• Transactions of Materials Processing
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• v.11 no.4
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• pp.355-362
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• 2002

In this study, an axi-symmetric finite element program for elastic analysis of the die set shrink fitted in cold extrusion was developed. The geometrical constraint according to shrink fit was enforced by employing the Lagrange multiplier method. The numerical results for strain and stress distributions in the die set including single and multi stress rings assembled by shrink fit were compared well with the Lame's equation for thick-walled solution available in the literature. To extend the applicability of the analysis program developed, various cases without or with stress ring and with pre-stress applied on stress ring were numerically investigated as well. This numerical approach enables the optimization study to determine optimal dimensions of die set to improve tool life for practical use in industry.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.195-198
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• 2002

Residual stress of sheet occurs during cold rolling and it is hard to avoid and inevitable. The residual stress in the sheet cause etching curls when it suffers peroration process. The residual stress through the thickness direction in the sheet is a function of a friction coefficient, total reduction, mil size and initial sheet thickness. To estimate the residual stress and deformation due to etching curl, FEM analysis is performed. A numerical analysis is used a ANSYS 5.6 and an elastic-plastic constitutive equations. rho simulation results indicate a distribution of residual stress.

• Journal of Oriental Medical Thermology
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• v.6 no.1
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• pp.69-75
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• 2008

Purpose: We investigated the effect of far-infrared radiating products on cold hypersensitivity of lower limbs using CST. Methods: 7 patients with cold hypersensitivity of lower limbs were investigated in this study. Exclusive criteria was skin diseases, spinal nervous disease and external wounds. They were asked to answer the VAS of cold hypersensitivity at baseline and after 3 weeks. We measured temperature of lower limbs with Spectrum 9000 MB (Dorex Inc, USA). We performed cold stress test (CST) by 3 thermographic observation using DITI : 1st was taken after 15 minutes resting at $25^{\circ}C$, the 2nd was immediately taken after 1 minute soak in $20^{\circ}C$ water, the 3rd was taken at 15 minutes after soak. We performed 3 times of CST : 1st CST was perfomed at baseline, 2nd CST was perfomred after 1 week and just observation, 3rd CST was performed after 1 week using far-infrared radiating products (lasner, UMT, Korea). Results: After using products, temperature of foot incresed more than thigh area, but there was no significance. There was no statistical difference of VAS, change of temperature and CST between before and after using far-infrared radiating products. Conclusion: There was no statistical effect of far-infrared radiating products on change of temperature of lower limbs.

• Horticultural Science & Technology
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• v.33 no.1
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• pp.114-123
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• 2015

Plants can respond and adapt to cold stress through regulation of gene expression in various biochemical and physiological processes. Cold stress triggers decreased rates of metabolism, modification of cell walls, and loss of membrane function. Hence, this study was conducted to construct coexpression networks for time-based expression pattern analysis of genes related to cold stress in Chinese cabbage (Brassica rapa ssp. pekinensis). B. rapa cold stress networks were constructed with 2,030 nodes, 20,235 edges, and 34 connected components. The analysis suggests that similar genes responding to cold stress may also regulate development of Chinese cabbage. Using this network model, it is surmised that cold tolerance is strongly related to activation of chitinase antifreeze proteins by WRKY transcription factors and salicylic acid signaling, and to regulation of stomatal movement and starch metabolic processes for systemic acquired resistance in Chinese cabbage. Moreover, within 48 h, cold stress triggered transition from vegetative to reproductive phase and meristematic phase transition. In this study, we demonstrated that this network model could be used to precisely predict the functions of cold resistance genes in Chinese cabbage.

• Journal of Korea Foundry Society
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• v.40 no.5
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• pp.129-133
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• 2020

The outcomes of solution annealing and stress corrosion cracking in cold-worked 316L austenitic stainless steel have been studied using x-ray diffraction (XRD) and the slow strain rate test (SSRT) technique. The good compatibility with a high-temperature water environment allows 316L austenitic stainless steel to be widely adopted as an internal structural material in light water reactors. However, stress corrosion cracking (SCC) has recently been highlighted in the stainless steels used in commercial pressurized water reactor (PWR) plants. In this paper, SCC and inter granular cracking (IGC) are discussed on the basis of solution annealing in a chloride environment. It was found that the martensitic contents of cold-worked 316L stainless steel decreased as the solution annealing time was increased at a high temperature. Moreover, mode of SCC was closely related to use of a chloride environment. The results here provide evidence of the vital role of a chloride environment during the SCC of cold-worked 316L.

