• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.524-527
• /
• 1997

Conventional target tracking algorithms based on the linear estimation techniques perform quite efficiently when the target motion does not involve maneuvers. Target maneuvers involving short term accelerations, however, cause a bias in the measurement sequence. Accurate compensation for the bias requires processing more samples of which adds to the computational complexity. The primary motivation for employing a neural network for this task comes from the efficiency with which more features can be as inputs for bias compensation. A system architecture that efficiently integrates the fusion capabilities of a trained multilayer neural net with the tracking performance of a Kalman filter is described. The parallel processing capability of a properly trained neural network can permit fast processing of features to yield correct acceleration estimates and hence can take the burden off the primary Kalman filter which still provides the target position and velocity estimates.

• Journal of Advanced Marine Engineering and Technology
• /
• v.9 no.3
• /
• pp.225-239
• /
• 1985

The beams with a circular hole are often used for constructing structures. The center of the circular hole is normally located in neutral axis and the stress state around the hole due to bending moment is trivial. But the stress level around the hole due to shear force is expected to be significant especially in the case of beams made of shape steels. In this paper, the stress distributions around the circular hole of beams were presented. Using polar coordinates and generallized stress function, the formulas of stress components were derived. The aspects of plastic area propagations based on von Mises yield criteria were also shown graphically. In order to verify the formulas presented in this paper, a beam of I-shape steel with a circular hole was made and the strains around the hole were measured under various loading conditions. The experimental results were proved to coincide fairly well with the calculated values.

• Journal of the Korean Society for Heat Treatment
• /
• v.7 no.4
• /
• pp.277-287
• /
• 1994

The effect of grain size on the tensile properties and fatigue behavior of austenitic high Mn steel has been investigated. The recrystallized austenite grain size of the cold rolled high Mn steel was increased as the annealing temperature increased from $600^{\circ}C$ to $1000^{\circ}C$. Larger austenite grain size decreased the yield strength and the tensile strength, and increased the uniform elongation due to transformation of some austenite into twins or E-martensite phase during deformation. Austenite grain refinement increased the tendency to form dislocation cells, instead. The specimen annealed at $1000^{\circ}C$ with large grain size showed lower fatigue crack propagation rate in low ${\Delta}K$ region due to rougher fracture surface caused by formation of deformation twins during fatigue at the crack tip region.

• Journal of KSNVE
• /
• v.11 no.1
• /
• pp.156-166
• /
• 2001

This work uses tensor calculus to derive a complete set of three-dimensional field equations well-suited for determining the behavior of thick shells of revolution having arbitrary curvature and variable thickness. The material is assumed to be homogeneous, isotropic and linearly elastic. The equations are expressed in terms of coordinates tangent and normal to the shell middle surface. The relationships are combined to yield equations of motion in terms of orthogonal displacement components taken in the meridional, normal and circumferential directions. Strain energy and kinetic energy functionals are also presented. The equations of motion and energy functionals may be used to determine the static or dynamic displacements and stresses in shells of revolution, including free and forced vibration and wave propagation.

• Journal of the Korean Society of Safety
• /
• v.17 no.2
• /
• pp.1-7
• /
• 2002

In this paper, the maximum minimum strain energy density criterion was applied to the mixed mode fatigue test of A5052 H34 alloy. In this study result we can have seen that the authors stress intensity factor for the finite width specimen and method of determining testing load, based on the plastic zone size and the limited maximum stress intensity factor by ASTM STANDARD E-647-95, is useful.

• Structural Engineering and Mechanics
• /
• v.3 no.4
• /
• pp.325-340
• /
• 1995

The iterative procedure to use the nonconforming elements in elasto-plastic problems is established and applied to the variable node transition solid element developed for the automated three-dimensional local mesh refinement. Through numerical tests, the validity and performance of the element are examined. As the nonlinear iterative procedure presented in this paper is accomplished for the general three-dimensional case, it can also be easily applied to the two-dimensional elements such as membranes, plates and shells.

• Journal of the Korean Society for Precision Engineering
• /
• v.7 no.4
• /
• pp.130-139
• /
• 1990

It is well known that mechanisms of fracture and crack growth depend upon material characteristics such as fracture toughness, environmental condition, crack geometry and mechanical properties. It seems to be very important to investighate the effects of the above factors on the behavior of structural components which contain flaws for the detailed evaluation of their integrity. In this experimental research, fracture behaviors of SK-5 high carbon steel was investigated by using Acoustic Emission(AE) technique. Fracturing processes of materials were estimated through both the tension test with nominal specimens and the fracture test with compact tension specimens. The critical applied load which corresponds to the crack initiation and propagation is very improtant for the determination of yield strength of fracture toughness. The critical applied load($P_Q$) was determined through AE method and the source of AE signal was estimated by fractography analysis. The experimental results may contribute to the safety analyses and strength evaluation of structures.

• Journal of the Korean Society of Safety
• /
• v.12 no.4
• /
• pp.15-20
• /
• 1997

This study is to investigate the behavior of fatigue crack growth with ATOS 55 steel which can be applied to the commercial car Dump Frame. It is to obtain the material coefficients after tensile and fatigue crack growth test with the variation of thickness or heat treatment. Also, that is proved the Pari's law by experiment. The summarized results are as follows ; 1) Increasing thickness, tensile and yield strength measured highly regardless to heat treatment and measured lowly as variation of heat treatment temperature. 2) Specimen of thickness 8.0㎜ measured the faster of crack growth rate than another thickness according to the results of experiment. It was the different of stress conditions in crack tip. 3) It was found that the experimental constant m was range of 2∼5 to the relationship between fatigue crack growth rate and stress intensity factor range. Also, it was to prove the Paris's law by the experiment.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1996.06c
• /
• pp.1045-1054
• /
• 1996

Tissue culture, or micropropagation , is being used for the vegetative multiplication of several hundred millions of superior plants annually for horticulture and forestry. It is often more expensive than other forms of propagation using cuttings or seeds, because it is labor intensive and more specialized . The aim of automation is to reduce the cost per plantlet by reducing labor input, and finally, to yield profit, as business activity . Labor usually account for 70-80% of th ein vitro and ex vitro cost. This paper aspects of tissue culture automization , such as technical and economical approaches in view of automization.

• Journal of the Korean Chemical Society
• /
• v.57 no.3
• /
• pp.370-376
• /
• 2013

A back propagation artificial neural network model with one hidden layer is established to correlate the liquid-liquid equilibrium data of hydrocarbon-water systems. The model has four inputs and two outputs. The network is systematically trained with 48 data points in the range of 283.15 to 405.37K. Statistical analyses show that the optimised neural network model can yield excellent agreement with experimental data(the average absolute deviations equal to 0.037% and 0.0012% for the correlated mole fractions of hydrocarbon in two coexisting liquid phases respectively). The comparison in terms of average absolute deviation between the correlated mole fractions for each binary system and literature results indicates that the artificial neural network model gives far better results. This study also shows that artificial neural network model could be developed for the phase equilibria for a family of hydrocarbon-water binaries.