• 조명전기설비학회논문지
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• 제28권12호
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• pp.65-73
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• 2014

In this paper, the detection scheme of the voltage variation using a two difference voltage is proposed. The conventional sag detector is from a single-phase digital phase-locked loop (DPLL) that is based on a d-q transformation using an all-pass filter (APF). The APF generates a virtual q-axis voltage component with $90^{\circ}$ phase delay but the APF cannot generate the virtual q-axis voltage depending on the phase of the grid voltage. To overcome the problem, q-axis voltage component is generated from difference between the current and previous value of d-axis voltage component in the stationary reference frame. However, the difference voltage around the zero crossing is not enough to detect the voltage sag. Therefore, the new detection scheme using the two difference voltage which can detect the sag around the zero crossing voltage is proposed.

• Journal of Magnetics
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• 제15권4호
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• pp.213-220
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• 2010

Since the hypothalamus immediately reacts to a nerve by processing all the information from the human body and the external stimulus being conducted, it performs a significant role in internal secretion; thus, a diverse and rapid stimulus pulse is required. By detecting Zero Detector accurately via the application of AVR on-Chip (ATMEL) using commercial electricity, chopping generates a stimulus pulse to the brain using an IGBT gate to designate a new magnetic stimulation following treatment and diagnosis. To simplify and generate a diverse range of stimuli for the brain, chopping can be used as a free magnetic stimulator. Then, commercial frequency (60Hz) is chopped precisely at the first level of the leakage transformer to deliver an appropriate stimulus pulse towards the hypothalamus when necessary. Discharge becomes stable, and the chopping frequency and duty-ratio provide variety after authorizing a high-pressure chopping voltage at the second level of the magnetic stimulator. These methods have several aims. The first is to apply a variable stimulus pulse via accurate switching frequency control by a voltaic pulse or a pulse repetition rate, according to the diagnostic purpose for a given hypothalamus. Consequently, the efficiency tends to increase. This experiment was conducted at a maximum of 210 W, a magnetic induced amplitude of 0.1~2.5 Tesla, a pulse duration of $200{\sim}350\;{\mu}s$, magnetic inducement of 5 Hz, stimulus frequency of 0.1~60 Hz, and a duration of stimulus train of 1~10 sec.

• 전기의세계
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• 제19권4호
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• pp.18-23
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• 1970

A neutron detector, in general, can not be utilized as the thermal neutron detecting chamber in the nuclear power reactor, especially P.W.R. due to the characteristics of high temperature, high pressure and high neutron flux in a reactor vessel. We have performed an experiment to detect the thermal neutrons at 400.deg. C and high flux of thermal neutron in a power reactor. Coating boron-10 on the aluminium plates by means of surface diffusion method at 600.deg. C for 5 hours in an electric furace, also we made a typical chamber which was compensated ionization chamber filled with free air as an ionization gas. It was checked the chamber characteristics in the TRIGA MARK-II Reactor at the power level from zero to 250KW. The chamber current showed a perfect linear increase to power increase. However, many variation of the measured current were observed within the power of 50KW.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권9호
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• pp.562-568
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• 2004

The frequency and phase angle of the utility voltage are important in many industrial systems. In the three-phase system, they can be easily known by using the utility voltage vector. However, in the case of single phase system, there are some difficulties in detecting the information of utility voltage. In conventional system, the zero-crossing detection method is widely used, but could not obtain the information of utility voltage instantaneously. In this paper, the new digital PLL control using virtual two phase detector is proposed with a detailed analysis of single-phase digital PLL control for utility connected systems. The experimental results under various utility conditions are presented and demonstrate an excellent phase tracking capability in the single-phase grid-connected operation.

• 전자공학회논문지
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• 제53권7호
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• pp.138-143
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• 2016

본 논문에서 설계 및 제작된 보안 검색 시스템은 물체 및 사람으로부터 방사된 에너지를 수신하여 이미지화 하는 시스템이다. 제안한 보안 검색 시스템은 다채널 수신을 위한 집적화된 어레이 안테나를 적용하였으며, 16개의 4단 저잡음 증폭기와 디텍터, CCD/IR 카메라와 반사판 그리고 밀리미터파 렌즈로 구성된다. 본 시스템은 공기 중의 열잡음 신호를 감지해야 하므로, 높은 수신감도와 넓은 대역폭이 요구된다. 시스템에 사용된 저잡음 증폭기 모듈의 이득특성은 82GHz~102GHz의 대역에서 65.8dB의 평균 이득특성을 가진다. 또한 증폭기 모듈로부터 입력된 열잡음 신호를 DC 전압 값으로 나타낼 수 있는 검출기를 제작하였다. 제작된 검출기는 제로-바이어스 쇼트키 다이오드를 사용하여 물체에서 방사된 밀리미터파 신호를 DC 출력 전압으로 변환하는 방사 분석 센서이다. 제작된 검출기의 특성은 0dBm 입력전력에서 350~400mV/mW, 검출 가능 입력 전력 범위는 -10~13dBm으로 우수한 성능을 보였다. 제작된 보안 검색 시스템은 은닉된 금속 재질의 물체뿐만 아니라, 플라스틱 등으로 이루어진 물체들도 검색이 가능하다.