• Korean Journal of Breeding Science
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• v.43 no.1
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• pp.1-13
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• 2011

Low temperature stress is one of the major negative factors affecting vegetative and reproductive growth of rice. To better understand responses of rice plants to low temperature we analyzed transcriptome expression patterns in glumous flower of cold-tolerant japonica rice variety, Stejaree45, and cold-susceptible variety, HR19621-AC6 at booting stage under cold water irrigation. A total of 2,411 probes were differentially expressed by low temperature in glumous flowers of the two varieties. Some important genes involved in hormone biosynthesis showed variety-specific regulation. Expression of GA20ox3 and GA2ox, among the genes involved in GA biosynthesis, was regulated differentially in the two varieties. Among the genes involved in IAA biosynthesis, YUCCA1 and TAA1:1 showed variety-specific regulation. Among the genes involved in cytokinin biosynthsis and signaling, expression of LOG, HK1 and HK3 was significantly down-regulated only in the cold-susceptible variety. Among the genes involved in ABA biosynthesis, NSY and AAO3 were down-regulated only in the cold-tolerant variety. In general, genes involved in GA, IAA and cytokinin biosynthesis responded to cold temperature in such a way that capacity of those bioactive hormones is maintained at relatively higher levels under cold temperature in the cold-tolerant variety, which can help minimize cold stress imposed to developing reproductive organs in the cold-tolerant variety.

• Journal of the Korean Society of Safety
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• v.12 no.1
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• pp.19-28
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• 1997

This study was made of the effect of cold working on the stress corrosion cracking(SCC) of austenitlc 304 stainless steel in boiling 42% $MgCl_2$ solution. For this experiment, specimens cold-worked of 0%, 10%, 20%, 30%, 40% were fabricated respectively, and then experiments of mechanical properties and stress corrosion cracking(SCC) of these specimens were carried out. The results of these experiments indicate that the maximum resistance to SCC showed at 20% of cold working degree and that the SCC susceptibility depended on the volume fraction of deformation-induced martensite by cold working and the work hardening of matrix. On the other hand, the fracture mode was changed. This phenomenon was considered that deformation-induced martensite was grown from transgranular fracture mode to intergranular fracture mode and caused by increased of dislocation density along the slip planes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.101-105
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• 2000

In cold forging die the shrink fitting is generally used to decrease stress and increase die life. In this paper we have studied about the effect of fitting type, When the die insert is splitted into several pieces the maximum stress could be decreased as much as 50~70% The fitting angle could be selected to minimize the maximum stress and the variation of stress on loading and unloading, . In F, E.M result in case 3。 fitting angle the maximum and variation of stress may be minimized.

• Proceedings of the Korean Society of Grassland Science Conference
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• 2000.09a
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• pp.119.1-119
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• 2000

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.389-394
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• 2008

The ecophysiological changes occurring upon cold stress were studied using cold tolerant transgenic and wild-type tobacco plants. In a previous study, cold tolerance in tobacco was induced by the introduction of a gene encoding the zinc finger transcription factor, PIF1. Gas-exchange measurements including net photosynthesis and stomatal conductance were performed prior to, in the middle of, and after a cold-stress treatment of $1{\pm}2^{\circ}C$ for 96 h in each of the four seasons. In both transgenic and wild-type plants, gas-exchange parameters were severely decreased in the middle of the cold treatment, but had recovered after 2-3 h of adaptation in a greenhouse. Most t-test comparisons on gas-exchange measurements between the two plant types did not show statistical significance. Wild-type plants had slightly more water-soaked damage on the leaves than the transgenic plants. A light-response curve did not show any differences between the two plant types. However, the curve for assimilation-internal $CO_2$ in wild-type plants showed a much higher slope than that of the PIF1 transgenic plants. This means that the wild-type plant is more capable of regenerating Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and has greater electron transport capacity. In conclusion, cold-resistant transgenic tobacco plants demonstrated a better recovery of net photosynthesis and stomatal conductance after cold-stress treatment compared to wild-type plants, but the ecophysiological recoveries of the transgenic plants were not statistically significant.