• The KSFM Journal of Fluid Machinery
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• v.13 no.2
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• pp.12-17
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• 2010

A kind of disk-shape boundary layer pump is designed numerically by using a software of computational fluid dynamics, which is widely used for the special purposes such as artificial hearts, bio-fluidics and transportation of oceanic lives, etc. From the numerical simulation with an axisymmetric model, some benchmark problems are tested and compared with experimental results. The performance of disk pump is graphically visualized from the computational results, and converted to the dimensionless parameters. Finally, the obtained numerical data in the present investigation can be used for the baseline for new design to achieve a more efficient disk pump.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.84-91
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• 2008

Generalized hydrodynamic (GH) theory for multi-species gas and the computational models are developed for the numerical simulation of hypersonic rarefied gas flow on the basis of Eu's GH theory. The rotational non-equilibrium effect of diatomic molecules is taken into account by introducing excess normal stress associated with the bulk viscosity. The numerical model for the diatomic GH theory is developed and tested. Moreover, with the experience of developing the dia-tomic GH computational model, the GH theory is extended to a multi-species gas including 5 species; O$_2$, N$_2$, NO, O, N. The multi-species GH model includes diffusion relation due to the molecular collision and thermal phenomena. Two kinds of GH models are developed for an axisymmetric flow solver. By compar-ing the computed results of diatomic and multi-species GH theories with those of the Navier-Stokes equations and the DSMC results, the accuracy and physical consistency of the GH computational models are examined.

• Journal of computational fluids engineering
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• v.2 no.1
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• pp.109-116
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• 1997

The objective of this paper is to develop a computational model for the prediction of the pollutant spread from a mass source over a complex terrain. The model comprises a two-dimensional, steady state flow model and a concentration model which employs the results of the computed flow field. The computational model is applied to predict the spread of pollutants for Sanbon city, and the two cases have been compard with the results of SF/sub 6/ trace experiments.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.84-91
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• 2008

Generalized hydrodynamic (GH) theory for multi-species gas and the computational models are developed for the numerical simulation of hypersonic rarefied gas flow on the basis of Eu's GH theory. The rotational non-equilibrium effect of diatomic molecules is taken into account by introducing excess normal stress associated with the bulk viscosity. The numerical model for the diatomic GH theory is developed and tested. Moreover, with the experience of developing the dia-tomic GH computational model, the GH theory is extended to a multi-species gas including 5 species; $O_2,\;N_2$, NO, O, N. The multi-species GH model includes diffusion relation due to the molecular collision and thermal phenomena. Two kinds of GH models are developed for an axisymmetric flow solver. By compar-ing the computed results of diatomic and multi-species GH theories with those of the Navier-Stokes equations and the DSMC results, the accuracy and physical consistency of the GH computational models are examined.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.483-487
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• 2011

In the present study, a CFD program based on a finite volume method was developed by using an unstructured polyhedral grid system for the accurate simulation with the complex geometry of computational domain. To simulate the transient flow induced by the moving solid object, the program used a fractional step method and a ALE (Algebric Lagrangian-Eulerian) method. The grid deformation for the moving of solid object were performed with a spring analogy based on the center coordinate of each computational grid. To verify the present program with these methodologies, the numerical results of the flow around the fixed and oscillating circular cylinder were compared with the previous numerical results.

• Journal of applied mathematics & informatics
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• v.3 no.1
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• pp.25-34
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• 1996

Many important large-scale linear programs with special structures lead to special computational procedures which are more ef-ficient than the ordinary procedure of the generalized methods. Prob-lems and their solvers taking advantage of multiple updatings of the basis in the dual simplex type method are presented. Computational results run by the efficient algorithm and a presented. Computational results run by the efficient algorithm and a standard code MINOS for the test problems are compared and analyzed. It is shown that the amount of work for the optimal solution for the prblem can be re-duced by the new algorithm.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.68-74
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• 1998

A finite element analysis for physical phenomenon which are governed by parabolic equation, has some inefficiencies caused by much computational time and large storage space. In this paper, a comparative study is performed to suggest the best efficient transient analysis algorithms for parabolic equations. First, the general finite element analysis techniques are summarized in views of formulation procedures, treatments of convection terms. and time stepping methods. Results of several combinations applied to one dimensional convection-diffusion equation and Burger equation are represented and compared using some criteria such as accuracy, stability, and computational time. Through the results, some guidelines to select a algorithm for solving parabolic equations are proposed for diffusion dominant and convection dominant cases. Finally applicability of two dimensional extension of the result is also discussed.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.167-173
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• 2003

For the measurement of mass flow rate at a wide range of operation conditions, it is required that the critical nozzle gas different diameters, since the mass flow rate through the critical nozzle depends on the nozzle supply conditions and the nozzle throat diameter. In the present study, both computational and experimental investigations are performed to explore the variable critical nozzle. Computational work using the 2-dimensional, axisymmetric, compressible Navier-Stokes equations are carried out to simulate the gas flow through variable critical nozzle. In experimnet, a cylinder with several different diameters is inserted into the critical nozzle to vary the nozzle throat diameter. Computational results are compared with the experimented ones. The computed results are in close agreement with experiment. It is found that the displacement and momentum thickness of variable critical nozzle are given as a function of Reynolds numbers. The discharge coefficient of the variable critical nozzle is predicted using an empirical equation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.93-96
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• 2022

DTW can eliminate gaps between sequences of different lengths and find out the similarity of patterns, but due to the time and space complexity, it requires a high computational cost on large datasets. In this paper, we propose a DDTW algorithm that not only reduces computational costs but also has no error in the results. In addition, the algorithm complexity of DTW and DDTW is compared by measuring the computational time according to the length of the sequence. Simulation results show a noticeable reduction in computational time in DDTW compared to DTW.

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.518-526
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• 2013

The notion of computational thinking is currently gaining much attention from a variety of disciplines. Accordingly, computer education community needs to address this issue for formal education. In the paper, the translation issue on the terminology - 'computational thinking' - is discussed. As a brief introduction to computational thinking the characteristics and necessities as well as its importance are presented. The types of learning computational thinking are presented, which are learning with computing tools on one hand and without them on the other hand. Furthermore, learning objectives of computational thinking as well as the contents are also investigated for the application of computational thinking in elementary education. A survey was conducted for thirty three elementary school teachers on behalf of investigating directions of teaching computational thinking in elementary education. It shows that almost all respondents agree to teaching computational thinking in formal education and it also shows other interesting results as stated in the paper.