• Bulletin of the Korean Mathematical Society
• /
• v.47 no.1
• /
• pp.89-102
• /
• 2010

This paper concerns the problem of global robust stability of a time-delay discontinuous system with a positive-defined connection matrix under polytopic-type uncertainty. In order to give the stability condition, we firstly address the existence of solution and equilibrium point based on the properties of M-matrix, Lyapunov-like approach and the theories of differential equations with discontinuous right-hand side as introduced by Filippov. Second, we give the delay-independent and delay-dependent stability condition in terms of linear matrix inequalities (LMIs), and based on Lyapunov function and the properties of the convex sets. One numerical example demonstrate the validity of the proposed criteria.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.4
• /
• pp.1169-1174
• /
• 2000

Human-compute interface (HCl) should be designed with ease and flexibility for users for providing convenience and friendliness to users. The natural language processing is one of the aspects of HCl. This paper presents the method of design and implementation of SENKOV( Semantic Networks for Korean Verbs) System, which deals with isa hierarchies of Korean verbs for the natural language processing. The system's architecture is based on the differential theory and Levin verb classes. This paper selects about 600 Korean verbs which are commonly used in the daily life, and implements the SENKOV System. The experiments show that SENKOV has 44 top nodes and depth of about 2.35. In addition this paper applied the SENKOV System to co-occurrence constraint relationship among a adverbs and verbs, and proves the validity of the system. This paper is important in that it has made the first trial to classify Korean verb concept for HCl.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.3
• /
• pp.110-117
• /
• 1998

A continuum-based configuration design sensitivity analysis method is developed for kinematically driven mechanical systems. The configuration design variable for mechanical systems is defined. The 3-1-3 Euler angle is employed as the orientation design variable. Kinematic admissibility conditions of configuration design change. Direct differentiation method is used to derive the governing equations of the design sensitivity. Numerical examples are presented to demonstrate the validity and effectiveness of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.73-80
• /
• 2006

In order to examine the validity of an asymptotic solution for nonlinear interaction in asymmetric vibration modes of a perfect circular plate, we obtain the numerical solution. The motion of the plate is governed by nonlinear partial differential equation. The initial and boundary value problem is solved by using the finite difference method. The numerical solution is compared with the asymptotic solution. It is found that traveling waves relating clockwise and counterclockwise as well as standing wave are depicted by the numerical solution.

• Journal of Biomedical Engineering Research
• /
• v.20 no.4
• /
• pp.485-493
• /
• 1999

Human can generate various posture and motion with nearly 350 muscle pairs. From the viewpoint of mechanisms, the human skeleton mechanism represents great kinematic and dynamical complexity. Physical and behavioral fidelity of human motion requires dynamically accurate modeling and controling. This paper describes a mathematical modeling, and dynamic simulation of human body. The human dynamic model is simplified as a rigid body consisting of 18 actuated degrees of freedom for the real time computation. Complex kinematic chain of human body is partitioned as 6 serial kinematic chains that is, left arm, right arm, support leg, free leg, body, and head. Modeling is developed based on Newton-Euler formulation. The validity of proposed dynamic model, which represents mathematically high order differential equation, is verified through the dynamic simulation.

• Journal of electromagnetic engineering and science
• /
• v.7 no.2
• /
• pp.59-63
• /
• 2007

This paper suggests a novel method to efficiently calculate the spatial-domain Green's functions of 2D electromagnetic problems Briefly speaking, this method combines spectral and spatial domain calculation schemes and prevents the Green's functions from poor convergence due to the singularities that complicate the process of the Method of Moment(MoM) applications For the validation of this proposed method, fields will be evaluated along the spatial distance including zero distance for 2D free-space and periodic homogeneous geometry The numerical results show the validity of the prosed method and correspondng physics.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.3
• /
• pp.755-760
• /
• 1990

VAXIMA is a computer software which gives us results in terms of parameters. We use VAXIMA to analyze quantitatively a conservative dynamical system with cubic and quintic nonlinear terms. The system is described by a nonlinear second-order autonomous ordinary differential equation. Using the Lindstedt-Poincare method, we obtain period-amplitude characteristics. In order to check the validity of the approximate solution, we integrate numerically the equation of motion.

• International Journal of Control, Automation, and Systems
• /
• v.4 no.3
• /
• pp.365-371
• /
• 2006

This paper presents an algorithm based on a combination of Discrete Wavelet Transforms and neural networks for detection and classification of internal faults in a two-winding three-phase transformer. Fault conditions of the transformer are simulated using ATP/EMTP in order to obtain current signals. The training process for the neural network and fault diagnosis decision are implemented using toolboxes on MATLAB/Simulink. Various cases and fault types based on Thailand electricity transmission and distribution systems are studied to verify the validity of the algorithm. It is found that the proposed method gives a satisfactory accuracy, and will be particularly useful in a development of a modern differential relay for a transformer protection scheme.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.5
• /
• pp.350-357
• /
• 2020

This study presents the design of an 18 kW two-phase interleaved buck converter that uses a coupled inductor for an electric vehicle rapid charger. The designs of a two-phase coupled inductor for current ripple and physical size reduction and a two-phase interleaved buck converter based on silicon carbide metal - oxide - semiconductor field-effect transistor for high efficiency were described in detail. The operating principle of the two-phase interleaved buck converter was analyzed, and the coupled inductor was investigated using a magnetized equivalent circuit. Simulation and experiments were conducted to verify the validity of the proposed two-phase interleaved buck converter, and the theoretical design method and experimental results were confirmed.

• Proceedings of the KIEE Conference
• /
• 1999.07a
• /
• pp.220-222
• /
• 1999

This paper presents a numerical analysis of the eddy current testing with cracked pipe using finite element method (FEM). ${\vec{A}},\;{\phi}-{\vec{A}}$ method is adopted for the formulation of 3-dimensional(3-D) FEM with the brick element. The cracks investigated here are the inner and outer surface of axial symmetry, 90 degree circular one. The algorithm of 3-D numerical analysis is employed for the axisymmetric pipe with the cracks. In order to verify the validity of 3-D numerical analysis, the results are compared with those of 2-D analysis with the same type of the model. The differential impedance is obtained by using energy method and its locus are various 8-shaped curves for each cracks. The ICCG method is used for the calculation of a matrix.