• Nuclear Engineering and Technology
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• v.16 no.1
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• pp.21-28
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• 1984

The reduction of the truncation error including numerical diffusion, has been one of the most important tasks in the development of numerical methods. The stream line method is used to cancel cross numerical diffusion and some of the non-diffusion type truncation error. The two-step stream line method which is the combination of the stream line method and finite difference methods is developed in this work for the solution of the govern ing equations of incompressible buoyant turbulent flow. This method is compared with the finite difference method. The predictions of both classes of numerical methods are compared with experimental findings. Truncation error analysis also has been performed in order to the compare truncation error of the stream line method with that of finite difference methods.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.04a
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• pp.187-192
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• 2009

Nowadays, global warming and high oil prices were a threat to the survival of the whole human race. One of a solution to respond to these problems is to reduce energy consumption of building. By adopting energy-saving design, the dissemination of low energy building is required. Therefore, to improve energy efficiency while reducing the usage of the design method is necessary to study actively. BIM-based systems applied to buildings, scheduled to be built by reducing the amount of energy reduction technologies can be analyzed. Depending on various design and equipment to set energy savings goals, you can select an alternative. If it is possible to predict the energy efficiency from the initial stage of design and support designing low energy building, we would be able to expect improvement in the economics of housing due to the reduction of energy consumption.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.12
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• pp.623-627
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• 2006

This paper deals with the optimum rotor design solution on torque ripple reduction for a SynRM with concentrated winding using response surface methodology (RSM). The RSM has been achieved to use the experimental design method in combination with finite element method (FEM)and well adapted to make analytical model for a complex problem considering a lot of interaction of design variables. Comparisons are given with characteristics of a SynRM according to flux barrier number, flux barrier width variation, respectively.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.669-670
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• 2006

This paper deals with the optimum rotor design solution on torque ripple reduction for a SynRM with concentrated winding using response surface methodology (RSM). The RSM has been achieved to use the experimental design method in combination with finite element method (FEM)and well adapted to make analytical model for a complex problem considering a lot of interaction of design variables. Comparisons are given with characteristics of a SynRM according to flux barrier number, flux barrier width variation, respectively.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2066-2073
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• 2021

The use of nuclear reactors is a large studied possible solution for thermochemical water splitting cycles. Nevertheless, there are several problems that have to be solved. One of them is to increase the efficiency of the cycles. Hence, in this paper, a thermal energy optimization of a Sulfur-Iodine nuclear hydrogen production cycle was performed by means a heuristic method with the aim of minimizing the energy targets of the heat exchanger network at different minimum temperature differences. With this method, four different heat exchanger networks are proposed. A reduction of the energy requirements for cooling ranges between 58.9-59.8% and 52.6-53.3% heating, compared to the reference design with no heat exchanger network. With this reduction, the thermal efficiency of the cycle increased in about 10% in average compared to the reference efficiency. This improves the use of thermal energy of the cycle.

• Structural Engineering and Mechanics
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• v.76 no.5
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• pp.599-611
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• 2020

A state-space method is developed to investigate the time-dependent behaviors of an angle-ply cylindrical shell in cylindrical bending with surface-bonded piezoelectric layers. Both the interfacial diffusion and sliding are considered to describe the properties of the imperfect interfaces. Particularly, a matrix reduction technique is adopted to establish the transfer relations between the elastic and piezoelectric layers of the laminated shell. Very different from our previous paper, in which an approximate numerical technique, i.e. power series expansion method, is used to deal with the time-dependent problems, the exact solutions are derived in the present analysis based on the piezoelasticity equations without any assumptions. Numerical results are finally obtained and the effects of imperfect interfaces on the electro-mechanical responses of the laminated shell are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.39-47
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• 2003

UEGI (Unburned Exhaust Gas Ignition) is an alternative method for fast light-off of a catalyst. It ignites the unburned exhaust mixture using two glow plugs installed in the upstream of the close-coupled catalysts. In addition, a hydrocarbon adsorber was applied to the UEGI, for more effective reduction of HC emission. Engine bench tests show that the CCC reaches the light-off temperature laster than the baseline exhaust system and HC and CO emissions are reduced significantly during the cold start. From the vehicle test, it was observed that a few amount of HC emission was reduced even the catalysts were aged. It is expected to develop a solution kit applicable to a new vehicle or used one, to meet the emission regulation

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06b
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• pp.87-107
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• 1996

The fine Co powder with an average particle sie of less than 1$\mu\textrm{m}$ was prepared by hydrothermal reduction with hydrogen from Co(OH)2 slurry obtained by mixing the solutons of CoSO4$.$7H2O and NaOH. A method to control pH of the end solution around neutrality was proposed. The reduction rate was found to be a function of pH, temperature, hydrogen pressure and the amount of catalyst.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.46-50
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• 2011

In order to perform the satellite structural analysis, FE-Model(Finite Element Model) considering all mechanical properties is necessary. Generally, different companies develop several satellite components, and sometimes it is very difficult to obtain FE-Model. In this case, FE-Model reduction using superelement method can be good solution. For developing satellite, antenna manufacturer required satellite FE-Model to calculate microvibration induced by antenna operation, and condensed model using superelement method was provided. Superelement method is based on Craig-Bampton method, and it is applied to spacecraft FE-Model reduction in this paper. From modal analysis and the frequency response analysis results between full FE-Model and condensed model, the usefulness of reduced model is confirmed.

• Journal of the Korean Ceramic Society
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• v.35 no.2
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• pp.107-114
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• 1998

ZnO powder as phosphor was prepared by precipitation method with zinc acetate and ammonia solution and the size and shapes of precipitates were examined with variation of pH and concentration of solution. Its cathodoluminesence properties was evaluated with various heat tratment condition. Optimum con-dition for uniform precipitates was 11.8 of pH and 0.4M of concentration. ZnO:Zn phosphor was obtained by heat treatment of precipitates in reduction atmosphere using ZnS powder. With addition of 20wt% ZnS and 1 hour firing at 1000$^{\circ}C$ the highest cathodoluminescence was obtained.