• Advances in nano research
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• v.13 no.5
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• pp.453-463
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• 2022

This paper aims to investigate the vibration analysis of functionally graded porous (FGP) beams using State-space approach with several classical and non-classical boundary conditions. The materials properties of the porous FG beams are considered to have even and uneven distributions profiles along the thickness direction. The equation of motion for FGP beams with various boundary conditions is obtained through Hamilton's principle. State-space approach is used to obtain the governing equation of porous FG beam. The comparison of the results of this study with those in the literature validates the present analysis. The effects of span-to-depth ratio (L/h), of distribution shape of porosity and others parameters on the dynamic behavior of the beams are described. The results show that the boundary conditions, the geometry of the beams and the distribution shape of porosity affect the fundamental frequencies of the beams.

• Journal of Digital Contents Society
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• v.17 no.6
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• pp.603-611
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• 2016

Generally, the doctors manually delineated the prostate boundary seeing the image by their eyes, but the manual method not only needed quite much time but also had different boundaries depending on doctors. To reduce the effort like them the automatic delineating methods are needed, but detecting the boundary is hard to do since there are lots of uncertain textures or speckle noises. There have been studied in SVM, SIFT, Gabor texture filter, snake-like contour, and average-shape model methods. Besides, there were lots of studies about 2 and 3 dimension images and CT and MRI. But no studies have been developed superior to human experts and they need additional studies. For this, this paper proposes a method that delineates the boundary predicting its texture features and its average distribution on the prostate image. As result, we got the similar boundary as the method of human experts.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.1
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• pp.54-63
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• 1992

Force distribution of incomplete meshing teeth for the OHC drive timing belt system is investigated analytically. Finite difference equations of the belt tension are derived based on the force equilibrium and the deformation of the belt tooth. From the numerical results, it is found that of the force distribution prior to the boundary point shows higher values compared with those of the complete meshing state and the force distribution after the boundary point shows lower values. Also, the magnitude of the incomplete meshing region increases as the rotational speed increases and the tight side belt tension decreases.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.828-830
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• 2000

This paper describes BIEM(Boundary Integral Equation Method) for computation of three dimensional electric field distribution and numerical method that an equivalent charge density is unknown variable. After computing numerically the surface charge distribution. the distribution of both potential and electric field are obtained. Finally, this numerical method is applied to the concentric sphere and the coaxial cylindrical model and numerical result is compared to the analytic solution.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.903-909
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• 2012

This study analyzed the temperature distribution in DPF with five partitioned electric heaters. The temperature distribution in DPF is an important design factor for regeneration and durability of filter. The design Factors that influence the temperature distribution in DPF there are several. In this study, the characteristics of temperature distribution in DPF were analyzed according to the following changes. First, the thermal conductivity of the filter was analyzed about effect on the durability of the filter. Second, the length from exhaust manifold to inlet of DPF was analyzed about effect on the temperature distribution in DPF. The boundary conditions of analysis has been verified with comparison to the results of existing experimental study and the numerical analysis. Based on the identified boundary condition, on assuming the condition of the actual driving, the temperature distribution in DPF was analyzed according to material properties of filter and the position of DPF.

• Geomechanics and Engineering
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• v.11 no.2
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• pp.269-288
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• 2016

The jointed rock mass behavior often plays a major role in the design of underground excavation, and their failures during excavation and in operation, are usually closely related to joints. This research attempts to evaluate the effects of two basic geometric factors influencing tunnel behavior in a jointed rock mass; joints spacing and joints orientation. A hybridized indirect boundary element code known as TFSDDM (Two-dimensional Fictitious Stress Displacement Discontinuity Method) is used to study the stress distribution around the tunnels excavated in jointed rock masses. This numerical analysis revealed that both the dip angle and spacing of joints have important influences on stress distribution on tunnel walls. For example the tensile and compressive tangential stresses at the boundary of the circular tunnel increase by reduction in the joint spacing, and by increase the dip joint angle the tensile stress in the tunnel roof decreases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.220-223
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• 2003

