• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.125-132
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• 2011

Drought is a major limiting factor in turfgrass management. Turfgrass responses to water deficit depend on the amount and the rate of water loss as well as the duration of the stress condition. This review paper was designed to understand responses such as photosynthesis, canopy spectral reflectance, plant cell, root, hormone and protein alteration when turfgrass got drought stress. Furthermore, mechanisms to recover from drought conditions were reviewed in detail. However, there are still many questions regarding plant adaptation to water deficit. It is not clear that the mechanism by which plants detect water deficit and transfer that signal into adaptive responses. Turfgrass research should focus on the best management practices such as how to enhance the ability of self-defense mechanism through understanding plant responses by environmental stress.

• Genomics & Informatics
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• v.7 no.2
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• pp.97-106
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• 2009

Epigallocatechin gallate (EGCG), a well-known antioxidant molecule, has been reported to cause hepatotoxicity when used in excess. However, the mechanism underlying EGCG-induced hepatotoxicity is still unclear. To better understand the mode of action of EGCG-induced hepatotoxicity, we examined the effect of EGCG on human hepatic gene expression in HepG2 cells using microarrays. Analyses of microarray data revealed more than 1300 differentially expressed genes with a variety of biological processes. Upregulated genes showed a primary involvement with protein-related biological processes, such as protein synthesis, protein modification, and protein trafficking, while downregulated genes demonstrated a strong association with lipid transport. Genes involved in cellular stress responses were highly upregulated by EGCG treatment, in particular genes involved in endoplasmic reticulum (ER) stress, such as GADD153, GADD34, and ATF3. In addition, changes in genes responsible for cholesterol synthesis and lipid transport were also observed, which explains the high accumulation of EGCG-induced lipids. We also identified other regulatory genes that might aid in clarifying the molecular mechanism underlying EGCG-induced hepatotoxicity.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.07a
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• pp.79-84
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• 1999

Oxidative stress is one of the major environmental stresses to plants. Reactive oxygen species (ROS) generated during metabolic processes damage cellular functions and consequently lead to cell death. Fortunately plants have in vivo defense system by which the ROS is scavenged by enzymes such as superoxide dismutase (SOD) and ascorbate peroxidase (APX). In attempts to understand the protection mechanism of plant against oxidative stress, we developed transgenic tobacco (Nicotiana tabacum cv. Xanthi) plansts thet expressed both SOD and APX in chloroplast using Agrobacterum-mediated transformation and evaluated their protection capabilities against methyl viologen (MV, paraquat) -mediated oxidative damage. Three double transformants (CAI, CA2, and CA3) expressed the chimeric CuZnSOD and chimeric APX in chloroplast, and one transformant (AM) expressed the chimeric APX and chimeric MnSOD in chloroplast. In addition, we obtained three lines of transformants (C/Al, C/A2, and A/C) that expressed the APX and SOD than control plants, and more resistant to oxidative stress caused by MV. TRansformants (C/A and A/C) overexpressing MnSOD, CuZnSOD and APX at the same time showed the highest resistance to MV-mediated oxidative stress among the transformants.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.6
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• pp.83-88
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• 2011

Magnesium alloys have been focussed for the applications for lightweight of vehicle and electronics due to their high strength, low specific density and good damping capacity. This paper deals with the creep strength of Mg-Nd-Zr-Zn alloy. For the alloy, pure magnesium(99.9%) was melt with atmosphere of $0.3%SF_6$ and $25%CO_2$. After melting, 0.3% of zinc was inserted to stir for 10min at elevated temperature of $770^{\circ}C$. Master alloys of Mg-15%Nd and Mg-15%Zr were stirred in furnace. The creep tests were performed to obtain creep rate and rupture in the temperature range of 200 to $220^{\circ}C$ and 280 to $310^{\circ}C$ at an applied stress of 156 to 172MPa and 78 to 94MPa, respectively. The deformation mechanism was predicted dislocation climb from measured apparent activation energy and stress exponent. Also the increaser the temperature and stress the lower the stress exponent and activation energy. Finally, LMP parameter gives good information for the predicted creep rupture life.

• Journal of Applied Biological Chemistry
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• v.55 no.2
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• pp.71-77
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• 2012

Many of biochemical or physiological processes can be regulated by non-coding RNAs as well as coding RNAs in plants, animals and microbes. Recently, many small RNAs including microRNAs (miRNAs) and endogenous small interference RNAs (siRNAs) and long non-coding RNAs have been discovered from ubiquitous organisms including plants. Biotic and abiotic stresses are main causal agents of crop losses all over the world. Much efforts have been performed for understanding the complex mechanism of stress responses. Up to date, many of these researches have been related with the identification and investigation of stress-related proteins, showing limitation to resolve the complex mechanism. Recently, non-coding RNAs as well as coding genes have been gradually interested because of its potential roles in plant stress responses as well as other biophysical aspects. In this review, various potential roles of non-coding RNAs, especially miRNAs and siRNAs, are reviewed in relation with plant biotic and abiotic stresses.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1575-1588
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• 2019

