• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.285-292
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• 2004

The objective of this paper is to develop a simplified method to determine yield line patterns of reinforced concrete floor slabs based on the elastic fields. Unlike other methods mainly focused on the plasticity theory, this paper emphasizes the elastic fields, especially principal moments and maximum shears and shows a link between elasticity field and yield line patterns. General criteria on both positive and negative yield lines are suggested in terms of principal moments and maximum shear forces. The proposed method can predict starting point (or regions) of yielding and the further development of yield lines on whole structures. The yield line patterns determined by the proposed method are shown to be coincident with the classical yield line theory. Furthermore, orthotropy in reinforced concrete slab is investigated and yield line patterns for different type of flat slab with non-isotropic strip are studied broadly.

• Structural Engineering and Mechanics
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• v.3 no.6
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• pp.529-539
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• 1995

The rigid-plastic yield-line analysis of isotropically reinforced concrete slabs acting in conjunction with torsionally weak supporting beams is developed as the lower-bound form of a linear programming formulation. The analysis is extended to consider geometric variation of chosen yield-line patterns by the technique of sequential linear programming. A strategy is followed of using a fine potential yield-line mesh to identify possible collapse modes, followed by analysis using a coarser, simplified mesh to refine the investigation and for use in conjunction with geometric optimization of the yield-line system. The method is shown to be effective for the analysis of three slabs of varying complexity. The modes detected by the fine and simplified analyses are not always similar but close agreement in load factors has been consistently obtained.

• 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.

• Computers and Concrete
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• v.12 no.6
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• pp.819-829
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• 2013

The objective of this study is to determine whether or not the yield line theory, an effective method widely used for slabs made of ordinary concrete, can be used also for the reinforced concrete slabs made of high-strength concrete. Flexural behavior of simply supported slabs in three different sizes were investigated under concentrated load at mid-span. Additionally, behavior of high strength reinforced concrete slabs with 50 mm and 150 mm reinforcement spacings also studied. Failure loads, deflections, experimental and theoretical failure mechanisms were evaluated. The difference between the moments based on yield line theory and experimental moments varied between 1% to 3%. Experimental and analysis results revealed that yield line analysis could conveniently be employed in the analysis of high strength reinforced concrete slabs.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.1
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• pp.23-30
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• 2022

This study proposed a simplified finite element analysis procedure for designing the nonstructural masonry wall in the out-of-plane direction. The proposed method is a two-step elastic analysis procedure by bilinearizing the behavior of the masonry wall. The first step analysis was conducted with initial stiffness representing the behavior up to the effective-yield point, and the second step analysis was conducted with post-yield stiffness. In addition, the orthotropic material property of the masonry was considered in the FE analysis. The maximum load was estimated as the sum of the maximum loads in the first and second step analyses. The maximum load was converted into the moment coefficients and compared with those from the yield line method applied in Eurocode 6. The moment coefficients calculated through the proposed procedure showed a good match with those from the yield line method with less than 6% differences.

• Structural Engineering and Mechanics
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• v.42 no.6
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• pp.883-897
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• 2012

Cold-formed channel sections are used in a variety of applications in which they are required to absorb deformation energy. This paper investigates the collapse behaviour and energy absorption capability of cold-formed steel channels with flange edge stiffeners under large deformation major-axis bending. The Yield Line Mechanism technique is applied using the energy method, and based upon measured spatial plastic collapse mechanisms from experiments. Analytical solutions for the collapse curve and in-plane rotation capacity are developed, and used to model the large deformation behaviour and energy absorption. The analytical results are shown to compare well with experimental values. Due to the complexities of the yield line model of the collapse mechanism, a simplified procedure to calculate the energy absorbed by channel sections under large bending deformation is developed and also shown to compare well with the experiments.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.335-335
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• 2017

