• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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• pp.246-250
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• 2005

The forward voltage drop of IGBT is studied numerically and analytically as a function of gate length. An analytical expression is presented for the first time for the surface potential variation along the channel layer under the gate of IGBT. The surface potential drop and the carrier density near the surface allow calculation of the forward voltage drop of IGBT analytically as a function of the gate length. The voltage-drop in the drift region near the gate decreases exponentially, whereas that on the surface increases linearly with increasing the gate length, the sum of which exhibits an optimum gate length, resulting in a minimum forward voltage drop. Based on the surface potential drop, a remodelling of the forward voltage drop of IGBT is also proposed.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.478-481
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• 1991

This paper discusses the principle and structure of instantaneous voltage drop compensator, which protects damage from instantaneous voltage drop in systems such as computer, variable speed drive, high voltage discharge-lamp, magnet switch. When instantaneous voltage drop occurs, control circuits detect it, then produce output voltage the same as normal condition voltage. Instantaneous voltage drop compensator has condenser bank as energy storage component, so system can be made small, light weight compared with UPS. In normal state, utility source transfers power, and in instantaneous voltage drop state, the energy of condenser bank transfers power through inverter, so high efficiency, compact, and especially low cost system can be manufactured.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.400-402
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• 1994

The voltage drop in distribution path of battery-reserved DC power system can affect the total of battery, cable and electricity costs. To determine an optimum voltage drop in distribution path for minimizing the total cost, battery, cable and electricity costs are represented as a function of the voltage drop, respectively, and are summed up to the total cost. An optimum voltage drop is selected as the value giving the minimum total cost. In this paper, a design technique of optimum voltage drop in distribution path of DC power system is proposed to minimize the total of battery, cable and electricity costs. The design procedure is described and design curve for selecting optimum voltage drop is also presented as a function of distribution distance.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.7
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• pp.11-17
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• 1982

In this paper, a reliable and convenient evaluation method for the adequacy of any radial distribution line's voltage drop is proposed for improvement of the voltage regulation of the distribution line under operation. Using the voltage measurement of the first load branch point and the last point on the given distribution line its average line voltage drop and the line voltage drop variance by pure load variation are computed. And by these values and allowable or required line drop from proper voltage regulation view point, present adequency index and operation improvement index of the line drop are newly introduced for the evaluation of the given distribution line's voltage regulation. As a result of application to the 4 cases of study, the proposed method is proved to be reliable and convenient.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.118-120
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• 2002

Voltage drop of low voltage distribution line is closely related with proper voltage regulation. It depends on the voltage drop of pole transformer, low voltage distribution line, and low voltage customer entrance line. Using above voltage drop factors, we proposes an estimation method of voltage drop in low voltage distribution line. Proposed method has been applied to a 22.9kV practical distribution system.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.940-947
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• 2011

Load capacity varies according to a day of the week in traction power supply system, because time schedule in railway is changed as demand for passengers and freights. Therefore, Voltage drop also varies as load capacity. In Korea railway, Voltage collected from catenary in train is decreased, as load supplied traction power supply system is increased. Therefore, investigation about voltage drop should be performed, before development of countermeasure against voltage drop. The investigation can be performed by simulation or field test. Naturally, field test is more precise than simulation. In addition, field test should be carried out at peak load. This paper presents test and analysis about voltage drop in railway. The test is performed in both a day of the week and weekend. The analysis is figured out comparison load capacity between two days and voltage drop across terminal.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2210-2211
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• 2011

Load capacity varies according to a day of the week in traction power supply system, because time schedule in railway is changed as demand for passengers and freights. Therefore, Voltage drop also varies as load capacity. In Korea railway, Voltage collected from catenary in train is decreased, as load supplied traction power supply system is increased. Therefore, investigation about voltage drop should be performed, before development of countermeasure against voltage drop. The investigation can be performed by simulation or field test. Naturally, field test is more precise than simulation. In addition, field test should be carried out at peak load. This paper presents test and analysis about voltage drop in railway. The test is performed in both a day of the week and weekend. The analysis is figured out comparison load capacity between two days and voltage drop across terminal.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.5
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• pp.411-416
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• 2010

A voltage drop characteristics of a transformer-based voltage disturbance generator with series transformers is analysed. It is well known that a voltage disturbance generator with series transformer is cost-effective and reliable compared with other types. The voltage drop depends on the %Z of the transformer, power rating, and output power factor. A wrong design of the transformer results in a severe voltage drop, which can not guarantee the proper performance of the generator. The voltage drop is analysed under the condition of 10kVA output power rating and 4% of %Z with the variation of power factor. It is found through simulations and experiments that the drop increases as the power factor decreases in lagging mode, and the drop is 4% of the rated voltage in case of 0.85 lagging power factor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.11
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• pp.681-684
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• 2016

This research was carried out experiments of variety IGBTs for industrial inverter and electric vehicle. The devices for this paper were planar gate IGBT, trench gate IGBT and dual gate IGBT and we designed using same design and process parameters. As a result of experiments, the electrical characteristics of planar gate IGBT were 1,459 V of breakdown voltage, 4.04 V of threshold voltage and 4.7 V of on-state voltage drop. And the electrical characteristics of trench gate IGBT were 1,473 V of breakdown voltage, 4.11 V of threshold voltage and 3.17 V of on-state voltage drop. Lastly, the electrical characteristics of dual gate IGBT were 1,467 V of breakdown voltage, 4.14 V of threshold voltage and 3.08V of on-state voltage drop. We almost knew that the trench gate IGBT was superior to dual gate IGBT in terms of breakdown voltage. On the other hand, the dual gate IGBT was better than the trench gate IGBT in terms of on state voltage drop.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1708-1714
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• 2011

AT feeding system of the electric railway system is installed every about 10km at between the feeder and catenary in parallel and the mid-point of the transformer is connected to the rail The supply voltage of this system is doubled than rolling stock voltage. So the voltage drop is smaller than usual. And the other merit of this system is the decreasing inductive disturbance to the communication line because of the reduced current in rail which runs reversed in a point of view of rolling stock. Also, ATP(Auto Transformer Post) is installed to reduce the voltage drop and to mitigate the inductive disturbance, but still now the proper distance between the ATP and AT feeding system is not established which ranges from 2 to 10[km]. The stable result of simulation(which is set that the end of the line AT is installed) to the voltage drop and inductive disturbance can not analyzes the effect to the supply system due to the ATP. This paper analyzes the effect to the system depending on the location of ATP by forecasting the voltage drop and inductive disturbance.