• Journal of Magnetics
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• v.16 no.4
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• pp.427-430
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• 2011

The rolled steels for welded structure applied tensile stress have been examined by means of magnetic Barkhausen noise (MBN) method and of a physical parameter obtained from a hysteresis loop. The behaviors of MBN parameters and coercive force with tensile stress were discussed in relation to microstructure changes. There is no change in MBN parameters and coercive force below yield strength. The coercive force rises rapidly with tensile stress above yield strength. On the other hand, the rms voltage and the peak in averaged rms voltage take a maximum around yield strength and then decreases. The magnetomotive force at peak in the averaged rms voltage shows a minimum around yield strength. These phenomena are attributed to the combined effects of cell texture and dislocation density. In addition, the behaviors of MBN parameters around yield strength may be reflected by the localized changes in strain field due to the formation of dislocation tangles.

• Journal of The Korean Digital Architecture Interior Association
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• v.4 no.2
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• pp.44-51
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• 2004

It is generally known in seismic design that the beam yield type frames have more advantages than column yield type of which damage is likely to concentrate to any story. However we may design a building as a beam yield type, it becomes actually a column yield type collapse mode for slab floor diaphragm effect. Considering these points, the column yield type frames are selected and designed as the specimens. The object of this study is to grasp quantitatively the restoring force characteristic values and to estimate the seismic performances of column yield type steel rahmen.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.281-284
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• 2008

Performance evaluation exposing the performance of structure is affected by the material and structural characteristics. these should be necessary for the analysis about the effect of structure performance. Thus, to evaluate the structural performance affected the material properties and structural characteristics, firstly it is conducted the eigenvalues analysis and non-linear static analysis of the structure, secondly it is analyzed the performance influence factor of the structure. The performance influence factors affecting the performance of structure divided into five classes(strength of concrete, longitudinal and transverse reinforcement, aspect ratio, axial force). From the result of analysis about the change of performance influence factor, the more the strength of concrete is increasing, the more the maximum shear force is increasing and the yield displacement is not changed, the more longitudinal reinforce is increasing, the more yield displacement and the maximum basis shear force is increasing, the more the transverse reinforce is increasing, the change of maximum basis shear force is trivial. The yield displacement of structure is increasing and the maximum basis shear force is decreasing by increasing the aspect ratio, the more the axial force increases, the more yield displacement and maximum basis shear force decease.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.37-45
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• 2002

This paper presents the field-dependent Bingham characteristics and damping force control of an electro-rheological (ER) fluid under squeeze mode operation. The squeeze force of the ER fluid due to the imposed electric field is analyzed and an appropriate size of the disk-type electrode is devised. On the basis of the theoretical model of the ER fluid under squeeze mode operation, the yield stress and response speed of the ER fluid are distilled from the time responses of squeeze force to the step electric potentials. Measured squeeze forces under various excitation conditions are compared with the predicted ones from Bingham model and time constant obtained at the transient response test. In addition, the controllability of the field-dependent damping force of the ER fluid under squeeze mode is experimentally demonstrated by implementing simple PID controller.

• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.4
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• pp.26-31
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• 1993

In this paper, the axial force of high tension bolt is measured by using ultrasonic wave. In the case of the different materials the conclusion obtained are as follows : (1) The relation of the material quality of each high tension bolt and form(diameter or section area), and yield axial force can be observed. (2) As 0.1 is devided by the apparent elongation the measurement accuracy of high tension bolt can be achived. Also, it is founded that the Joint axial force of high tension bolt is determined by the yield force.

• Journal of the Korean Home Economics Association
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• v.26 no.3
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• pp.93-102
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• 1988

Rheological properties of cowpea and mung bean starch gels and pastes were investigated and compared with Instron Universal Testing machine and Brabender Viscometer. As the result of puncture test of gels, yield point force of mung bean starch gel was higher than that of cowpea starch gel. Compression coefficient of cowpea starch gel calculated by Bourne's equation was lower than that of mung bean starch gel. the stress relaxation test showed that viscoelastic properties of cowpea and mung bean starch gels may be represented by six element Maxwell model consisting of three Maxwell element in parallel. Cowpea and mung bean starch pastes showed bingham pseudoplastic behavior in 3, 5, 6, 7 and 8%. The consistency index in 7∼8% of cowpea starch paste were lower than those of mung bean starch paste. concentration dependence on consistency index and yield stress in mung bean starch were higher than those of cowpea starch. The yield stress of starch pastes was significantly correlated with yield point force by puncture test (r=0.996).

