• Title/Summary/Keyword: Yield Criterion

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Effects of Organic Material Application on the Growth and Yield of Crops in Korea (우리나라에서의 유기물(有機物) 시용효과(施用效果))

  • Park, Chon-Suh
    • Korean Journal of Soil Science and Fertilizer
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    • v.11 no.3
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    • pp.175-194
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    • 1979
  • The soil organic matter contents in arable land are generally low in Korea. Thus it is generally agreed that the application of organic materials to soils would be much beneficial. Present paper is a review on the effectiveness of organic mat ter application in uplands and lowlands. 1. The effect of organic matter application in uplands are of more clear and simple to explain as compared to that in lowlands. In uplands, appropriate application of organic matters such as compost and various crops residues improves the physical properties of soils leasing to increased water holding capacity, better aeration, and decrease in soil erosion. 2. In lowland, rice soils under water logged conditions the effect of organic matter application on rice yield is not straight borward and demands more refined knowledges for the interpretation of it. 3. It is found that the application of compost in rice soils is more effective when nitrogen fertilizer application is limited it dicating that nitrogen contained in the organic maerials can become available to rice plant and plays an important role for increased yield of rice under the condition where nitrogen fertilizer supply is limited. 4. Application of organic matter does not always bring about the desirable effects. Very often the organic matter application results in more intensive soil reduction leading to the accumulation of harmful substances which would can cancel out the positive effects of organic matter. This is partiunlarly true in poorly drained soils. 5. Rice straw or compost, when applied rice soils, supply sizeable amounts of available silicate to rice plant resulting in yield increase. 6. Although the effectiveness of organic matter application on rice yield in short term experiments is not consistent due to many reasons, the long term effect of organic matter is significant. 7. The term of the $O.M/SiO_2$ ratio in rice soils can serve as a criterion for the judgement of whether organic matter or silicate fertilizer is needed to be applied in a certain soil.

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Coupling numerical modeling and machine-learning for back analysis of cantilever retaining wall failure

  • Amichai Mitelman;Gili Lifshitz Sherzer
    • Computers and Concrete
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    • v.31 no.4
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    • pp.307-314
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    • 2023
  • In this paper we back-analyze a failure event of a 9 m high concrete cantilever wall subjected to earth loading. Granular soil was deposited into the space between the wall and a nearby rock slope. The wall segments were not designed to carry lateral earth loading and collapsed due to excessive bending. As many geotechnical programs rely on the Mohr-Coulomb (MC) criterion for elastoplastic analysis, it is useful to apply this failure criterion to the concrete material. Accordingly, the back-analysis is aimed to search for the suitable MC parameters of the concrete. For this study, we propose a methodology for accelerating the back-analysis task by automating the numerical modeling procedure and applying a machine-learning (ML) analysis on FE model results. Through this analysis it is found that the residual cohesion and friction angle have a highly significant impact on model results. Compared to traditional back-analysis studies where good agreement between model and reality are deemed successful based on a limited number of models, the current ML analysis demonstrate that a range of possible combinations of parameters can yield similar results. The proposed methodology can be modified for similar calibration and back-analysis tasks.

Design of Shear Fracture Specimens for Sheet Metals Using Finite Element Analyses (유한요소해석을 이용한 금속 판재용 전단 파단 시편 설계)

  • C. Kim;H.J. Bong;M.G. Lee
    • Transactions of Materials Processing
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    • v.32 no.2
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    • pp.92-99
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    • 2023
  • In this study, shear fracture specimens are designed using finite element analyses for the characterization of ductile fracture criteria of metal sheets. Many recently suggested ductile fracture criteria require experimental fracture data at the shear stress states in the model parameter identification. However, it is challenging to maintain shear stress states in tension-based specimens from the initial yield to the final fracture, and the loading path can be different for the different materials even with the same shear specimen geometries. To account for this issue, two different shear fracture specimens for low ductility/high ductility metal sheets are designed using the sensitivity tests conducted by finite element simulations. Priorly mechanical properties including the Hosford-Coulomb fracture criterion of the aluminum alloy 7075-T6 and DP590 steel sheets are used in the simulations. The results show that shear stress states are well-maintained until the fracture at the fracture initiation points by optimizing the notch geometries of the shear fracture specimens.

