pressure drops along the major flow path inside reactor vessel. To preserve the flow characteristics of prototype plant, the test facility was designed based on a preservation of major flow path geometry. An Euler number is considered as primary dimensionless parameter, which is conserved with a 1/40.9 of Reynolds number scaling ratio. ACOP simplifies each fuel assembly into a hydraulic simulator having the same axial flow resistance and lateral cross flow characteristics. In order to supply boundary condition to estimate thermal margins of the reactor, the distribution of inlet core flow and core exit pressure were measured in each of 257 fuel assembly simulators. In total, 584 points of static pressure and differential pressures were measured with a limited number of differential pressure transmitters by developing a sequential operation system of valves. In the current study, reactor flow characteristics under the balanced four-cold leg flow conditions at each of the cold legs were quantified, which is a part of the test matrix composing the APR+ flow distribution test program. The final identification of the reactor flow distribution was obtained by ensemble averaging 15 independent test data. The details of the design of the test facility, experiment, and data analysis are included in the current paper.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.435-447
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• 2019

Energy Flow Finite Element Analysis (EFFEA) is a promising tool for predicting dynamic energetics of complicated structures at high frequencies. In this paper, the Energy Flow Finite Element (EFFE) formulation of complicated Mindlin plates was newly developed to improve the accuracy of prediction of the dynamic characteristics in the high frequency. Wave transmission analysis was performed for all waves in complicated Mindlin plates. Advanced Energy Flow Analysis System (AEFAS), an exclusive EFFEA software, was implemented using $MATLAB^{(R)}$. To verify the general power transfer relationship derived, wave transmission analysis of coupled semi-infinite Mindlin plates was performed. For numerical verification of EFFE formulation derived and EFFEA software developed, numerical analyses were performed for various cases where coupled Mindlin plates were excited by a harmonic point force. Energy flow finite element solutions for coupled Mindlin plates were compared with the energy flow solutions in the various conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1103-1111
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• 2011

This paper is developed to Energy Balance Flow show the flow of total energy resource be used nationally. The Energy Balance Flow is applicable of demand management factor through the analysis of foreign energy model of supply and demand and energy statistic data in the country. This study is based on and developed to Energy system management model is able to appraisal efficient of energy cost cutting, CO2 emission reduction and Energy saving at the national level calculated effect reached amount of primary energy to change of energy flow followed application of demand side management factor is able to appraisal quantitatively at the total energy to model of demand and supply.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.5
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• pp.617-623
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• 2003

In the present study, the characteristics of upward bubble flow were experimentally investigated in a liquid bath. The velocity of upward bubble flow was calculated for two different experimental conditions：1) bubble flow without kinetic energy 2) bubble flow with kinetic energy. Bubble flow without kinetic energy starts to undergo the effect of buoyancy l0cm away from the nozzle. Whereas. kinetic energy is dominant before 30 cm away from the nozzle in bubble flow but after this point kinetic energy and inertial force are applied on bubble flow at the same time In addition, as the flow rate increases the maximum velocity point moves to the nozzle. The velocity Profiles near free surface is extremely irregular due to surface flow. Gas volume fraction is high near the nozzle due to gas concentration. but decreases with the increasement of axial position. Gas volume fraction does not vary after the axial position, z=60 in spite of the increasement of flow.

• Journal of the Korea Society for Simulation
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• v.6 no.2
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• pp.1-14
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• 1997

The characteristics of the flow and energy conversion in OMACON liquid-metal MHD system are investigated. Numerical simulation of two-phase flow in the OMACON system without magnetic field was carried out by the Phoenics code and the energy conversion characteristics are studied in association with the fact that the mechanical energy loss at the nozzle of the OMACON system are to be converted into electrical energy. In this system, working fluid (gas) is injected through the mixer located at the bottom of the riser, and is mixed with hot liquid metal. Therefore in the riser two-phase flow is developed under the influence of the gravity. In this study, the interaction between the gas and liquid is considered by the use of IPSA(InterPhase Slip Algorithm) where standard drag coefficient has been used. It has been assumed that in the flow regime the liquid is continuous and the gas is dispersed. For the liquid and gas, the continuity equations, momentum equations and energy equations are solved respectively in association with void fraction in the flow field. In order to calculate the energy conversion efficiency, firstly the ratio of the mechanical energy loss of liquid metal flow at the nozzle to the input thermal energy is considered. Secondly flow pattern of liquid metal in the generator has been analyzed, and the characteristics of the conversion of the mechanical energy into the electrical energy has been investigated. For an representative case where Hartmann number is 540 and magnetic field is 0.35 T, the present analysis shows that the energy conversion efficiency is 0.653. This result is considered to be reasonable in comparison with published experimental results.

• Journal of the Korean Solar Energy Society
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• v.34 no.6
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• pp.103-109
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• 2014

It is important to control the amount of supply water flow rate at all kinds of HVAC systems in order to maintain IAQ and energy efficiency. The most of buildings installed geothermal heat pumps is using fixed water flow rate in spite of the excellent performance of geothermal heat pumps. Especially when the air-conditioning load is low, the flow rate control may be possible to save energy to operate. However, it is effective to apply the variable flow control system in order to reduce energy consumption. Therefore, the purpose of this study, change a water flow rate and improve the whole performance of the geothermal heat pump. Geothermal heat pump system is modeled after the selection of the applied building, by setting the flow rate control to be analyzed through a simulation of performance evaluation. Building energy saving according to the flow rate of the ground circulating water analyze quantitatively and to investigate the importance of the flow control.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.4
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• pp.32-38
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• 2019

In this study, the effect of hot water supply flow rates on energy consumption for radiant floor heating system in apartment were researched by computer simulation. The parametric study of different hot water supply flow rates was done with regard to energy performance and control characteristics, respectively. Also the effect of different hot water supply flow rates on the hot water supply temperatures is studied. As a result, energy consumption were reduced but the response time is increased by reducing the supply flow rate. And energy consumption can be saved by adjusting the hot water supply temperatures with different supply flow rates.