• Journal of the Korean Geotechnical Society
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• v.29 no.5
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• pp.19-27
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• 2013

Most of the landslides induced by rainfall in summer rainy season appear in the type of debris flow. Debris flow gives a lot of economic losses and human casualties due to high moving velocity and volume of debris flow. In order to analyze movement and deposition characteristics of debris flow, numerical analysis using FLO-2D program was conducted with various viscosities and yield stresses. As a result of numerical analysis, velocity and runout distance of debris flow decreased as its viscosity increased due to resisting force between particles of debris flow. Consequently, flow depth of debris flow increased and impact force decreased. Yield stress of debris flow affected its initiation and deposition characteristics. As yield stress increased, runout distance of debris flow decreased and its impact force increased. Based on the results of numerical analysis, it was found that velocity of debris flow mainly depended on viscosity, while deposition characteristics (runout distance, deposition width, deposition area) of debris flow depended on both viscosity and yield stress.

• Journal of Biosystems Engineering
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• v.19 no.1
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• pp.17-21
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• 1994

This reasearch was performed to provide the fundamental intonation for the mechanization of Korean pine cone harvest when the shoot shearing method is adopted. Shear force and stress of pine cone shoots were measured and analyzed for this purpose. Samples are selected along their harvesting time and tested in 17 levels of shoot diameter from 10 to 26mm with 1mm increment. 1) Shear force-deformation characteristics showed that shoot reached its rupture point after 2 to 4 of bio-yield points. It was supposed that these multiple bio-yield points were caused by the discrete compression of wood parts which are composed of water, nutrient, resin, etc. 2) Required shear force to shear shoot was proportional to the square of shoot diamter, however, shear force for shoots of early harvesting time(Aug. 31) was proportional to the shoot diameter. Variance of shear force was increased as the harvesting time was delayed. Shear forces were distributed from 468N(Aug. 31, 12mm dia) to 4153N(Aug. 31, 26mm dia) disregarding the sampling date. 3) The average shear stresses by sampling dates were 744,822, and 883N/m2, respectively, and for the earlier shoot samples shear stress was quite smaller than the others. Shear stress was proportional to shoot diameter squared, and the effect of shoot diameter on the shear stress was decreased as harvesting time was delayed.

• Computational Structural Engineering
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• v.8 no.4
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• pp.159-171
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• 1995

The parameters describing a complete hysteresis loop include pinch force, drift offset, effective stiffness, unloading and reloading trangential stiffness. Analytical equations proposed to quantify the nonlinear, inelastic behavior of reinforced shear walls can be used to predict these parameters as a function of axial load and drift ratio. For example, drift offset, effective stiffness, and first and second unloading and reloading tangential stiffness are calculated using equations obtained from test data for a desired drift ratio or ductility level. Pinch force can also be estimated for a given drift ratio and axial load. The effective virgin stiffness at the first yield and its post yield reduction can be estimated. The load deflection response of flexural reinforced concrete shear walls can now be estimated based on the effective wall stiffness that is a function of axial force and drift ratio.

• Structural Engineering and Mechanics
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• v.46 no.5
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• pp.673-693
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• 2013

This paper presents a systematic design and training procedure for the feed-forward back-propagation neural network (NN) modeling of both forward and inverse behavior of a rotary magnetorheological (MR) damper based on experimental data. For the forward damper model, with damper force as output, an optimization procedure demonstrates accurate training of the NN architecture with only current and velocity as input states. For the inverse damper model, with current as output, the absolute value of velocity and force are used as input states to avoid negative current spikes when tracking a desired damper force. The forward and inverse damper models are trained and validated experimentally, combining a limited number of harmonic displacement records, and constant and half-sinusoidal current records. In general the validation shows accurate results for both forward and inverse damper models, where the observed modeling errors for the inverse model can be related to knocking effects in the measured force due to the bearing plays between hydraulic piston and MR damper rod. Finally, the validated models are used to emulate pure viscous damping. Comparison of numerical and experimental results demonstrates good agreement in the post-yield region of the MR damper, while the main error of the inverse NN occurs in the pre-yield region where the inverse NN overestimates the current to track the desired viscous force.