• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.108-115
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• 2001

SDH-based SHR networks are the reconfiguration process in case of failure and APS protocol used. In this study, addresses the maximum allowed recovery time in two fiber bidirectional networks. We analyse the APS protocol and derive the Processing time domains of each n order to cope with the maximum reconfiguration time of 50㎳, as specified in the ITU-T standard. We finally analyze the interleaved failures. One is the signal degrade then the signal failure, the other is the signal failure then the signal failure. Any case analysis is carried out. reconfiguration time can be guaranteed.

• Journal of Korean Library and Information Science Society
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• v.35 no.4
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• pp.1-21
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• 2004

The purpose of this study is to investigate historical backgrounds, maintenance, revision and application areas of UDC(Universal Decimal Classification) in order to understand current issues of it systematically. Since 1905, n has been extensively developed and is now administered by UDC Consortium(UDCC). UDCC updates MRF(Master Reference File), an electronic form of the UDC schedules, once a year. UDC updates and publishes standard edition extended edition, and abridged edition according to the degrees of notion abridgement, and is available on the web. UDC can be now applicable to collection arrangement, SDI(Selective Dissemination of Information) service, searching subject bibliographies, switching language or subject gateway and metadata on the Internet, and automatic classification.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.82-82
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• 2009

현재 국내에는 많은 가구들이 전기를 사용하고 있다. 아파트, 주택에 들어가는 전기 시스템들이 많이 발전하였지만 뜻하지 않은 사고로 인해 정전이 되는 경우가 있다. 정전시에는 아파트 같은 경우는 비상등, 엘리베이터 등 최소한의 장치만이 작동하도록 되어있다. 그러므로 각 세대에는 전기가 들어가지 않는다. 우리나라 경우에는 태풍이나 여름 같은 경우에는 전기를 많이 사용하기 때문에 발전기가 과부화 걸리는 현상이 생기기도 한다. 장기간 정전시에 가장 문제가 되는 기기는 냉장고, 전등이 될 것이다. 냉장고 같은 경우는 음식들이 상하게 되고, 전등 같은 경우에는 밤에 활동하는데 지장을 주게 된다. 따라서 본 논문에서는 정전시에는 자동적으로 비상발전기의 전원을 사용하고, 상시에는 다시 한전의 전원을 사용하게 하는 초소형 자동 스위칭 전원 모듈을 설계 제작한 논문이다. 설계된 스위칭 모듈에 대해서 시뮬레이션한 결과 예상한대로 비상시에 자동적으로 스위칭되는 결과를 알 수 있었다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.397-403
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• 2009

In this paper, an exciter current control of a synchronous generator for ships using a compound type digital automatic voltage regulator (DVAR) in order to provide a constant output voltage of the generator is presented. The compound type DAVR is composed of a controller part to adjust output voltage and an power source unit to supply power to the exciter. The controller part, which generates the PWM switching pattern via the PI controller, drives a power MOSFET for bypass to limit the SG's exciter current. The power source unit part is parallel connected to an output terminal of the generator through a reactor and a power CT. The residual magnetic flux of SG provides exciter current to the exciter through the reactor during the initial running or no load state and load current supplies field current to the exciter through the power CT during loading state. This paper confirmed an experiment to verify the validity of compound type DAVR system for controlling output voltage of synchronous generator.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1088-1090
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• 2001

In general, Power SCR(Silicon Controlled Rectifier) is most widely used in Power Plant as well as Industrial field. It has been controlled and operated according to its own control method. Especially, in case of Power plant, it plays a major role in AVR(Automatic Voltage Regulator) or electro chlorination control circuits. Generally, they used in Analog control system at above field. But each SCR current value is different because of load unbalance or switching characteristic variations, it may cause power plant unit trip or system disorder according to SCR element burn out or bad operating condition. Therefore, in this paper a development of 3 phase current balance control unit is described, it gets over the past analog control system limit, uses DSP(Digital signal processor) had high speed response, controls SCR gate firing angle for 3 phase current balance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.564-581
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• 1999

This paper introduces a new, small, low cost, robust and quick replaceable pavement-based vehicle detector using CW radar, magnetometer, and UHF small antennal techniques. The detector has been developed for a replacement of loop detectors having wide surface areas, for a more accurate operation under all weather conditions, and for no algorithmic change of the existing traffic information system. The detected vehicle information is sent by a small helical antenna embedded in a plastic material and received by a 5/8 $\lambda$ long GP antenna for signal processing. In a relatively good weather condition, the detector operates at 24 GHz. But in a heavy rain condition, magnetometer is activated by automatic switching.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.448-455
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• 1996

In this study, to reduce vibration of step motor we use Microstep control. Microstep control of stepmotor is usually thought of as an extension of conventional stepmotor control technology. The essence ofmicro stepping is that we divide the full step of a stepmotor into a number of substep called microstep and cause the stepmotor to move through a substep per input pulse. In ideal case, bycontrolling the individual phase currents of a two-phase step motor sinusoidally we can get uniform torque and step angles. But due to the monlinear characteristics of the step motor, we need to compensate current waveform to improve the overall smoothness of the conventional micro stepping system. We implement digital Pulse Width Modulation(PWM) driver to drive step motor and microphone was used for detecting vibration. Driver enables speed change automatically byincreasing or decreasing micro stepping ratio which we call Automatic Switching on the Fly. To compensate the torque harmonics, Neural Networks is applied to the system and we foundcompensated optimal input current waveform. Finally we can get smooth motion of step motor in a wide range of motor speed.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.3
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• pp.148-158
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• 2003

In this study, a user oriented CFD program for optimum design of a regenerative combustion furnace, REBURN was developed. For user's convenience, user friendly Graphic User Interface was made and the renumbering interface program was developed in order to directly input any generated mesh system from ICEM CFD/FEA. Also an automatic processing system for switching mode was developed. The program was verified through compahng with commercial CFD code about regenerative combustion furnace. Then, numerical simulation of real walking beam furnace used in real industry was performed and the parametric analysis was studied about the arrangement mode. As a results, the uniform temperature was appeared in the cross mode.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.275-288
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• 2010

In order to improve the quality of electricity in large scale power systems, stability of power system has to be achieved. This can be done by the means of preventative diagnosis of power equipments and protection, monitoring and control of the power system. Since the recent adoption of digital controllers, an improvement in stability was observed; in particular, IED, which contained self-diagnostic abilities such as fault tolerance, allowed for automatic recovery via redundancy or switching-over functions should there be faults with the equipments. Furthermore, communication lines have been hugely simplified, thus adding to the improvement in stability significantly. Taking these error reports and forecasting emergency reports and by effectively responding to them in the overiding controlling systems, high levels of system stability can be obtained. Power Management System that is being applied to automated power sub-stations, takes the IEC61850 international standard as its specification. In this paper, additional research into achieving stability of already developed PMS system and also the stability of the overall system was carried out, and the results of development of communication servers, which play a pivotal role in connecting systems, are stated.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.23-28
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• 2013

This study focuses on finding ways to derive train's optimal ECO driving pattern, which can improve the ride quality and reduce driving energy consumption with keeping the time interval between the stations. As research method, we compared difference of currently operating train's ATO and MCS driving patterns, and concentrated upon the things need to consider in simulation in order to improve the existing pattern of ATO driving pattern's issues with securing the train operation safety. Determining driving pattern minimizing energy consumption by controlling powering within speed limit and controlling switching to coasting at appropriate point considering the track conditions for each section, and determining braking control starting time considering ride comfort and precise stopping is considered to be most important.