• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.269-276
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• 1993

Co/Pd multilayered thin films with various ratios of Co sublayers to Pd sublayers(nCo/nPd = 1/4, 2/4, 3/4, 5/4) were fabricated at different substrate temperatures($R.\;T.,\;100,\;150,\;200\;^{\circ}C$) with the conventional vacuum evaporation method, and their Hall voltage hysteresis curves were measured. These Hall curves were decomposed on the basis of the superpose of the transverse Hall effect term from the magnetizations of Co and Pd sublayers and the magnetoresistivity term, by the optimal fitting method. In the results, both of the ferromagnetic and anti ferromagnetic states coexisted through whole samples, and the uniaxial or unidirectional easy axis type Hall hysteresis curves occured were dependent upon the effects of the exchange anisotropy between both magnetic states and the domain wall pinning by the antiferromagnet inclusions.

• Journal of the Korean Magnetics Society
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• v.5 no.4
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• pp.251-260
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• 1995

It has been reported that Co-based amorphous ferromagnetic alloys annealed in a small magnetic field develop a reproducible, asymmetric hysteresis loop. If the direction of the field during annealing is regarded as +, the magnetization reversal from - to + is smooth and reversible, with its slope determined by the demagnetizing field of the sample. This phenomenon is called the asymmetric magnetization reversal (AMR). The shape of the hyster-esis loop depends sensitively on the condition during the anneal and the alloy composition. Here, we report on the effect of the annealing temperature and time on AMR in a zero magnetostrictive ferromagnetic amorphous alloy. The AMR effect develops in a very short time at a reasonably high temperature, but is stabilized by annealing for a prolonged time.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.1-6
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• 1996

To simulate the characteristics of magnetic exchange coupling at the interface of MR/TbCo thin films, the directions of magnetizations were calculated by minimizing energy in the films. Newton method and Gauss-Seidel method were used. The width of M-H curve increased with TbCo anisotropy constant, and with the thickness of the transition region of TbCo layer. Hysteresis loop width became extremely narrow (less than 10 Oe of coercivity), when the TbCo transition region length was $400\;\AA$. Also the hysteresis loop of films with low interfacial exchange coupling constant was similiar to that of short transition region length. When interfacial exchange coupling constant was 1/100 of perfect coupling, hysteresis loop showed a coercivity of less than 10 Oe. Comparing the measured hysteresis loop of a fabricated sample with that of simulated one, exchange coupling con¬stant could be estimated.

• Water for future
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• v.28 no.4
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• pp.215-222
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• 1995

The water retention function which has the hysteresis phenomena is required to analyze the Richards equation which is a governing equation of the unsaturated flow, and its hysteresis phenomena has influence upon the characteristics of the unsaturated flow. The accuracy of the published hysteresis models is compared by using experimental data of the water retention function. The apparatus to experiment the hysteresis phenomena on the soil is developed, and experimental data for the main wetting process and the main drying process of the water retention function are obtained. The parameters of the van Genuchten equation are calibrated by using experimentally obtained data. As a result of the comparison of the selected hysteresis models which simulate the main drying curve from the main wetting curve, the Model I-1(Mualem) overestimates and the Model II-1(Mualem) underestimates but the Model III-2(Park and Sonu) similarly estimates the experimental data of the main drying curve.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.353-367
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• 2003

This paper describes the extension of the numerical model, which was developed to simulate the nonlinear behavior of reinforced concrete (RC) structures subjected to monotonic in plane shear and introduced in the companion paper, to simulate effectively the behavior of RE structures under cyclic loadings. While maintaining all the basic assumptions adopted in defining the constitutive relations of concrete under monotonic loadings, a hysteretic stress strain relation of concrete, which across the tension compression region, is defined. In addition, unlike previous simplified stress strain relations, curved unloading and reloading branches inferred from the stress strain relation of steel considering the Bauschinger effect we used. The modifications of the stress strain relation of steel are also introduced to reflect pinching effect depending on the shear span ratio and an average stress distribution in a cracked RC element. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.67-75
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• 2016

