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Gwangju, South Korea

Jung B.-I.,Dongkang College | Choi H.-S.,Chosun University
Progress in Superconductivity and Cryogenics (PSAC) | Year: 2016

The study of superconducting fault current limiter (SFCL) is continuously being studied as a countermeasure for reducing fault-current in the power system. When the fault occurred in the power system, the fault-current was limited by the generated impedance of SFCLs. The operational characteristics of the flux-offset type SFCL according to turn ratios between the primary and the secondary winding of a reactor were compared in this study. We connected the secondary core to a superconductor and a SCR switch in series in the suggested structure. The fault current in the primary and the secondary winding of the reactor and the voltage of the superconductor on the secondary were measured and compared. The results showed that the fault current in the load line was the lowest and the voltage applied at both ends of the superconductor was also low when the secondary winding of the reactor had lower turn ratio than the primary. It was confirmed based on these results that the turn ratio of the secondary winding of th e reactor must be designed to be lower than that of the primary winding to reduce the burden of the superconductor and to lower the fault current. Also, the suggested structure could increase the duration of the limited current by limiting the continuous current after the first half cycle from the fault with the fault current limiter. © 2016, Korea Institute of Applied Superconductivity and Cryogenics. All rights reserved.

Kim D.-W.,Chosun University | Sapkota K.,Chosun University | Sapkota K.,Tribhuvan University | Choi J.-H.,Chosun University | And 3 more authors.
Process Biochemistry | Year: 2013

A direct acting antithrombotic serine protease (CCP) was purified from brown seaweed Costaria costata. CCP was a monomeric protease with molecular mass of 60,547.598 daltons as determined by mass spectrometry. The N-terminal sequence of CCP was SCNSCLDKVDADGLN. Proteolytic activity was inhibited by PMSF and APMSF. CCP exhibited high amidolytic activity toward substrate S-2251 with apparent Km and Vmax values were 14.5 μM and 183.5 U/ml respectively. Fibrin plate and fibrin zymography results revealed that CCP was able to degrade fibrin clots directly. It specifically hydrolyzed Aα and α and Bβ and β chains followed by γ and γ-γ chains of human fibrinogen and fibrin respectively. Cleavage of fibrin clot and fibrinogen was emphasized by observing the alteration of secondary structure using FTIR spectroscopy. Morphological alteration of fibrin clot was also evidenced by fluorescent microscopic observation. CCP reduced thrombus effectively in vitro. In vivo observation showed that it prevented/decreased thrombus formation in carrageenan-induced mice tail model. CCP prolonged activated partial thromboplastin time (APTT) and had little effect on prothrombin time (PT). Platelet function analyzer (PFA-100) tests showed that CCP prolonged closure time (CT). These data suggest that CCP could have therapeutic potential for the treatment of thrombosis. © 2012 Elsevier Ltd. All rights reserved.

Kim H.-K.,Seoul National University | Kim N.-S.,Pusan National University | Jang J.-H.,TM Enc. | Kim Y.-H.,Dongkang College
Journal of Bridge Engineering | Year: 2012

Abstract The conformity between predicted and actual configurations of a suspension bridge is examined through a field survey with the compensation of temperature effects. The tension in the main cable is estimated from the surveyed configuration utilizing force equilibriums at the cable junction nodes. The measured hanger tensions and rigorous dead load information are also incorporated. The as-built configuration of the bridge shows fairly good agreement with the designed shape. The reproducibility of the dynamic properties is also examined for dominant vertical modes. The only tuning in the connection conditions of bearings produces natural frequencies that are in good agreement with the measured values. © 2012 American Society of Civil Engineers.

Lee H.,Dongkang College | Jung J.,Chonnam National University | Lim Y.,Chonnam National University
Microwave and Optical Technology Letters | Year: 2012

In this letter, a printed dipole antenna for wireless local area network (WLAN) communication is proposed.The proposed antenna consists of two dipole strips, which have modified dual monopoles and modified strip arms with tapered matching by the ground plane. The proposed antenna is increased radiation gain than the conventional dipole structure. The operating frequency band of the antenna is able to support WLAN of 5∼6.45 GHz. The measured peak gain is 4.8 dBi at 5.3 GHz. © 2011 Wiley Periodicals, Inc.

Jung J.,Chonnam National University | Lee H.,Dongkang College | Lim Y.,Chonnam National University
Microwave and Optical Technology Letters | Year: 2012

A compact inverted triangle planar monopole antenna (10 mm × 22 mm × - 1.6 mm) with a modified ground plane for ultra-wideband operation is proposed.With an inverted triangle radiator and modified ground plane with quarter circular patches, the proposed antenna has impedance bandwidth measured at 7.51 GHz (3.1-10.61 GHz), defined by 2:1 VSWR. The group delay and phase are also measured and discussed. © 2011 Wiley Periodicals, Inc.

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