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정일엽,문성일 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.2
This paper proposes a new islanding detection method for inverter-interfaced distributed generators (DG). To detect islanding conditions, this paper calculates the phase angle variation of the system voltage by using the phase-locked loop (PLL) in the inverter controllers. Because almost all inverter systems are equipped with the PLL, the implementation of this method is fairly simple and economical for inverter-interfaced DGs. The detection time can also be shortened by reducing communication delay between the relays and the DGs. The proposed method is based on the fact that islanding conditions result in the frequency and voltage variation of the islanded area. The variation depends on the amount of power mismatch. To improve the accuracy of the detection algorithm, this paper injects small low-frequency reactive power mismatch to the output power of DG.
Production of Interferon-$\gamma$ from Human Peripheral Blood Lymphocytes
정일엽,염영일,이상기,정태화,한문희,Chung, Il-Yup,Yeom, Young-Il,Rhee, Sang-Ki,Chung, Tai-Wha,Han, Moon-Hi 생화학분자생물학회 1986 한국생화학회지 Vol.19 No.3
인체혈액에서 분리한 임파구세포를 PHA-M, Con A, PWM등의 mitogen으로 자극시켜 여러가지 조건하에서 감마-인터페론을 생산하였다. 유도물질로 사용된 T-세포 mitogen인 PHA-M이나 Con A가 B-세포 mitogen 인 PWM보다 감마-인터페론 유도에 훨씬 효율적이었으며 이로부터 임파구세포 중에서 T-세포가 감마-인터페론을 생산하는 주요세포원 임을 확인하였다. 감마-인터페론 생산시 Con A의 적정농도는 $5-10\;{\mu}g/ml$이었다. 유도개시 약 48시간 경과 후 인터페론이 최대로 생산되었고 그 이후에도 인터페론의 활성은 감소되지 않았다. Phorbolester인 TPA를 첨가할 경우 Con A 또는 PHA-M 단독으로 인터페론을 유도시킨 것보다 10배 이상의 감마-인터페론의 생산이 증가되었다. 생산배양액에 첨가되는 혈청의 농도가 인터페론의 생산에 마치는 영향은 매우 극적이어서 태아 송아지 혈청농도 2%에서 최대로 생산되었고 농도가 증가함에 따라 생산역가는 급격히 떨어졌다. 혈청 대신 사용한 알부민 단백질도 비슷한 효과를 나타냈다. 혈액중에 임파구세포에 처리된 Con A가 DNA 합성을 촉진시키는 성질을 이용하여 $^3H$-thymidine 표식으로 cpm을 측정해 본 결과, 이와같은 현상은 10-20%의 높은 혈청농도에서 Con A가 과량의 혈청단백질과 흡착하여 실제적인 Con A 농도를 적정농도 이하로 떨어뜨리기 때문인 것으로 나타났다. Interferon-$\gamma$(IFN-$\gamma$) was produced from human peripheral blood lymphocytes (Hu-PBL) by stimulating them with various kinds of mitogens. T-cell mitogens such as Con A and PHA-M were much more potent than B-cell mitogen such as PWM in producing IFN-$\gamma$ from Hu-PBL. The combined treatment of TP A with these mitogens enhanced IFN-$\gamma$ production ten fold compared with the single treatment of each mitogen. Both DNA synthesis and IFN-$\gamma$ production yielded bell-shaped dose-response curves for a given population of Hu-PBL in response to Con A. The effect of fetal calf serum(FCS) on IFN-$\gamma$ production was found to be critical: titer of IFN-$\gamma$ produced was very low in the absence of FCS and reached peak point at 2% FCS, beginning to decrease precipitously with an increasing FCS concentration up to 20%. Using the relationship between IFN-$\gamma$ production and mitogenic stimulation, it was found that one of factors responsible for the decrease of IFN-$\gamma$ production at the high serum concentration could be the binding of Con A to serum proteins which rendered Con A to be removed from the production system.
다중 분산전원으로 구성된 마이크로그리드의 유무효전력 제어원리 연구
丁一燁(Il-Yop Chung),元東俊(Dong-Tun Won),文承逸(Seung-Il Moon) 대한전기학회 2008 전기학회논문지 Vol.57 No.4
Microgrids are new distribution level power networks that consist of various electronically-interfaced generators and sensitive loads. The important control object of Microgrids is to supply reliable and high-quality power even during the faults or loss of mains (islanding) cases. This paper presents power control methods to coordinate multiple distributed generators (DGs) against abnormal cases such as islanding and load power variations. Using speed-droop and voltage-droop characteristics, multiple distributed generators can share the load power based on locally measured signals without any communications between them. This paper adopts the droop controllers for multiple DG control and improved them by considering the generation speed of distribution level generators. Dynamic response of the proposed control scheme has been investigated under severe operation cases such as islanding and abrupt load changes through PSCAD/EMTDC simulations.