• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.375-382
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• 2001

This study is attempted to predict experimentally the fatigue crack propagation behavior of two-span beams with steel fibrous for various steel fibrous contents. The static tests and the fatigue tests were performed on a series of SFRC(steel fibrous reinforced concrete) to investigate the fatigue behavior of SFRC varying with the steel fibrous contents. Through this test, the diagonal cracking loads, ultimate loads, deflections, strains of concrete and steels. Fatigue crack length were measured by the eye-observation. As a result of test, A model for S-N relationship, and propagation life of fatigue crack of SFRC was proposed. The crack growth and failure of SFRC beams were studied.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.200-205
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• 2000

Fatigue failure modes of load-carrying cruciform weld joints are dependent on the characteristics of the fatigue crack initiation and propagation from the weld toe or the weld root. In this study, constant amplitude fatigue tests on load-carrying fillet welded specimen carried out, and fatigue strengths were evaluated. Also, an attempt is made to develop a new analytical model with more accuracy to predict the fatigue crack propagation life of fillet welded cruciform joints of SWS 490B steels containing lack of penetration defects. From the result of this study, fatigue crack growth characteristics of load-carrying fillet welded cruciform joints, containing lack of penetration defects are found to be affected by the weld geometry, stress range and microstructures of the weld zone.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.40-44
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• 2000

The fatigue and tensile test were carried out with Mild steel using the Dump Frame of commercial car. The specimens were heat-treated at $810^{\circ}C$ and $930^{\circ}C$ and worked 4.5, 6.0, 8.0mm thickness in order to look over the mechanical properties and fatigue life by heat treatment and thickness from the tensile test result, the yield strength of the heat treated specimens was increased about 35% more than that of the non-heat treated specimen. The fatigue life of non-heated specimen was decreased 15% but that of heat treated specimens at $870^{\circ}C$ and $930^{\circ}C$ were decreased 16.38% and 13.16% respectably according to increasing the thickness from 4.5 to 8.0mm.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.535-539
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• 2010

The formation and elongation of runners, growth of runner plants, and transplant propagation rates of 'Maehyang' strawberry were investigated at various photosynthetic photon flux (PPF) levels. Strawberry plants having $3.1{\pm}0.4$ leaves and $7.0{\pm}1.1mm$ of crown diameter were used as propagules and were cultured for 35 days in 9 transplant production modules using fluorescent lamps as artificial lighting sources. Applied PPF levels were $137.4{\pm}2.1$, $217.0{\pm}1.0$, and $274.7{\pm}8.4{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as measured on the surfaces of empty shelves. The numbers of runners and runner plants per propagule were the greatest at $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPF. The runner plant propagation rate was 0.27 plant/day/propagule at $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, which was significantly greater than that of conventional propagation methods. Results indicate that high PPF levels promotes the formation of runners and runner plants of strawberry and that the rapid propagation method with high PPF levels can be feasible for production of vigorous transplants in a closed transplant production system.

• BMB Reports
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• v.56 no.12
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• pp.657-662
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• 2023

Neurodegenerative diseases are characterized by distinct protein aggregates, such as those of α-synuclein and tau. Lysosomal defect is a key contributor to the accumulation and propagation of aberrant protein aggregates in these diseases. The discoveries of common proteinopathies in multiple forms of lysosomal storage diseases (LSDs) and the identification of some LSD genes as susceptible genes for those proteinopathies suggest causative links between LSDs and the proteinopathies. The present study hypothesized that defects in lysosomal genes will differentially affect the propagation of α-synuclein and tau proteins, thereby determining the progression of a specific proteinopathy. We established an imaging-based high-contents screening (HCS) system in Caenorhabditis elegans (C. elegans) model, by which the propagation of α-synuclein or tau is measured by fluorescence intensity. Using this system, we performed RNA interference (RNAi) screening to induce a wide range of lysosomal malfunction through knock down of 79 LSD genes, and to obtain the candidate genes with significant change in protein propagation. While some LSD genes commonly affected both α-synuclein and tau propagation, our study identified the distinct sets of LSD genes that differentially regulate the propagation of either α-synuclein or tau. The specificity and efficacy of these LSD genes were retained in the disease-related phenotypes, such as pharyngeal pumping behavior and life span. This study suggests that distinct lysosomal genes differentially regulate the propagation of α-synuclein and tau, and offer a steppingstone to understanding disease specificity.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.4
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• pp.164-171
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• 1988

