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EMTP MODELS를 사용한 거리계전기법 구현에 관한 연구
이명희,최해술,서용필,김철환 成均館大學校 科學技術硏究所 1995 論文集 Vol.46 No.2
This paper presents a new distance relay modeling techniques which avoids unnecessary computational procedure. A general-purpose simulation language, called MODELS, has been added to the software ATP(Alternative Transients Program) providing a new option to perform numerical and logical manipulations of variables of an electrical system. This language has been designed to replace the previous option TACS(Transient Analysis of Control Systems) which permits to simulate a control system in conjunction with a large power network. One purpose of this study is to build a structure for modeling of digital distance relays within EMTP MODELS. Contrary to the traditional methods, the new method using MODELS reduce the number of simulation steps in modeling the distance relay.
B_(2)O_(3)첨가에의한 LNT(Li_(1/2)Nd_(1/2)TiO_(3))-CT(CaTiO_(3)) 세라믹의 저온 소결 및 마이크로파 유전특성
이찬우,최명호,김남철 公州大學校 工學硏究院 生産技術硏究所 2004 論文集 Vol.12 No.-
The effect of B_(2)O_(3) addition on the microstructures and the microwave dielectric properties of 0.5LNT(Li_(1/2)Nd_(1/2)TiO_(3)) - 0.5CT(CaTiO_(3)) Ceramics have been investigated. It is found that B_(2)O_(3)(up to 5wt%) can significantly improve the density and dielectric properties of 0.5LNT(Li_(1/2)Nd_(1/2)TiO_(3)) - 0.5CT(CaTiO_(3)) Ceramics. 0.5LNT-0.5CT Ceramics with additives could be sintered to a density higher then 95% at 900℃, due to the liquid phase effect of B_(2)O_(3) addition, as observed by Scanning electron microscopy(SEM). A secondary pahse was not observed at the level of 5 ~ 10wt% B_(2)O_(3) addition. The microwave dielectric properties of 0.5LNT(Li_(1/2)Nd_(1/2)TiO_(3)) - 0.5CT(CaTiO_(3)) with 5wt%B_(2)O_(3) were as follows : ε_(r) = 85, Qxf_(0) = 2,500 and Tcf = -9ppm/℃, sintered at 900℃/2hr.
이종석,이종철,김명웅,최순복,김영길,유은일 한국공업화학회 2003 응용화학 Vol.7 No.1
The whole process of manufacturing diabatic leather for upper and lining is investigated into raw skin, pelt wet bule, crust leather and finished leather It is tried to make the more functional upper leather and lining leather in the whole leather process by the use of developed recipr. The lower chrommed wet blue for upper and lining is developed through tanning process. The air-permeability of crust leather for upper and lining is incerased through miling The hygiene of finished leather for upper and lining is increased by the of antibacterial and deodorization agents. The upper leathe and lining leather through these have the more improved physical properies of the finished leather than those through other treatments.
이명호,이재철,이승우,서장일,박세희 강원대학교 부설 석재복합신소재 제품연구센터 2004 석재연 논문집 Vol.9 No.-
폴리머 콘크리트 복합체를 이용하여 악천후에도 시인성이 좋고 주위의 경관과 어울리는 자동점멸 표지병을 개발하였다. 아날로그 회로에 비해 설계상의 난해한 점이 있으나 상대적으로 간편한 디지털 회로를 사용하여 자동점멸 회로를 구성하였으며, 작업의 능률을 높이고 개발비를 줄이기 위하여 OrCAD를 사용한 Simulation을 실시후 회로를 구성하였다. 표지병의 시공시와 같은 환경에서의 실험에서는 디지털회로의 작은 전류와 표지병간의 거리, 전선의 저항으로 인하여 클럭 및 클리어 신호에 전압강하와 상승/하강 시간의 증가가 나타났다. 표지병은 전자회로와 함께 설치되어야 하므로 방수성을 고려하여 표지병과 전자회로를 일체형으로 설계하였다. 실제 시공시의 환경에서 시행한 실험에서 나타난 문제점을 검토하였으며, 향후 연구방향에 관하여 고찰하였다. Using polymer concrete composite, the automatic-on/off road marker that is well distinguished in a bad weather condition of rainy or foggy day and is well harmonized with. Digital circuit that is hard to design but simpler than an analog circuit is used in designing the automatic-on/off circuit, and it order to raise the working efficiency and lower the development cost, OrCAD, a simulation tool of electric circuit, was used in simulating the circuit. In an experiment conducted under the circumstance of practical application, voltage drop and raising/lowering time increment in the clock and the clear signals are occurred because of small current of digital circuit and resistance of electrical line. Because that the road marker is assembled with the digital circuit, it is designed as one assembled unit by considering water proof. Some problems occurred in the experiment and the future work are discussed.
