• Steel and Composite Structures
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• v.29 no.1
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• pp.39-51
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• 2018

Position of a circular or elliptical cutout within an orthotropic plate has great influence on its buckling behavior. This paper aims at finding the optimal position (both location and orientation) of a single circular/elliptical cutout, within an orthotropic rectangular plate, that maximizes the critical buckling load. We consider linear buckling of simply supported orthotropic plates under uniaxial edge loads. To obtain the optimal positions of the cutouts, we have employed a MATLAB optimization routine coupled with buckling computation in ANSYS. Our results show that the position of the cutout that maximizes the buckling load has great dependence on the material properties, laminate configurations, and the geometrical parameters of the plate. These optimal results, for a number of plate geometries and cutout sizes, are reported in this paper. These results will be useful in the design of perforated orthotropic plates against buckling failure.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.150-152
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• 2000

This paper introduces an advanced three-phase load flow analysis algorithm in the radial distribution network. This method is an extension of the Novel method for solving radial distribution networks with the emphasis on expanding from single phase to three-phase. The proposed method involves only simple algebraic computation without any form of Jacobian matrix but has a desirable convergence characteristic. Computationally, The suggested technique is very efficient and requires less computer memory storage and maintains high execution speed. Also, the submitted process can be easily programmed and be simply extended to different types of load characteristics. A simulation results applied to the IEEE 34 bus radial distribution feeder are examined by using the MATLAB.

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.55-59
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• 2002

Delamination means that cracking occurs on the interface layer between composite laminates. In this paper, to predict the delamination growth in composite laminates subjected to low-velocity impact, the unit load method was introduced, and an eighteen-node 3-D finite element analysis, based on assumed strain mixed formulation, was conducted. Strain energy release rate, necessary to determine the delamination growth, was calculated by using the virtual crack closure technique. The unit load method saves the computation time more than the re-meshing method. The virtual crack closure technique enables the strain energy release rate to be easily calculated, because information of the singular stress field near the crack tip is not required. Hence, the delamination growth in composite laminates that are subjected to low-velocity impact can be efficiently predicted using the above-mentioned methods.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.868-875
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• 1999

In this paper, digital motor control center using protection relay is developed in order to protect power systems by means of timely fault detection and diagnosis during operation for induction motor which have various load environments and capacities in power systems. Digital motor control center is employed by power supervisory control systems without separate remote terminal unit and transducers adding communicational ability. Also we develope a maximum demand controller to control the load effectively at peak status and a power factor controller to minimize real power losses and improve the power factor. Therefore, when using the developed controller, real time computation is possible by loading DSP in hardware and applying real-time kernel which can convert each algorithm to task module.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.10
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• pp.44-52
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• 1994

In this paper, we assume that the dynamics of DC motor and nonlinear load are unknown. We propose an inverse dynamic model of DC motor and nonlinear load using the artificial neural network and construck speed control system based on the proposed dynamic model. We also propose another dynamic model with speed prediction scheme using the artificial neural network that removes the undesirable time delay effect caused by the computation time during the real-time control. We suggest a dynamic model which has arbitrary number of speed arguments and is especially effective when the motor and load has large moment of inertia. Next, we suggest a controller that combine the neurocontrol and PID control with constant gain. We show that the proposed neurocontrol systems have capabilities of noise rejection and generalization to have good velocity tracking through computer simulations and experiments.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.218-220
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• 1997

In power system, economic dispatch problem is to minimize fuel cost with inequality constraints of generator output. To solve this problem it is very important to express power loss equation that have Quadratic function of generator power included B-coefficient. This paper presents a method in determining B-coefficient by use A-matrix that is calculated by power flow considering voltage dependent static load model. The proposed algorithm is tested with IEEE 6 bus sample system, which shows the result in each cases by the change of load component factor.

• Journal of the military operations research society of Korea
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• v.34 no.2
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• pp.1-26
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• 2008

This study presents a new estimation of optimal amount of B/L for infantry rifles and artillery weapons which are currently using in Korean Army. To do that, we analyzed current concept of B/L and methodologies used to compute B/L before, and re-calculate optimal amount of B/L to solve some problems founded. We also applied ARENA simulation model to propose estimated values of optimal B/L. The proposed optimal B/L will certainly help to improve efficiency for wartime readiness in the future.

• International Journal of Aeronautical and Space Sciences
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• v.5 no.1
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• pp.64-74
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• 2004

The Grid is a communication service that collaborates dispersed highperformance computers so that those can be shared and worked together. It enablesthe analysis of large-scale problem with the reduction of computation time bycollaborating high performance computing resources in dispersed organizations. Thus,the present paper focuses on the efficient flow calculation using the Grid. To increaseparallel efficiency, a simple load balance algorithm for the Grid computing is proposedand applied to various aerodynamic problems.

• Journal of the Korean Institute of Intelligent Systems
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• v.6 no.2
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• pp.111-119
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• 1996

In this paper, we propose time-optimal trajectory planning algorithms for cooperative multi-robot manipulators system considering optimal load distribution. Internal forces essentially effect on time optimal trajectory planning and if they are comitted, the time optimal scheme is not no longer true. Therefore, we try to find the internal force factors of cooperative robot manipulators system in a time-optimal aspect. In this approach, a specific generalized inverse is used and is fuzzified for the purpose. In this optimal method, the fuzzy logic concept is used and selected for diminishing computation time, for finding the load distribution factors.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.134-136
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• 1993

This paper presents a novel and efficient method to calculate the critical point of voltage collapse. Conjugate gradient and modified Newton-Raphson methods are employed to calculate two pairs of multiple load flow solutions for two operating conditions, i.e., both +mode and -mode voltages for two loading conditions respectively. Then these four voltage magnitude-load data sets of the bus which is most susceptible to voltage collapse, are fitted to third order polynomial using Lagrangian interpolation in order to represent approximate nose curve (P-V curve). This nose curve locates first estimate of the critical point of voltage collapse. The procedure described above is repeated near the critical point and the new estimate will be very close to the critical point. The proposed method is tested for the eleven bus Klos-Kerner system, with good accuracy and fast computation time.