Recently with the rapid development in marine and shipbuilding industries such as marine structures, ships and chemical plants, it takes much interest in the study of corrosion fatigue characteristics that was close up an important role in mechanical design. In this study, characteristics of corner crack propagation on the base metal and heat affected zone of 5086 Al-Alloy was tested by using of a rotary bending fatigue tester and was investigated under the environments of specific resistance, $\rho$=25$\Omega$ cm and air. The corrosion fatigue crack initiation and corrosion fatigue life sensitivity were quantitatively inspected for 5086 Al-Alloy in the specific resistance, $\rho$=25$\Omega$ cm. Main results obtained are as follows: (1) The corrosion sensitivity of heat affected zone under specific resistance, $\rho$=25$\Omega$cm shows approximately 1.69~2.22 and corrosion sensitivity of base metal is more susceptible than that of heat affected zone. (2) The corrosion fatigue life sensitivity on heat affected zone decreases eminently than that of initial corrosion fatigue crack. (3) The characteristics of quarter elliptical corner crack propagation shows that depth crack is more grown than surface crack at crack initiation, but the surface crack is more propagated than depth crack as the crack propagation is increased. (4) The surface crack and depth crack growth on heat affected zone by softness show delayed phenomenon than that of base metal.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2004.05a
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• pp.172-172
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• 2004

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.258-269
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• 1999

It is important to evaluate fatigue damage of in-service material in respect to assure safety and remaining fatigue life in structure and mechanical components under cyclic load . Fatigue damage is represented by mathematical modelling with crack growth rate da/dN and cycle ration N/Nf and is detected by X-ray diffraction and ultrasonic wave method etc. But this is estimated generally by single parameter but influenced by many test conditions The characteristics of it indicates fatigue damage has complex fracture mechanism. Therefore, in this study we propose that back-propagation neural networks on the basis of ration of X-ray half-value breath B/Bo, fractal dimension Df and fracture mechanical parameters can construct artificial intelligent networks estimating crack growth rate da/dN and cycle ratio N/Nf without regard to stress amplitude Δ $\sigma$.

• Structural Engineering and Mechanics
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• v.9 no.2
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• pp.111-126
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• 2000

Truss type structures are attractive to a variety of engineering applications on earth as well as in space due to their high stiffness to mass ratios and ease of construction and fabrication. During the service life, an individual member of a truss structure may lose load carrying capacity due to many reasons, which may lead to collapse of the structure. An analytical and computational procedure has been developed to study the response of truss structures subject to member failure under static and dynamic loadings. Emphasis is given to the dynamic effects of member failure and the propagation of local damage to other parts of the structure. The methodology developed is based on nonlinear finite element analysis technique and considers elasto-plastic material nonlinearity, postbuckling of members, and large deformation geometric nonlinearity. The pseudo force approach is used to represent the member failure. Results obtained for a planar nine-bay indeterminate truss undergoing sequential member failure show that failure of one member can initiate failure of several members in the structure.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.407-414
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• 2002

The knowledge of interaction of electromagnetic waves in composite structures is important for designing the shielding structure for antenna such as radome. Recently, radomes are constructed in the form of foam core sandwich structures that have many mechanical advantages such as high strength, long fatigue life, low density and adaptability to the intended function of structure. However, the propagation of electromagnetic waves is affected by high anisotropic permeability and loss tangent of the composite skin. In this study, the analytical model to understand the propagation of electromagnetic waves in the anisotropic composites and foam core sandwich structures with composite skins was proposed. Numerical analyses of unidirectional composites and foam core sandwich structure as a function of incident angle were performed. From the results of analysis, the general tendencies of transmittance of electromagnetic wave through composites and foam core sandwich structure were obtained.