• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.464-465
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• 2008

Concrete poles(CP) are popular supports for distribution lines. Various types of grounding electrode, such as copper-clad rods, have been used to maintain CP's ground resistance under the required value. The buried part of CP can also have structural grounding effect because of its iron reinforcing rods inside CPs. In this paper, we measured the total ground current injected into CP ground while measuring the ground current splitting to the metal electrode as well as the total injecting current. By this, it was able to measure the ground current splitting to CP structure. Based on the measured results, interrelationship between ground resistance of metal electrodes and current split factor to CP structure was analyzed.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2100-2101
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• 2008

This paper is studied on a protective control system for electrical fire and electrical faults due to over current or electric short circuit faults by using electrical thermal characteristics of PTC (Positive Temperature Coefficient) thermistor and current response characteristics of high sensitive reed switch. The PTC thermistor has characteristic of positive resistivity temperature coefficient according to the temperature variation, which is construction of a regular square and cube demarcation with BaTiO3_Ceramics of positive temperature coefficient. Also PTC thermistor shows the phenomenon which is rapidly increased in the resistivity if the temperature is increased over Curie temperature point, and reed switch, which is used for electrical fault current sensing devices, have a excellent characteristic of response velocity in degree of ${\mu}s{\sim}ms$ that sensing magnetic flux in proportion to dimension of line current. This paper is proposed on a protective control system use PTC thermistor and reed switch for sensor which is protected from electrical fire due to overload faults or electric short circuit faults. Some experimental results of the proposed electric safety control device are confirmed to the validity of the analytical results.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.48-53
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• 1994

In this paper, we present the analytical models for substrate current and gate current of stressed SC-PMOSFET using the change of the lateral electric field distribution due to the trapped electron. Calculated Isub and Ig of stressed SC-PMOSFET agree with experimental data. Our model can be very useful explaining the logarithmic time dependence of Isub and Ig. and also the trapped electron distribution.

• Membrane and Water Treatment
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• v.1 no.1
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• pp.13-37
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• 2010

The performance of an electrodialyzer for concentrating seawater is predicted by means of a computer simulation, which includes the following five steps; Step 1 mass transport; Step 2 current density distribution; Step 3 cell voltage; Step 4 NaCl concentration in a concentrated solution and energy consumption; Step 5 limiting current density. The program is developed on the basis of the following assumption; (1) Solution leakage and electric current leakage in an electrodialyzer are negligible. (2) Direct current electric resistance of a membrane includes the electric resistance of a boundary layer formed on the desalting surface of the membrane due to concentration polarization. (3) Frequency distribution of solution velocity ratio in desalting cells is equated by the normal distribution. (4) Current density i at x distant from the inlets of desalting cells is approximated by the quadratic equation. (5) Voltage difference between the electrodes at the entrance of desalting cells is equal to the value at the exits. (6) Limiting current density of an electrodialyzer is defined as average current density applied to an electrodialyzer when current density reaches the limit of an ion exchange membrane at the outlet of a desalting cell in which linear velocity and electrolyte concentration are the least. (7) Concentrated solutions are extracted from concentrating cells to the outside of the process. The validity of the computer simulation model is demonstrated by comparing the computed results with the performance of electrodialyzers operating in salt-manufacturing plants. The model makes it possible to discuss optimum specifications and operating conditions of a practical-scale electrodialyzer.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.285-290
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• 2002

Power systems are becoming larger and larger for meeting electric power demand. Therefore, the over-currents resulting from contingencies such short circuits are increasing higher. The Maximum short circuit current of modern power system is becoming so large that circuit breaker are not expected th be able to shut down the current in the future. In order to cut over-currents, a system composed of a superconducting fault current limiter(SFCL) and traditional breaker seems to provide a promising solution for future power operation. In present paper, three line-to-ground fault is assumed to happen at the center of 345kV transmission lines in a large capacity electric power system The superconducting fault current limiter was represented using a commutation type, which consists of a non-inductive superconducting coil and current limiting element(resistor or reactor). The introduction merits of the SFCL were investigated quantitatively by RTDS/EMTDC from the viewpoint of current limiting performance, the prevention of the voltage drop at the load bus and comparison characteristics for two type SFCL. Desired design specification and operation parameters of SFCL were also given qualitatively by the performance evaluation of the two type SFCL in the power system.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.3
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• pp.19-24
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• 2005

Arc Fault Current is an electric discharge which is occurred in two opposite electrode. In this paper, arc current control algorithm is designed for the interruption of arc fault current which is occurred in the local electric network. This arc is one of the main causes of electric fire. Arc fault in electrical network has the characteristics of low current, high impedance and high frequency. Conventional arc current controller does not have the arc current interrupt function. Hence, Controller of arc current is designed for the interruption of arc fault current which has the modified arc characteristics.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.615-620
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• 2015

DOB (Disturbance Observer) is an useful control method for estimating the disturbance applied to dynamic systems. Disturbance observer can be used to implement a robust control system to generate a control input for rejecting the disturbance, and it can be also used to estimate the disturbance to obtain information. The system that uses disturbance estimation is investigated for high performance control such as automatic door systems, walking robot and electric power steering system in vehicles. In this paper, a novel disturbance observer which is called disturbance and current observer for estimating load torque in the motor system is proposed. The difference between the DOB for disturbance rejection and DCOB is mathematically verified. Current and angular velocity are required for estimating the load torque of the motor in DOB. However, the DCOB can estimate load torque and current without current sensor. DCOB is designed based on modeling of the motor system. Appropriate Q-filter is selected and the applicability of DCOB is verified by simulation. The estimated disturbance and current of the electric motor can be verified without current sensor, as experiments of the actual motor system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.547-550
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• 2004

Superconducting fault current limiter(SFCL) is expected to be introduced into electric power system in future as an effective countermeasure for the increase of the short-circuit current due to the growth of the electric power system. SFCL has a merit that the fault current can be limited by the resistance generated when a superconductor transits from a superconducting state to a normal state without additional detecting device. In this paper, we investigated the resistance variance of resistive type SFCL and the fault current limiting characteristics due to the amplitude of source voltage. We could obtain the more effective fault current limiting characteristics of SFCL as the source voltage increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.523-526
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• 2004

According to the continuous demand for power and the growth of electric power utilities, the electric power transmission capacity was increased. The increase of the electric power transmission capacity results in an increase of the fault current level a fault happened. So the superconducting fault current limiter(SFCL) has been reached as the countermeasure for the reduction of the fault current. In this paper, we investigate the fault currents characteristics of resistive type SFCL according to fault angles when AC power source applied. As the fault angles increase, the first peak value of fault current decreased lower. On the other hand, the power burden of SFCL increased.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.1
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• pp.55-62
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• 2015

The electromagnetic force induced by an intense electric current pulse, which generates an electromagnetic field around the metal jet originating from a shaped charge, can disperse and scatter the high-speed metal jet. An electric device consisting of an RLC circuit applies an intense electric current pulse that flows in the circuit while the metal jet passes between two electrodes. In this study, the metal jet formation was simulated using the ALE technique in 2-D, and a 3-D finite element model was mapped using 2-D simulation results to induce the electric current directly. The deformed shapes of the metal jet and the electromagnetic force were calculated using a finite element analysis by inducing the electric current directly, and the major parameters of the intense electric current pulse for breaking up the metal jet were examined.