• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.486-496
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• 2018

This study was conducted to confirm an effect of span length on bending properties of larch dimensional lumber in the four point bending test. The size of specimen in this study was 38 (width) ${\times}$ 89 (depth) ${\times}$ 3,600 (length) $mm^3$, and average air-dry density and moisture content of the specimens was $543.5kg/m^3$ and 10.5%, respectively. Visually graded No. 1 dimensional lumbers of 248 were divided by two groups to compare modulus of rupture (MOR) and modulus of elasticity (MOE). One group was tested in the four point bending test with span length of 1,650 mm, and other was tested with span length of 3,000 mm. While MOE was not different according to span length in 5% significance level, MOR was different in accordance with span lengths and was in inverse proportion to change of span length. Fifth percentiles of MOR in span length of 1,650 and 3,000 mm were 28.65 and 25.70 MPa, respectively. It was confirmed that the difference between MORs in each case increased as normalized rank increased. This is because of size effect in Weibull weakest link failure theory. Therefore, KS F 2150, in which there is only regulation about span to depth ratio of 15 or more, is needed to be revised to contain a method considering size effect for MOR. From the method, various results of bending test with different size of lumber could be used to determine design value of lumber.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.873-878
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• 2007

Stability of high-speed roll-to-roll printing machines is one of the most important factors that are required for the printing machines to operate properly and to obtain reasonable printing performance. This paper proposes a new model for the web-tension system of a high-speed gravure printing machine considering span-length variations due to dancer rollers, and analyzes the stability of plant dynamics of the printing machine using the proposed model. Span-length variations due to dancer motions are considered for the modeling of plant dynamics in two ways; one is to include the effect of span-length variations without considering dancer inertias and viscous frictions, and the other is to include the effect of span-length variations with considering dancer inertias and viscous frictions. The stability of the plant model is analyzed for various web-speeds using the eigenvalues of the linearized model about operating points.

• Computers and Concrete
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• v.22 no.1
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• pp.39-51
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• 2018

This study introduces a new algorithm to determine size independent values of fracture energy, fracture toughness, and fracture process zone length in three-point bending specimens with shallow to deep notches. By using the exact beam theory, a concept of equivalent notch length is introduced for specimens with no notches in order to predict the peak loads with acceptable precisions. Moreover, the method considers the variations of fracture process zone length and effects of higher order terms of stress field in each specimen size. In this paper, it was demonstrated that the use of some recently developed size effect laws raises some concerns due to the use of nonlinear regression analysis. By using a comprehensive fracture test data, provided by Hoover and Bazant, the algorithm has been assessed. It could be concluded that the proposed algorithm can facilitate a powerful tool for size effect study of three-point bending specimens with different notch lengths.

• Journal of the Korean Wood Science and Technology
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• v.26 no.2
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• pp.16-23
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• 1998

This paper examines the effects of specimen length and grade on the strength and stiffness properties of structural timber of radiata pine. The tensile strength and modulus of elasticity of 1,902 machine-graded boards with 3.15- and 1.62-m clear span lengths, were determined using a horizontal tension test machine. The mean failure and characteristic stress values for tensile strength show an extremely high dependency on test specimen length. The mean and characteristic values of both modulus of elasticity and tensile strength show significant dependency on machine stress grades.

• Journal of the Korean Ceramic Society
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• v.22 no.5
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• pp.23-28
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• 1985

A model for degradation of $eta$-$Al_2O_3$ is derived from sress generated by Poiseuille pressure capillary effect and effulent flux in charging process of Na-S Battery. Critical current density for degradation increase with increasing the crack length and crack tip radius. radius 10-7cm and crack length 10-5cm Dependence of crack growth velocity on crack lengh is seperated two regions that is for a large crack length it is predominated by Poiseuille pressure and effulent fluex but in the case of small crack length it is controlled by capillary effect.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.4
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• pp.1631-1635
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• 2018

