• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1604-1613
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• 2018

The paper presents the equivalent circuit of an induction machine (IM) model which includes fundamental stray load and iron losses. The corresponding equivalent resistances are introduced and modeled as variable with respect to the stator frequency and flux. Their computation does not require any tests apart from those imposed by international standards, nor does it involve IM constructional details. In addition, by the convenient positioning of these resistances within the proposed equivalent circuit, the order of the conventional IM model is preserved, thus restraining the inevitable increase of the computational complexity. In this way, a compromise is achieved between the complexity of the analyzed phenomena on the one hand and the model's practicability on the other. The proposed model has been experimentally verified using four IMs of different efficiency class and rotor cage material, all rated 1.5 kW. Besides enabling a quantitative insight into the impact of the stray load and iron losses on the operation of mains-supplied and vector-controlled IMs, the proposed model offers an opportunity to develop advanced vector control algorithms since vector control is based on the fundamental harmonic component of IM variables.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1654-1663
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• 1994

Even if the ball bearing was conservatively designed considering the dynamic capacity and the rating life, sometimes the bearing was early failed on account of the misalignment and the lubricant contaminations etc. Misalignment was generated when bearing-shaft system transmitted large power and when the bearing was inadequately mounted. It was possible to predict the fatigue life of ball bearing under the misalignment considering the motions of ball, cage and raceway, and the factors of the effect on fatigue life. Misalignment affected on ball bearing as radial and moment load and the relationships between misalignment and moment were obtained. In this paper, the analysis of the load distributions between ball and raceway, and the prediction of fatigue life of deep groove ball bearing under radial and moment loads were carried out. And, the new formulation of equivalent dynamic load considering the effects of moment load was proposed.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.316-318
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• 1998

This paper presents an approach that provides an equivalent initial operating condition of UPFC in load-flow study for stability analysis. The UPFC model for load-flow implemented by IPLAN in PSS/E is represented by an equivalent load injection. In doing so, the transmission line to which UPFC is connected is disconnected and the function of UPFC is represented by the equivalent load variation. This operating condition may not be adequate as an initial condition for subsequent dynamic simulation. The proposed approach provides a way of equivalencing UPFC load injection without line disconnection. The method was applied to a realistic power system for validity.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.3
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• pp.282-289
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• 2009

This paper presents an estimation technique of the equivalent circuit parameters for an underwater acoustic piezoelectric transducer from the measured impedance. Estimated equivalent circuit can be used for the design of the impedance matching network of the sonar transmitter. A fitness function is proposed to minimize the error between the calculated impedance of the equivalent circuit and the measured impedance of the transducer. The equivalent circuit parameters are estimated by using the fitness function and the PSO(Particle Swarm Optimization) algorithm. The effectiveness of the proposed method is verified by the applications to a sandwich-type transducer and a dummy load. In addition, the impedance matching network is also designed by using the estimated equivalent circuit model.

• Structural Engineering and Mechanics
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• v.63 no.4
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• pp.509-519
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• 2017

Wind field in mountainous regions demonstrates unique distribution characteristic as compared with the wind field of the flat area, wind load and wind effect are the key considerations in structural design of television towers situated in mountainous regions. The television tower to be constructed is located at the top of Xiushan Mountain in Nanjing, China. In order to investigate the impact of terrain factors of hilltops on wind loads, firstly a wind tunnel test was performed for the mountainous area within 800m from the television tower. Then the tower basal forces such as bending moments and shear strength were obtained based on high frequency force balance (HFFB) test. Based on the experiments, the improved method for determining the load combinations was applied to extract the response distribution patterns of foundation internal force and peak acceleration of the tower top, then the equivalent static wind loads were computed under different wind angles, load conditions and equivalent goals. The impact of terrain factors, damping ratio and equivalent goals on the wind load distribution of a television tower was discussed. Finally the equivalent static wind loads of the television tower under the 5 most adverse wind angles and 5 most adverse load conditions were computed. The experimental method, computations and research findings provide important references for the anti-wind design of high-rise structure built on hilltops.

