중온형 고체전해질 연료전지용 전해질 개발

임형렬,이주성,정순기 한양대학교 에너지 ·환경기술연구소 1995 에너지·環境技術論文集 Vol.2 No.-

고체전해질형 연료전지의 작동온도를 낮추기 위해 고체전해질인 ??를 고상반응법으로 제조하여 그 전기화학적 특성을 살펴보았으며 소결온도 및 첨가제 함량이 이온전도도에 미치는 영향에 대해서도 고찰하였다. 1500℃에서 10시간동안 소결한 ??의 경우 Yb₂O₃의 함량이 ZrO₂에 대해 8㏖%일 때 가장 뛰어난 특성을 보여 890℃, 공기 중에서 ??의 이온전도도를 나타내었다. ?? were prepared by solid state reaction and its electrochemical characteristics were investigated to lower the operating temperature of solid oxide fuel cell. Also the effects of sintering temperature and additive content on ionic conductivity were studied. In case of ?? sintered at 1500℃ for 10hr, the best characteristics were showed when x is 0.08 and the value was ?? at 890℃ in air.

젖소 말초혈액 림프구로부터 소백혈병 바이러스 배양 및 전자현미경적 관찰

윤순식,박중원,변재원,강문일,유한상,한홍율 韓國電子顯微鏡學會 2005 Applied microscopy Vol.35 No.1

국내 젖소의 54.2%가 BLV에 감염되어 있지만 현재까지 국내에서는 소백혈병 바이러스 (BLV) 입자를 확인한 연구 보고가 없기 때문에 BLV 항체 양성 소의 말초혈액림프구를 배양, BLV를 발현시켜 전자현미경으로 바이러스 입자를 검출하였고 배양조건에 따른 바이러스 발현율 및 발현 시간을 비교하였다. 검사 결과 전형적인 C-형 바이러스를 확인할 수 있었으며 BLV 단크론 항체를 이용한 면역염색결과 BLV 항원 양성으로 확인되었다. BLV 는 대부분 세포 외부에 분포하고 있었으며 세포질 막에서 생성, 발아되어 나오는 것도 관찰되었다. 전체 바이러스의 크기는 90~100 nm였으며 nucleocapsid는 40~60nm였다. 소태아혈청 (FBS)과 T- 및 B-림프구 분열촉진물질(mitogen)을 각각 첨가하여 배양한 결과 두 군 모두에서 BLV 발현이 확인되었다. Lipopolysaccharide 첨가군은 배양 12시간, Conconavalin A 첨가군은 배양 24시간에 각각 림프구의 10%에서 바이러스가 관찰되었다. 또한 FBS만 첨가한 군과 FBS와 mitogen을 모두 첨가하지 않은 군에서도 관찰되었으나 바이러스의 수는 적었다. 본 연구에서 확립된 BLV 배양 기법을 활용하면 BLV에 감염된 소 중 바이러스를 발현하는 소, 즉 전파능이 있는 개체를 찾아내어 우선적으로 도태할 수 있기 때문에 BLV 감염으로 인한 피해를 막는데 효과적으로 이용될 수 있을 것으로 사료된다. Many studies have been performed on the bovine leukemia virus (BLV) since bovine leukosis had been reported in 1968 in Korea. However, there was no report on the ultrastructural examination of BLV. An attempt to detect C-type viral particles in the cultured peripheral blood lymphocytes of Holstein-Friesian dairy cattle, was made to determine whether in vitro viral expression might be used as a reliable method to identify the cow which is likely to transmit BLV. In transmission electron microscopic (TEM) examination, the virus particles were found predominantly outside of the lymphocytes even though a few particles were also observed within the membrane bound cytoplasmic vacuoles. All of them were C-type particles consisting of a central, electron-dense core separated by a clear area from a limiting envelope with a unit membrane structure. Virus particles were easily detected in the lymphocyte which was cultured with medium supplemented with either T-lymphocyte mitogen (conconavalin A) or B-lymphocyte mitogen (lipopolysaccharide). Identical viral particles, although fewer, were also consistently present in the lymphocytes cultured with medium which was containing foetal bovine serum (FBS) only and which was containing neither FBS or mitogen. By contrast, no virus particle was detected in extensive examination of lymphocytes before culture. In conclusion, the BLV cultivation and detection methods established in this study could be used as a tool to identify and eliminate the cattle which can transmit the BLV.

Nonlinear Cardiac Dynamics and Morning Dip : 위험한 일중리듬 An Unsound Circadian Rhythm

염명걸,김남수,오재원,김창렬,이재웅,김순길,이철범,노정일,최정연,윤용수 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.3

A Method for Estimating an Instantaneous Phasor Based on a Modified Notch Filter

Soon-Ryul Nam,Jin-Man Sohn,Sang-Hee Kang,Jong-Keun Park 대한전기학회 2006 Journal of Electrical Engineering & Technology Vol.1 No.3

A method for estimating the instantaneous phasor of a fault current signal is proposed for high-speed distance protection that is immune to a DC-offset. The method uses a modified notch filter in order to eliminate the power frequency component from the fault current signal. Since the output of the modified notch filter is the delayed DC-offset, delay compensation results in the same waveform as the original DC-offset. Subtracting the obtained DC-offset from the fault current signal yields a sinusoidal waveform, which becomes the real part of the instantaneous phasor. The imaginary part of the instantaneous phasor is based on the first difference of the fault current signal. Since a DC-offset also appears in the first difference, the DC-offset is removed from the first difference using the results of the delay compensation. The performance of the proposed method was evaluated for a-phase to ground faults on a 345 ㎸ 100 ㎞ overhead transmission line. The Electromagnetic Transient Program was utilized to generate fault current signals for different fault locations and fault inception angles. The performance evaluation showed that the proposed method can estimate the instantaneous phasor of a fault current signal with high speed and high accuracy.

