• 전기학회논문지
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• 제59권12호
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• pp.2125-2130
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• 2010

The neutral section on electric railway system is significant sector in order to prevent short circuit of two electric powers. However, while electric trains pass the neutral section, those speed is decreased and the accident of AC electric traction system and the electric train would be occurred. So the countermeasures are urgently needed. The automatic power switching technology system that is current being research and development is system to improve these problems. Because main object of this system is power change using static switch in the neutral section, it's expected to cause a variety of transients. Especially, onboard transformer inrush current for electric railway train can be occurred more than rated current according to switching time. Therefore, the analysis and improvement are needed to ensure the stability of this system. In this paper, we analyze the operating characteristics of the automatic power switching technology system. Especially, it reviews inrush current according to the closing phase angle. And we propose control plan of inrush current considering the case that voltage is maintained due to counter electromotive force and regenerative braking operation of electric railway train. Finally, the proposed control scheme was reviewed using the transient analysis program.

• 전기학회논문지
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• 제60권6호
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• pp.1146-1151
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• 2011

There are two methods for train control in information transmission by using track circuit system and installing wayside transmitter. Information signal is transmitted to the on-board antenna by using rails. Continuous information about train intervals, speed and route is received by on-board antenna in AF track circuit system. The information signal is included with carrier wave and received by magnetic coupling in the on-board antenna. Therefore, it is important to define standard current level in the AF track circuit system. When current flowed to rails is low, magnetic sensors are not operated by decreasing magnetic field intensity. Hence, SNR is decreased because electric field intensity is decreased. When the SNR is decreased, there is the serious influence of noise upon demodulation. So, the frequency of information signal is not extracted in frequency response. Thus, it is possible to happen to train accident and delay as the information signal is not analyzed in the on-board antenna. In this paper, standard energy density is calculated by using Parseval's theory in UM71c track circuit. Hence, detection time of information signal is presented.

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.772-777
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• 2012

Accidents caused by water absorption in water-cooled generator stator windings often occur all over the world. The absorption into the insulator of the coolant, which is used to cool down the heat generated by stator windings during operation, leads to the deterioration of dielectric strength, and insulation breakdown. An insulation breakdown may cause not only an enormous economic loss but also a very serious grid accident that would compromise stable supply of electric power. More than 50 % of domestic generators have been in operation for more than 15 years, and water absorption tests performed on 50 water-cooled generator stator windings during a five-year planned preventive maintenance period beginning in 2006 identified water absorption problems in 10 of them, all of which required repair. Because the existing water absorption test detects this problem by utilizing stochastic methods after measuring the capacitances at the final positions of insulation breakdown, its accuracy is limited. This study demonstrates that water absorption can be more accurately diagnosed by utilizing method along with a more precise one.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.19-25
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• 2009

본 연구는 변전소(사무실) 설비 환경 개선 차원으로 기존 비상등하에서 조도 부족으로 인한 근무자의 오조작 및 복구 시간 지연을 단축하기 위하여 현재 설치된 등기구의 형태를 백열등에서 형광등으로 대체하였으며, AC/DC 겸용 비상등 및 스위치에 관하 연구하였다. 조도 기준 또한 상시등의 5${\sim}$10[%] 가 아닌 한국 산업 조도 기준(KSA)에 따른 원자력 발전소 조도 기준 및 안전 조명에 의한 조도 기준을 참고로 정확한 변전소 각 실별 조도 기준을 책정하였고 그에 따른 변전소 내선 전기 설계를 표준화하였다. 또한 배터리 용량 산정 기준과 중요도에 따른 각 실별 등기구 설치 수량을 표준화하여 조도 부족으로 인한 2차 사고나 광역 정전 사고로 인한 대형 사고를 방지하고자한다.

• 한국정보통신학회논문지
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• 제7권4호
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• pp.819-825
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• 2003

본 논문은 전신마비환자를 위한 FES(Functional Electrical Stimulator) 시스템 모드 변환 중의 하나를 선택할 수 있게 하는 화자 인식 시스템을 개발하고자 한다. 교통사고나 산업재해로 인한 마비환자가 늘어나고 있는 현대사회에서 환자의 운동 보조를 위해서 또는 운동 능력의 회복을 위하여 FES 시스템에 대한 연구가 늘어나고 있다. FES의 동작은 휴지, 운동, 치료 등 몇 개의 모드를 선택해야 하는데, 사지마비환자의 경우에는 키패드 조작이 불가능하므로 가장 일반적이고 자연스러운 언어로 이들 모드를 선택하고자 한다. 화자 인식 소자로는 Sensory(주)의 RSC-300을 사용하였고, FES 시스템과 RSC-300의 인터페이스는 PIC16F84마이크로 콘트롤러를 사용하였다.

