• Journal of Korean Society of Water and Wastewater
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• v.32 no.4
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• pp.309-315
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• 2018

Currently, the commercialization of the $5^{th}$ Generation (5G) service is becoming more prevalent in domestic communication network technology. This has reduced communication delay time and enabled large-capacity data transmission and video streaming services in real-time. In order to keep pace with these developments, K-water has introduced a smart process control system in water purification plants to monitor the status of the water purification process. However, since wireless networks are based on the public Long Term Evolution (LTE) network, communication delay time remains high, and high-resolution video services are limited. This is because communication networks still have a closed structure due to expense and security issues. Therefore, with 5G in its current form, it is very difficult to accommodate future services without improving the infrastructure of its communication networks. In recognition of these problems, this study implemented the authentication and management function of wireless networks on a wired network management system in the K-water Bansong water purification plant. The results confirmed that wired Local Area Network (LAN) services give a higher security performance than an expensive commercial wireless LAN system. This was achieved by using an Internet Protocol (IP) address management system of wired networks and the packet filtering function of the Layer2 (L2) switch. This study also confirmed that it is possible to create a wireless LAN service that is 3.7 times faster than the existing LTE communication network.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.4
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• pp.135-140
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• 2015

The WDSS improves defensive capacity against web application layer DDoS attack by using web cache server and L7 switch which are added on the DDoS shelter system. When web DDoS attack occurs, security agents divert traffic from backbone network to sub-network of the WDSS and then DDoS protection device and L7 switch block abnormal packets. In the meantime, web cache server responds only to requests of normal clients and maintains stable web service. In this way, the WDSS can counteract the web DDoS attack which generates small traffic and depletes server-client session resource. Furthermore, the WDSS does not require IP tunneling because it is not necessary to retransfer the normal requests to original web server. In this paper, we validate operation of the WDSS and verify defensive capability against web application layer DDoS attacks. In order to do this, we built the WDSS on backbone network of an ISP. And we performed web DDoS tests by using a testing system that consists of zombie PCs. The tests were performed by three types and various amounts of web DDoS attacks. Test results suggest that the WDSS can detect small traffic of the web DDoS attacks which do not have repeat flow whereas the formal DDoS shelter system cannot.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.561-569
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• 1999

In this paper, the diode bridge-type ZVT(Zero- Voltage Transition) inverter is proposed. It consists of one a auxiliaI${\gamma}$ switch, three resonant inductors and six blockin당 diodes. So, the main advantage of the proposed t torXJ!ogy is the reduction of the auxiliar${\gamma}$ switch compare to the conventional ZVT inverter. The topology of t the propostxl lVT inverter is analyztxl with a description of the control conditions based on the load current. A And the resonant period control for operating the proposed inverter optimally is discussed by using resonant i inductor current ftxxlback. To verify the proposed topology, the detailed simulation and exJX끼mental results i indicate that zero volta당e operation during transition can be achieved.

• Phonetics and Speech Sciences
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• v.2 no.4
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• pp.3-10
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• 2010

The present study aims to investigate neural activations according to the level of code switching in English proficient bilinguals and to find the relationship between the performance of language switching and proficiency level using ERPs (event-related potentials). First, when comparing high-proficient (HP) with low-proficient (LP) bilingual performance in a native language environment, the activation level of N2 was observed to be higher in the HP group than in the LP group, but only under two conditions: 1) the language switching (between-language) condition known as indexing attention of code switching and 2) the inhibition of current language for L1. Another effect of N400 can be shown in both groups only in the language non-switching (within-language) condition. This effect suggests that both groups completed the semantic acceptability task well in their native language environment without the burden of language switching, irrespective of high or low performance. The latencies of N400 are only about 100ms earlier in the HP group than in the LP group. This difference can be interpreted as facilitation of the given task. These results suggest that HP showed the differential activation in inhibitory system for L1 in switching condition of L1-to-L2 to be contrary to inactivation of inhibitory system for the LP group. Despite the absence of an N400 effect at the given task in both groups, differential latencies between the peaks were attributed to the differences of efficiency in semantic processing.

• Journal of Plant Biology
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• v.33 no.2
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• pp.87-96
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• 1990

The role of S-adenosylmethionine (SAM) as an intermediate in interrelation between polyamine and ethylene biosynthesis was studied in suspension cultures of Nicotiana tabacum L. Exogenous SAM stimulated the polyamine and ethylene biosynthesis in 4 day-cultured cells, which were in active cell divisions, and 10 day cultured cells, which went on with active cell elongation and senescence. SAM-induced ethylene production was more effective in 10 day-cultured cells than in 4 day-cultured cells, but SAM-induced polyamine biosynthesis was more effective in 4 day-cultured cells than in 10 day-cultured cells. Polyamine contents were increased by the blockage of ethylene biosynthetic pathway in the conversion of SAM to ethylene via 1-aminocyclopropane-1-carboxylinc acid (ACC) with aminooxyacetic acid (AOA). Also, ethylene production was increased by the inhibitors of polyamine biosynthesis such as methylglyoxal bis-(guanylhydrazone) (MGBG), dicyclohexylamine (DCHA), $\alpha$-difluoromethylarginine (DFMA) and $\alpha$-difluoromethylorinithine (DFMO). These results suggest that there may be interrelations between polyamine and ethylene biosynthesis for the competition of SAM and the inherent mechanism of switch on-off in polyamine and ethylene biosynthetic activity with the progress of cell growth and senescence.

