• 전기의세계
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• v.28 no.6
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• pp.47-51
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• 1979

An optimal problem in which the dynamics is nonlinear and the cost functional includes a discontinuous integrand is investigated. By using Neustadt's abstract maximum principle, a necessary conditions in the form of Pontryagin's maximum principle is derived and it is further shown that this necessary condition is also a sufficient condition for normal problems with linear-in-the-state systems.

• Journal of applied mathematics & informatics
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• v.37 no.1_2
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• pp.123-131
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• 2019

In this paper, we introduce a uniform mesh method for a Maxwell's equation with discontinuous coefficients. We observe optimal O(h) order for the electric field and O(h) order for the curl.

• Honam Mathematical Journal
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• v.44 no.4
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• pp.485-503
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• 2022

In this work, a discontinuous singular Dirac system is studied. For this system, a spectral function is constructed. Finally, by using the spectral function, a spectral expansion formula is given.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.362-366
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• 2014

In recent years, a permanent magnet linear synchronous motor (PMLSM) has been used in various kinds of transportation applications for its relative high power density and efficiency. The general transportation system arranges the armature on the full length of transportation lines. However, when this method is applied to long distance transportation system, it causes increase of material cost and manufacturing time. Thus, in order to resolve this problem, we suggested stationary discontinuous armature PMLSM. However, the stationary discontinuous armature PMLSM contains the edges which always exist as a result of the discontinuous arrangement of the armature. These edges become a problem because the cogging force that they exert bad influences the controllability of the motor. Therefore, in this paper we proposed the combination of skewed magnets and stair shape auxiliary teeth to reduce the force by edge effect. Moreover, we analyzed the influence of the design factors by using a 3-D finite element method (FEM) simulation tool.

• Journal of Microbiology and Biotechnology
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• v.9 no.4
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• pp.522-524
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• 1999

A discontinuous Percoll gradient was used to separate islets from the collagenase-treated mouse pancreas easily and rapidly. Since the osmolality of Percoll is very low, adjustment of its osmolality to 340 mOs/kg $H_2$O was essential for securing the optimal separation. A discontinuous gradient layering with Percoll solution of 1.09 g, 1.07g, and1.05g/m, respectively, when centrifuged at 800$\times$g for 10 min, resulted in an optimal condition for separation and yielded a banding pattern with an even distribution of islet cells. No significant difference was observed in the morphological features between the Percoll-isolated and the manually-isolated islets. In conclusion, the discontinuous Percoll gradient can be effectively used to isolate the pancreatic islets from mice with four-fold higher efficiency compared to the handpicking method.

• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.428-434
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• 2013

With the increase of the frequency in large-scale floods and natural disasters, the demands for highly accurate numerical river models are also rapidly growing. Generally, flows in rivers are modeled with previously developed and well-established numerical models based on shallow water equations. However, the so-far-developed models reveal a lot of limitations in the analysis of discontinuous flow or flow which needs accurate modeling. In this study, the numerical shallow water model based on the discontinuous Galerkin method was applied to the simulation of one-dimensional transcritical flow, including dam break flows and a flow over a hump. The favorable agreement was observed between numerical solutions and analytical solutions.

• Tunnel and Underground Space
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• v.9 no.2
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• pp.149-157
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• 1999

A powerful numerical method that can be used for that purpose is the Discontinuous Deformation Analysis (DDA) method developed by Shi in 1988. In this method, rock masses are treated as systems of finite and deformable blocks. Large rock mass deformations and block movements are allowed. Although various extensions of the DDA method have been proposed in the literature, the method is not capable of modeling water-block interaction that is needed when modeling surface or underground excavation in fractured rock. This paper presents a new extension to the DDA method. The extension consists of hydro-mechanical coupling between rock blocks and water flow in fractures. A example of application of the DDA method with the new extension is presented. The results of the present study indicate that fracture flow could have a destabilizing effect on the tunnel stability.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1137-1147
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• 2020

The discrete ordinates method (S_N) is one of the major shielding calculation method, which is suitable for solving deep-penetration transport problems. Our objective is to explore the available quadrature sets and to improve the accuracy in shielding problems involving strong anisotropy. The linear discontinuous finite-element (LDFE) quadrature sets based on the icosahedron (in short, ICLDFE quadrature sets) are developed by defining projected points on the surfaces of the icosahedron. Weights are then introduced in the integration of the discontinuous finite-element basis functions in the relevant angular regions. The multivariate secant method is used to optimize the discrete directions and their corresponding weights. The numerical integration of polynomials in the direction cosines and the Kobayashi benchmark are used to analyze and verify the properties of these new quadrature sets. Results show that the ICLDFE quadrature sets can exactly integrate the zero-order and first-order of the spherical harmonic functions over one-twentieth of the spherical surface. As for the Kobayashi benchmark problem, the maximum relative error between the fifth-order ICLDFE quadrature sets and references is only -0.55%. The ICLDFE quadrature sets provide better integration precision of the spherical harmonic functions in local discrete angle domains and higher accuracy for simple shielding problems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1611-1616
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• 2012

Recently, the stationary discontinuous armature Permanent Magnet Linear Synchronous Motor(PM-LSM) was suggested as a driving source for long-distance transportation system. However, as these motors arrange armatures discontinuously, there occurs an edge which causes the cogging force. This works as a factor that bothers acceleration and deceleration that takes place when movers enter into and eject from the armatures. Therefore, installation of auxiliary teeth on the edge of armature of PM-LSM is suggested in order to reduce cogging force caused by the edge when the armature is placed in a discontinuous arrangement. But length of auxiliary teeth can be changed if install it with auxiliary pole in order to decrease more and more edge cogging force. On this, in the study, decided on a design variable of auxiliary teeth and used 2-D FEA, and examined edge cogging force characteristic along this in order to grasp length of auxiliary teeth changed according to installation positions of an auxiliary pole.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.311-317
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• 2011

The present paper deals with the continuous works of extending the multi-dimensional limiting process (MLP) for compressible flows, which has been quite successful in finite volume methods, into discontinuous Galerkin (DG) methods. From the series of the previous, it was observed that the MLP shows several superior characteristics, such as an efficient controlling of multi-dimensional oscillations and accurate capturing of both discontinuous and continuous flow features. Mathematically, fundamental mechanism of oscillation-control in multiple dimensions has been established by satisfaction of the maximum principle. The MLP limiting strategy is extended into DG framework, which takes advantage of higher-order reconstruction within compact stencil, to capture detailed flow structures very accurately. At the present, it is observed that the proposed approach yields outstanding performances in resolving non-compressive as well as compressive flaw features. In the presentation, further numerical analyses and results are going to be presented to validate that the newly developed DG-MLP methods provide quite desirable performances in controlling numerical oscillations as well as capturing key flow features.