• BMB Reports
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• v.50 no.7
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• pp.379-383
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• 2017

We previously reported that p53 plays a role as a key regulator in the tetraploid G1 checkpoint, which is activated by actin damage-induced cytokinesis blockade and then prevents uncoupled DNA replication and nuclear division without cytokinesis. In this study, we investigated a role of Skp2, which targets CDK2 inhibitor p27/Kip1, in actin damage-induced tetraploid G1 arrest. Expression of Skp2 was reduced, but p27/Kip1 was increased, after actin damage-induced cytokinesis blockade. The role of Skp2 repression in tetraploid G1 arrest was investigated by analyzing the effects of ectopic expression of Skp2. After actin damage, ectopic expression of Skp2 resulted in DNA synthesis and accumulation of multinucleated cells, and ultimately, induction of apoptosis. These results suggest that Skp2 repression is important for sustaining tetraploid G1 arrest after cytokinesis blockade and is required to prevent uncoupled DNA replication and nuclear division without cytokinesis.

• Composites Research
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• v.12 no.2
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• pp.62-69
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• 1999

During fatigue loading of composite materials, damage accumulation can be monitored by measuring their material properties. In this study, fatigue modulus is used as the damage index. Fatigue life of composite materials may be predicted analytically using damage models which are based on fatigue modulus and resultant strain. Damage models are propesed as funtions of applied stress level, number of fatigue cycle and fatigue life. The predicted life was comparable to the experimental result obtained using E-glass fiber reinforced epoxy resin materials and pultruded glass fiber reinforce polyester composites under two-stress level fatigue loading.

• Journal of Aerospace System Engineering
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• v.3 no.4
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• pp.27-34
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• 2009

This paper deals with the lifetime prediction of Aircraft Flaperon Joint made of AISI 4130 steel. Reviews are performed on the published damage models at first. And three different damage models are used for predicting the fatigue life of the structure subjected to variable amplitude fatigue loading. These models require no increase in complexity of use, nor do they require additional material property or mission loading information to achieve the improved accuracy. Finally a comparison among the fatigue results is performed. It is observed that the Miner's rule could predict longer life than other cumulative damage models which take into account loads below the endurance limit.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.1
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• pp.37-45
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• 2006

Damage of rivers construction is serious to natural disaster by concentration rainfall in summer. Specially, increase of soil erosion breeds flood calamity of river bed accumulation and pondage decline etc., and erosion increase in upper stream shows in rivers flood of earth and sand, farm land and form of urban district burying. Flood damage investigation through on-the-spot probe until present need effective and scientific modelling techniques because is not efficient. This research wished to examine practical use of monitoring data of high resolution satellite image through satellite image analysis of various space resolution. Research analyzed abstraction possibility of soil disaster information using high resolution satellite image. Also, studied soil disaster damage present condition interpretation practical use possibility through various resolution satellite image analysis, and studied practical use of KOMPSAT image for interpretation of river topography change analysis.

• Structural Engineering and Mechanics
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• v.17 no.5
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• pp.655-670
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• 2004

This paper aims to evaluate the effect of typhoons on fatigue damage accumulation in steel decks of long-span suspension bridges. The strain-time histories at critical locations of deck sections of long-span bridges during different typhoons passing the bridge area are investigated by using on-line strain data acquired from the structural health monitoring system installed on the bridge. The fatigue damage models based on Miner's Law and Continuum Damage Mechanics (CDM) are applied to calculate the increment of fatigue damage due to the action of a typhoon. Accumulated fatigue damage during the typhoon is also calculated and compared between Miner's Law and the CDM method. It is found that for the Tsing Ma Bridge case, the stress spectrum generated by a typhoon is significantly different than that generated by normal traffic and its histogram shapes can be described approximately as a Rayleigh distribution. The influence of typhoon loading on accumulative fatigue damage is more significant than that due to normal traffic loading. The increment of fatigue damage generated by hourly stress spectrum for the maximum typhoon loading may be much greater than those for normal traffic loading. It is, therefore, concluded that it is necessary to evaluate typhoon induced fatigue damage for the purpose of accurately evaluating accumulative fatigue damage for long-span bridges located within typhoon prone regions.

• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.671-678
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• 1998

Hertzian indentation tests with sphere indenters were used to study the mechanical properties of glass-in-filtrated alumina and spinel composites and evaluated the effect of preform microstructure and evaluated the effect of preform microstructure and glass con-tents on contanct damage and strength. The spinel composite showed more brittle behavior than the alumina composite which is verified from indentation stress-strain curve cone cracks and quasi-plastic deformation developed at subsurface. Failure originated from either cone cracks(brittle mode) or deformation zone(quasi-plastic mode) above critical load for cracking(Pc) and yield ({{{{ {P }_{Y } }}) with the brittle mode more dominant in the spinels and the quasi-plastic mode more dominant in the aluminas. Even though brittle mode was dominant in the spinel composites the strength degradation from accumulation of damage above these critical loads was conspicuously small suggesting that the glass-infiltrated composites should be highly damage tolerant to the blunt contacts.

• Structural Engineering and Mechanics
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• v.36 no.4
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• pp.481-497
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• 2010

The shaking table tests were conducted on two small-scale models (Model 1 and Model 2) to examine the earthquake-induced damage of a concrete gravity dam, which has been planned for the construction with the recommendation of the peak ground acceleration of the maximum credible earthquake of 0.42 g. This study deals with the numerical simulation of shaking table tests for two smallscale dam models. The plastic damage constitutive model is used to simulate the crack/damage behavior of the bentonite-concrete mixture material. The numerical results of the maximum failure acceleration and the crack/damage propagation are compared with experimental results. Numerical results of Model 1 showed similar crack/damage propagation pattern with experimental results, while for Model 2 the similar pattern was obtained by considering the modulus of elasticity of the first and second natural frequencies. The crack/damage initiated at the changing point in the downstream side and then propagated toward the upstream side. Crack/damage accumulation occurred in the neck area at acceleration amplitudes of around 0.55 g~0.60 g and 0.65 g~0.675 g for Model 1 and Model 2, respectively.

• Biomolecules & Therapeutics
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• v.31 no.3
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• pp.340-349
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• 2023

Mad2B (Mad2L2), the human homolog of the yeast Rev7 protein, is a regulatory subunit of DNA polymerase ζ that shares sequence similarity with the mitotic checkpoint protein Mad2A. Previous studies on Mad2B have concluded that it is a mitotic checkpoint protein that functions by inhibiting the anaphase-promoting complex/cyclosome (APC/C). Here, we demonstrate that Mad2B is activated in response to cisplatin-induced DNA damage. Mad2B co-localizes at nuclear foci with DNA damage markers, such as proliferating cell nuclear antigen and gamma histone H2AX (γ-H2AX), following cisplatin-induced DNA damage. However, unlike Mad2A, the binding of Mad2B to Cdc20 does not inhibit the activity of APC/C in vitro. In contrast to Mad2A, Mad2B does not localize to kinetochores or binds to Cdc20 in spindle assembly checkpoint-activated cells. Loss of the Mad2B protein leads to damaged nuclei following cisplatin-induced DNA damage. Mad2B/Rev7 depletion causes the accumulation of damaged nuclei, thereby accelerating apoptosis in human cancer cells in response to cisplatin-induced DNA damage. Therefore, our results suggest that Mad2B may be a critical modulator of DNA damage response.

• Biomedical Science Letters
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• v.17 no.3
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• pp.239-243
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• 2011

Radiation exposure may cause tissue damage by ionized or excited atoms. The molecules are transformed from water or they directly interact with cells. Antioxidants such as vitamin E, vitamin C are used to reduce the interference of radiation. Especially, vitamin E inhibits the formation and accumulation of lipid and oxidation and the activity of drug-metabolizing enzymes. After irradiation of 3 Gy to the testis, the entire shape of testis was partly depressed and an irregular vacuole was observed to the edge. The 3 Gy group after treatment with vitamin E showed the low destruction of spermatogonia and partial tissue damage as compared to the 3 Gy group. Vitamin E inhibited the production of vacuoles from the cell death and generated the block to prevent the condensation of the seminiferous tubules.

• Earthquakes and Structures
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• v.7 no.6
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• pp.937-953
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• 2014

A semi-active control platform comprising the mechanical model of magnetorheological (MR) dampers, the bang-bang control law and damage material models is developed, and the simulation method of steel plate shear wall (SPSW) and optimization method for capacity design of MR dampers are proposed. A 15-story steel frame-SPSW structure is analyzed to evaluate the seismic performance of nonlinear semi-active controlled structures with optimal designed MR dampers, results indicate that the control platform and simulation method are stable and fast, and the damage accumulation effects of uncontrolled structure are largely reduced, and the seismic performance of controlled structures has been improved.