• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.339-341
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• 2006

Increasing interconnection of power plants in modern large electric power system has made power system dynamic studies much more complex. For effective analysis of the power system, model reduction and aggregation is required. In this paper, a new relation index is presented to identify the coherent generators in the large scale power system. In order to demonstrate the effects of this relation index, it is applied to a small scale power system of IEEE 39-bus test system and the simulation results are presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1367-1372
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• 2007

The modem large electric power system has made power system analysis much more complex and difficult. For effective analysis of the power system, model reduction and aggregation is required. In this paper, a new relation index to identify the coherency among the generators is presented and also a new aggregation method is presented to aggregate the coherent generators in the large scale power system while matching the power flow. In order to demonstrate the effects of this aggregation method, it is applied to the IEEE 39 bus test power system and to the 2006 summer power system of Korea Electric Power Corporation, and the simulation results are compared with those of the original system.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.610-615
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• 2015

In order to study and obtain the mathematical relation between the electrification degree of transformer oil flow and the electrostatic current, a small amount of data about the electrification degree of oil flow and the corresponding electrostatic current is studied by linear regression method and grey model method. The results show that the linear correlation between the electrification degree and the electrostatic current was not good, and the relation between the electrification degree of oil flow and electrostatic current (i) could be expressed as ${\rho}(0)=0.2049\;i^{(0)}+169.4419$ according to grey model GM (0, 2) when the electrification degree of oil flow is represented by the charge number generated from transformer oil per unit volume, namely the charge density (${\rho}$).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.502-508
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• 2009

The method to determine the operating current of HTS magnets needs to be different from that of LTS magnets. This paper presented estimation of the critical current of pancake windings. The pancake windings can be excited by a single power source or by multiple power sources. Critical currents were determined by using field dependent E-J relation. For the better estimation of the critical current, a new method to define the magnetic field of the HTS wire has been proposed. Calculated critical currents of pancake windings were compared with measured ones of the HTS BSCCO magnet consisting of 10 pancake windings. According to the test results, the estimated critical currents of pancake windings agreed well with that of measured ones. Effects of the single and multiple power source excitation on the critical currents have been also examined.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.193-195
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• 2002

This paper presents the methods to solve the problem about Power System Protection Program(PROSET) and describe the database relation and schema with UML. PROSET is a overall program system to protect power system and correct it. In the context of the PROSET it is so difficult to edit database data when topology is changed. When the renewal of data is performed. all changed values are disappeared. Therefore, it will not be expected to know the present situation by using the information of the databases data. So it is necessary to solve this problem. Solution is copy of the user. Only E.R diagram is used to express database schema and relation. So, in this paper, UML(Unified Modeling Language) will be used to express PROSET and database of MCD-H and MDT-H.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1537-1546
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• 2011

The photovoltaic(PV) generation system have recently become widely used to solve the environmental problems and running out of fossil fuels. However, the study on maintenance is inadequate for PV system. This paper proposes the novel diagnosis method of output power decline to maintain the normal output performance of PV array. The diagnosis method used the proportional relation of irradiation-output current(S-I) of PV array at maximum power point(MPP). And, first order polynomial using the relation is proposed to easily apply PV system. To estimate the relation in case of separation of PV array producer and diagnosis system producer. Kalman Filter algorithm is also proposed at 30.2kW grid-connected PV system. Then, the performance of diagnosis method is evaluated using the hardware tests as well as the simulation.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.15-26
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• 1997

In this study, the theoretical investigation of the electrically heated catalyst(EHC) for vehicle application has been carried out using the thermal equivalence of EHC system and the data of vehicle tests to meet ultra low emission vehicle(ULEV) standard. To improve the efficiency of EHC system, it is necessary to understand relation between the power, the operating time and the conversion efficiency of EHC system. The relation was found with thermal equivalence of EHC system which considers the power supply to EHC, heat loss, chemical exothermic energy generated by oxidation reaction and net energy coming in via the exhaust gas. From this relation, the limits of needful power and operating time to meet the ULEV standard can be suggested, when the conversion efficiency of catalyst was known.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.8
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• pp.399-404
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• 2000

This paper presents new algorithms equivalencing large-scale power systems. Generators are identified to the coherent groups according to the relation factors, which represent the relative coupling degree between the generators. While the groups are identified, participation numbers, which are the measure of the relative participation of the generators in the group, are obtained. All generators and controllers in the group are weighted by participation numbers and aggregated to construct a dynamic equivalent. The proposed algorithms are applied to a 272-machine Korea Electric Power Corporation (KEPCO)'s system. The enclosed results indicate the accuracy and usefulness of the algorithms.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1666-1669
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• 1998

In General, Distribution Line is largely effected by temperature, humidity and natural system's condition. The power system network, particularly fault of power distribution system connected to comsumer would cause a magnificent effect to the society. And then Improvement in living conditions and increase in the industrial production brought by the development in economy and new technology, in due course, ask more and reliable electric energy. In this paper, we will describes that the effection of deterioration in Insulator and its relation of fault in power system.

• Journal of Korea Port Economic Association
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• v.27 no.2
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• pp.111-136
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• 2011

This article aims to reveal the relative influences to the Brand Power and Performance of Factors that comprise the port brand assets in order to control and manage the ports. And also this Paper want to suggest the useful strategies and implications for the improvement of Brand Power by comparing the level of brand competitiveness of Incheon Port with those of other Korean ports that are in competitive relation. In this research we can find out that the components of port brand asset are awareness level, image, service quality, and satisfaction of relation. And among those 4 factors, recognition level and satisfaction of relation are very significant relation factors for the loyalty in Incheon Port. In comparison study between Incheon and Pyungtack Ports, satisfaction of relation is revealed as especially significant factor for the customers that show highly effective management performances and we can find that, in Busan Port, image and service quality are significant as well.