Characteristics of Soil Parameter for Lade's Single Work-Hardening Constitutive Model with Relative Density of Bottom ash (석탄회의 상대밀도에 따른 Lade 단일항복면 구성모델의 토질매개변수 특성)

  • Kim, Chan-Kee;Lee, Jong-Cheon
    • Journal of the Korean Geosynthetics Society
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    • v.12 no.4
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    • pp.87-98
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    • 2013
  • This study was performed a series of the isotropic compression-expansion tests and the drained triaxial tests with various the relative densities 40%, 60%, 80% and 95% for bottom ash. Using the tests results the characteristic of the parameters of Lade's single hardening constitutive model were investigated. The soil parameters Kur and n representing elastic behavior are not much affected by the change of the relative density. The other parameters such as failure criterion(m, ${\eta}_1$), hardening function(c, p) and plastic potential(${\psi}_2$, ${\mu}$) are in a positive linear relationship with the relative density. Since the soil parameters h and ${\alpha}$ representing yield function do not change much to the change of relative density and also closely related to failure criterion, they can be replaced by failure criterion ${\eta}_1$. We also observed that predicted values from the Lade's single hardening constitutive model were well consistent with the observed data.

Evaluation of press formability of pure titanium sheet (순 티탄늄 판재의 프레스 성형성 평가(제 1보))

  • Kim, Young-Suk;In, Jeong-Hun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.3
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    • pp.380-388
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    • 2016
  • Commercially pure titanium (CP Ti) has been actively used in plate heat exchangers due to its light weight, high specific strength, and excellent corrosion resistance. However, compared with automotive steels and aluminum alloys, there has not been much research on the plastic deformation characteristics and press formability of CP Ti sheet. In this study, the mechanical properties of CP Ti sheet are clarified in relation to press formability, including anisotropic properties and the stress-strain relation. The flow curve of the true stress-true strain relation is fitted well by the Kim-Tuan hardening equation rather than the Voce and Swift models. The forming limit curve (FLC) of CP Ti sheet was experimentally evaluated as a criterion for press formability by punch stretching tests. Analytical predictions were also made via Hora's modified maximum force criterion. The predicted FLC with the Kim-Tuan hardening model and an appropriate yield function shows good correlation with the experimental results of the punch stretching test.

Experimental studies of validation and stability of Sweet Bee Venom using HPLC (Sweet BV의 조제물 농도분석 및 안정성 확인을 위한 시험적 연구)

  • Kang, Kye-Sung;Kwon, Ki-Rok
    • Journal of Pharmacopuncture
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    • v.12 no.4
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    • pp.33-50
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    • 2009
  • Objectives : This study was conducted to confirm validation and stability of concentration analysis method of pure melittin (Sweet Bee Venom-Sweet BV) extracted from the bee venom by utilizing protein isolation method of gel filtration. Methods : All experiments were conducted at Biotoxtech, a non-clinical studies authorized institution, under the regulations of Good Laboratory Practice (GLP). Standard solutions of melittin (SIGMA, USA) and test substances were dispensed and were analyzed with HPLC for Sweet BV to secure the validation of analysis. Results : 1. Measurement of system suitability of Sweet BV satisfied criterion of below 3%. 2. Confirming Linearity of Sweet BV in 10-200${\mu}g/m\ell$ solution yielded correlation coefficient (r) of 0.995 and accuracy of 85-115% which satisfy criterion. 3. Measurement of Specificity of Sweet BV didn't yield any substance affecting the peak of test substances, but detected at 21.22min verified as the test substance. 4. Confirming Intra-day of Sweet BV, accuracy and precision of 0.1, 100${\mu}g/m\ell$ were 105.70, 95.81 and 0.66, 0.73, respectively, satisfying both criteria of accuracy (85-115%) and precision (within 10%). 5. To measure Stability in autosampler, all samples used in Intra-day reproducibility sat in the autosampler for five hours and were re-analyzed. Both variability and precision satisfied the criteria. 6. Homogeneity of Sweet BV (0.1, 100${\mu}g/m\ell$) at upper, middle, and lower layers all satisfied the accuracy and precision criteria. 7. Stability of Sweet BV (0.1, 100${\mu}g/m\ell$) at room temperature for four hours and refrigerated for 7 days all satisfied the criterion. 8. For the measurement of Quality control, QC samples measured on the first and eighth day all satisfied accuracy and precision criteria. Conclusion : Above experiment data satisfies validation and stability of concentration analysis method of Sweet BV.

