• Journal of the Korean Society of Industry Convergence
• /
• v.3 no.1
• /
• pp.3-8
• /
• 2000

This paper describes a development of self tuning scheme for PI and PO type fuzzy controllers. The output scaling factor(SF) is adjusted on-line by fuzzy rules according to the current trend of the controlled process. The rule-base for tuning the output SF is defined on error and change of error for the controlled variable using the most natural and unbiased membership functions. Simulation results demonstrate the better control performance can be achieved in comparison with Ziegler-Nichols(Z-N) PID controllers.

• Proceedings of the IEEK Conference
• /
• 2003.07b
• /
• pp.1213-1216
• /
• 2003

This paper proposes an 3D graphics rendering processor for portable device. One the most important factor is chip size for portable device, but the conventional 3D graphics rendering processor is not a suitable because the processor needs a lot of multiplication and division units. So the proposed architecture substitutes single precision floating point by 32 bit fixed point, and uses recursive units for the same operation such as color values(z, r, g, b, a) and texture values (s, t, u, v). In this approach, we reduce numbers of multiplications and divisions by 66.1% and 75% respectively at the sacrifice of performance degradation by 2.12%.

• International Journal of Aerospace System Engineering
• /
• v.7 no.1
• /
• pp.7-15
• /
• 2020

In this paper the crack growth, modeling, and simulation of the stiffened and un-stiffened cracked panels presented using commercially available finite element software packages. Computation of stresses and convergence of stress intensity factor for single edge notch (SEN) specimens carried out using the finite element method (FEM) and extended finite element method (XFEM) and compared with an analytical solution. XFEM techniques like cohesive segment method and LEFM using virtual crack closure technique (VCCT), used for crack growth analysis and presented results for un-stiffened and stiffened panels considering various crack domain. The non-linear analysis considering both geometric and material non-linearity on stiffened panels with various stringers like a blade, L, inverted T and Z sections the results were presented. Arrived at the optimum stringer section type for the considered panel under axial loading from the numerical analysis.

• International Journal of Highway Engineering
• /
• v.16 no.4
• /
• pp.35-43
• /
• 2014

PURPOSES: This study provides a methodology for estimating proper number of equipment for ordinary road management works. METHODS: Utilizing a computerized data of record systems (KAMIS) in 18 regional offices, two evaluation indicators were calculated and then normalized for objective comparison. Applied magnifying factor to the outputs, the proper number of equipment can be estimated. RESULTS: As a result, proper number of equipment by regional offices were required 28% more than current conditions. CONCLUSIONS: Using the proposed a methodology, fundamental data for scientific and reasonable strategies can be stored as well as be used for the future plan for budget allocation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.603-606
• /
• 2000

This dissertation is concerned with ultra-precision profile measurement of aspheric surfaces using contact probing technique. A contact probe has been designed as a sensing device to obtain measuring resolutions in nanometer regime utilizing a leaf spring mechanism and a capacitive-type sensor. The contact probe is attached on the z-axis during measurement while aspheric objects are supported on an precision xy-stage whose lateral motions are monitored by a set of two orthogonal plane mirror type laser interferometers. Experimental results show that the contact probing technique developed in this investigation is capable of providing a repeatability of 50 nanometers with a $\pm$3$\sigma$ uncertainty of 300 nanometers. Thermal disturbance is found the most significant factor that should be precisely controlled for accurate measurement.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.1007-1014
• /
• 2015

An optimally designed six-phase induction motor (6PIM) is compared with an initial design induction motor having the same ratings. The Genetic Algorithm (GA) method is used for optimization and multi objective function is considered. Comparison of the optimum design with the initial design reveals that better performance can be obtained by a simple optimization method. Also in this paper each design of 6PIM, is simulated by MAXWELL_2D. The obtained simulation results are compared in order to find the most suitable solution for the specified application, considering the influence of each design upon the motor performance. Construction a 6PIM based on the information obtained from GA method has been done. Quality parameters of the designed motors, such as: efficiency, power losses and power factor measured and optimal design has been evaluated. Laboratory tests have proven the correctness of optimal design.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.11a
• /
• pp.192-197
• /
• 1994

High-Tc superconducting magnet properties were dependent upon design conditions such as its radius, length, critical current and notch size. In order to study, design and the simulation for small size magnet were implemented. We know that intensity of magnetic fields controled by critical current and factor ${\alpha}$( R$_2$/R$_1$) and uniformity controled by notch size. The optimal condition of intensity and uniformity magnetic field in this experiments are R$_1$=3[cm], R$_2$=12[cm], Z=10[cm], ${\alpha}$=4, notch=6[cm], critical current=12[A].

• Journal of the Microelectronics and Packaging Society
• /
• v.2 no.1
• /
• pp.29-34
• /
• 1995

Glass 물질을 첨가하여 저온소결한(Ba, Sr, Ca) TiO3 세라믹 유전체의 전기 및 기계 적 특성을 조사하였다. PbO-ZnO-B2O3 계 glass를 첨가하여 소결온도를 135$0^{\circ}C$ to 105$0^{\circ}C$ With 4wt% of glass material the sintered specimen at 115$0^{\circ}C$ for 2hrs showed a dielectric constant over 8000 with low dissipation factor. As fired ceramic capacitor satisfied the Z5U( +10~ +85$^{\circ}C$; +22% ~-56%) specifications of the EIAs. The mechanical hardness and toughness of glass reacted ceramics slightly decreased but it hows higher hardness and toughness values than Lead perovskite dielectrics.

• Advances in materials Research
• /
• v.4 no.1
• /
• pp.31-44
• /
• 2015

This paper presents a simple n-order four variable refined theory for buckling analysis of functionally graded plates. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The present theory is variationally consistent, uses the n-order polynomial term to represent the displacement field, does not require shear correction factor, and eliminates the shear stresses at the top and bottom surfaces. 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 n-order refined theory. The non-linear governing equations are solved for plates subjected to simply supported 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.

• Journal of KSNVE
• /
• v.2 no.1
• /
• pp.33-39
• /
• 1992

The problem of sound radiation from infinite elastic beams under the action of harmonic point forces is studied. The reaction due to fluid loading on the vibratory response of the beam is taken into account. The beam is assumed to occupy the plane z = 0 and to be axially infinite. The beam material and the elastic foundation re assumed to be lossless and Bernoulli-Euler beam theory including a tension force (T), damping coefficient (C) and stiffness of foundation $(\kappa_s)$ will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire beam. The expression for sound power is integrated numerically and the results are examined as a function of wavenumber ratio$(\gamma)$ and stiffness factor$(\Psi)$. Here, our purpose is to explain the response of sound power over a number of non-dimensional parameters describing tension, stiffness, damping and foundation stiffness.