• Journal of Communications and Networks
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• v.17 no.3
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• pp.286-295
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• 2015

Avionic databuses fulfill a critical function in the connection and communication of aircraft components and functions such as flight-control, navigation, and monitoring. Ethernet-based avionic databuses have become the mainstream for large aircraft owning to their advantages of full-duplex communication with high bandwidth, low latency, low packet-loss, and low cost. As a new generation aviation network communication standard, avionics full-duplex switched ethernet (AFDX) adopted concepts from the telecom standard, asynchronous transfer mode (ATM). In this technology, the switches are the key devices influencing the overall performance. This paper reviews the avionic databus with emphasis on the switch architecture classifications. Based on a comparison, analysis, and discussion of the different switch architectures, we propose a new avionic switch design based on a time-division switch fabric for high flexibility and scalability. This also merges the design concept of space-partition switch fabric to achieve reliability and predictability. The new switch architecture, called space partitioned shared memory switch (SPSMS), isolates the memory space for each output port. This can reduce the competition for resources and avoid conflicts, decrease the packet forwarding latency through the switch, and reduce the packet loss rate. A simulation of the architecture with optimized network engineering tools (OPNET) confirms the efficiency and significant performance improvement over a classic shared memory switch, in terms of overall packet latency, queuing delay, and queue size.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.1
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• pp.48-52
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• 2011

Over the years, traditionally, six-switch three-phase inverters have been widely utilized for variable speed alternating current motor drives. Recently, some efforts have been made on the application of four-switch three phase inverter for uninterruptible power supply and variable speed drives. This is due to some advantages of the four-switch three phase inverter over the conventional six-switch three-phase inverters such as reduced price due to reduction in number of switches, reduced switching losses, reduced number of interface circuits to supply logic signals for the switches, simpler control algorithms to generate logic signals, less chances of destroying the switches due to lesser interaction among switches, and less real-time computational burden. However such as slow di/dt and speed limitation, are the inherent characteristics and main drawbacks of the four-switch configuration. Those problems can be overcome in conjugation with Voltage-doublers which has additional advantage, such as unity power factor correction.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.67-70
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• 2006

This paper deals with a single crystalline silicon (SCS) RF MEMS switch for telecommunication system applications. The proposed SCS switch was fabricated using a silicon-on-glass (SiOG) process and its performances in terms of RF responses, switching time, lifetime were characterized. The proposed SCS switch consists of movable plates, mechanical spring structures, which are composed of robust SCS, resulting in mechanically good stability, The measured actuation voltage was 30 V, and with this applied voltage, the insertion loss and isolation characteristics were measured to be 0.05 and 44.6 dB at 2 GHz respectively. The measured switch ON and OFF time were 13 and $9{\mu}s$, respectively. The lifetime of the fabricated switch was tested. Even after over 1 billion cycles repeated ON/OFF actuations, the switch maintained its own characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.2033-2042
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• 1996

In this papre, we describe a recently implemented echo canceller for digital cellular communication of Code Division Multiple Access(CDMA) that features time sharing of digital signal processor(DSP) over four channels in one DSP to reduce per channel costs. In the Public Land Mobile Network(PLMN), it is important to cancel the echo reflected from the Public Switched Telephone Network(PSTN) side. In case of digital mobile system, the round-trip delay of the echo is in excess of about 180 milliseconds due to frame-by-frame voice coding. It is necessary to cancel the echo in PLMN. We have developed a multi-channel echo canceller tht operates with Time Switch Module in a Mobile Switching Center(MSC). The general echo canceller needs PCM trunk interface circuits and the tone detection and disabling circuits, but the multi-channel echo canceller linked with Time Switch Module does not need them. Therefore we could develop the effective and economical echo canceller.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.290-298
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• 2010

This paper proposes an adaptive carrier-based pulse width modulation (PWM) method for a four-switch three-phase (4S3P) inverter under dc-link voltage ripple conditions. The proposed method guarantees balanced output currents despite of the existence of the voltage oscillations across two dc-link capacitors. And also, this new approach achieves a linear over-modulation with calculation time reduction. Simulation and experimental results are given to validate the feasibility of the proposed method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.451-458
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• 2002