• The Journal of Korean Medicine
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• v.19 no.1
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• pp.419-429
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• 1998

Poncirus trifoliata (L.) Raf (Rutaceae) fruits (PTFE) has been used for the treatment of allergic disease. IgE is normally one of the least abundant immunoglobulin (Ig) isotypes in the serum of both humans and several species of experimental animals: however a number of different stimuli can result in profound increases in IgE levels relative to other isotypes. In rodents, infection with many parasitic helminths can cause approximately 100-fold elevation in IgE within 2 wks. Immunization of mice with small amounts of protein antigens on alum also results in 10-fold to fold increase in total serum IgE, much of it specific for the immunizing antigen. In this experiment, I investigated the effect of an aqueous extract of Poncirus trifoliata (L.) Raf (Rutaceae) fruits (PTFE) on a in vivo and in vitro IgE production. PTFE dose-dependently inhibited the serum levels of IgE induced by antigens. The regulation of IgE synthesis is influenced by T cells and T cell derived factors. IL -4, a T cell-derived cytokine, has been shown to stimulate murine IgE synthesis both in vitro and in vivo. Current evidence suggests that IL-4 induces IgE synthesis in the mouse by stimulating H chain isotype switch. Lipopolysaccharide (LPS) plus IL-4 cause about l00-fold increase in IgE secretion by murine B cells. The effects of PTFE on the IL-4-dependent IgE response by mouse whole spleen cells were studied. Whole spleen cells were cultured for 7 days in the presence of LPS plus IL-4 and PTFE and the supernatants were assayed for IgE. IL-4 dependent IgE production of LPS-stimulated whole spleen cells was inhibited by PTFE. Moreover, in the present study using U266Bl human IgE-bearing B cells, I found that PTFE inhibited the production of IgE activated by LPS plus IL-4. These results indicate that PTFE have antiallergic activity by inhibition of IgE production from B cells.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.785-793
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• 2016

This paper analyzes an LCL-type isolated dc-dc converter operating for constant output voltage in the continuous conduction mode(CCM) with resistances of parasitic losses-static drain-source on resistance of power switch, ESR of resonant network(L-C-L)-using a high loaded quality factor Q assumptions and fourier series techniques. Simple analytical expressions for performance characteristics are derived under steady-state conditions for designing and understanding the behavior of the proposed converter. The voltage-driven rectifier is analyzed, taking into account the diode threshold voltage and the diode forward resistance. Experimental results measured for a proposed converter at low input voltage and various load resistances show agreement to the theoretical performance predicted by the analysis within maximum 4% error. Especially in the case of low output voltages and large loads, It is been observed that introduction of both rectifier and the parasitic components of converter had considerable effect on the performance.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.415-421
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• 2014

In this paper, reactorless high efficiency boost DC/DC converter for EV is proposed. In proposed converter, improves efficiency because decrease power loss when the switches are turned on/off using zero current switching (ZCS) at all switch of primary full bridge. By replacing reactance ingredients of L-C resonance circuit for ZCS with leakage inductance ingredients of high frequency transformer, it reduces system size and expense because of not add special reactor. For validity verification of proposed converter, in the paper implements simulation using PSIM and perform experiment by making 5KW DC/DC converter. In experimental results, efficiency of proposed converter conformed superiority.

• Structural Engineering and Mechanics
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• v.6 no.4
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• pp.395-409
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• 1998

This paper concerns the development and implementation of an orthotropic, stress resultant elasto-plastic finite element model for the collapse load analysis of reinforced concrete plates. The model implements yield line plasticity theory for reinforced concrete. The behaviour of the yield functions are studied, and modifications introduced to ensure a robust finite element model of cases involving bending and twisting stress resultants ($M_x$, $M_y$, $M_{xy}$). Onset of plasticity is always governed by the general yield-line-model (YLM), but in some cases a switch to the stress resultant form of the von Mises function is used to ensure the proper evolution of plastic strains. Case studies are presented, involving isotropic and orthotropic plates, to assess the behaviour of the yield line approach. The YLM function is shown to perform extremely well, in predicting both the collapse loads and failure mechanisms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.4
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• pp.340-344
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• 2004

In this paper, We collected the data of communication network construction in Sangmyeong University and analyzed them. Moreover using the analysis instrument of communication network traffic, We tested a process of it, and an efficiency of each equipment. We proved the traffic flow and the load quantity during the register for class. As a result We suggested a efficient communication network design - add and change some equipments in order to break up the traffic.