• Journal of the Chungcheong Mathematical Society
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• v.15 no.2
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• pp.35-39
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• 2003

In this paper we study a ring over which every left module of finite length has an injective hull of finite length. We consider a ring that is a finite intermediate normalizing extension ring of such a ring. We also consider the subrings of such a ring.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.944-950
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• 2008

When small cogenerators are operated in connected with power system, there are many positive aspects such as the reduction of power plant construction, making a improvement of power security etc. At the same time, there are some negative effects or difficulties such as we should make sure of protective coordination, especially, Actually these are not fault, but it is likely to consider the current as the fault. This is one of major causes of malfunctions for protective relays in power distribution system which is including interconnection point. Thus, in this paper, We showed that the directional protection is necessary to the dispersed generation system which is including connection point. We also executed contingency analysis to find out the magnitude of fault current and direction which are classified by fault points, length of line and kinds of faults using ETAP power system analysis program.