• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1436-1444
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• 2002

A three dimensional numerical model was developed to analyze the mold filling and solidification processes straightforwardly in a casting processes. On the basis of the SIMPLER algorithm, the VOF method and the Equivalent Specific Heat method were adopted to deal with the free surface behavior and the latent heat evolution. The complete model has been validated using exact solutions and experimental results. The importance of three-dimensional effects has been highlighted by comparing the results from the three-dimensional analysis with those given by a two-dimensional analysis.

• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.877-886
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• 2005

Two-dimensional incompressible Navier-Stokes equations are solved using SIMPLER method in the intrinsic curvilinear coordinates system to study the unsteady viscous flow physics over two-dimensional ellipses. Unsteady viscous flows over various thickness-to-chord ratios of 0.6, 0.8, 1.0, and 1.2 elliptic cylinders are simulated at different Reynolds numbers of 200, 400, and 1,000. This study is focused on the understanding the effects of Reynolds number and elliptic cylinder thickness on the drag and lift forces. The present numerical solutions are compared with available experimental and numerical results and show a good agreement. Through this study, it is observed that the Reynolds number and the cylinder thickness affect significantly the frequencies of the force oscillations as well as the mean values and the amplitudes of the drag and lift forces.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.253-256
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• 2006

A numerical study for spray flow of fuel and oxidizer droplets in the combustion chamber has been conducted prior to the analysis of spray combustion of the liquid rocket engine. As the spray combustion model, DSF model and Euler-Lagrange scheme have been used. While the coupling effects of the droplets between gas phase and evaporated vapor have been calculated using PSIC model, SIMPLER algorithm and QUICK scheme have been used as numerical schemes. As the results, the calculations have shown velocity and temperature distribution in combustion chamber as well as mole fraction of fuel and oxidizer.

• Journal of Biomedical Engineering Research
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• v.31 no.3
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• pp.194-198
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• 2010

The effective Young’s modulus of a microfibril surrounded by water may be simply calculated by using the upper (Voigt) and lower (Reuss) bounds, which is one way to estimate the Young’s modulus in composite materials. The Steered Molecular Dynamics (SMD) has been used for estimating the Young’s modulus of a microfibril surrounded by water. In this paper, the result estimated by the upper (Voigt) and lower (Reuss) bounds shows 9.2% to 21.8% discrepancy from the result estimated by SMD, but introducing “efficiency of reinforcement parameter” removes the discrepancy and shows good agreement with the result estimated by SMD. We found the best fit for the Young’s modulus against the size of the gap between microfibrils. Also the steps using these bounds are much simpler than SMD.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.969-971
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• 2000

In this paper, shortening of product life cycle and wide disposal of consumer product have given rise to many environmental problems, it needs to propose module design principle for saving of disassembly cost and reusing of used part and subassembly. To analyze characteristics of module for recycling, materials and function of part and subassembly must be classified. In disassembly process, a unit operation can be grasped for disassembly function, worker, tool and sorting process. As a result of applying module design principle, simpler structure and reduced structural interference can be realized for product structure. For disassembly, simpler disassembly and quicker disassembly can be obtained for recycling.

• Journal of applied mathematics & informatics
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• v.5 no.3
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• pp.849-857
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• 1998

In this paper we have a concern on the Moore-Penrose inverse of two kinds of partitioned matrices of the form [V X] and [{{{{ {V atop {X} {{{{ {X atop { 0} }}] where V is symmetric. The Moore-Penrose inverse of the partitioned matrices can be reduced to be simpler forms according to some algebraic conditions. Firstly we investigate the representations of the Moore-Penrose inverses of the partitioned matrices under four al-gebraic conditions. Each condition reduces the Moore-Penrose inverses of the partitioned matrices under four al-gebraic conditions. Each condition reduces the Morre-Penrose inverse into some simpler form. Also equivalant conditions will be considered. Finally we will perform a simulation study to investigate which con-dition is the most important in the sense that which condition occurs the most frequently in the real situation. The simluation study will show us a particular condition occurs the most likely tha other conditions. This fact enables us to obtain the Morre-Penrose inverse with less computational efforts and computational storage.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.161-162
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• 2006

Micro-stereolithography technology is used for fabricating of 3-dimensional micro-structures. In some cases, this technology is more economical and simpler than MEMS and LIGA technologies based on semiconductor process. In this research, the micro-sterolithography apparatus that is more economical and simpler than current micro-stereolithography apparatus was developed. This apparatus uses UV lamp and optical fiber as a light source and tight delivery system, respectively.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.383-388
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• 2008

We are now developing a CFD program, AIRVIEW, with several numerical models and the SIMPLER solving method for constructing flow field and thermal comfort. This study is carried out for evaluating an accuracy of AIRVIEW. Comparisons of accuracy are carried out using Phoenics Version 3.4. In this study, we compare the turbulent kinetic energy distribution and local turbulent Re number obtained with Phoenics with those results simulated by AIRVIEW for three kinds of duct. It is observed from comparison of results that the turbulent kinetic energy values are significant due to the large velocity gradients in the region of flow. Numerical results for turbulent kinetic energy distribution and local turbulent Re number are that a good degree of agreement is found.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.5
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• pp.33-38
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• 2013

This paper presents a simpler calculation of the generator load sharing according to the change of system frequency and the droop setting of turbine-generator governor. The author firstly draws a graph based on the generator operation at rated MW output and normal frequency, and secondly, builds a proportional expression using the graph in order to obtain the solution in a simpler way rather than using conventional mathematical calculation, to provide the readers with an easier understanding of the droop setting of turbine-generator governor.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.140-150
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• 2000

In this paper module of a product is determined by the characteristics of a product itself and process. To analyze the characteristics of the product information on subassemblies and parts can be obtained by analyzing the existing product. Based on the analysis of characteristics of product structure and function determination rules of a module degree could be proposed for assembly and disassembly process and product structure and function. By applying these rules of a module, module of a product is classified into full half and non-module depending on the module degree of a product. As a result of module degree analysis simpler assembly process and reduced structural interference can be realized. For the product function simpler updated and multi function can be also achieved.