• Journal of the Korean Society of Safety
• /
• v.21 no.5 s.77
• /
• pp.34-39
• /
• 2006

In this paper, we investigated the electric field distribution according to the roughness in aramid insulating paper for electric machine. Aramid insulating paper has been used to electric insulating of the traction motor and generators for large capacity. We studied the electric field distribution using boundary element method for Aramid insulating paper. As a result of simulation, the electric field increased according to the surface roughness existence. Electric field decreased due to radius of surface roughness reduction, and Electric field concentration appeared at electrode boundary and rough surface.

• Proceedings of the KSRS Conference
• /
• 2007.10a
• /
• pp.270-273
• /
• 2007

In this paper, a SAR-despeck1ing approach of adaptive iteration based a Bayesian model using the lognormal distribution for image intensity and a Gibbs random field (GRF) for image texture is proposed for noise removal of the images that are corrupted by multiplicative speckle noise. When the image intensity is logarithmically transformed, the speckle noise is approximately Gaussian additive noise, and it tends to a normal probability much faster than the intensity distribution. The MRF is incorporated into digital image analysis by viewing pixel types as states of molecules in a lattice-like physical system. The iterative approach based on MRF is very effective for the inner areas of regions in the observed scene, but may result in yielding false reconstruction around the boundaries due to using wrong information of adjacent regions with different characteristics. The proposed method suggests an adaptive approach using variable parameters depending on the location of reconstructed area, that is, how near to the boundary. The proximity of boundary is estimated by the statistics based on edge value, standard deviation, entropy, and the 4th moment of intensity distribution.

• Proceeding of KASS Symposium
• /
• 2006.05a
• /
• pp.227-232
• /
• 2006

This paper investigate the optimum thickness distribution of plate structure with different essential boundary conditions in the fundamental natural frequency maximization problem. In this study, the fundamental natural frequency is considered as the objective function to be maximized and the initial volume of structures is used as the constraint function. The computer-aided geometric design (CAGD) such as Coon's patch representation is used to represent the thickness distribution of plates. A reliable degenerated shell finite element is adopted calculate the accurate fundamental natural frequency of the plates. Robust optimization algorithms implemented in the optimizer DoT are adopted to search optimum thickness values during the optimization iteration. Finally, the optimum thickness distribution with respect to different boundary condition

• Journal of the Korean Geographical Society
• /
• v.51 no.5
• /
• pp.577-612
• /
• 2016

The distribution of boundary markers, set up during the Yimjin(1712) Boundary Making and Demarcation(YBMD), has less been addressed so far, although it is key material evidence on which we can reconstruct the whole processes of YBMD, together with the correction of widespread myths around YBMD. This paper aims to clarify the questions on the distribution of boundary markers associated with YBMD, built during August 1712 to September 1713, by reinterpreting the key documents of Actual Survey on them: Huh Ryang and Park Dosang(1913), Kim Woosik(1883), Lee Joongha(1885), Wu Luzhen(1907), Osone Seiji(1907), and Liu Jianfeng(1908), together with topographic maps by Japanese Imperial Army(1933), the report of expedition to Mt. Baekdu by Chungjin Teachers' College(1948), and the report of field survey by Jilin province's expedition(1957). As a result, the distribution of boundary markers built in 1712~1713 is successfully reconstructed, and summarized in the format of table and maps.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2797-2802
• /
• 2007

It has been confirmed that implementation of the no-slip boundary conditions for the lattice-Boltzmann method play an important role in the overall accuracy of the numerical solutions as well as the stability of the solution procedure. We in this paper propose a new algorithm, i.e. the method of the dynamic boundary condition for no-slip boundary condition. The distribution functions on the wall along each of the links across the physical boundary are assumed to be composed of equilibrium and nonequilibrium parts which inherit the idea of Guo's extrapolation method. In the proposed algorithm, we apply a dynamic equation to reflect the computational slip velocity error occurred on the actual wall boundary to the correction; the calculated slip velocity error dynamically corrects the fictitious velocity on the wall nodes which are subsequently employed to the computation of equilibrium distribution functions on the wall nodes. Along with the dynamic selfcorrecting process, the calculation efficiently approaches the steady state. Numerical results show that the dynamic boundary method is featured with high accuracy and simplicity.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.17 no.2
• /
• pp.15-30
• /
• 2014

