• 대한수학회보
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• 제32권2호
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• pp.163-170
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• 1995

Let G be a Lie group with Lie algebra L(G) and let $\Omega$ be a nonempty subset of L(G). If $\Omega$ is interpreted as the set of controls, then the set of elements attainable from the identity for the system $\Omega$ is a subsemigroup of G. A system $\Omega$ is called a non-overlapping control system if any element attainable for $\Omega$ is only attainable at one time.

• 호남수학학술지
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• 제35권4호
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• pp.747-755
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• 2013

This paper deals with the unit groups of the endomorphism rings of projective modules over polynomial rings and further over formal power series rings. A normal subgroup of the unit group is defined and discussed. The local splitting properties of element of endomorphism rings of projective modules over polynomial rings are given.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제12B권1호
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• pp.7-12
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• 2002

This paper presents a method to estimate an effective length of a 1000-kVA superconducting generator using three-dimensional FE analysis. Flux linkage of stator coil and the induced voltage are calculated with FEM program and Faraday's law. An effective length of the stator coil is estimated using the calculated voltage and geometric configurationn of the machine. In order to verify the estimation method, 30-kVA superconducting generator is built and tested. The test result agrees reasonably well with the estimation.

• Architectural research
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• 제13권1호
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• pp.17-24
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• 2011

Isogeometric solution of Poisson equation is provided. NURBS (NonUniform B-spline Surface) is introduced to express both geometry of structure and unknown field of governing equation. The terms of stiffness matrix and load vector are consistently derived with very accurate geometric definition. The validity of the isogeometric formulation is demonstrated by using two numerical examples such as square plate and L-shape plate. From numerical results, the present solutions have a good agreement with analytical and finite element (FE) solutions with the use of a few cells in isogeometric analysis.

• 대한수학회지
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• 제50권6호
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• pp.1349-1367
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• 2013

The weighted Moore-Penrose inverse will be introduced and studied in the context of Banach algebras. In addition, weighted EP Banach algebra elements will be characterized. The Banach space operator case will be also considered.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1049-1050
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• 2007

In this paper, an electromagnet which is used in maglev(magnetic levitation) clean lift is designed and described. The electromagnet is firstly designed by using FEM(finite element method) tool and the simulation results are presented. The nominal airgap is 5mm and the nominal current is 2A. Also, the nominal magnetic force is 200N. From the results, we can get the electromagnet as an actuator used in maglev(magnetic levitation) clean lift for LCD process.

• Structural Engineering and Mechanics
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• 제5권2호
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• pp.149-165
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• 1997

A dynamic time-history analysis of the coupled internals and core in the vertical direction is performed as a part of the fuel assembly qualification program. To reflect the interaction between the fuel rods and grid cage, friction element is developed and is implemented. Also derived here is a method to calculate a hydraulic force on the reactor internals due to pipe break. Peak responses are obtained for the excitations induced from earthquake and pipe break. The dynamic responses such as fuel assembly axial forces and lift-off characteristics are investigated.

• 충청수학회지
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• 제33권3호
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• pp.365-374
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• 2020

Given a noncompact semisimple Lie group G and its maximal compact Lie subgroup K such that the right multiplication of each element in K gives an isometry on G, consider a principal bundle G → G/K, which is a Riemannian submersion. We study the infinitesimal holonomy isometries. Given a closed curve at eK in the base space G/K, consider the holonomy displacement of e by the horizontal lifting of the curve. We prove that the correspondence is continuous.

• Tribology and Lubricants
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• 제23권6호
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• pp.283-287
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• 2007

Permanent-magnet (PM) passive bearings use the repulsive forces between the rotor and the stator magnets for the bearing function. It is desirable that the stiffness of the bearing is maximized with the given volume of the magnet. The stiffness is affected by the magnet strength, the number of layers, and the magnetization patterns. Previously, finite-element method (FEM) has been used to maximize the stiffness of the bearing. In this paper, we used the equivalent current sheet method to calculate the stiffness. The validity of this approach is checked against FEM results. The optimized bearing is applied to a micro flywheel energy storage system.

• 대한수학회지
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• 제55권5호
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• pp.1257-1268
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• 2018

In this article we first investigate a sort of unit-IFP ring by which Antoine provides very useful information to ring theory in relation with the structure of coefficients of zero-dividing polynomials. Here we are concerned with the whole shape of units and nilpotent elements in such rings. Next we study the properties of unit-IFP rings through group actions of units on nonzero nilpotent elements. We prove that if R is a unit-IFP ring such that there are finite number of orbits under the left (resp., right) action of units on nonzero nilpotent elements, then R satisfies the descending chain condition for nil left (resp., right) ideals of R and the upper nilradical of R is nilpotent.