Recently NERICA (New Rice for Africa) was developed by a crossing of African rice (Oryza glaberrima Steud.) and Asian rice (Oryza sativa L.) in West Africa, and is considered to be drought resistant, but drought resistance of NERICA and differences between Asian rice are not clarified enough. In this research, NERICA (four cultivars and two lines), Asian rice (three cultivars and sativa parent of NERICA) and African rice (glaberrima parent of NERICA) were cultivated in the field in Shizuoka University under drought and traits of each cultivar and line relevant to drought resistance, stomatal conductance by porometer, soil water content of individual depths by TDR method, SPAD values by SPAD meter and leaf thickness by micrometer, were measured and compared with dry matter production and yield. Effects of compost were also compared among sativa parent, one NERICA cultivar and two NERICA lines. Glaberrima parent showed highest top dry weight. One NERICA line, one drought resistant Asian rice cultivar and sativa parent, showed higher top dry weight and yield (ear weight) than other Asian rice cultivars and NERICA cultivars and line tested. Compost tended to increase top dry weight and yield in one of NERICA line and sativa parent. But in one NERICA cultivar and line, top dry weight and yield were not increased. In one of Asian rice, one of NERICA line and sativa parent that showed high top dry weight and yield, stomatal conductance was high. On the contrary the glaberrima parent and in other NERICA cultivars and line it was low. In sativa parent compost increased stomatal conductance but in NERICA cultivar and lines it was not. Among cultivars and lines that showed high top dry weight and yield sativa parent and one of NERICA line SPAD value and leaf thickness were high but in one of Asian rice and glaberrima parent they were low. Cultivar and line differences in yield and top dry weight among Asian rice and NERICA were significantly correlated with those in stomatal conductance ($r=0.778^{**}$ and $r=0.654^*$, respectively) and those in leaf thickness ($r=0.600^*$ and $r=0.640^*$, respectively). In Asian rice cultivars average soil water content was significantly correlated with yield ($r=0.886^*$) but in NERICA cultivars and lines it was not significant correlated (r= -0.256). Cultivar and line differences in leaf thickness were significantly correlated with SPAD value ($r=0.773^{**}$). In Asian rice cultivars it was significantly correlated ($r=0.962^{**}$), but in NERICA cultivars and lines it was not significantly correlated (r=0.559). Asian rice cultivars tended to consume soil water to increase yield but in NERICA cultivars and lines the tendency was not clear. Correlation between SPAD value and leaf thickness was different between Asian rice and NERICA cultivars and lines, and in Asian rice cultivars it was significantly correlated but in NERICA cultivars and lines it was not significant. Importance of maintaining high stomatal conductance by high leaf thickness was clarified.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.76-81
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• 1980

Root yield, number of missing and diseased plant in each line were investigated in various ginseng farms. Root yield per unit area was negatively correlated to missing percentage. Missing percentage showed significant positive correlation with diseased rate. Among lines yield was significantly different in most fields while missing rate was not, indicating that yield of each line is affected by present shading method but disease occurrence is not. Thus there are two ways of yield increase, shading improvement and disease control.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.177-180
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• 2004

발광층에 Alq3와 rubrene을 mixed host로 사용하고 DCJTB를 형광 dopant로 사용한 다층 박막 구조의 red OLEDs를 제작하였다. 소자의 구조는 $ITO:Anode(120nm)/{\alpha}-NPD:HTL(40nm)/Alq_3+Rubrene(mixed\;host\;1:1)+DCJTB(red\;dopant\;3%)+:EML(20nm)/Alq_3:ETL(40nm)/MgAg(Mg\;5%\;wt):Cathode(150nm)$ 로서 EML내부에 DCJTB를 Totally Doping Method와 Dotted-Line Doping Method의 두 가지 방법으로 도핑 하였다. Mixed host구조에 DCJTB를 6구간으로 나누어 Dotted Line Doping한 소자는 luminance yield가 $9.2cd/A@10mA/cm^2$ 이었다. 이 소자는 DCJTB만을 Totally Doping한 소자의 luminance yield $3.2cd/A@10mA/cm^2$에 비해 약 190%정도의 높은 효율 향상을 보였다. 또한 $10mA/cm^2$에 도달하는 전압은 5.5V Vs. 8.5V로서 mixed host를 사용한 소자에서 약 3V정도 구동전압이 낮아지는 효과가 있었다. 발광 스펙트럼의 Full Width Half Maximum(FWHM)은 각각 56.6nm와 61nm로서 rubrene을 mixed host로 사용한 소자에서 높은 색 순도를 얻을 수 있었다. 이러한 성능의 향상은 $Alq_3$와 혼합된 rubrene에 의한 낮은 전하주 입장벽, 높은 전류밀도에서 나타나는 발광감쇄현상의 감소, 그리고 발광층의 DLD구조에 의한 전하의 trap & confinement 에 따른 발광 exciton의 형성확률이 증가한데서 나타났다고 생각된다.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2338-2343
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• 2007

The practical studies on the method of particle contamination control for yield enhancement in the cleanroom were carried out. The method of the contamination control was proposed, which are composed of data collection, data analysis, improvement action, verification, and implement control. The partition check method for data collection and data analysis was used in the cellular phone module production lines. And this method was evaluated by the variation of yield loss between before and after improvement action. In case that the partition check method was applied, the critical process step was selected and yield loss reduction through improvement actions was observed. From these results, it is concluded that the partition check method is effective solution for particle contamination control in the cleanroom production lines.