• Steel and Composite Structures
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• v.19 no.6
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• pp.1467-1481
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• 2015

This paper presents a contribution to improving an analytical thermo-mechanical modeling of Oxley's machining theory of orthogonal metals cutting, which objective is the prediction of the cutting forces, the average stresses, temperatures and the geometric quantities in primary and secondary shear zones. These parameters will then be injected into the developed model of Karas et al. (2013) to predict temperature distributions at the tool-chip-workpiece interface. The amendment to Oxley's modified model is the reduction of the estimation of time-related variables cutting process such as cutting forces, temperatures in primary and secondary shear zones and geometric variables by the introduction the constitutive equation of Johnson-Cook model. The model-modified validation is performed by comparing some experimental results with the predictions for machining of 0.38% carbon steel.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.806-811
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• 2004

Currently, in the design criteria for the high speed railway bridges, the maximum distance between bridge expansion joint is limited to 80m using a continuous welded mil, in order to limit the additional stress in the rail due to the rail-bridge interaction. In the past study on the resonance effect of HSR train, it is known that the reduction of resonance and dynamic responses of bridge deck occurs at the specific expansion length of 28.05m and 46.75m. In this study, the stability of track structure on the HSR bridges with expansion length of 90m has checked by finite element method. And the track behavior including mil stresses and relative displacements are compared to the current state of track structures on the bridge system with 80m long expansion length.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.201-204
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• 2000

Thermal shock resistance of 80Al2O3-20Al composite and monolithic alumina ceramics was compared. Fracture strength was measured by using a 4-pont bending test after quenching. Thermal stresses of the ceramics and ceramic-metal composites were calculated using a finite element analysis. The bending strength of the Al2O3 ceramics decreased catastropically after quenching from 20$0^{\circ}C$ to $0^{\circ}C$. The bending strength of the composite also decreased after quenching from 200~2$25^{\circ}C$, but the strength reduction was much smaller than for Al2O3. The maximum thermal stress occured in the monolithic alumina ceramics when exposed to a temperature difference of 20$0^{\circ}C$ was 0.758 GPa. The same amount of stress occured in the Al2O3-Al composite when the temperature difference of 205$^{\circ}C$ used.

• YAKHAK HOEJI
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• v.31 no.5
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• pp.308-314
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• 1987

In cardiovascular disease the flow adaptation of erythrocytes can be affected by reduced shear stresses and metabolic influences on red cell fluidity as a consequence of tissue hypoxia. In addition there are indications that risk factors of cardiovascular diseases are able to decrease the intrinsic red cell deformability. Erythrocyte deformability was studied by the filtration technique of Reid et al. to investigate the relationship between blood pressure chances and erythrocyte deformability. In this experiment normotensive rats, spontaneously and DOCA-salt treated hypertensive rats were used. Erythrocyte deformability was significantly reduced by blood pressure elevation in hypertensive rats but was not fully recovered by normalization of blood pressure after antihypertensive drug treatment. Therefore other factors than blood pressure may be involved in erythrocyte deformability reduction during blood pressure elevation.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1069-1073
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• 2019

In this paper, an alternative non-isolated DC-DC converter with a high voltage boosting capability is proposed. Two inductors are used and one of them has its flux linkage increases during its charging period to achieve a high step-up voltage gain. Among the three integrated capacitors, one portrays the partial characteristic of the switched-capacitor technique, while the other two are connected in series across the load. With the two switches controlled using the same duty cycle, the proposed topology demonstrates the merits of a higher and wider range of step-up voltage gain when compared with recent topologies. In addition, a reduction in loss is induced and a higher efficiency is ensured with all the voltage stresses constrained within the output voltage. Operation of the proposed converter is analyzed and validated through experimental results obtained with a prototype.

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.240-248
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• 2015

PURPOSE. To explore whether there is matching relation between the length and the tilting angle of terminal implants in the All-on-Four protocol by studying the effects of different implant configurations on stress distributions of implant, bone, and framework. MATERIALS AND METHODS. Four implants were employed to support a full-arch fixed prosthesis and five three-dimensional finite element models were established with CT images, based on the length (S and L) and distal tilt angle ($0^{\circ}$, $30^{\circ}$ and $45^{\circ}$) of terminal implants for an edentulous mandible, which named: Tilt0-S, Tilt30-S, Tilt30-L, Tilt45-S and Tilt45-L. An oblique 240 N was loaded at second molar. The von Mises Stresses were analyzed. The implants were consecutively named #1 to #4 from the loading point. RESULTS. 1) Tilt0-S had the greatest stress on the implants, with the other groups exhibiting variable reductions; the four implants of Tilt45-L demonstrated the greatest reduction in stress. 2) Tilt0-S had the greatest stress at bone around #1 implant neck, and Tilt45-L exhibited the least stress, which was a 36.3% reduction compared to Tilt0-S. 3) The greatest stress in the framework was found on the cantilevers distal to #1 implant. Tilt45-S exhibited the least stress. CONCLUSION. Matching different length and tilting angle of the terminal implants led to variable stress reductions on implants, bone and the superstructure. By optimizing implant configuration, the reduction of stress on implants and surrounding bone could be maximized. Under the present condition, Tilt45-L was the preferred configuration. Further clinical testings are required.