In this paper, a pressure-time history curve of blast load and Conwep model are presented, and a simplified blast load formula is suggested. Generally, a blast load are applied as a pressure-time history curve, and it is calculated by blast load formula such as Conwep model. The Conwep model which is used in most of the blast analysis is quiet difficult to calculate because of its complex process. Therefore, a simplified formula is proposed to calculate blast load by simple rational expressions and to make a simplified pressure-time history curve. In this process, a curve fitting method was used to find the simple rational expressions. The calculation results of the simplified formula have an error of less than 1% in comparison with the Conwep model. And, blast analyses using finite elements method are accomplished with the Conwep model and simplified formula for verification.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.696-699
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• 2003

In this study, we suggested the model to precisely evaluate the ferroelectric hysteresis loop, using the modified Sawyer-Tower circuit and the ferroelectric capacitor with a MDFM(Metal-Dielectric-ferroelectric-Metal) structure. The mathematical expression of dipole polarization is applied to the numerical integration algorithm, and the fatigue property can be considered including the dielectric layer between ferroelectrics and bottom electrode. The validity of our model is proved comparing the estimated value of our model and the measured results of PLT(10) thin film.

• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.91-100
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• 2012

Soil-water characteristic curves (SWCCs), which represent a physical property in partially saturated soils, show the relation between volumetric water content and matric suction. The SWCCs exhibit hysteresis during wetting and drying, however experimental expressions used to describe SWCCs have generally ignored the hysteresis. In addition, the shape of SWCC may depend on the void ratio which is changed by soil skeleton deformations or hysteretic behavior under various loading conditions. Hence, it is necessary to understand, both empirically and analytically, the relationship between soil skeleton deformations and the SWCCs of various soils. The typical SWCCs experimentally have drying, wetting, and the second drying curve. The measurement of a complete set of hysteretic curves is severely time-consuming and difficult works, then the first drying curve of SWCC is generally determined to estimate the hydraulic conductivity and shear strength function of partially saturated soils. This paper presents the hydraulic-mechanical behavior of partially saturated soils (weathered soil and silty soil) for volume changes and hysteresis in SWCCs regarding the difference between the first drying and wetting curve.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1137-1143
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• 1994

Through the numerical analysis of the capillary pressure-based Richards equation with and without the effect of the capillary hysteresis under the boundary condition having an antecedent rainfall. the moving tendency of the wetting front, the redistribution of the moisture content, infiltration rate, cumulative infiltration etc, were computed. The effect of the capillary hysteresis cannot be neglected in analyzing an unsaturated flow, and the more accurate results may be obtained by the consideration of the hysteresis effect. If the effect of the hysteresis cannot be considered, the analysis by the use of the main wetting curve may give more reliable result than that of the main drying curve.

• Journal of the Korean Magnetics Society
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• v.25 no.4
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• pp.123-128
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• 2015

The iron is an element having a high yield strength, mechanical hardness, good electrical conductivity, and also it has been used in various fields because of ease machining. In bridges have been used tendon made of a steel wire for large loads and light weight. Tension measurement of tendon employed in PreStressed Concrete (PSC) bridge is very important for the bridge safety check. NDT (Non-Destructive Testing) is essential for the safety check, however, magnetic NDT is difficult to apply due to the non-linear magnetization curve and hysteresis loop in the magnetic properties. In this work, for basic study of magnetic NDT application, we have constructed a B-H loop measuring system for 7-strand tendon of which diameter is 15.5 mm, and which can apply tensile stress up to 2.0 GPa. We have measured hysteresis loops of two kinds of tendons under different tensile stress. Amplitude permeability and maximum magnetic induction near knee show the most sensitive and high linearity depends on tensile stress. Relative amplitude permeability was decreased from 500 to 200 and maximum magnetic flux density changed 0.6 T.