• Journal of Magnetics
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• v.21 no.4
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• pp.570-576
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• 2016

The shape optimization of the stator and the rotor is important for electrical motor design. Among many motor design parameters, the stator tooth and yoke width are a few of the determinants of noload back-EMF and load torque. In this study, we proposed an equivalent magnetic circuit of motor stator for efficient stator tooth and yoke width shape optimization. Using the proposed equivalent magnetic circuit, we found the optimal tooth and yoke width for minimal magnetic resistance. To verify if load torque is truly maximized for the optimal tooth and yoke width indicated by the proposed method, we performed finite element analysis (FEA) to calculate load torque for different tooth and yoke widths. From the study, we confirmed reliability and usability of the proposed equivalent magnetic circuit.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.729-737
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• 2013

The environmental load of concrete pavement can be categorized by temperature and moisture loads, which mean temperature distribution, and drying shrinkage and creep in the concrete slab. In this study, a method calculating the environmental load essential to mechanistic design of airport concrete pavement was developed. First, target area and design slab thickness were determined. And, the concrete temperature distribution with slab depth was predicted by a pavement temperature prediction program to calculate equivalent linear temperature difference. The concrete drying shrinkage was predicted by improving an existing model to calculate differential shrinkage equivalent linear temperature difference considering regional relative humidity. In addition, the stress relaxation was considered in the drying shrinkage. Eventually, the equivalent linear temperature difference due to temperature and the differential shrinkage equivalent linear temperature difference due to moisture were combined into the total equivalent linear temperature difference as terminal environmental load. The environmental load of eight civilian and two military airports which represent domestic regional weather conditions were calculated and compared by the method developed in this study to show its application.

• Journal of the Korean Geotechnical Society
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• v.25 no.8
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• pp.57-64
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• 2009

In this study, a method using equivalent transformation for estimation of the axial load capacity of tapered piles is proposed. While preexistent methods for estimating the axial load capacity of tapered piles have been based on the effect of soil state and taper angle, a new design method is proposed considering cone resistance $q_c$ and equivalent transformation in sand. Through tapered pile simplified by using equivalent transformation, a new method fur quick and easy estimation of the axial load capacity of tapered pile is proposed for practical use. In order to verify the proposed method, calibration chamber test and field test were conducted. In calibration chamber test, comparison of estimated axial load capacity with measured one showed that the standard deviation and COV (Coefficient Of Variation) of estimated $Q_t$ is $0.05{\sim}0.121$, $0.04{\sim}0.05$ respectively. For field test, axial load capacity by proposed method shows 2.5% under-estimation in comparison with measured value. As a result, it is found that proposed method produces satisfactory predictions for tapered piles.

• KCI Concrete Journal
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• v.13 no.1
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• pp.11-17
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• 2001

The purpose of this state-of-the-art paper is to explore several important methods thor obtaining the equivalent loads in prestressed concrete structures. and to clarify the theoretical basis and implied assumptions of each method. The method devised in this stuffily include the use of curvature of tendon, characteristics of primary moment, self-equilibrium condition and linear segments approximation of tendon. It is shown that equivalent loading system it not uniquely determined depending on the approach adopted to calculate the equivalent loads. Self-equilibrium conditions of the equivalent loading system are carefully discussed. Numerical examples are presented to show the differences among the methods arid results of the approximations in each method explicitly.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.122-126
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• 2000

In particle or short-fiber reinforced composites cracking of the reinforcements is a significant damage mode because the broken reinformcements lose load carrying capacity . The average stress in the inhomogeneity represents its load carrying capacity and the difference between the average stresses of the intact and broken inhomogeneities indicates the loss of load carrying capacity due to cracking damage. The composite in damage process contains intact and broken reinforcements in a matrix, An incremental constitutive relation of particle or short-fiber reinforced composites including the progressive cracking damage of the reinforcements have been developed based on the Eshelby's equivalent inclusion method and Mori-Tanaka's mean field concept. influence of the cracking damage on the Eshelby's equivalent inclusion method and Mori-Tanaka's mean field concept. Influence of the cracking damage on the stress-strain response of the composites is demonstrated.