Hyosung Heavy Industries Corporation

Yuhan Corporation

Byung Choul Kim

Jung Ki Hong

Young Seong Han

Chang Sik Kim

Se Hee Han

Jong Wook Lee

Choong S Kim

Bong Yong Lee

Byung H Han

Jung J Suh

Provided is a DC breaker that can block a fault current generated in a direct current line, by using a unidirectional semiconductor switch device. The DC breaker includes: a mechanical switch that is connected between first and second direct current lines; a first unidirectional semiconductor switch device that transfers a resonant current to the first direct current line when the fault current is generated, so that a current of the first direct current line becomes zero; an LC resonant circuit that is charged by receiving a steady state current of the first direct current line, and generates the resonant current to the first unidirectional semiconductor switch device when the fault current is generated; and a second unidirectional semiconductor switch device that enables a capacitor of the LC resonant circuit to be charged with the steady state current of the first direct current line.

DC breaker capable of blocking fault current generated in direct current lines

Disclosed is a DC circuit breaker capable of interrupting fault currents flowing in both forward and backward directions. The DC circuit breaker includes: a mechanical switch installed on a DC transmission line and being opened to interrupt a current in the DC transmission line when a fault occurs at one side or remaining side thereof on the DC transmission line; a first bidirectional switching device connected in parallel with the mechanical switch and switching currents flowing in both forward and backward directions; an LC circuit connected in parallel with the mechanical switch and including a capacitor and a reactor connected in series to induce LC resonance; a first unidirectional switching device connected in parallel with the LC circuit and switching a current to induce LC resonance; and a second bidirectional switching device connected in series with the LC circuit and switching currents flowing in both forward and backward directions.

DC circuit breaker

Disclosed is a DC circuit breaker capable of interrupting fault currents flowing in both forward and backward directions. The DC circuit breaker includes: a first mechanical switch for interrupting a current in a DC transmission line; a first diode connected in parallel with the first mechanical switch; a second mechanical switch, connected in series with the first mechanical switch, for interrupting a current in the DC transmission line; a second diode connected in parallel with the second mechanical switch; an LC circuit connected in parallel with the first and second mechanical switches and including a capacitor and a reactor connected in series to induce LC resonance; a first unidirectional switching device connected in parallel with the LC circuit and switching a current to induce LC resonance; and a bidirectional switching device connected in series with the LC circuit and switching currents flowing in both forward and backward directions.

The present invention relates to 1,4-dihydropyridine of the formula(I) ##STR1## wherein R.sup.1 represents a phenyl group which may be substituted by one or two substituents selected from halogeno, nitro, trifluoromethyl and difluoromethoxy group, or 2,1,3-benzoxadiazole-4-yl group, R.sup.2 represents a lower alkyl or phenyl group, R.sup.3 represents a lower alkyl group and Y represents an oxygen or sulfur atom. The compounds of the formula(I) can be employed for treatment or prevention of cardiovascular diseases.

Growing community of inventors

Incheon, South Korea

Byung Choul Kim