A Modified Selective Ground Relay for Ungrounded Distribution Systems

Soon-Ryul Nom,Sang-Hee Kang,Jong-Keun Park 대한전기학회 2006 Journal of Electrical Engineering & Technology Vol.1 No.1

Selective ground relays (SGRs) are useful for distinguishing a faulted feeder from the sound feeders in ungrounded systems. However, they sometimes mis-operate due to human or device errors. Particularly, the reversed polarity of zero-sequence current transducers (ZCTs) is the most frequent cause of mis-operation. This paper presents a modified SGR for reducing the probability of mis-operations caused by the reversed polarity of ZCTs. The modification is achieved by introducing an adaptive time delay, which depends on the magnitude of the zero-sequence current and the phase angle deviation from the reference. The modified SGR was successfully demonstrated on a sample ungrounded system without mis-operation.

Fundamental Frequency Estimation in Power Systems Using Complex Prony Analysis

Soon-Ryul Nam,Dong-Gyu Lee,Sang-Hee Kang,Seon-Ju Ahn,Joon-Ho Choi 대한전기학회 2011 Journal of Electrical Engineering & Technology Vol.6 No.2

A new algorithm for estimating the fundamental frequency of power system signals is presented. The proposed algorithm consists of two stages: orthogonal decomposition and a complex Prony analysis. First, the input signal is decomposed into two orthogonal components using cosine and sine filters, and a variable window is adapted to enhance the performance of eliminating harmonics. Then a complex Prony analysis that is proposed in this paper is used to estimate the fundamental frequency by approximating the cosine-filtered and sine-filtered signals simultaneously. To evaluate the performance of the algorithm, amplitude modulation and harmonic tests were performed using simulated test signals. The performance of the algorithm was also assessed for dynamic conditions on a singlemachine power system. The Electromagnetic Transients Program was used to generate voltage signals for a load increase and single phase-to-ground faults. The performance evaluation showed that the proposed algorithm accurately estimated the fundamental frequency of power system signals in the presence of amplitude modulation and harmonics.

Clinical, ophthalmological, and pathological findings of hypovitaminosis A in cattle

Soon Seek Yoon,Soon Wuk Jeong,Kang Moon Seo,Jae Hoon Kim,Young Hwa Jean,Eui Kyung Hwang,Gab Soo Chung,Hong Ryul Han 한국수의병리학회 2003 한국수의병리학회지 Vol.7 No.1

유도 전동기의 고정자 권선 사고에 대한 모델링 방법

남순열(Soon-Ryul Nam),홍정기(Jung-Gi Hong),박종근(Jong-Keun Park) 대한전기학회 2003 대한전기학회 학술대회 논문집 Vol.2003 No.11

A Method for Estimating an Instantaneous Phasor Based on a Modified Notch Filter

Nam Soon-Ryul,Sohn Jin-Man,Kang Sang-Hee,Park Jong-Keun The Korean Institute of Electrical Engineers 2006 Journal of Electrical Engineering & Technology Vol.1 No.3

A method for estimating the instantaneous phasor of a fault current signal is proposed for high-speed distance protection that is immune to a DC-offset. The method uses a modified notch filter in order to eliminate the power frequency component from the fault current signal. Since the output of the modified notch filter is the delayed DC-offset, delay compensation results in the same waveform as the original DC-offset. Subtracting the obtained DC-offset from the fault current signal yields a sinusoidal waveform, which becomes the real part of the instantaneous phasor. The imaginary part of the instantaneous phasor is based on the first difference of the fault current signal. Since a DC-offset also appears in the first difference, the DC-offset is removed trom the first difference using the results of the delay compensation. The performance of the proposed method was evaluated for a-phase to ground faults on a 345kV 100km overhead transmission line. The Electromagnetic Transient Program was utilized to generate fault current signals for different fault locations and fault inception angles. The performance evaluation showed that the proposed method can estimate the instantaneous phasor of a fault current signal with high speed and high accuracy.

PSS/E를 이용한 제주계통의 DFIG 풍력발전단지 및 HVDC 동적모델 개발

남순열(Soon-Ryul Nam),강상희(Sang-Hee Kang),남해곤(Hae-Kon Nam),최준호(Joon-Ho Choi) 대한전기학회 2011 전기학회논문지 Vol.60 No.12

Since main portion of the required electric power in Jeju Island is provided from the mainland through two HVDC lines, Jeju HVDC has a most significant impact on Jeju power system. Average wind speed of Jeju Island is the highest among several candidates in South Korea. So, Jeju Island has been a suitable site for the construction of wind farms where several wind farms are now operating and several others to be sited. Since the large-scale wind generation could have adverse impacts on the stable operation of Jeju power system, wind power is also important for the stability of Jeju power system. Therefore, accurate modeling of Jeju HVDC and wind farms is required for stability analysis of Jeju power system. In this paper, PSS/E-based dynamic modeling of Jeju HVDC and DFIG wind farms is proposed. Model-writing technique of PSS/E is used to develop USRAUX model and USRMDL model for controlling the frequency of HVDC and imposing an operation limit of wind power, respectively. Dynamic characteristics of Jeju HVDC and DFIG wind farms are analyzed through the dynamic simulations. The simulation results show the effectiveness of the developed models for Jeju power system.