Systematic management of wetlands should be a priority to build the data for the extent and distribution of wetlands all over the country. However there are no clear guidelines for the wetland boundary delineation, so researchers have to determine the boundary of wetlands in each different way. As a result, it is very difficult to identify the extent and distribution of wetlands. This study proposes applicable criteria of setting boundary of wetlands which consider their wetland vegetation and geographical characteristics, according to wetland classification. The proposed site in this study is selected wetlands that represent each wetland type and have been ecologically well preserved like the wetland protected areas. GIS data for setting the boundary of wetlands selected were land-cover maps, aerial photographs, high resolution satellite images, and digital topographic maps. In this study, 'wetland unit determination' of the Washington State Wetlands Rating System(WSDE, 1993) and the concept of 'Wetland and Deep-water Habitats' was suggested by Wetland Delineation Manual(USACE, 1987) were used as criteria for setting the boundary of wetlands. As a result, it was found that the boundary of wetlands could be, in general, set consistently. Also, it seemed possible to set systematic and standardized boundary of wetlands and to provide more objective data for establishing national wetland policies, if maps of wetlands are made and an investigation of wetlands is implemented according to the criteria.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.8 no.2
• /
• pp.153-168
• /
• 2016

Sloshing phenomenon is a complicated free surface flow problem that increases the dynamic pressure on the sidewalls and the bottom of the storage tanks. When the storage tanks are partially filled, it is essential to be able to evaluate the fluid dynamic loads on the tank's perimeter. In this paper, a numerical code was developed to determine the pressure distribution on the rectangular and trapezoidal storage tanks' perimeters due to liquid sloshing phenomenon. Assuming the fluid to be inviscid, the Laplace equation and the nonlinear free surface boundary conditions were solved using coupled boundary element - finite element method. The code performance for sloshing modeling was validated using Nakayama and Washizu's results. Finally, this code was used for partially filled rectangular and trapezoidal storage tanks and free surface displacement, pressure distribution and horizontal and vertical forces exerted on the tanks' perimeters due to liquid sloshing phenomenon were estimated and discussed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.2
• /
• pp.594-599
• /
• 2011

In this paper, the effect of the boundary conditions on the reliability and the cumulative distribution characteristics of the fatigue failure life is analyzed in a magnesium alloy AZ31. The boundary conditions are specimen thickness, stress ratio, and maximum fatigue load. The statistical data of the fatigue failure life are obtained by fatigue crack propagation tests under the detail conditions for each boundary condition. The 3-parameter Weibull distribution is used to analyze a statistical characteristics of the fatigue failure life in magnesium alloy AZ31. It is found that the statistical fatigue failure life is long in the case of a thicker specimen, a larger stress ratio, and a smaller maximum fatigue load. Under the opposite cases, the reliability on the fatigue failure life is rapidly dropped.

• Smart Structures and Systems
• /
• v.18 no.2
• /
• pp.267-291
• /
• 2016

In this research work, an exact analytical solution for thermal buckling analysis of functionally graded material (FGM) sandwich plates with clamped boundary condition subjected to uniform, linear, and non-linear temperature rises across the thickness direction is developed. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory accounts for parabolic distribution of the transverse shear strains, and satisfies the zero traction boundary conditions on the surfaces of the plate without using shear correction factor. A power law distribution is used to describe the variation of volume fraction of material compositions. Equilibrium and stability equations are derived based on the present refined theory. The non-linear governing equations are solved for plates subjected to simply supported and clamped boundary conditions. The thermal loads are assumed to be uniform, linear and non-linear distribution through-the-thickness. The effects of aspect and thickness ratios, gradient index, on the critical buckling are all discussed.

• Steel and Composite Structures
• /
• v.24 no.3
• /
• pp.359-367
• /
• 2017

In this work, transient heat transfer analysis of functionally graded (FG) carbon nanotube reinforced nanocomposite (CNTRC) cylinders with various essential and natural boundary conditions is investigated by a mesh-free method. The cylinders are subjected to thermal flux, convection environments and constant temperature faces. The material properties of the nanocomposite are estimated by an extended micro mechanical model in volume fraction form. The distribution of carbon nanotube (CNT) has a linear variation along the radial direction of axisymmetric cylinder. In the mesh-free analysis, moving least squares shape functions are used for approximation of temperature field in the weak form of heat transform equation and the transformation method is used for the imposition of essential boundary conditions. Newmark method is applied for solution time depended problem. The effects of CNT distribution pattern and volume fraction, cylinder thickness and boundary conditions are investigated on the transient temperature field of the nanocomposite cylinders.