• 전기학회논문지
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• 제56권12호
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• pp.2078-2083
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• 2007

We have analyzed operating characteristics of transformer-type superconducting fault current limiter (SFCL) according to the serial or parallel connections of secondary coils with $YBa_2Cu_3O_7$ (YBCO) thin films. The turn ratio between the primary and secondary coils was 63:21. Transformer-type SFCL using a transformer with secondary winding of serial or parallel coils could reduce the unbalanced quench caused by differences of the critical current density between YBCO thin films. We found that transformer-type SFCL having serial or parallel connections induced simultaneous quench between the superconducting units. The limiting current in the transformer-type SFCL with a parallel connection was lowered to 30 % compared to the SFCL with a serial connection. In the meantime, when the currents generated in the superconducting units were similar, the voltage value in the parallel connection was 60 % as low as that in the serial connection. However, the voltage generated in the primary winding was some higher. In conclusion, we found that transformer-type SFCL with parallel connection of secondary coils was more effective in fault current limiting characteristics and in the reduction of the consumption power for superconducting units compared to those of the transformer-type SFCL with serial connection of secondary coils.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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• pp.87-88
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• 2007

We investigated the current limiting characteristics of flux-lock type superconducting fault current limiter using YBCO films University, Gwangju health college. The flux-lock type SFCL consisted of the transformer with a primary winding and a secondary winding connected in parallel, and the superconducting element was connected with secondary winding in series or parallel. Serial and parallel connections of superconducting elements are necessary for the increase of voltage and current capacities when we intend to apply the flux-lock type SFCL.

• 전기학회논문지P
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• 제58권1호
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• pp.27-32
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• 2009

A technical system generally comprise a number of subsystems and components that are interconnected in such a way that the system is able to perform a set of required function. Because of the complex system structure with serial, parallel and bridged connections, some certain subsystems or components are more critical than the others. The main concern of a reliability engineer is to identify potential failures and to prevent these failures from occurring. In order to prevent fatal failures, proper inspections and maintenance actions for each component are required Considering above objectives of reliability engineers and characteristics of a practical system, several practical method for evaluating system and component reliabilities have developed namely Birnbaum's and Fussell & Vesely's measures. However there are several critical weaknesses in traditional calculation process as the target system gets larger. In this paper, a new technique for calculating component's structural importance is proposed and compared to Birnbaum's with representative system examples (serial, parallel. k out of n, and bridge type).

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권11호
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• pp.647-657
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• 2004

Helical magneto-cumulative generator(HMCG)s are very useful devices in suppling pulsed high current to inductance loads. To apply fast high voltage pulses to high impedance loads, high current outputs of HMCGs are required to be conditioned to higher voltages by using various pulse components such as opening/closing switches and pulse transformer. In this paper, stepping with the trends of requirements for ever-increasing energy in pulsed power applications coupling methods is investigated to obtain higher output energy by connecting several HMCGs in series or parallel way. The coil dimension of HMCGs used in series or parallel connections was 50 mm in diameter and 150 mm in length. The coil was fabricated by using enamel-coated copper wire of 1 mm in diameter. The highest energy amplification ratio and peak voltage of load were achieved from the serially connected four-barrel HMCG system. They were 68 and 34 kV, respectively, when the initial energy of 0.36 kJ was supplied into that system with the load of 0.4 μH. Within the tested range of inductance ratio, energy amplification ratio was found to be highly dependent on the inductance ratio of serial- and parallel-connected HMCG systems to load, which to be optimal around 500 was turned out. The experimental results showed that the output energy and voltage of load are controlled by connecting HMCGs in series or parallel.

• 대한기계학회논문집
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• 제14권1호
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• pp.251-258
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• 1990

본 연구에서는 제 1보에서 다루었던 프로세스 해석의 결과들을 토대로 하여 열교환기의 최적 설계를 행하는데 주력하였다. 먼저, 열교환기의 최적 설계를 행하 는데 주력하였다. 먼저, 열교환기의 열설계에 필요한 CO$_{2}$와 Natrium의 물성치 및 열전달에 관한 기존의 실험식들을 여러문헌으로부터 연구 검토한 후 프로그램에 편 리하게 이용할 수 있도록 전산화 하였으며, 열교환기의 설계시 필요한 전체 경비의 최 소화를 기하는 방향으로 최적화된 설계인자들을 결정하도록 시도하였고 또한 최적화된 프로그램을 개발함으로써 인력, 외화 및 에너지 절감의 효과를 얻고자 하였다.