• Proceedings of the KSR Conference
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• 2003.10c
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• pp.547-551
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• 2003

This paper presents the magnetic fields shielding properties of the light rail transit which are produced by the ripple-shaped currents in the power lines. To analyze these properties, the equivalent circuit model of the DC power supply system at the light rail transit system was induced by MATLAB-SIMULINK, and with the calculated results of the ripple-shaped currents, the magnetic fields shielding properties of the light rail transit were analyzed. The results are as follows. First The frequency of the ripple-shaped currents is 200[Hz] and its magnitude is 1.5[A]. Second the magnetic fields produced by the ripple-shaped currents of the DC power supply systems are well shielded by the aluminum made body of the light rail transit.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.193-198
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• 1996

Low power superconducting persistent current switch(PCS) for the superconducting magnet systems in the persistent mode was developed and its experimental results were analyzed when the system was charged or discharged. The multifilament NbTi wire with Cu matrix was used for the PCS. The constructed NbTi superconducting switch with superconducting magnet system operated successfully. It also operated on-off switching action with good stabilization. The maximum operating current in persistent mode was 60A (at 1T). In persistent current mode, the decay of the persistent current at 60A was observed. Its decay was 3.55% in 60 min. It is possible to make the persistent current switch with the better decaying of persistent current if some problems for joint resistance are solved.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.14-17
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• 1996

We analyzed the characteristics of a power system with superconducting fault current limiter and showed the possibility of the application of a superconducting fault current limiter to a real power system through manufacturing of and experiment about 220Vrms/100Apeak class superconducting fault current limiter. We experimentally confirmed that the overvoltage of superconducting fault current limiter increased as the rate of current sharing to the limiting coil grew. The fault current could be limited within a few milliseconds when it was applied to a power system in series. Therefore, we could confirm that superconducting fault current limiter was effective in protection of a substation or power plant at short-circuit fault. (author). 7 refs., 7 figs., 2 tabs.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.119-121
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• 1995

This paper is a study on inductive superconducting fault current limiter design.. We have created simulation for an imaginery power system with inductive superconducting fault current limiter. Then input variables for characteristic analysis and actual manufacturing, and output variables for design results was assigned. Using the results from these variables, the design criterion was determined which was fed into concept design arising from characteristic analysis to determine the inductance of limiting coil and normal state resistance value of triggering coil. These result was put back into design details to finally give out the design result for inductive superconducting fault current limiter.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.134-136
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• 1995

A superconducting parallel bifilar winding shows the phenomenon which is known as 'fast quench'. We analyzed the temperature characteristics on the winding by computer simulation, and confirmed theses by experiment. The temperature of the quenched point rose gradually as the source voltage was increased. The temperature changed radically as first, but had a gentle slope after a few milliseconds. As the source voltage was large, the initial quenched length also increased. The points in this quenched length showed almost the same temperature. but the points where initial quench had not occurred showed radical temperature gradient. We could observe that the temperature of the whole wire increased simultaneously as the fast quench occurred on the superconducting parallel bifilar winding, because a number of quenched points in that wire appeared at the same time.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.122-124
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• 1995

Electrical transmission and distribution networks must withstand an occasionally abnormal condition such as a fault, with prejudicial consequences for the line, transformers or generators. And the improvement of reliability and quality of the delivered power from an electric utility motivates the development of new technologies in power applications. As a part of these studies, the usefulness and utility of a superconduction fault current limiter(SFCL) are shown. The SFCL is applied to 22.9KV three-phase power system and performed short circuit studies. The verified quench characteristic of SFCL is adopted for fault simulation and the results are compared with those of system which have not SFCL.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.125-127
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• 1995

A superconducting parallel bifilar winding with one strand in each branch was tested and analyzed. When the superconducting parallel bifilar winding was quenched by fault current, it showed the so-called 'fast quench' and the results of experiment well explained the resistance curve. Also the experiments confirm that the current redistribution of magnetically coupled strands develops new normal zones after the initial quench, and that the size of normal zones at an early stage increases almost linearly as dI/dt increases. By these results, we could explain the resistance rise of superconducting parallel bifilar winding when it is quenched by the current above the critical value.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.175-177
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• 1996

This paper is studied on the numerical analysis of temperature distribution on the Nb-foil due to the eddy current under operating a superconducting power supply. The increase of rotating speed and magnetic flux above critical magnetic field lead to the temperature rising in the normal spot, the heat was distributed in the region of 30% distance from the center of the normal spot, but the most of the heat was transferred to LHe. Under operation of the sc power supply, the increase of rotation speed has the more influence on the temperature rising than that of magnetic flux. we can conclude that the totaling speed of normal spot is the main design consideration of the sc power supply, and get the optimal value of rotating speed.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.190-192
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• 1996

This paper is a study on the rotating type of superconducting power supply(R.S.P.S.) with superconducting excitation coils. In this paper, a new idea of excitation coil is introduced to control the pole-flux in air gap. We manufactured the R.S.P.S. by using superconducting excitation coils and measured the charging current of superconducting load with respect to rotational speeds and excitational current. Through this experiment, 425A of maximum current was obtained a few minutes. It turned out that the charging rate of load current is proportional to rotational speeds and excitational current. Furthermore, it is found that it's possible to generate the charge current of thousands of amperes by using wires of larger critical current.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.467-470
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• 2005

지구온난화 현상과 화석연료의 고갈에 대한 두려움 때문에 재생에너지에 대한 관심이 지속적으로 증가하고 있다. 이에 따라 대체에너지, 합성가스, 화학 원료, 오일 등으로 전환할 수 있는 바이오매스 활용에 대한 연구도 활발히 진행되고 있다. 바이오매스의 열화학적 전환 공정에는 열분해, 연소, 가스화 등이 이용되고 있다. 특히 열분해는 syringol, levoglucosan, guaiacol등의 고부가가치 물질들을 생산하기에 적합한 기술로 인정받고 있다. 본 연구에서는 국내에서 쉽게 구할 수 있는 톱밥, 폐목재 등의 바이오매스의 열화학적 전환 특성을 분석하였다. 사용된 바이오매스의 열분해 특성은 열중량 분석기 및 열천칭 반응기를 통해 분석하였으며 이를 통해 유동충 반응기(지름 0.2m, 높이 2m)를 설계 및 제작하였다. 반응온도 및 산소 농도가 증가할수록 levoglucosan 등의 고부가가치 물질들의 수율이 낮아지며 페놀류가 급격히 증가함을 알 수 있었다. 회재 성분이 높은 왕겨의 바이오오일 수율은 톱밥보다 $30\%$이상 낮게 나타났다