• Explosives and Blasting
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• v.33 no.4
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• pp.7-13
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• 2015

Recently, as the demand for development and utilization of underground space is increasing worldwide, the blast damaged zone has become a major issue in constructing underground structures. In this study, to verify the explosion modelling method for blast-damaged zone (BDZ) around underground cavern, a series of small-scale test blasts was conducted using the concept of momentum trap. According to the test results, the input parameters to the numerical model (ANSYS LS-DYNA) were corrected. It is concluded that the suggested method of miniature blasting and numerical modelling using the MT concept well simulates the velocity of the MT projectile under given conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.58-65
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• 1994

In order to reduce particulate emissions from diesel vehicles, mathematical model is established and analyzed on ceramic wall-flow monolith filter. A wall-flow monolith filter placed in the exhaust stream of a diesel engine can effectively limit the emission of diesel particulates through the monolith. The accumulated particulates can then be periodically combusted inside the monolith by directing hot gas to the monolith while normal engine exhaust is routed around the monolith system. The resulting low flow rates through the monolith require consideration of gas dynamics through the channels as well as particulate combustion to analyze this regeneration process. A mathematical model of the regeneration is formulated as a system of nonlinear partial differential equations describing the conservation of mass, momentum and energy. Numerical solutions are obtained by using a finite difference techniques for the spatial discretization. So we can use filter simulation program for the purpose of filter design and actual filter regeneration

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.234-240
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• 1999

This paper presents a new approach for large-scale generator maintenance scheduling optimizations. The generator preventive maintenance scheduling problems are typical discrete dynamic n-dimensional vector optimization ones with several inequality constraints. The considered objective function to be minimized a subset of{{{{ { R}^{n } }}}} space is the variance (i.g., second-order momentum) of operating reserve margin to levelize risk or reliability during a year. By its nature of the objective function, the optimal solution can only be obtained by enumerating all combinatorial states of each variable, a task which leads to computational explosion in real-world maintenance scheduling problems. This paper proposes a new priority search mechanism based on each generator's discrete sensitivity value which was analytically developed in this study. Unlike the conventional capacity-based priority search, it can prevent the local optimal trap to some extents since it changes dynamically the search tree in each iteration. The proposed method have been applied to two test systems (i.g., one is a sample system with 10 generators and the other is a real-world lage scale power system with 280 generators), and the results anre compared with those of the conventional capacith-based search method and combinatorial optimization method to show the efficiency and effectiveness of the algorithm.