Stroke can cause leg weakness, sensory abnormalities, and balance disorders. The purpose of this study was to investigate the effect of elastic taping on postural sway in patients with stroke. This study randomly applied elastic taping to 20 patients with stroke in two ways. The center of pressure (COP) distribution was measured before and after the elastic taping. The measurement variables were COP area and length, and measurements were performed immediately after taping. The elastic taping on tibialis anterior muscle showed a significant decrease in COP area and length compared to that without elastic taping. The elastic taping on gastrocnemius muscles showed a significant decrease in COP area and length compared to that without elastic taping. There was no significant difference in COP area and length between the elastic taping on tibialis anterior muscle and gastrocnemius muscles. Our results suggested that applying elastic taping on the ankle joints is effective in decreasing postural sway after in patients with stroke.

• Journal of ILASS-Korea
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• v.27 no.1
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• pp.18-25
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• 2022

Hot-firing tests were performed to experimentally confirm the effect of the eigenmode in the fuel-air mixing section on combustion instability by changing mixing section length, inlet mean velocity, equivalence ratio, and swirler geometry. A premixed gas composed of air and ethylene was supplied to the combustion chamber through an mixing section and an axial swirler. As the mixing section length increased, the inlet velocity perturbation decreased, but the combustion instability increased more. It was found that the resonance frequency of the first longitudinal mode in the mixing section shifted to the third longitudinal mode as the length of the mixing section increased. The results implied that the transition of the resonace frquency by changing the length of the mixing section might cause combustion instability.

• Earthquakes and Structures
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• v.26 no.4
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• pp.299-309
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• 2024

The present paper develops application of third-order shear deformation theory (TSDT) and modified couple stress theory (MCST) to size-dependent bending analysis of a functionally graded cylindrical micro-shell. The radial and axial displacement components are described based on TSDT for more accurate analysis. The effect of small scales is accounted based on MCST. The principle of virtual work is used for derivation of bending governing equations. The solution is presented for a simply-supported boundary condition to account the influence of various important parameters such as micro length scale parameter, in-homogeneous index and some dimensionless geometric parameters such as length to radius and length to thickness ratios on the bending results. A comparative analysis is presented to examine the effect of order of employed shear deformation theory on the axial and radial displacements.

• Journal of the Korean Society of Tobacco Science
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• v.9 no.2
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• pp.37-47
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• 1987

This experiment was conducted to obtain basic information on breeding of flue-cured tabacco varieties . Nine cultivars and partial diallel set of 36 Fl hybrids were grown at Daegu Experiment Station, Korea Ginseng & Tobacco Research Institute in 1983. Partial dominance with high additive gene effect was observed for yield, leaves per plant , days to flower, leaf weight, nicotine and reducing sugar content. partial dominance with additive and dominant gene effect was observed for stalk height , leaf width midrib weight Overdominance with high dominant gene effect was observed for leaf length and midrib width. The directions of dominance were positive for yield, stalk height, leaf weight, leaf length, leaf width, midrib weight, midrib width and reducing sugar content, and the negative was days to flower. The estimates of effective genes were 1 for leaves per plant, 2 for stalk height, days to flower and leaf shape. 3 to 6 for leaf length, leaf width, leaf weight and midrib weight.

• Environmental Analysis Health and Toxicology
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• v.8 no.1_2
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• pp.11-17
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• 1993

Radioactive elements Li/sup +/, Rb/sup +/and Cs/sup +/ effect the period shortening in proportion to the higher concentration on the growth of Neurospora crassa. 1 mM LiCl presented the result of the period length 0.52 h shorter than average circadian rhythm 21.66 h. 1 mM RbCl reduced the period length 1.13 h than control period 21.89 h and 1 mM CsCl reduced 2.12 h than control period 21.89 h. In the equal concentration Cs/sup +/ had an extreme effect. Fatal doses of Li/sup +/, Rb/sup +/ and Cs/sup +/ are 20mM, 30mM and 20mM. In the fatal concentration Neurospora didn't develop more after 7 days and the formation of spores were not given in regular order. Circadian length of Neurospora decreased generally at the last cycle of the growth.