전력계통의 실시간 대칭성분 계산을 위한 알고리즘에 관한 연구
신명철,이복구,성낙환 成均館大學校 科學技術硏究所 1987 論文集 Vol.38 No.1
Nowadays as the power systems have been more complicated and have grown to ultra high voltage, it requires an accurate and high speed relaying scheme to improve the reliablity and stability of power systems for a harmonious power supplying. This paper presents a real-time algorithm for calculating symmetrical components from the distorted transient voltage and current signals in a power system. To compute the sequence components and hence to analyze the nature of the disturbance it is necessary to extract the fundamental frequency signals from the noise-ridden transient signals. The fundamental frequency components are filtered out from the transient signals using discrete Fourier technique. The fundamental frequency components of the 3-phase signals are first extracted using an algorithm based on discrete Fourier transformation and then real-time symmetrical components transformation is applied to obtain the sequence components. The algorithm presented is computationally efficient and fast. Experiment results on artificial transmission line demonstrate the validity of the proposed algorithm.
朴永圭,李哲熙,魯明英 嶺南大學校 環境問題硏究所 1987 環境硏究 Vol.6 No.2
The study was carried out on the pathway and the trend of copper pollution of sediments in the Kumho River. It was difficult to establish the actual copper pollution level of sediment only with a data on copper contents sediment because measured values of copper fluctuated intensely even in an identical sampling station. Then the trianglar coordinate chart method was applied to compare the pictures of copper pollution among different sampling stations with several items (Cd, Cr, Zn, Pb, Mn and Fe) of the measurement. It was useful for the selection of metals in trianglar coordinate chart to check the probable distribution of metal concentration in sediments. The combination of copper, cadimum and manganese was appeared to be most excellant among fifteen combination of metals in trianglar coordinate charts for the investigation of copper pollution. The plot in the Cu-Cd-Mn trianglar coordinate chars successfully account for the pathway of copper pollution of sediments.
조인숙,이춘모,신명철 成均館大學校 科學技術硏究所 1990 論文集 Vol.41 No.1
Today, the power systems have been complicated and large-scaled. In order to analyze such system promptly and maintain it efficiently, the application of computer to power system is introduced. Accordingly, the interest in analysis of power system by computer has been growing around the world. But there are many additional problems, such as inaccurate solution, computing time delay, and immense memory size. This paper deals with ordering algorithm and diakoptic method in large eletric power system, and its main concern is significant reduction in computing time and memory size. In this thesis a new diakoptic method is designed. It takes the good points of diakoptic method and MPRLD, a kind of optimal ordering algorithm, which had improved sparse vector method. Reducing in computing time and memory size by the diakoptic method designed is verified with a model system. It is possible to reduce because each teared area is analyzed independently and the concept of parallel processing is adopted.
손명환(Myong Hwan Sohn),이광민(Kwamg Min Lee),김철완(Chul Wan Kim),이의재(Eui Jae Lee),이상준(Sang Joon Lee) 한국가시화정보학회 2010 한국가시화정보학회 학술발표대회 논문집 Vol.2010 No.11
Many samaras or winged seeds make an autorotation during their fall. The autorotation slows down the descent of the seed such that the seed can be carried further away from the parent trees by wind. In the present study, the autorotation mechanism of maple seeds was examined by employing both experimental and numerical techniques. The present study confirmed several prominent features for the autorotation mechanism of maple seeds observed in previous investigations. Especially, it was found that the attached and strong leading edge vortex caused a suction pressure distribution of large magnitude on the reward surface of the seed, and this contributed to the high lift whichmakes the seeds descend slowly.