• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.70-72
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• 1993

In this paper, we propose the One-Ampere Conductor Method which is able to calculate the flux distribution conventionally and easily, and the improved winding method which suppress space harmonics of magnetomotive force and enhance the utilization of primary iron core in tubular linear induction motor. We examine no-load test to verify propriety of proposed method and analyze characteristics by finite element method. As a result, performances are improved and propriety of primary iron core is enhanced comparing with conventional model.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1578-1583
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• 2007

The suspension system of railway rolling-stock is composed of the primary and secondary suspension elements. Recently, a conical rubber spring is widely used as the primary suspension element due to the merits of the three directional stiffness characteristics. So, understanding the properties and characteristics of the conical rubber spring is very important from the viewpoint of vehicle stability and efficient maintenance. Thus, this study is started to acquire the basic data for maintaining spring elements efficiently. For this, we tested the conical rubber spring samples including a new and old specimen with aging. As a test result, we have obtained the property characteristics of the aged spring comparing with the new product and we describe the results.

• Nuclear Engineering and Technology
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• v.29 no.4
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• pp.310-319
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• 1997

A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized into the average (membrane) stress, the linearly varying (bending) stress and the peak stress through the thickness. The resulting stresses are interpreted per Section III of the ASME Boiler and Pressure Vessel Code from which the Primary(B$_1$), Secondary(C$_1$) and Peak(K$_1$) stress indices for pressure, the Primary (B$_2$), Secondary(C$_2$) and Peak(K$_2$) stress indices for moment are developed. Based on the comparison between stress value by stress indices derived in this paper and stress value represented by the ASME Code Case N-391-1, the empirical equations for stress indices are effectively used in the piping stress analysis. Therefore, the use of empirical equations can simplify the procedure of evaluating the local stress in the piping design stage.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1316-1321
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• 2003

The systematic method to construct equivalent static load from the given dynamic load is proposed in the present study. Previously reported works to construct equivalent static load were based on ad hoc methods. They may results in unreliable structural design. The present study proposes a selection scheme of degrees of freedom(d.o.f) for imposing the equivalent static loads. The d.o.fs are selected by Two-level condensation scheme(TLCS). TLCS consists of two two-steps. The first step is the energy estimation in element-level and the second step consists of the traditional sequential elimination precudure. Through several numerical examples, the efficiency and reliability of proposed scheme is verified.

• KSTLE International Journal
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• v.7 no.2
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• pp.45-50
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• 2006

In this paper, the leakage safety of prestressed concrete structure including the insulation panels has been analyzed using a finite element analysis just after a collapse of 9% nickel inner tank. This FEM study shows that the outer tank may contain the leaked cryogenic liquid for the time being until the primary pump in the inner tank transports stored cryogenic liquids to the nearest LNG storage tank before the outer tank is demolished. This means that the total tank thickness from the insulation panel to the outer tank system safely may retain the leaked cryogenic fluids. The FE computed results indicate that the current structure in a full containment tank is obviously enough to securing the leak-proof safety of the tank system with two primary pumps.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.198-201
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• 2008

We investigated the operating characteristics of the flux-lock type superconducting fault current limiter(SFCL) with the parallel connection between the primary and secondary windings which are connected with two superconducting units in series. The parallel connection for current level increase of the flux-lock type SFCL is necessary to apply the SFCL into the power system. The resistance generated in superconducting units was dependent upon the winding direction of the primary and the secondary coils, which can reduce the power burden. The resistance of the superconducting elements in the subtractive polarity winding is higher than that of the additive polarity winding. The fault current limiting effect of the subtractive polarity winding is better than that of the additive polarity winding. From this results, we confirmed that the power capacity of the flux-lock type SFCL could be increased by the parallel connection of the superconducting units.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.148-150
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• 1999

This paper deals with characteristic analysis of Permanent Magnet Linear Synchronous Motor(PMLSM). Parameters and characteristic variations are evaluated by using Finite Element Method (FEM) and Equivalent Magnetizing Current Method. PMLSM can be classified into the short primary type PMLSM and the short secondary type PMLSM according to their structural features. Especially, the short secondary type PMLSM is focused on because of good control characteristics. And this paper presents the difference of analysis results between the short primary type PMLSM and short secondary type PMLSM and investigates the end effect of two PMLSM's.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2090-2091
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• 2007

We investigated the characteristics of transformer type SFCL with neutral line. The transformer type SFCL having neutral line has achieved the simultaneous quench because the secondary winding has acted as parallel reactor. The fault current of SFCL was limited according to ratio of turn number between primary and secondary windings. Therefore, the power burden of superconducting element can be reduced by reduction of ratio of turn number between primary and secondary windings. As a result, we could expect reduction of it's volume in the transformer type SFCL.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.316-320
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• 2008

A light rail transit, using a linear induction motor, is generally composed with reaction plates along railroad track and the three phase primary on the vehicle. This linear induction motor is driven to keep clearance between the primary and the secondary of the ground for preventing any contact. Therefore efficiency and power factor is very low. In addition, the reaction plate installed on the ground throughout entire railway is impossible to keep uniform gap and it may cause system deterioration. In this paper, A rotary-type small-scale model of a linear induction motor for various characteristic analysis is designed. Thrust force, normal force and input current of the model by air-gap variation have been analyzed by using a Finite Element Method (FEM). The effects of air-gap variation on system performance have been considered by analysis results.

• Korean Journal of Mathematics
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• v.30 no.3
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• pp.425-431
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• 2022

Let ℤ and ℚ be the ring of integers and the field of rational numbers, respectively. Let h(ℤ, ℚ) be the ring of composite Hurwitz polynomials. In this paper, we study the factorization of composite Hurwitz polynomials in h(ℤ, ℚ). We show that every nonzero nonunit element of h(ℤ, ℚ) is a finite *-product of quasi-primary elements and irreducible elements of h(ℤ, ℚ). By using a relation between usual polynomials in ℚ[x] and composite Hurwitz polynomials in h(ℤ, ℚ), we also give a necessary and sufficient condition for composite Hurwitz polynomials of degree ≤ 3 in h(ℤ, ℚ) to be irreducible.