• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.291-298
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• 2001

When the compression members have the variable cross sections along their member axes, the determination of the elastic critical loads by classical methods becomes impossible and if possible involves complicated calculation only to obtain the approximate values of critical load. In this paper the elastic critical load coefficients of the tapered members with simply supported ends were determined by finite element method. And then the results were represented by simple algebraic equations of two parameters, a( =taper parameter) and m ( = sectional property parameter). One the basis of algebraic equations, the equivalent moment of inertia concept originally proposed by Bleich for a spesific case, are extended to the general cases.

• Special Issue of the Society of Naval Architects of Korea
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• 2011.09a
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• pp.106-111
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• 2011

The use of thin plate increases due to the need for light weight in large ship. Thin plate is easily distorted and has residual stress by welding heat. Therefore, the thin plates should be carefully joined to minimize the welding deformation. In this study, the welding deformation of PCTC which use a thin plate is investigated by using equivalent load method. The analysis model of 10, 11, 12, upper and garage deck is composed of thin plate of 6mm which is susceptible to welding heat. For two different welding sequences, the welding deformation is calculated and its trend is investigated. The influence of gravity on welding deformation is studied.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.199-205
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• 2012

This paper propose a improved parameter estimations of five-phase squirrel-cage induction motor(IM) for speed control system on field oriented control(FOC). In order to high performance control of ac the motors using a FOC and DTC(direct torque control) algorithm, there are required precise motor parameters for slip calculation, flux observer, controller gain, rotor position and speed estimation, and so on. We are suggest a estimation method of the motor parameters that developing five-phase squirrel-cage IM have a stator of concentrated winding for experimental. There are results of stator winding test, no-load test, locked rotor test, and obtained equivalent circuits using manufactured experimental apparatus. For presenting the superior performance of the speed control system in adapted the parameters, experimental results are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[KW] IM.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.93-98
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• 2002

This study presents a new method to derive the constraint coefficient from the degree of angular deformation caused by welding, as measured experimentally by varying the shape of welded joints and the magnitude of constraints and from analysis results given by the elastic FEM method. The equivalent load was then calculated with this constraint coefficient. The validity of the numerical analysis involved in this new method was confirmed by its agreement with the experimental results. As for the effects of the constraints based on the shape of the welded joints in the case of Butt welding when the constraint coefficients are not considered, the deformed quantity produced by analysis is larger that produced by experiment and consequently is largely affected by the constraints.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.171-173
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• 1993

This paper deals with a methodology of the dynamic voltage stability analysis. The several physical power system constraints e.q upper and lower lomit of SVC and OLTC are considered. The proposed equivalent load model is the combination induction motor and impedance load. The variation of System voltages and equivalent induction motor slips for actual power systems are simulated and plotted in this paper.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.91-98
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• 1999

In this study a modified ground strain model is developed for an equivalent earthquake load and is applied to the seismic analysis of buried pipelines, The ground strain can be obtained using the ratio of a maximum ground velocity to a wave propagation velocity. To reflect soil conditions and seismic characteristics the wave propagation velocity is evaluated by a proposed dispersion curve based on wave energy distribution. In order to verify the procedures the observed earthquake data and the results of this study are compared. For the application of an equivalent earthquake load to the seismic analysis the buried pipelines are modeled using the beam theory. the results of the analyses are compared with those of a dynamic analysis code and those obtained from the response displacement method. Finally various parametric studies considering different soil conditions and seismic loads are examined.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.295-298
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• 1997

In large system, design margin makes relatively price higher. So, optimal design through exact analysis of thermal behavior is needed. In this paper, we propose the equivalent load test facility using two inverter & converter system and inductors. Applying actual electrical profiles for motor drive, thermal characteristics of power converter fed AC motor drive are obtained, and the results are compared with simulation results.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.207-212
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• 1993

Rail carrying structures in international routes as well as domestic ones shall be designed to carry HL(High Speed Railway live Load) loads, The loads shall be placed in the most unfavourable position for the part of the structure in question. In general, influence lines may be used to determine the maximum bending moments and maximum shear forces in the reinforced concrete rahmen bridge structures. In this study, based on the finite element analysis, equivalent distributed loads of HL loading for design of the rahmen bridges are deterimined.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.593-596
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• 1999

Steel fibers are added to concrete to improve energy absorption, impact resistance and apparent ductility, and to provide crack resistance and crack control. This study is to investigate the toughness index and post-crack equivalent tensile strength of steel fiber reinforced concrete properties on the load-deflection behaviors of the steel fiber reinforced concrete beam model specimens.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.2
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• pp.87-92
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• 2003

This paper presents a flux estimator for the sensorless vector control of induction motors. The proposed method utilize the combination of the voltage model based on stator equivalent model and the current model based on rotor equivalent model, which enables stable estimation of rotor flux in high speed region and in low speed region. The dynamic performance of proposed method is verified through the experiment. The experimental results show that motors ran easily start even under 150[%] load condition and operate continuously below 0.5[Hz].