• Water for future
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• v.21 no.2
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• pp.173-182
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• 1988

Characteristics of finite difference schemes for St. Venant equation were compared with two input cases. One is the monoclinal wave which has large friction slope without discontinuity and the other is the shock wave with discontinuity. For monoclinal wave, Keller Box scheme is the best in terms of accuracy, efficiency and stability when two parameters were selected with a rele : $0.5{\leq}{\theta}{\leq}1.0$, ${\theta}+{\psi}$=1, But for shock wave only the Preissmann type of parameter ${\psi}$(=0.5) showed stable results. Numerical experiments of monoclinal wave showed that Lax-Wendroff and Richtmyer schemes were more stable than leap Frog and more accurate than Lax-Fredrich scheme. For shock wave Lax-Fredrich showed larger numerical dissipation than other explicit schemes and Leap Frog produced slower mass transport.

• Journal of computational fluids engineering
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• v.12 no.2
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• pp.53-62
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• 2007

A high resolution numerical method aimed at solving cavitating flow is proposed and applied to gas-liquid two-phase shock tube problem. The present method employs a finite-difference 4th-order Runge-Kutta method and Roe's flux difference splitting approximation with the MUSCL TVD scheme. By applying the homogeneous equilibrium cavitation model, the present density-based numerical method permits simple treatment of the whole gas-liquid two-phase flow field, including wave propagation and large density changes. The speed of sound for gas-liquid two-phase media is derived on the basis of thermodynamic relations and compared with that by eigenvalues. By this method, a Riemann problem for Euler equations of one dimensional shock tube was computed. Numerical results such as detailed observations of shock and expansion wave propagations through the gas-liquid two-phase media at isothermal condition and some data related to computational efficiency are made. Comparisons of predicted results and exact solutions are provided and discussed.

• Communications of Mathematical Education
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• v.29 no.4
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• pp.661-685
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• 2015

This study is to search for a program of professional development of mathematics teachers on the viewpoint of content knowledge of mathematics. To do this, we select algebraic subject as content knowledge for solution of polynomials and develop material for group study based on selected subject. We supply the developed material to teachers and discuss the possibility of application and the acceptability of it. For discussion, we collect data through tests and questionnaire. Through analysing the data, we obtain the positive result.

• Resources Recycling
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• v.26 no.3
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• pp.69-78
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• 2017

Magnesium has been used as parts of vehicles, case materials of notebook PC and mobile phone, and its demand has been increasing recently. Its extraction technologies were classified according to the two major reduction methods: the fused salt electrolysis and the thermal reduction method. A research on the extraction of magnesium from magnesite which has been being carried out at KIGAM was briefly introduced here. Magnesium was prepared using a fused salt electrolysis method through preparation of anhydrous magnesium chloride with lab scale experiments.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.31-31
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• 2003

• Proceedings of the Korean Society of Rheology Conference
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• 2003.05a
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• pp.45-48
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• 2003

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.231-231
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• 1992

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1998.04a
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• pp.101-101
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• 1998

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.10b
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• pp.30-30
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• 1998

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.396-396
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• 1998