• 디지털융복합연구
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• 제17권10호
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• pp.243-249
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• 2019

본 논문에서는 사용하지 않는 전기제품에서 불필요하게 소비되는 대기전력을 절감하기 위한 장치를 개발하였다. 도플러 센서를 사용하여 사람이 콘센트 주변에 존재 유무에 따라 콘센트의 전원공급과 차단을 자동으로 수행하는 장치이다. 도플러 센서는 동축 케이블 트랩을 사용하여 송신 안테나를 설계하였으며 10GHz 대역의 RF신호를 방사하여 대상 물체로부터 반사된 파장이 변화된 반사파 신호를 수신부로 수신하여 물체를 감지하여 사람의 접근을 인지하도록 하였다. 대기전력을 자동으로 차단 및 복구하여 불필요한 전력소모를 방지하여 에너지를 절약하고 누설전류에 의한 대형 화재의 위험성을 방지할 수 있는 대기전력 자동 차단 및 복구 장치를 개발하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2089-2092
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• 1999

Partial discharge(PD) tests were performed both when the pumped storage generator(rated 13.8kV and 220MVA) was on-line and off-line. This generator has been equipped with 12 bus coupler sensors in directional mode. PD tests were conducted using partial discharge analyzer(PDA), partial discharge meter(PDM) and digital partial discharge detector. PDA showed that the patterns of the normalized quantity number(NQN) and the partial discharge magnitude are in accord with on-line and off-line. The insulation condition was estimated by diagnostic tests(off-line) such as PD magnitude and dissipation factor.

• Journal of Advanced Marine Engineering and Technology
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• 제7권1호
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• pp.40-48
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• 1983

Nowadays electromagnetic contactors are used for power on-off in various electrical loads. If the severe arc are occurred when power off, the magnetic contactor can not long run because of damage of contactor. In this paper, Authors indicate a method of how to minimize the arc when power off, Authors contrived a electronic circuit which can adjust the demagnetizing point of electro magnetic contactor, and control the demagnetizing point, utilizing our circuit, so as to occur the extinguish of arc at near the AC current zero point which is indispensibly exists. From the results of study, Authors could get confirmations the AC circuit could cut off with occurrence of mininum arc, and that possibility of extensive utilization of our method to hightension circuit.

• Journal of Advanced Marine Engineering and Technology
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• 제22권5호
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• pp.617-625
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• 1998

A passive energy recovery snubber for high-power-factor boost rectifier, in which the main switch is implemented with a MOSFET, is described in terms of the equivalent circuits that are operational during turn-on and turn-off sequences. These equivalent circuits are analyzed so that the overshoot voltage across the main switch, the snubber current, and the turn-off transition time can be predicted analytically. From these results, the normalized overshoot voltage is reduced to 1 as $_W2T_on$ varies from zero to $\pi$/2, and then it is fIxed at 1 for $_W2T_on$> $\pi$/2. The peak snubber inductor current is directly proportional to the input current. The turn-offtransition time wltoffvaries from 0 to 2.57, depending on $_W2T_on$. The main switch combined with proposed snubber can be turned on with zero current and turned off at limited voltage stress. The high-power-factor boost rectifier with proposed snubber is implemented, and the experimental results are presented to confirm the validity of proposed snubber.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1984년도 하계학술회의논문집
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• pp.207-208
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• 1984

• 한국컴퓨터산업학회논문지
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• 제10권3호
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• pp.99-104
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• 2009

본 논문에서는 형광등 on/off 제어 및 조도를 전력선 통신을 이용하여 원격으로 제어할 수 있는 시스템을 설계하고자 하였다. 각각의 조명기기를 전력선으로 구성되는 네트워크를 구현하였으며 원격 제어 및 조명기기의 on/off 및 조도를 제어하기 위하여 서버를 구성하고 서버에서 각각의 크라이언트를 제어할 수 있도록 하였다. 또한 기존 on/off 시스템을 디지털화하여 에러율을 감소시켰으며 회로를 단순화하는데 주안점을 두었다.

• Journal of information and communication convergence engineering
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• 제5권1호
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• pp.59-63
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• 2007

In this paper, a CLB-based CPLD low-power technology mapping algorithm considered a Trade-off is proposed. To perform low-power technology mapping for CPLDs, a given Boolean network has to be represented in a DAG. The proposed algorithm consists of three steps. In the first step, TD(Transition Density) calculation has to be performed. Total power consumption is obtained by calculating the switching activity of each node in a DAG. In the second step, the feasible clusters are generated by considering the following conditions: the number of inputs and outputs, the number of OR terms for CLB within a CPLD. The common node cluster merging method, the node separation method, and the node duplication method are used to produce the feasible clusters. In the final step, low-power technology mapping based on the CLBs packs the feasible clusters. The proposed algorithm is examined using SIS benchmarks. When the number of OR terms is five, the experiment results show that power consumption is reduced by 30.73% compared with TEMPLA, and by 17.11 % compared with PLA mapping.

• Journal of Communications and Networks
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• 제12권6호
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• pp.544-557
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• 2010

This paper addresses the problem of controlling the envelope's power peak of single carrier modulated signals, band limited by root-raised cosine (RRC) pulse shaping filters, in order to reduce power amplifier back-off for very small aperture terminals ground stations. Magnitude modulation (MM) is presented as a very efficient solution to the peak-to-average power ratio problem. This paper gives a detailed description of the MM concept and its recent evolutions. It starts by extending the look-up-table (LUT) based approach of the MM concept to M-ary constellations with M ${\leq}$ 16. The constellation and RRC symmetries are explored, allowing considerable reduction on LUT computation complexity and storage requirements. An effective multistage polyphase (MPMM) approach for the MM concept is then proposed. As opposed to traditional LUT-MM solutions, MM coefficients are computed in real-time by a low complexity multirate filter system. The back-off from high-power amplifier saturation is almost eliminated (reduction is greater than 95%) with just a 2-stage MPMM system even for very demanding roll-off cases (e.g., ${\alpha}$ = 0,1). Also, the MPMM is independent of modulation in use, allowing its easy application to constellations with M > 16.

• Journal of Power Electronics
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• 제17권3호
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• pp.716-724
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• 2017

The output voltage of an off-grid inverter is influenced by load current, and the voltage harmonics especially the 5th and 7th are increased with nonlinear loads. In this paper, to attenuate the output voltage harmonics of off-grid inverters with nonlinear loads nearby, a load current feedforward is proposed. It is introduced to a voltage control loop based on the Positive and Negative Sequence Harmonic Regulator (PNSHR) compensation to modify the output impedance at selective frequencies. The parameters of the PNSHR are revised with the output impedance of the off-grid inverter, which minimizes the output impedance of the off-grid inverter. Experimental results verify the proposed method, showing that the output voltage harmonics caused by nonlinear loads can be effectively suppressed.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2240-2248
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• 2015

The integration of the large-scale wind power brings great challenge to the stability of the power grid. This paper investigates and studies the fault on May 14, 2012 of the large-scale cascading trip-off of wind turbines in North China. According to the characteristics of the voltage variation, the fault process is divided into three stages: the pre-event stage, the critical stage before cascading, and the cascading stage. The scenes in the fault are reproduced, using the full-size actual power system model. Simulation models of double-fed induction generators (DFIGs) and SVCs including protection settings and controller strategies are carefully chosen to find out the reason of voltage instability in each stage. Some voltage dynamic that have never been observed before in the faults of the same kind are analyzed in detail, and an equivalent voltage sensitive dynamic model of DFIG is proposed for the fast computation. The conclusions about the voltage dynamics are validated by the actual PMU observation evidence.