• Journal of Biosystems Engineering
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• v.1 no.1
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• pp.64-72
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• 1976

This experimental work was carried out to investigate the fatigue bending strength on various shapes and sizes of notches of the domestically manufactured steel plate. The notch types tested were a circular hole, U-and V-notches. The S-N diagram for different notch shapes were discussed in relation to plan bending strength and stress concentration factor of notches .The results of the experiments are summarized as follows : (1) The difference between stress concentration factor and notch factor was greater as the radium of notch root became smaller, and these values approached to an identical value as the radium of notch root increased. (2) It was shown that the plane bending fatigue limit of bar without notch for the hotrolled steel having the tensile strength of 33.1kg/$mm^2$was 17.0kg/$mm^2$. (3) U-and V-notch had a greater effect of stress concentration factor on the endurance limit, but O-hole showed the same effect only for $\o\pm2mm$. (4) For the same radius of notch root, U-notch showed a lower value of fatigue limit compared to V-notch and O-hole.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.3-10
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• 2002

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of spur gear, using 2-dimension model considered near the tooth by root stress. Determine root stress is carried out for the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. And from those estimated results, the comparing estimate value with boundary element method value was discussed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.85-95
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• 2001

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of spiral bevel gear , using 2-dimension model considered near the tooth by root stress. Determine root stress is carried out far the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. And from those estimated results, the comparing estimate value with boundary element method value was discussed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.24-33
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• 2003

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of transmission contact element using 2-dimension model considered near the tooth by root stress. Determination of root stress is carried out far the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. The predicted results of boundary element method are good accordance with that of finite element method.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.5
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• pp.1-9
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• 1995

The purpose of this study is to develop a computer simulation program for analyzing load transmission characteristics of a helical gear system in design stage. In this analysis, the rotational delay, load distribution, root stress, and contact area are investigated. That is, the influence function of deflection is obtained by finite element analysis and the influence function of approach and gear tooth error are considered. Load distribution, rotational delay, and contact area are calculated by solving load-deflection equation which includes these influence functions and tooth error, and the influence function of the bending moment is obtained by finite element analysis. The root stress is calculated by the load distribution and the influence function of the bending moment. The results of the simulation are cross-checked through a specially designed experimental set-up.

• Journal of The Korean Society of Grassland and Forage Science
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• v.41 no.3
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• pp.162-167
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• 2021

Aluminum (Al) stress in acidic pH is known to decrease the growth and productivity of alfalfa. However, not much is known about how the application of silicon (Si) affects the Al stress response in alfalfa. This study was conducted to evaluate the effect of exogenous application of Si on the growth of alfalfa seedlings exposed to Al stress in pots. Alfalfa seedlings grown in pots for 2 weeks were treated either Al stress (pH 4.0, 0.2 mM Al) or Al stress + Si (1 mM) for 5 days, lengths and biomass of shoot and root, and chlorophyll and carotenoid contents in leaf tissues were analyzed respectively. Al stress treatment inhibited shoot and root growth, and decreased fresh and dry weights, and chlorophyll content in leaves, but increased carotenoid content. In contrast, when alfalfa seedlings treated with Al stress combined with Si, delayed growth caused by Al stress of shoot and root of alfalfa seedlings was restored, dry weight was increased and chlorophyll content of leaf tissue was increased, but carotenoid content was decreased. These results suggest that Si has a function of alleviating Al toxicity in alfalfa, of which it exhibits a mitigating effect by a function that overlaps with some of the intracellular functions of carotenoids.

• Journal of Environmental Science International
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• v.11 no.11
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• pp.1165-1172
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• 2002

The effects of salicylic acid(SA) and water deficit on growth and proline accumulation were investigated in cucumber(Cucurmis sativus L.) seedlings. Exogenous application of SA(100 $\mu$M-1 mM) led to a noticeable decrease in root and shoot growth, and dry weight of seedlings. Anatomical observation on leaf of cucumber revealed that the thickness of all leaf tissue components decreased in SA-treated plants. The effect was most pronounced on the width of the adaxial epidermis. In the separate effects of SA(0, 100, 500 and 1000 $\mu$M) and water deficit induced by PEG(0, 4.4, 7.0 and 9.6 %) on growth, the water deficit treatments had greater effects on growth traits than SA. Combinations of SA and PEG(SA+PEG) decreased shoot and root dry matter, and root length. Proline increased slightly in SA-treated seedlings, but exhibited a marked increase in water deficit application. Combinations of SA+PEG induced higher proline in both shoots and roots than SA stress alone. Shoots had higher proline than roots. Our data support a role of SA potentiating the osmotic stress response of germinating cucumber seedling.

• The Korea Journal of Herbology
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• v.27 no.6
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• pp.91-98
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• 2012

Objectives : Rhodiola rosea L. (Crassulaceae) is a plant living at the areas of high-altitude mountain, and Rhodiolae Radix(the root of R. rosea) has been used as a traditional medicine to decrease the symptoms of mental- or physical-stress in Asia and Europe. To examine the efficacy of Rhodiolae Radix on the oxidative stress, the anti-oxidative effects of the radix were examined, Methods : The effects of Rhodiolae Radix on several oxidative factors were examined in vitro, and also the effects were tested in the liver of rats which were treated with a high dose of alcohol during 2 weeks. Results : The extract of Rhodiolae Radix in vitro scavenged some oxidants, such as DPPH, Superoxide anion radical and LDL, and the extract also inhibited the oxidative capacity of linoleic acid, significantly. Meanwhile, in the in vivo test, the methanol-extract decreased some oxidation parameters, such as relative liver weight, TBARS and SOD activities, and also increased catalase activity in the liver of alcohol-loaded rats, But, the extract had no effects on GSH content and GSH-px activiy in the rats. Conclusion : The root of Rhodiola rosea has a strong anti-oxidative capacity, and also has some preventive properties aginst the alcoholic stress.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1033-1039
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• 2002

Partial penetration welding joint refers to the groove weld that applies to the one side welding which does not use steel backing and to both side welding without back gouging, that is, the partial penetration welding joint leaves an unwelded portion at the root of the welding area. In this study, we analyzed the residual stress and fracture on the thick metal plates that introduced the partial penetration welding method. According to the above-mentioned welding method, we could draw a conclusion that longitudinal stress and traverse stress occurred around the welding area are so minimal and do not affect any influence. We also performed the fracture behavior evaluation on the partial penetration multi pass welding with 25.4 mm thick plate by using the J-integral, which finally led us the conclusion that the partial penetration multi-pass welding method is more applicable and effective in handling the root face with less than 6.35 mm.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.738-744
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• 2011

The reliability of blade root fixing section is required to endure the centrifugal force and vibration stress for the last stage blade of steam turbine in thermal power plant. Most of the domestic steam turbine last stage blades have finger type roots. The finger type blade is very complex, so the inspection had been performed only on the exposed fixing pin cross-section area due to the difficulty of inspection. But the centrifugal force and vibration stress are also applied at the blade root finger and the crack generates, so the inspection method for finger section is necessary. For the inspection of root finger, inspection points were decided by simulating ultra-sonic path with 3D modeling, curve-shape probe and fixing jig were invented, and the characteristics analysis method of ultrasonic reflection signal and defect signal disposition method were invented. This invented method was actually executed at site and prevented the blade liberation failure by detecting the cracks at the fingers. Also, the same type blades of the other turbines were inspected periodically and the reliability of the turbine increased.