• Transactions of Materials Processing
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• v.20 no.8
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• pp.527-533
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• 2011

In order to take into account the strong anisotropy and the tension-compression asymmetry of AZ31 sheet alloy, the Cazacu-Plunkett-Barlat yield criterion(Cazacu, 2006), CPB06, was adopted in the present material modeling. The variation of anisotropic coefficients which describe the yield surface evolution of AZ31 is optimized using an interpolation function based on specific calibration results. It generates continuous yield surfaces, which makes it possible to describe the different hardening rates in tension and compression as well as tension-compression asymmetry of magnesium alloys. The ability of the CPB06 yield criterion to predict experimental results was demonstrated and compared with that of the Hill(1948) yield criterion.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.720-724
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• 1998

Open-top field chamber study was carried out to investigate effect of ambient ozone level on the yield of rice cultivar 'Dongjin' in Kwangyang area located in the vicinity of the industrial complex of Yechon petrolium refinery and chemical works or Kwangyang Iron and Steel works during the summer of 1997. mean ozone concentration of ambient air during daytime (9:00∼17:00) was revealed to exceed over 40 ppb which is defined to be a critical level causing plant injury and yield reduction in Europe. Yield component analysis showed that there was no significant difference in rice yield between ambient air and charcoal-filtered air. The results suggest that the ambient ozone levels during the exposure period had no effect on yield reduction of rice cultivar 'Dongjin' and it is likely that the cultivar is tolerant to ambient ozone levels.

• Journal of Mechanical Science and Technology
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• v.15 no.10
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• pp.1349-1355
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• 2001

As most fractures of ductile materials in metal forming processes occurred due to the results of evolution of internal damage - void nucleation, growth and coalescence. In this paper, an approximate yield criterion for voided (porous) anisotropic ductile materials is developed. The proposed approximate yield function is based on Gurson's yield function in conjunction with the Hosford's non-quadratic anisotropic yield criterion in order to consider the characteristic of anisotropic properties of matrix material. The associated flow rules are presented and the laws governing void growth with strain are derided. Using the proposed model void growth of an anisotropic sheet under biaxial tensile loading and its effect on sheet metal formability are investigated. The yield surface of voided anisotropic sheet and void growth with strain are predicted and compared with the experimental results.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.1
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• pp.93-101
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• 1997

This paper presents yield surfaces and hardening laws for describing the state of an unsaturated soil under isotropic compression and suction changes. The yield surface is formulated within the framework of hardening plasticity using two independent sets of stress variables : the excess of total stress over air pressure and the suction. And the application of the yield surfaces and hardening laws are confirmed from the result of the experiment. To this end a series of suction-controlled isotropic tests are conducted on clayey soils. Matric suction is controlled by the axis translation technique using high air entry ceramic disk. The specimens are compacted using a half of Proctor compaction energy with 5 % lower of water content than the optimum moisture contents. From test results, existence of the yield surfaces and an application of hardening laws to samples are confirmed by comparison between test and predicted results. And it is confirmed that LC yield locus is extened with the total plastic deformations induced by suction or stress changes, however, SI yield locus is only extended with the plastic deformations by induced suction changes.

• Structural Engineering and Mechanics
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• v.6 no.4
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• pp.395-409
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• 1998

This paper concerns the development and implementation of an orthotropic, stress resultant elasto-plastic finite element model for the collapse load analysis of reinforced concrete plates. The model implements yield line plasticity theory for reinforced concrete. The behaviour of the yield functions are studied, and modifications introduced to ensure a robust finite element model of cases involving bending and twisting stress resultants ($M_x$, $M_y$, $M_{xy}$). Onset of plasticity is always governed by the general yield-line-model (YLM), but in some cases a switch to the stress resultant form of the von Mises function is used to ensure the proper evolution of plastic strains. Case studies are presented, involving isotropic and orthotropic plates, to assess the behaviour of the yield line approach. The YLM function is shown to perform extremely well, in predicting both the collapse loads and failure mechanisms.

• Journal of Magnetics
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• v.21 no.2
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• pp.244-248
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• 2016

Aiming to improve the shear yield stress of magnetorheological fluid, magnetorheological fluids with different particle characteristics are prepared, and the influence rules of particle mass fraction, particle size, nanoparticles content and application temperature on shear yield stress are investigated. Experimental results indicate that shear yield stress increases approximate linearly with the enhancement of particle mass fraction. Particle size and the nanoparticles within 10% mass fraction can improve the shear yield stress effectively. When the application temperature is higher than $100^{\circ}C$, the shear yield stress decreases rapidly because of thermal expansion and thermal magnetization effect.

• Journal of the Korean Society of Tobacco Science
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• v.3 no.1
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• pp.41-48
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• 1981

Dihaploid lines were derived from the anthers of the F, of single cross, "Va 115" x"SC 72" (Nicotiana tabacum L.). The path-analysis, correlation coefficient, and variation of characteristics among dihaploid families were evaluated. Dihaploid lines displayed much greater variation than their parents. The genetic correlation coefficient between yield and total alkaloids of dihaploids was significantly lower than that of conventional varieties and lines. In path-analysis which relates yield components to yield, number of leaves harvested and leaf width had a direct effect on yield. a direct effect on yield.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.131-138
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• 1996

A new yield criterion for metal powder compaction based on continuum mechanics has been proposed. It includes three parameters to characterize the geometrical hardening of powder compact and strain hardening of incompressible metal matrix. The elasto-plastic finite element method to describe compaction of metal powders has been formulated using the new yield criterion. The values of parameters in the yield criterion can be determined using cold isostatic pressing(CIP). The finite element method can simulate compaction behavior of various copper powders.

• Environmental and Resource Economics Review
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• v.9 no.4
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• pp.641-661
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• 2000

The study examines the relation between yield insurance and nitrogen fertilizer in Korea. Since the yield insurance has never been introduced in Korea, the simulation method developed by Babcock & Hennessy is used to see the effect. From the simulation, we obtained the following results: (1) When a farmer is assumed to have a risk-neutral utility function, the yield insurance reduces nitrogen fertilizer by 19.74% (2) When a farmer is assumed to have a risk-averse utility function, the yield insurance reduces nitrogen fertilizer by 24.53%.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1992.03a
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• pp.59-70
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• 1992

Appropriate yield criteria are necessary to perform computer simulation for densification processes of powder compacts and sintered metals. Various yield functions have been reviewed and a new form for yield criterion has been advanced. The yield criterion satisfies experimental results from combined tension and torsion tests of sintered porous iron specimens.