This paper is aimed at determining the e-field distribution by apply voltage of air void, which can be generate air void in the XLPE cable for ultra high voltage. E-field distribution had an effect in XLPE due to the type and position of void, compared and studied. This method of analysis is based on the quasi-static electromagnetic 3D simulation program by boundary element method (BEM): Applied AC 3[kV], discretization of 2000 elements, 4 angular periodicity, The result of experiment indicate that E-field distribution appeared the highest levels on the void position of electrode 2[nm] outer boundary and shape of the smallest inner angle in the void. This will serve to explain the XLPE cable degradation studied of possible, connected cable variation of position and shape of void effects to e-field concentration.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1821-1829
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• 2023

The temperature distribution of the reactor pool under natural circulation induced by the RVACS operation was experimentally studied. According to the Bo' based similarity law, which could reproduce the temperature distribution of the working fluid under natural circulation, SINCRO-2D facility was designed based on the PGSFR. It was reduced to 1 : 25 in length scale, having water as a simulant of the sodium, which is the original working fluid. In general, temperature was stratified, however, effect of the natural circulation flow could be observed by the entrainment of the stratified temperature. Relative cooling contribution of the upper plenum (narrow gap) and lower plenum was approximately 0.2 and 0.8, respectively. In the range of decay heat from 0.2% to 1.0%, only the magnitude of the temperature was changed, while the normalized temperature maintained. Boundary temperature distribution change made a global temperature offset of the pool, without a significant local change. Therefore, the decay heat and cooling boundary condition had no significant effect on temperature distribution characteristics of the pool within the given range of the decay heat and boundary temperature distribution.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.608-613
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• 2003

In this paper, the effect of interconnected boundary between journal and thrust bearings on the performance of self-acting air-lubricated bearings is investigated. When journal and thrust bearings have common boundary, conventional boundary condition which assumes that the boundary pressure is equal to atmosphere is no more valid. Instead, new boundary condition by mass conservation at interconnected boundary is needed. To do this, a duct model satisfying mass conservation at interconnected boundary is developed. Using this model, pressure distribution at interconnected boundary is numerically analyzed with changing the volume of interconnecting part. As a result, it is shown that load capacity of thrust bearing can be greatly increased when journal and thrust have a common boundary.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.250-254
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• 2002

Intergranular corrosion of austenitic stainless steels is a conventional and momentous problem during welding and high temperature use. One of the major reasons for such intergranular corrosion is so-called sensitization, i.e., chromium depletion due to chromium carbide precipitation at grain boundaries. Conventional methods for preventing sensitization of austenitic stainless steels include reduction of carbon content in the material, stabilization of carbon atoms as non-chromium carbides by the addition of titanium, niobium or zirconium, local solution-heat-treatment by laser beam, etc. These methods, however, are not without drawbacks. Recent grain boundary structure studies have demonstrated that grain boundary phenomena strongly depend on the crystallographic nature and atomic structure of the grain boundary, and that grain boundaries with coincidence site lattices are immune to intergranular corrosion. The concept of "grain boundary design and control", which involves a desirable grain boundary character distribution, has been developed as grain boundary engineering. The feasibility of grain boundary engineering has been demonstrated mainly by thermomechanical treatments. In the present study, a thermomechanical treatment was tried to improve the resistance to the sensitization by grain boundary engineering. A type 304 austenitic stainless steel was pre-strained and heat-treated, and then sensitized, varying the parameters (pre-strain, temperature, time, etc.) during the thermomechanical treatment. The grain boundary character distribution was examined by orientation imaging microscopy. The intergranular corrosion resistance was evaluated by electrochemical potentiokinetic reactivation and ferric sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was reduced by the thermomechanical treatment and indicated a minimum at a small roll-reduction. The frequency of coincidence-site-lattice boundaries indicated a maximum at a small strain. The ferric sulfate-sulfuric acid test showed much smaller corrosion rate in the thermomechanically-treated specimen than in the base material. An excellent intergranular corrosion resistance was obtained by a small strain annealing at a relatively low temperature for long time. The optimum parameters created a uniform distribution of a high frequency of coincidence site lattice boundaries in the specimen where corrosive random boundaries were isolated. The results suggest that the thermomechanical treatment can introduce low energy segments in the grain boundary network by annealing twins and can arrest the percolation of intergranular corrosion from the surface.