• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.114-117
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• 2001

A higher order zig-zag plate theory is developed to refine accurately predict fully coupled of the mechanical, thermal, and electric behaviors. Both the displacement and temperature fields through the thickness are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field. Smooth parabolic distribution through the thickness is assumed in the transverse deflection in order to consider transverse normal deformation. Linear zig-zag form is adopted in the electric field. The layer-dependent degrees of freedom of displacement and temperature fields are expressed in terms of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses and transverse heat flux The numerical examples of coupled and uncoupled analysis are demonstrated the accuracy and efficiency of the present theory. The present theory is suitable for the predictions of fully coupled behaviors of thick smart composite plate under mechanical, thermal, and electric loadings.

• Tribology and Lubricants
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• v.20 no.2
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• pp.102-108
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• 2004

In this paper, friction and wear behaviors between monocrystalline, defect-free copper and carbon on the atomic scale are investigated by using 2-dimensional molecular dynamics simulation. It is assumed that all interatomic forces are given by Morse potential. The deformation of carbon is assumed to be neglected and vacuum condition is also assumed. Average friction and normal forces for various surface conditions, various scratch speeds and scratch depths are obtained from simulations. Changes of wear behaviors for various scratch speeds and surface conditions are investigated by observing snapshots in scratch process. The effects of surface conditions, scratch speeds, and scratch depths on the friction force, normal force, and friction coefficient are also investigated.

• Tribology and Lubricants
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• v.18 no.1
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• pp.34-41
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• 2002

This paper presents the contact thermal behaviors of mechanical seals depending on the contacting face geometry. Using the finite element analysis, the temperature distribution, thermal distortion and leakage have been analyzed as functions of sealing gap and rotating speed of the seal ring shaft. The FE results indicate that the inclined contacting face may be more effective and stable based on the results of thermal characteristic analysis if the seal ring has been designed with a same thermal capacity between conventional rectangular sealing faces and inclined seating surface of seal rings.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.310-315
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• 2001

The most general feature of contact zone among the mechanical components is elliptical circle. In particular, continuously variable transmission (CVT) of toroidal type has elliptical shape of contact zone under the elastohydrodynamic lubrication condition, where the power is transmitted by the shearing the efluid. Due to the traction of the shear behaviors of lubricant over the small elliptical contact zone, high power of torque is transmitted. During the power transmission, many kinds of mechanical movements occur such as squeezing, sliding, rolling and spinning. The spinning effect that is not common contact behavior in tribological components frequently makes significant abnormal wear damage. In this work, the analysis of elliptical contact of elastohydrodynamic lubrication with spin effect is performed, which will give very useful information to understand the traction behaviors in toroidal type of CVT system.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.2
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• pp.9-18
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• 2019

The objective of this study is to investigate the feasibility of simulating the mechanical properties of irradiatied austenitic stainless steels by cold-working. In this study, the tensile properties, cyclic hardening behaviors and fracture toughness of cold-worked TP316L stainless steel were compared with those of austenitic stainless steels irradiated by neutrons. It showed that cold-working can properly simulate the increase in strength and the decrease in ductility and fracture resistance of austenitic stainless steels by neutron irradiation, even though it could not perfectly simulate the microstructures of irradiated austenitic stainless steels. Also, cold-working can appropriately simulate the hardening behaviors of neutron irradiated austenitic stainless steels under monotonic and cyclic loading conditions.

• 전기의세계
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• v.25 no.2
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• pp.100-106
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• 1976

A comparative study on thermal, static mechanical and dielectric characteristics were made over a temperature range of ca.20.deg.C to 320.deg.C and a frequency range of KHZ to MHZ band on low density polyethylene specimens crosslinked, respectively, by radiation and chemical method. The thermal property of both specimens shows that softening point appears to unchange by crosslinking, however, melting and liquidizing temperatures attain rapid increase at the imitiation of crosslinking. Mechanical properties show little difference to both specimens crosslinked by different method, further the behaviors were discussed in connection with the relaxation of molecular segments in amorphous phase. Dose dependent dielectric characteristics observed at ambient temperature under several fixed frequencies exhibit extremities at ca. 20 Mrad and the behaviors also were interpreted qualitatively by taking into consideration of dipole concentration change in amorphous phase together with the role of specimen geometry to the depth of oxidative layer. Observing frequency dependent dielectric characteristics, it was also proved that ionic conduction loss is appreciably greater in the specimen prepared by chemical method than that by radiation.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.65-78
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• 2015

In recent years, implants have gained growing importance in all areas of medicine. The success of the treatment depends on many factors affecting the bone-implant, implant-abutment and abutment-prosthesis interfaces. In this paper, static and dynamic behaviors of the dental prosthesis are investigated. Three-dimensional finite element models of dental prosthesis were constructed. Dynamic loads in 5 sec applied on occlusal surface. Therefore, FEA was selected for use in this study to examine the effect of the static and dynamic loads on the stress distribution for an implant-supported fixed partial denture and supporting bone tissue.

• Transactions of the Society of Information Storage Systems
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• v.11 no.2
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• pp.26-30
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• 2015

Recently, military vehicles are driven with a lot of electronic devices such as radar, antenna, and information storage devices. However, the military vehicles can be exposed to impact easily. Therefore, they have to be designed robustly in order to ensure the stability of the vehicle and the electronic devices. To achieve that, the dynamic behaviors of the military vehicle should be exactly identified. Therefore, in this research, dynamic behaviors of the vehicles were identified by carrying out road tests and we constructed finite element model to analyze the dynamic characteristics of the vehicle.

• Korea-Australia Rheology Journal
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• v.17 no.4
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• pp.171-180
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• 2005

We present numerical results for inertialess elliptic particle suspensions in a Newtonian fluid subject to simple shear flow, using the sliding bi-periodic frame concept of Hwang et al. (2004) such that a particulate system with a small number of particles could represent a suspension system containing a large number of particles. We report the motion and configurational change of elliptic particles in simple shear flow and discuss the inter-relationship with the bulk shear stress behaviors through several example problems of a single, two-interacting and ten particle problems in a sliding bi-periodic frame. The main objective is to check the feasibility of the direct simulation method for understanding the relationship between the microstructural evolution and the bulk material behaviors.

• Advances in nano research
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• v.7 no.2
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• pp.135-143
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• 2019

The important effect of porosity on the mechanical behaviors of a continua makes it necessary to account for such an effect while analyzing a structure. motivated by this fact, a new two-step porosity dependent homogenization scheme is presented in this article to investigate the wave propagation responses of functionally graded (FG) porous nanobeams. In the introduced homogenization method, which is a modified form of the power-law model, the effects of porosity distributions are considered. Based on Hamilton's principle, the Navier equations are developed using the Euler-Bernoulli beam model. Thereafter, the constitutive equations are obtained employing the nonlocal elasticity theory of Eringen. Next, the governing equations are solved in order to reach the wave frequency. Once the validity of presented methodology is proved, a set of parametric studies are adapted to put emphasis on the role of each variant on the wave dispersion behaviors of porous FG nanobeams.