Fracture near the U-10Mo/cladding material interface impacts fuel service life. In this work, a mesoscale stress model is developed with the fuel foil considered as a porous medium having gas bubbles and bearing bubble pressure and surface tension. The models for the evolution of bubble volume fraction, size and internal pressure are also obtained. For a U-10Mo/Al monolithic fuel plate under location-dependent irradiation, the finite element simulation of the thermo-mechanical coupling behavior is implemented to obtain the bubble distribution and evolution behavior together with their effects on the mesoscale stresses. The numerical simulation results indicate that higher macroscale tensile stresses appear close to the locations with the maximum increments of fuel foil thickness, which is intensively related to irradiation creep deformations. The maximum mesoscale tensile stress is more than 2 times of the macroscale one on the irradiation time of 98 days, which results from the contributions of considerable volume fraction and internal pressure of bubbles. This study lays a foundation for the fracture mechanism analysis and development of a fracture criterion for U-10Mo monolithic fuels.

• Journal of Korean Association for Spatial Structures
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• v.23 no.4
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• pp.97-105
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• 2023

The membrane structure should maintain the membrane materials in tension for structural stability guaranty. The anchoring part in the membrane structure is an important part. It has the function to introduce tension into membrane materials and function to transmit stress which membrane materials receives to boundary structure such as steel frames. In this paper, it grasps anchoring system of the anchoring part in the membrane structure concerning the fracturing characteristic condition of membrane structure, and the influence which is caused to yield it designates the stress state when breaking the membrane structure which includes the anchoring part and that stress transition mechanism is elucidated as purpose. This paper follows to previous paper, does 1 axial tensile test concerning the bolting part specimen, grasp of fracturing progress of the bolting part and the edge rope and hardness of the rubber, does the appraisal in addition with the difference of bolt tightening torque. As a result, the influence which the bolt anchoring exerts on the fracturing characteristics of the membrane material in the membrane structure anchoring part is examined.

• Journal of Physiology & Pathology in Korean Medicine
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• v.30 no.4
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• pp.250-256
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• 2016

The prevalence of renal disease is increased with the overweight and obesity. High fat diet-associated oxidative stress increases production of reactive oxygen species (ROS) and induces apoptosis. There are two types of antioxidant defense mechanisms for oxidative stress. One is the enzyme defense mechanism by antioxidant enzymes such as superoxide dismutase (SOD), and catalase (CAT). The other is non-enzyme defense mechanism by signaling molecules such as nuclear factor-like 2 (Nrf-2), HO-1. In this study, we induced obesity in mice with high fat diet for six weeks and thereafter administered orally Viola mandshurica for 4 weeks. V. mandshurica is known to clear heat, detoxify and cool blood, and subside a swelling effect. In the V. mandshurica administered group, the immunoreactive signal of the Tunel staining was weaker than that of obesity group. Proapoptotic Bax, caspase 3 immunoreactives of the V. mandshurica administered group was lower than those of obesity group, whereas anti-apoptotic Bcl-2 immunoreactity was higher in the V. mandshurica administered group. Antioxidant enzyme mechanism such as superoxide dismutase 2 (SOD2), catalase (CAT) immunoreactives of the V. mandshurica administered group and Antioxidant non-enzyme mechanism such as Nuclear factor-like 2 (Nrf2), Heme Oxygenase 1 (HO-1) immunoreactives of the V. mandshurica administered group was higher than those of obesity group. These results demonstrate that V. mandshurica had the antioxidant and anti-apoptosis effects on obese mice.

• Journal of Welding and Joining
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• v.22 no.5
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• pp.4-8
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• 2004

• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.131-139
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• 1992

The understanding and appllication of fatigue crack propagation mechanism in variable amplitude loading is very important for life prediction of the air travel structures. Particularly, the retardation and arrest behavior of fatigue crack propagation by single tension overloading is essential to the understanding and appllication of fatigue crack propagation mechanism in variable amplitude loading. Numerous studies of the retardation behavior have been performed, however investigations of the arrest behavior have not been enough yet. As for the arrest behavior, Willenborg had reported that the overload shut-off ratio $[R_{so}=(K_{OL})/K_{max})_{crack arrest}]$ had been the material constant, but recently several investigators have reported that the overload shut-off ratio depends upon the stress ratio. In this study, authors have investigated the effect of stress ratio on the threshold overload shut-off ratio to generate arrest of fatigue crack growth in high tensile aluminum alloy 7075-T735 which have used in material for air travel structures, It has been $-0.4\leqqR\leqq0.4$ till now, the region of stress ratio investigated. The threshold overload shut-off ratio has decreased as stress ratio has increased in overall region of -$-0.4\leqqR\leqq0.4$ and the linearity has been seen in this material. Moreover, the experimental equation between $R_{so}$ and R has been made; The relation has been $R_{so}=-R+2.6$.