• 전기학회논문지
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• 제63권3호
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• pp.376-382
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• 2014

E-Actuator is an essential part of an eVGT, it receives the command from the main ECU and controls the vane. An e-Actuator failure can cause an abrupt change in engine output and it may induce an accident. Therefore, it is required to detect anomalies in the e-Actuator in real time to prevent accidents. In this paper, an e-Actuator fault detection method using on-line parameter identification is proposed. To implement on-line fault detection algorithm, many constraints are considered. The test input and sampling rate are selected considering the constraints. And new recursive system identification algorithm is proposed which reduces the memory and MCU power dramatically. The relationship between the identified parameters and real elements such as gears, spring and motor are derived. The fault detection method using the relationship is proposed. The experiments with the real broken gears show the effectiveness of the proposed algorithm. It is expected that the real time fault detection is possible and it can improve the safety of eVGT system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.395_396
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• 2009

This paper handles with effect of electromagnetic force on the cables by fault current accompanied by accident of underground transmission cable. Even though underground transmission cable is an essential transmission method to supply stable power for downtown and population center, interaction of electromagnetic force from fault current is very large comparing to overhead transmission line due to restricted installation space such as tunnel, etc. and close consideration is required for it. This paper describes the effect of electromagnetic force through results of three phase short-circuit test and electromagnetic force analysis using theoretical calculations and electrical evaluation test after three phase short-circuit test, which will be utilized as basic materials for improvement and development of cleat, hanger, etc. to reduce and release effect of electromagnetic force in the future.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.285-299
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• 2016

Although South Korea experienced a rolling blackout in 2011, the possibility of a blackout in South Korea continues to increase due to rapid electrification. This study examines the problems of energy taxation and price distortions as possible reasons for the rapid electrification in South Korea, which is occurring at a faster rate than in Japan, Europe, and other developed countries. Further, we suggest new energy taxation and price systems designed to normalize electricity prices. In order to do so, we consider two possible scenarios: the first imposes a tax on bituminous coal for electricity generation and the second levies a tax to provide compensation for the potential damages from a nuclear accident. Based on these scenarios, we analyze the effects of a new energy system on electricity price and demand. The results show that a new energy system could guarantee the power generation costs and balance the relative prices between energy sources, and could also help prevent rapid electrification. Therefore, the suggested new energy system is expected to be utilized as a basis for energy policy to decrease the speed of electrification, thus preventing a blackout, and to induce the rational consumption of energy in South Korea.

• 전기학회논문지P
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• 제58권4호
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• pp.469-475
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• 2009

Accident dangerousness of domestic hydro power generators which are operated in Korea is on the increase because of use at the long term. On this, the Off-line diagnosis techniques developed to the On-line by continued domestic technical development since 2000. Especially, On-line insulation diagnosis of domestic hydro power generator is possible by localization of partial electric discharge sensor and On-line insulation diagnosis system. This paper shows the diagnosis result that is applied localized Ceramic Coupler and PDMS-HG(Partial Discharge Monitoring System for Hydro Generator) at four Chung-ju hydro Generator used for 25 years. Particularly, the confidence of insulation diagnosis is improved by using high frequency filter and sampling the partial discharge signals which occur in site. For reviewing the confidence of On-Line insulation diagnosis system, we measured the outside noises and partial discharge signals during practical operation by using the partial discharge diagnosis system of the Full A/D process. And we reviewed the confidence of the On-Line insulation diagnosis system by comparing and analyzing these data.

• 조명전기설비학회논문지
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• 제24권6호
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• pp.99-106
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• 2010

본 논문에서는 조명에너지 사용을 절감하기 위하여 설계된 자동 조명제어시스템에 전력선 통신(PLC : Power Line Communication)과 단문문자서비스(SMS : Short Message Service)를 적용한 개선된 자동 조명제어시스템을 구현하였다. 본 시스템은 자동 조명제어장치와 함께 재실감지센서에 의하여 화재나 침입자 발생 시 경고음 뿐만 아니라 관리자나 사용자에게 경고 메세지를 전송하여 2차 사고를 예방할 수 있도록 설계되어 있다. 또한 본 논문에서는 전력전송을 위하여 설치된 기존의 전력선에 데이터를 실어 보냄으로써 신호선과 전원선의 통합하여 조명 제어를 위하여 사용되는 라인의 수를 획기적으로 줄이는 개선된 자동 조명제어시스템을 제안하였다.