• Composites Research
• /
• v.22 no.1
• /
• pp.9-14
• /
• 2009

This paper suggested the electric potential method with a bridge circuit concept for the detection of the location and crack growth of carbon fiber reinforced composites to reduce the measurement numbers. 2 pairs of electrodes were fabricated on the center cracked thin composite plates, and potential changes at one pair of adjacent electrodes were observed while external voltage input was applied to the other pair of adjacent electrodes. The effects of the size and interval of electrodes, location and propagating direction of center cracks were investigated by experiments and finite element analyses. Detectable crack size was influenced by the electrode interval rather than the electrode size, and crack detection was enhanced as the size and interval of electrodes were smaller. Besides, output potential changes were larger as the crack grew and was nearer the voltage input electrodes.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1401-1403
• /
• 1995

This paper investigates the light output characteristics of an electrodeless H-discharge lamp. The existing cylindrical fluorescent lamps were wound around with an induction coil of varying size, and were driven by RF power. The light output and the luminous efficacy were measured according to variations of the induction coil gap and the lamp power, respectively. The experimental results show that the luminous efficacy of the lamp is as much as existing electrodeless lamps and the luminous efficacy of lamps are high between 10W and 20W. Theoretical analyses using computer simulation show that the circuit matching is easier in the external coil configuration than in the internal one, and that the current and the power distributions near the coil are shower in t.

• Proceedings of the KWS Conference
• /
• v.43
• /
• pp.171-173
• /
• 2004

Electromagnetic force is one of the most important factor that effect on metal transfer mode, short-circuit rate, spatter generation rate and mechanical properties of weld metal etc. Also, shielding gas and welding current have influence on metal transfer mode in GMAW. In this paper, different ways for external electromagnetic forces are applied by attaching cylindrically rounded conducting wire solenoid on touch tip holding. With the applied electromagnetic field, the arc transfer mode changes from normal mode to rotating mode and spatter generation decreased in electromagnetic fields(N-pole). In MIG welding, the influences of electromagnetic force on the spatter generation showed different tendency as in the $CO_2$ welding. It is possible reasons were discussed.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.5
• /
• pp.854-859
• /
• 2007

A wind farm consists of many wind generator(WG)s therefore, it is generally a complex power system. A wind farm as a distributed generation(DG) affects utility power system. If a conventional protection schemes are applied, it is difficult to detect faults correctly and the schemes can't provide proper coordination in some cases. This paper presents a protection algorithm for a wind farm which consists of a looped collection circuit. Because the proposed algorithm can distinguish between an internal fault and an external fault in a wind farm, The proposed algorithm can disconnect the faulted section in a wind farm. This algorithm is based on an overcurrent protection technique with the change of the ratio of the output current of a generator to the current of the looped line connected to each generator to collect the each generator's power. In addition, operating time of the algorithm is shortened by using the voltage drop at a generator collection point. The performance of the proposed algorithm was verified under various fault conditions using PSCAD/EMTDC simulations.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1263-1266
• /
• 2006

A circuit model simulating the electrical characteristics of EEFL(External Electrode Fluorescent Lamp) is proposed. The model is based on linear approximation that represents the equivalent resistance and capacitance as a function of power. Simulation waveforms and experimental results are presented to verify feasibility of the equivalent model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.7
• /
• pp.578-583
• /
• 2001

The bushing for high voltage and large and power should endure weight of itself and force of pushing from contact with circuit breaker. Like this, epoxy mold bushing has to be strong without fault. However, the external circumstances and internal factors was caused by partial discharge, flashover and dielectric breakdown. Therefore, to remove external factor of defect and to prevent the internal cracks and cavity generated from the contraction on interface of Cu-Epoxy, we should form semi-conductive layer on Cu bar by carbon. Then, the PD properties and the insulation qualities of epoxy mold type bushing was able to improved by roles of cushions for the direction of diameter and by effects fo natural sliding like as separated from conductor for the direction of length. So, in this work, we could prove the method of semi-conductive layer in making the long conductor.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.343-345
• /
• 2005

In the study, the noise involved on the active circuit is identified using correlation function. In order to figure out the unknown location of noise source, signals from each sections in the system are collected and the location is identified by a concept called "Noise Source SUI-face". Experiment is conducted to confirm the validity of the proposed method. Also a method to reduce and control the noise in the system signal by using Matrix Pencil Method is introduced. Experiment is attempted to prove that the total noise of system can be reduced by controlling the external noise.

• Journal of Magnetics
• /
• v.16 no.2
• /
• pp.140-144
• /
• 2011

We report on a numerical calculation study of two new functional properties in magnetic tunnel junctions (MTJs), negative dynamic resistance and RF amplification. The magnetic dynamics in a conventional CoFeB/MgO/CoFeB MTJ with in-plane magnetization was investigated using a macro-spin model simulation. To examine the influence of thermal fluctuations, random external magnetic fields were also included. Using a voltage controlled bias circuit, the negative dynamic resistance was obtained from time averaged I-V characteristics at both 0 K and 300 K under appropriate external magnetic fields and bias voltages. Using this negative dynamic resistance property, we demonstrated RF amplification with a 100 MHz high frequency signal. Sizable RF amplification gain was observed without thermal fluctuation. However, at 300 K, the RF signal was not amplified because low frequency magnetization dynamics were dominant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.9-12
• /
• 2000

Insulators for high-voltage and large-power should be endured mechanically the weight of mold bushing itself and the force of pushed from contact with circuit breaker and conductor. But dielectric breakdown could be occurred result from the external circumstances and internal factors such as chemical reaction, partial discharge, change of temperature and the relation of temperature-time in process of casting. Therefore, to get rid of external and internal factors of dielectric breakdown. Furthermore, to prevent the internal cracks, void, cavity which resulted from the contraction originated on the interface between copper and epoxy resin, formed semi-conductive layer with partially carbon painted on copper bar. The PD properties and the insulation qualities of epoxy molded insulators were improved by roles of cushions for the direction of diameter and natural sliding effects as like separated from conductor for the direction of length.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.3
• /
• pp.632-637
• /
• 2008

On board Weapon Control Unit for a military aircraft, as a core equipment of the Weapon Management System, generates signals for selective jettison, emergency jettison and rocket fire and controls the external stores according to a pilot's weapon selection, aircraft's flight status and external store's installation status. This paper describes about detail design process and performance evaluation for Weapon Control Unit developed by a sequence control circuit design methodology.