Absorptive type SP3T(Single Pole Three Throw) and SP8T switch modules over the 6-18 GHz are designed and fabricated. The epitaxial structure of GaAs PIN diode for switch modules are designed for low loss and high power capability. The maximum input power of SP3T and SP8T switch modules are 2 W and 1 W, respectively. The switching time with driver circuit is less than 130 nsec. The maximum insertion loss of SP3T switch module and SP8T module shows 2.8 dB and 4.2 dB, respectively. The isolation between input port and output port is more than 55 dB. Two switch modules for electronic warfare system have passed the environment tests of the related test items.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.71-79
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• 2011

This paper proposes a reliability enhancement of industrial real-time Ethernet using master redundancy method for NPPs(Nuclear Power Plants). In this paper, Ethernet Powerlink is investigated for distributed control systems for NPPs considering real-time and reliability performance. The proposed method can reduce a master switch-over time using PReq signal when Ethernet Powerlink master(Managing Node) failure was occurred. Using the OPNET simulation results, the performance enhancement of master switch-over time of Ethernet Powerlink is verified for NPPs.

• Health Policy and Management
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• v.23 no.2
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• pp.112-123
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• 2013

Background: Under the risk of financial sustainability of National Health Insurance, Korean government attempted a series of regulations over pharmaceutical prices. The first price-cut was implemented to the hyperlipidemial treatments, and the prices of statins were reduced on 15th, April in 2009. The purposes of this study are 1) to investigate the impact of this price-cut on pharmaceutical expenditure, and 2) to identify the factors associated with drug-switch among statins. Methods: Using the national patients sample data, this study conducted time series analysis on the expenditures, prices, and volumes of statin drugs. To understand the factors associated with drug-switch, the multinomial logit model was analyzed at the patients level. Results: The results of time series analysis demonstrated that the price-cut of hyperlipidemic medicines did not lead to the reduced expenditure, suggesting the increased volume was the major cause. The multinomial logit analysis identified the switch of healthcare provider as the significant factor that was highly associated with drug-switch, implying the physicians' preference was the major motivation of drug-switch. Conclusion: Without control of utilization, price regulation itself could not reduce pharmaceutical expenditure. This suggests that the pharmaceutical regulations should be implemented on the basis of understanding of provider behaviors. The findings of this study will form the first step for further empirical studies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.1-7
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• 2016

In this paper, the tunable filter based on high power cavity using mechanical switch for 1.5 GHz band is presented. The LPF is inserted to eliminate the spurious wave, coupler is embeded to extract the output power, and then the tunable filter system is configured using mechanical switch. The LPF obtains attenuation over 40 dB between 4 GHz and 12.75 GHz, Coupler is satisfied with coupling value 40 dB and coupling isolation over 55 dB. The tunable filter system using mechanical switch obtains insertion loss 0.88 dB at bypass mode between 1,495.9 MHz and 1,510. 9 MHz, 3.29 dB at fil mode between 1,495.9 MHz and 1,500.9 MHz. It is also satisfied with output power of 132 W at the center frequency 1,498.4 MHz, and switching time below 10 ms.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.157-165
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• 2006

This paper proposes a new output-buffered multicast ATM switch with tandem crosspoints switching fabric, named the MTCOS(Multicast Tandem Crosspoint Output-buffered Switch). The MTCOS consists of multiple simple crosspoint switch fabrics, named TCSF(Tandem Crosspoint Switch Fabric) , and concentrated output buffers for efficient multicasting. The TCSF resolves the cell delay deviation problem which the self-routing crossbar switches inherently have. Further, it offers multiple concurrent pathes from one input to multiple output ports. It also provides multi-channel switching by easy software configuration and has several desirable characteristics such as scalability, high Performance, and modularity. A shared traffic concentration and output queuing strategies of the MTCOS results in lower cell loss as well as lower cell delay time over a wide range of multicast traffic. Furthermore, it has lower hardware complexity than that of the SCOQ and Knockout multicast switch to achieve the same Knockout concentration rate as the conventional switches. It is shown that the proposed switch can be easily applied to design high performance for any multicast traffic by analytic analysis and computer simulation.