• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.655-656
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• 2015

In this paper, diagnosis for 85 high voltage induction motors which have operated for more than 20 years in 18 wide area water supply offices were applied and the results of diagnosis were analysed. Furthermore, main factors that would be affecting rotor defects were selected and correlations between dependent variables which was magnitude for sideband frequency on current during operation and independent variables such as starting characteristic, operating time, number of operation, load factor, maker, rotation speed, capacity were analysed. It was clear that factors including starting characteristic, number of operation, maker, rotation speed caused break by correlation analysis. From this, regression equation was deduced through regression analysis. Based on suggested regression equation, it is applied usefully that we can estimate the condition of rotor without onsite diagnosis and plan the schedule of diagnosis.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.193-196
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• 2003

For a power source of usual electronic devices such as PDA, smart phone, UPS and electric vehicle, the battery made of serially connected multiple cells is generally used. In this case, if there are some unbalanced among cell voltages, the total lifetime and the total capacity of the battery are limited to a lower value. To maintain a balanced condition in cells, an effective method of regulating the cell voltage in indispensable. In this paper introduced a method for battery balancing system using dissipation in the resistance.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.324-329
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• 2017

The phase controlled rectifier using thyristor is suitable for the high capacity and low-cost system. However, the rectifier output voltage drop is influenced by the grid inductance effect. Supposing the commutation area voltage and current are analyzed, the grid inductance can be estimated using the proposed algorithm. This paper presents the grid inductance estimation method for improved commutation compensation control of the phase controlled rectifier, and the proposed control algorithm effectiveness is verified by simulation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.11
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• pp.425-432
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• 1984

This paper is to propse a new self-excitation method of synchronous generator. Instead of conventional exciter of synchronous generator, the additional winding which is arranged in addition to the armature winding, is used in this generator. The output terminal of the additional winding is connected to a capacitor and to a full wave rectifier in series. In this configuration, one source double excitation which is composed of capacitor-self-excitation by lead urrent and direct current excitation by rectifier, is induced. The result is that` The excetation efficency is improved greatly and output waveform is improved also. In three-phase synchronous generator using the new method of the one source double excitation, voltage element (shunt characteristics) and current element (series characteristics)are compounded in scalar by adapting star-point-open-rectifier system. The result is as following` The effect of load power factor angle on voltage regulation is reduced greatly, compound characteristics is become manifold by controlling capacity of capacitor, and transient response is improved.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.207-210
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• 1990

The purpose of this study is to research and develop polymer secondary battery. This paper describes the first discharge characteristics of PAn/Li-Al secondary battery. PAn was prepared in $HBF_4$ aqueous solution by galvanostatic electropolymerization and then used as cathode active material. PAn/Li-Al secondary battery was prepared in 2025 coin type. Characteristics of this battery are summarized as follows. ${\bullet}$ Open curcuit voltage and discharge end voltage was 3.5V and 2.9V, respectively. ${\bullet}$ The ratio of electricities in discharge to theoretical electricities in all undoping of PAn cathode was 56% at constant current discharge of 1mA. ${\bullet}$ The capacity density, energy density and maximum power density per weight of PAn electroactive material were 56.1Ah/kg, 168.4Wh/kg and 16.9kW/kg, respectively.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1731-1733
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• 1998

This report is the first intermediate report of a series of field test result of large high voltage motors. Major specimens were 3.3/6.6kV class pump motor that was installed and operated for public water service by KOWACO(KOrea WAter resources COperation). The capacity of specimen motors were in range of several hundred kVA. Until now, we get the 22 field test result by testing technique discribed in IEEE standards and discharge-map technique reported by Japanese engineers. The test result were varied very wide range, and there was a tendency according to insulation material and manufacture.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.1
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• pp.37-41
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• 2018

In this paper, the ESS(Energy Storage System) is interconnected in order to reduce the maximum load in the distribution system and the target location of the ESS is set to be close to the rated voltage. We also applied the weights to nodes with large capacity and number of customers in the system. In the future, the interconnected location of the ESS was determined until 2029 in consideration of the load increase rated of the system. We propose a cooperative decision algorithm of interconnected location of ESS for Power Distribution System.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1505-1508
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• 1994

Lately in KEPCO, the power plant capacity has increasingly become larger than before and it has become difficult to get R.O.W for T/L. Therefore KEPCO decided to increase its system voltage level from 345kV to 765kV. By doing this, KEPCO would like to expand its transmission capability by less T/L route. In 765kV system, we should consider various kinds of environmental impacts that can be neglected in lower voltage level. These environmental impacts are very important factor in T/L design. That can be changed greatly according to the selected conductor. And also conductor selection has relation with the economy of T/L construction directly. This paper deals with some general factors to be considered and basic principles about the conductor and ground wire selection for 765KV T/L with referring to the experiences of foreign utilities.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.26-35
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• 2010

The maximum output torque developed by the machine is dependent on the allowable current rating and maximum voltage that the inverter can supply to the machine. Therefore, to use the inverter capacity fully, it is desirable to use the control scheme considering the voltage and current limit condition, which can yield the maximum torque per ampere over the entire speed range. This controller is controlled speed and current using hybrid PI(HBPI) controller and estimation of speed using ANN. Also, this paper is proposed maximum torque control of induction motor using slip angular speed and current condition at widely speed range. The performance of the proposed induction motor drive with maximum torque control using HBPI controller is verified by analysis results at dynamic operation conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.256-257
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• 2008

Recently, with the increase of demand of electricity, electric cable or electric transfer machine are rapidly developed and meet the demand with the extra high voltage and massive capacity, the dangers of electrical accident of insulator are increasing by the electric stress, insulation degradation and insulation breakdown in insulator. In this paper, it is investigated that the temperature dependance of dielectric strength in nano-composites. We obtained that breakdown voltage of 0.4 [wt%] specimens is higher than the other $SiO_2$ content.