• Tunnel and Underground Space
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• v.13 no.1
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• pp.44-51
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• 2003

Changes of the hydraulic conductivity resulting from the redistribution of stresses by underground excavation are examined using the strain-dependent hydraulic conductivity modification relation, where the modulus reduction ratio and induced strain are the major parameters. The modulus reduction ratio is defined in terms of RMR(Rock Mass Rating) to represent the full gamut of rock mass condition. Though shear dilation has the effect on the modification of hydraulic conductivity, the extent of it depends on RMR When the extensional strain is applied to a fracture, the hydraulic conductivity increases with the decrease of RMR Loading configuration has the effect on the modification of hydraulic conductivity, where the differential stress mode with a magnitude of the minimum principal stress $($\sigma$_x)$ fixed and a magnitude of the maximum principal stress $($\sigma$_y)$ varied is found to exert the greatest effect on the change of hydraulic conductivity.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.152-162
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• 2005

Coolant rubber hoses for automobile radiators can be degraded and thus failed due to the influence of contacting stresses of air and coolant liquid under the thermal and mechanical loadings. In this study, test analysis was carried out for evaluating the degradation and failure mechanisms of coolant hose materials. Two kinds of EPDM rubber materials applicable to the hoses were adopted: commonly-used ethylene-propylene diene monomer(EPDM) rubbers and EPDM rubbers with high resistance against electro-chemical degradation (ECD). An increase of surface hardness and a large reduction of failure strain were shown due to the formation of oxidation layer for the specimens which had been kept in a high temperature air chamber. Coolant ageing effects took place only by an amount of pure thermal degradation. The specimens degraded by ECD test showed a swelling behavior and a considerable increase in weight on account of the penetration of coolant liquid into the skin and interior of the rubber specimens. The ECD induced material softening as well as drastic reduction in strength and failure strain. However EPDM rubbers designed for high resistance against ECD revealed a large improvement in reduction of failure strain and weight. This study finally established a procedure for reliability analysis and evaluation of the degradation and failure mechanisms of EPDM rubbers used in coolant hoses for automobile radiators.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.238-248
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• 2014

The metalloid arsenic (Z = 33) is considered to be a significant potential threat to human health due to its ubiquity and toxicity, even in rural regions. In this study a rural region contaminated with arsenic, located at longitude $85^{\circ}$ 32'E and latitude $25^{\circ}$ 11'N, was initially examined. Arsenic tolerant bacteria from the rhizosphere of Amaranthas viridis were found and identified as Bacillus licheniformis through 16S rRNA gene sequencing. The potential for the uptake and removal of arsenic at 3, 6 and 9 mM [As(V)], and 2, 4 and 6 mM [As(III)], and for the reduction of the above concentrations of As(V) to As(III) by the Bacillus licheniformis were then assessed. The minimal inhibitory concentrations (MIC) for As(V) and As(III) was determined to be 10 and 7 mM, respectively. At 3 mM 100% As(V) was uptaken by the bacteria with the liberation of 42% As(III) into the medium, whereas at 6 mM As(V), 76% AS(V) was removed from the media and 56% was reduced to As(III). At 2 mM As(III), the bacteria consumed 100%, whereas at 6 mM, the As(III) consumption was only 40%. The role of pH was significant for the speciation, availability and toxicity of the arsenic, which was measured as the variation in growth, uptake and content of cell protein. Both As(V) and As(III) were most toxic at around a neutral pH, whereas both acidic and basic pH favored growth, but at variable levels. Contrary to many reports, the total cell protein content in the bacteria was enhanced by both As(V) and As(III) stress.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.81-92
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• 2008

As the process of the Korea is highly industrialization and knowledge information the extent of fire fighting business is getting wide with the development and change. But work environment is not improved much compared with the past. For the situation that threaten life is exposed greatly, compared with the other profession there are also much stress. Moreover, the professional stress of fire official influence not only the safety of fire official. In this paper based on the reduction countermeasure for professional stress of fire official the following are proposed: Lively communication activity between constituents, application of people system as a result work field, improvement of treatment and welfare institution, safety of fire official and health rule enactment, the establishment of specialty hospital for fire fighting and appointment of fire medical specialist.