• Journal of electromagnetic engineering and science
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• v.16 no.3
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• pp.182-190
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• 2016

The problem of resolution in antenna ground-penetrating radar (GPR) is very important for the investigation and detection of buried targets. We should solve this problem with software or a numeric method. The purposes of this paper are the modelling and simulation resolution of antenna radar GPR using three antennas, arrays (as in the software REFLEXW), the antenna dipole (as in GprMax2D), and a bow-tie antenna (as in the experimental results). The numeric code has been developed for study resolution antennas by scattered electric fields in mode B-scan. Three frequency antennas (500, 800, and 1,000 MHz) have been used in this work. The simulation results were compared with experimental results obtained by Rial and colleagues under the same conditions.

• Structural Engineering and Mechanics
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• v.55 no.3
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• pp.495-510
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• 2015

Free vibration of non-uniform embedded nanoplates based on classical (Kirchhoff's) plate theory in conjunction with nonlocal elasticity theory has been studied. The nanoplate is assumed to be rested on two-parameter Winkler-Pasternak elastic foundation. Non-uniform material properties of nanoplates have been considered by taking linear as well as quadratic variations of Young's modulus and density along the space coordinates. Detailed analysis has been reported for all possible casesof such variations. Trial functions denoting transverse deflection of the plate are expressed in simple algebraic polynomial forms. Application of the present method converts the problem into generalised eigen value problem. The study aims to investigate the effects of non-uniform parameter, elastic foundation, nonlocal parameter, boundary condition, aspect ratio and length of nanoplates on the frequency parameters. Three-dimensional mode shapes for some of the boundary conditions have also been illustrated. One may note that present method is easier to handle any sets of boundary conditions at the edges.

• Ocean Systems Engineering
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• v.10 no.2
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• pp.227-241
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• 2020

This paper deals with the problem of the global stabilization for a class of tension leg platform (TLP) nonlinear control systems. Problem and objective: Based on the relaxed method, the chaotic system can be stabilized by regulating appropriately the parameters of dither. Scope and method: If the frequency of dither is high enough, the trajectory of the closed-loop dithered chaotic system and that of its corresponding model-the closed-loop fuzzy relaxed system can be made as close as desired. Results and conclusion: The behavior of the closed-loop dithered chaotic system can be rigorously predicted by establishing that of the closed-loop fuzzy relaxed system.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.681-683
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• 2004

This paper describes the control of a geared DC motor having a backlash for implementation of a humanoid robot using disturbance observer. Critical problem of the humanoid robot is caused by the nonlinearity such as a backlash. To meet this problem, a control method using disturbance observer has been proposed. The disturbance observer is designed to estimate the effects of nonlinearities in the system, to make the nonlinear system behave linearly. To design the low-pass filter in the disturbance observer, cut-off frequency of the output should be found. The goal of this paper is the implementation of the proposed system, compensating the backlash effect. To accomplish the goat, PD control and disturbance observer are employed to the system with no load and full load. As a result, system stability can be guaranteed by compensating the effect of backlash. In addition, real experiment shows the proposed control methodology will satisfy the stable working of a humanoid type in the future.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.779-782
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• 1998

This paper describes a high-speed Dual-modulus Prescaler (DMP) for RF mobile communication systems with pulse remover using selective latch technique. This circuit achieves high speed and low power consumption by reducing full speed flip-flops and using a selective latch. The proposed DMP consists of only one full speed flip-flop, a selective latch, conventional flip-flops, and a control gate. In order to ensure the timing of control signal, duty cycle problem and propagation delay must be considered. The failling edgetriggered flip-flops alleviate the duty cycle problem andthis paper shows that the propagation delay of control signal doesn't matter. The maximum operating frequency of the proposed DMP with 0.6um CMOS technology is up to 2.2㎓ at 3.3V power supply and the circuit consumes 5.24mA.

• Korean Journal of Child Studies
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• v.14 no.1
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• pp.59-75
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• 1993

Based upon the ABC-X model and family systems theory, this study examined (1) problem-solving and behavioral strategies utilized by children in divorced families, and (2) factors related to children's post-divorce adjustment. Date were collected from 158 elementary school aged children and adolescents of divorced families in an urban area (56 male and 102 female). Results of this study indicated that there were significant age differences in problem-solving and behavioral strategies utilized by difficult family situations. Factors that are useful in predicting adjustment of divorced children are the following variables: sex, visitation frequency of noncustodial parent, quality of custodial parent-child communication, and length of divorce. Implications for knowledge as well as recommendations for future research are discussed.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1338-1339
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• 2011

Recently the wind turbine generating systems are increasing world widely. This type of systems will change the nation's energy environment which largely depends on the fossil fuels. It will also bring new problems to the power industry and the customers. The expected problem is the voltage and frequency stability of the power distribution network, when a wind turbine generating system is connected to the line. It becomes necessary and important to evaluate their impact on the electrical network stability. This paper shows the electrical data measurement and analysis of a inductive wind turbine generator affecting the power quality problem of the distribution line.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.58-63
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• 2000

The dynamics of spindle-bearing-workpiece system significantly affects the cutting condition and stability in milling process. The present paper investigates the chatter stability of milling process due to the change in the dynamics of spindle-bearing-workpiece systems. In particular, the present paper focuses on chatter stability due to the presence of gyroscopic effect. An eigenvalue problem approach to the stability of milling process is extensively used in this paper. To incorporate the rotational speed dependent gyroscopic effect, an iterative algorithm is proposed. A numerical example is provided for examining the chatter stability problem in the presence of gyroscopic effects.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.108-111
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• 2007

Phase angle in grid-connected inverter is important information for current control. When different loads are connected to PCC(Point of Common Coupling) of grid, distorted grid voltage is taken place by load utility generating distorted current. Especially, in case the grid voltage is distorted by low order frequency such as $3^{rd}$, $5^{th}$ harmonic, phase angle of PLL output is distorted. This paper analyze problem of current THD(Total Harmonic Distortion) due to distorted phase angle by distorted grid voltage, and propose control method compensating this problem. Also, it‘s validity is verified by simulation and experiment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.3
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• pp.28-34
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• 2010

The suggested coupled system was analyzed using FRF and mode analysis. The eigen-mode of FRF analysis is consistent with that of conventional FFT in spectrum. Also, three numerical responses of second order system, which are coupled, was obtained using the Runge-Kutta Gill method. The displacement, velocity and acceleration response were calculated for the numerical analysis of coupled system and the displacement response was used for the calculation of FRF of this system. Using the mixed response of 1st and 2nd mode in example, the FRF was analysed for the analysis of mixed mode coupled system. Also, its mode shape was acquired by solving the eigen problem of coupled system.