Dongkang College

Gwangju, South Korea

Dongkang College

Gwangju, South Korea

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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.


Kumar S.,Chonnam National University | Lee H.J.,Dongkang College | Park H.-S.,Chonnam National University | Lee K.,Chonnam National University
BMC Genomics | Year: 2016

Background: Ras-related proteins in brain (Rab)-family proteins are key members of the membrane trafficking pathway in cells. In addition, these proteins have been identified to have diverse functions such as cross-talking with different kinases and playing a role in cellular signaling. However, only a few Rab proteins have been found to have a role in male germ cell development. The most notable functions of this process are performed by numerous testis-specific and/or germ cell-specific genes. Here, we describe a new Rab protein that is specifically expressed in male germ cells, having GTPase activity. Results: Testis-specific GTPase (TSG) is a male-specific protein that is highly expressed in the testis. It has an ORF of 1593 base pairs encoding a protein of 530 amino acids. This protein appears in testicular cells approximately 24 days postpartum and is maintained thereafter. Immunohistochemistry of testicular sections indicates localized expression in germ cells, particularly elongating spermatids. TSG has a bipartite nuclear localization signal that targets the protein to the nucleus. The C-terminal region of TSG contains the characteristic domain of small Rab GTPases, which imparts GTPase activity. At the N-terminal region, it has a coiled-coil motif that confers self-interaction properties to the protein and allows it to appear as an oligomer in the testis. Conclusion: TSG, being expressed in the male gonad in a developmental stage-specific manner, may have a role in male germ cell development. Further investigation of TSG function in vivo may provide new clues for uncovering the secrets of spermatogenesis. © 2016 The Author(s).


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.


Lee H.,Dongkang College | Cho B.,Sunchon National University
Proceedings - 2014 6th International Conference on Computational Intelligence and Communication Networks, CICN 2014 | Year: 2014

A CPW-fed to CPS dipole antenna with inversed triangular loop director is proposed in this paper. The proposed antenna is consisted of a CPW-fed to CPS transform, CPS dipole driver and inversed triangular loop director. The inversed triangular loop of proposed antenna is operated director. A wide bandwidth and a omni directional directivity of the proposed dipole antenna is realized by introducing the inversed triangular loop director. The proposed antenna is easily obtained to match between a dipole antenna to several directors than a conventional Yagi dipole antenna. The operating frequency bandwidth is about 2.1 GHz (6.8 - 8.9 GHz) to return loss criterion of less than 10 dB. The measurements of proposed antenna showed good results of the wide band operating frequency and the radiation pattern. The proposed antenna can support wireless communication applications. © 2014 IEEE.


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.


Hwang W.-C.,Chosun University | Cha C.-S.,Dongkang College | Yang I.-Y.,Chosun University
Materials Research Innovations | Year: 2011

The designing of vehicles should be more concerned with the aspect of securing safety performance, while reducing the weight of vehicle structural members should also be taken into consideration. Carbon fibre reinforced plastics (CFRPs) of the advanced composite materials as structural materials for vehicles have a wide application in lightweight structural materials of air planes, ships and automobiles because of their high strength and stiffness. The objective of this study is to investigate the energy absorption characteristics of CFRP hat shaped section members under the axial impact collapse test. The CFRP side members were made of 8-ply unidirectional prepreg sheets stacked at different angles (± 15°, ± 45°, 90°, 0°/90° and 90°/0°, where 0° direction coincides with the axis of the member) and interface numbers (2, 3, 4, 6 and 7). The axial impact collapse tests were carried out for each section member. The collapse mode and the energy absorption characteristics of each member were analysed. © W. S. Maney & Son Ltd. 2011.


Jung B.-I.,Dongkang College | Choi H.-S.,Chosun University
Transactions of the Korean Institute of Electrical Engineers | Year: 2016

These days, SFCLs are being developed in order to limit fault current. However, the superconducting elements that limit the fault current have such problems as capacity increase and require auxiliary devices including cooling device. If devices that comprise the current power network can withstand fault current for at least one cycle, it is possible to limit the fault current with current limiting elements by bypassing it on the fault line. In this study, the fault current limiter was configured with current transformer, vacuum interrupter, and current limiting element. Through the experience, it was confirmed that the fault current was limited within one cycle. The superconducting element, as a current limiting element, limited the fault current by 80 % within one cycle from fault occurrence, and the passive element limited it more than 95 %. Also, through the comparison between resistance curve and power consumption curve, it was confirmed that the current limiting element using a passive element was more stable than the superconducting element that required capacity increase and other auxiliary devices. It was considered that the FCL proposed in this study could limit fault current stably within one cycle from fault occurrence by using the existing power technologies such as fault current detection and solenoid valve operating circuit. Copyright © The Korean Institute of Electrical Engineers.


Jung B.-I.,Dongkang College | Choi H.-S.,Chosun University
Transactions of the Korean Institute of Electrical Engineers | Year: 2016

This paper proposed the structure that applied superconductors to the neutral line of a transformer and applied the normal conductors to the third line. The superconductor applied to the neutral line of a transformer limited the peak value of initial fault current, while the normal conductor finally limited the fault current. In order to secure the operating reliability of transformer type Superconducting Fault Current Limiter (SFCL) of previously proposed structure, we analyzed the operating characteristics according to the fault types. We tested a line-to-ground fault and a line-to-line fault. As a result of the experiment, all the faults showed that the superconductor stably limited the peak-value of initial fault current. Also, the normal conductor finally limited the fault current. Based on this research results, We thought that if the structure of inserting superconductor into the neutral line is applied to the real system, it could improve the reliability and stability of the power system. Copyright © The Korean Institute of Electrical Engineers.


Lee H.,Dongkang College
Journal of Electrical Engineering and Technology | Year: 2015

In this paper a printed pair dipole antenna with double tapered microstrip balun for wireless communications is proposed. The proposed antenna consists of a pair arm of different sizes that is branched microstrip line and microstrip line with the ground plane on opposite side of the dielectric substrate plane. The proposed antenna is matched between the ground plane to the microstrip line by double tapered microstrip balun. This antenna obtains multi-band radiation frequency band. The impedance bandwidths for a reflection coefficient of VSWR ≤ 2 are about 1.01 GHz (2.35~3.336 GHz), 1.56 GHz (4.7~6.26 GHz) and 1.15GHz (6.85~8.0[GHz]). Additionally, the measurement peak gain is about 3.6 dBi. The proposed antenna is able to support wireless communication applications. © 2015 The Korean Institute of Electrical Engineers.

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