Characteristics of Soil Parameter for Lade's Single Work-Hardening Constitutive Model with Dry Density of Pocheon Granite Soil (포천 화강토의 건조단위중량에 따른 Lade의 단일항복면 구성모델의 토질매개변수 특성)

  • Cho, Won-Beom;Kim, Chan-Kee
    • Journal of the Korean Geosynthetics Society
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    • v.10 no.4
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    • pp.29-36
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    • 2011
  • In this study, a series of the isotropic compression-expansion tests and the drained triaxial tests were performed on Pocheon granite soil with various the dry densities of $16.67kN/m^3$, $17.26kN/m^3$ and $17.65kN/m^3$. Using the tests results the characteristic of the parameters of Lade's single hardening constitutive model were investigated. The soil parameters such as kur and n related to elastic behavior, m and ${\eta}_1$ related to failure criterion, c and p related to hardening function and ${\psi}_2$ and ${\mu}$ related to plastic potential show in a positive linear relationship with the dry density. Since the soil parameters h and representing yield function do not change much to relative density and also are closely related to failure criterion, they can be replaced by failure criterion. We also observed that predicted values from the Lade's single hardening constitutive model were well consistent with the observed data.

Characteristics of Soil Parameter for Lade's Single Work-Hardening Constitutive Model with Relative Density of Baekma River Sands (백마강 모래의 상대밀도에 따른 Lade의 단일항복면 구성모델의 토질매개변수 특성)

  • Cho, Won-Beom;Kim, Chan-Kee;Kim, Joong-Chul
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.1C
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    • pp.11-17
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    • 2011
  • This study was performed a series of the isotropic compression-expansion tests and the drained triaxial tests with various the relative densities 25%, 50%, 80% and 100% for Baekma river sand. Using the tests results the characteristic of the parameters of Lade's single hardening constitutive model were investigated. The soil parameters Kur and n representing elastic behavior are not much affected by the change of the relative density. The other parameters such as failure criterion (m, ${\eta}_1$), hardening function (C, p) and plastic potential (${\Psi}_2$, ${\mu}$) are in a positive linear relationship with the relative density. Since the soil parameters h and $\alpha$ representing yield function do not change much to the change of relative density and also closely related to failure criterion, they can be replaced by failure criterion ${\eta}_1$. We also observed that predicted values from the Lade's single hardening constitutive model were well consistent with the observed data.

Influences of Environmental Factors on Wheat Quality I. Relationship between Grain Yield and Quality of the Wheat as related to Cultivated Locations (재배 환경조건이 소맥품질에 미치는 영향 I. 지역별 수량성과 품질과의 관계)

  • 류인수;장학길;안완식;송현숙
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.22 no.2
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    • pp.59-64
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    • 1977
  • The relationship between grain yield. protein content and sedimentation value in wheat were studied using 9 varieties cultivated at 8 locations in Korea. The grain yields of wheat varied widely, according to varieties and locations. Negative correlations between grain yield and protein content, and grain yield and sedimentation value were observed, while a positive correlation between protein content and sedimentation value was observed. Specific sedimentation values of soft wheats were below 4, while those of hard wheats were above 5. The intermediate varieties had sedimentation values of 4-5. This showed that specific sedimentation values could be used as a criterion in the classification of wheat quality.

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Ultimate Strength Assessment of Bollard and Its Foundation Considering Production Costs (생산성을 고려한 볼라드 및 볼라드 지지 구조의 최종강도 평가)

  • Oh, Chang-Min;Choung, Joon-Mo;Cho, Sang-Rai
    • Journal of the Society of Naval Architects of Korea
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    • v.43 no.5 s.149
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    • pp.604-610
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    • 2006
  • Common structural rules of JBP(Joint Bulker Project) and JTP(Joint Tanker Project), which will come into effect in 2006, invoke the necessity of the ultimate limit state(ULS) design for ship structures. Even though the many applications of ULS analysis have been performed for ship structures, there have few studies carried out for deck machineries and their supporting structures. Recently four major Korean shipbuilders(DSME, HHI, HHIC, SHI) jointly developed and proposed a new design standards for mooring fittings and also proposed the SWL (Safety Working Load) obtained based on the first yield criterion. In this study, various ultimate strength analyses were performed for bollards and their foundation structures whose yield strengths were quantified by the research consortium. Prior to performing the ultimate strength analyses, the numerical calculation method was substantiated with the test results provided in the joint work report. Based upon the results of this study, it can be concluded that the reinforcements to increase the yield strength are not always resulted in the enhancement of the ultimate strength. Furthermore, the additional production costs for the reinforcements can not be rewarded by the ultimate strength. Therefore, another alternative arrangements should be developed in the view point of ultimate strength.