• 한국전기전자재료학회논문지
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• 제22권8호
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• pp.694-697
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• 2009

The separated three-phase flux-coupling type superconducting fault current limiter(SFCL) is composed of a series transformer and superconducting unit of the YBCO coated conductor. The primary and secondary coils in the transformer were wound in series each other through an iron core and the YBCO coated conductor was connected with secondary coil in parallel. In this paper, we investigated the current limiting characteristics through winding number of coil 2 and winding direction in the flux-coupling type SFCL. Through the analysis, it was shown that additive polarity condition and lower winding number of coil 2 have advantaged from the point of view of fault current limiting and burned of YBCO coated conductor.

• 전기학회논문지P
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• 제57권3호
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• pp.323-327
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• 2008

We investigated the quench characteristics of a flux-lock type superconducting fault current limiter (SFCL) depending on the methods of the serial and parallel connections between the superconducting elements. The flux-lock type SFCL consists of two coils. The primary coil is wound in parallel to the secondary coil through an iron core, and the secondary coil is connected to the superconducting elements in series and parallel. In this paper, the analyses of voltage, current, and resistance of the superconducting elements connected in serial and parallel were performed to increase the power capacity of the flux-lock type SFCL. A part of the superconducting elements was not quenched in $2{\times}2$ serial connection between the elements and then the power burden of the quenched elements was increased. However the elements with $2{\times}2$ parallel connection was all quenched. This means that the power burden of each superconducting element can be reduced under the same conditions. We found that $2{\times}2$ parallel connection was more profitable for the current limiting effects and the increase of the power capacity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.257-258
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• 2008

The inrush current of a transformer is a high-magnitude and harmonic-rich current generated when the transformer core is driven into saturation during energizing. The inrush current usually leads to undesirable effects, for example potential damage to the transformer, misoperation of a protective relay, and power quality deterioration in the distribution power system. Inrush current reduction is therefore important for power system operation. In this paper, to reduce the inrush current, the insertion resistance of the Superconducting Fault Current Limiter (SFCL) that is connected in series with the transformer in the distribution system is used. This paper implements the SFCL by using the Electromagnetic Transient Program-Restructured Version (EMTP-RV) to model the SFCL in the distribution system. The simulation results show the beneficial effects of the SFCL for reduction of the inrush current.

• 항공우주시스템공학회지
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• 제8권2호
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• pp.21-26
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• 2014

The aircraft manufacturers are constantly driving to reduce manufacturing lead times and cost at the same time as the product complexity increases and technology continues to change. Integrated Modular Avionics (IMA) is a solution that allows the aviation industry to manage their avionics complexity. IMA defines an integrated system architecture that preserves the fault containment and 'separation of concerns' properties of the federated architectures. In software side, the air transport industry has developed ARINC 653 specification as a standardized Real Time Operating System (RTOS) interface definition for IMA. It allows hosting multiple applications of different software levels on the same hardware in the context of IMA architecture. This paper describes a study that provided the avionics software design for separation of fault and backup of core function to reduce workload of pilot with cost efficiency.

• 조명전기설비학회논문지
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• 제23권2호
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• pp.77-81
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• 2009

병렬연결된 두 코일을 가진 자속구속형 초전도 전류제한기의 사고발생시 철심의 포화를 억제하기 위한 방안으로 공극을 도입하였다. 하지만, 공극의 도입으로 인해 자화전류가 증가하게 되어 자속구속형 초전도 전류제한기의 임피던스 감소를 초래하게 된다. 본 논문에서는 공극유무에 따른 병렬연결된 두 코일을 가진 자속구속형 초전도 전류제한기의 전류제한 특성을 등가회로와 실험결과에 대한 비교분석을 통해 공극도입의 장.단점을 확인하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.249-251
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• 2008

We investigated a flux-coupling type superconducting fault current(SFCL) limiter. The SFCL consisted of the primary and secondary coils, which were wound in series each other through an iron core. Superconducting unit was connected with secondary coil in parallel. The flux generated from a coil in normal operation is cancelled out by its structure and the zero resistance of the superconducting unit. In this paper. In order to compare the current limiting effects of the SFCL by applied voltage. When a lied voltage was increased, quench time was shortened Fast quench time is important component under the same fault condition because power burden of the SFCL is reduced by that of the superconducting units. The current limiting behavior of flux-coupling type SFCL was dependent upon the applied voltage.

• 전기학회논문지P
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• 제52권4호
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• pp.179-188
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• 2003

Percentage differential characteristic scheme has been recognized as the principal basis for large transformer protection. Nowadays, relaying signals can contain second harmonic component to a large extent even in a normal state, and second harmonic ratio indicates a tendency of relative reduction because of the advancement of transformer's core material. And then, conventional second harmonic restraint differential relaying exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for the effective and accurate discrimination. This paper deals with advanced fuzzy logic based relaying by using flux differential, and a new fault detection criterion logic scheme by using wavelet transform. To comparative analysis of proposed techniques, the paper constructs power system model including power transformer, utilizing the EMTP, and collects data through simulation of various internal faults and magnetizing inrush. The proposed fuzzy relaying and a new fault detection scheme were tested. The former, fuzzy relaying, was proven to be faster and more reliable than the latter.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.563-564
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• 2017

클라우드 컴퓨팅 기술의 핵심은 데이터 센터이며 데이터 센터 내에서는 네트워킹 기술이 중요하다. 클라우드 데이터 센터에는 수만에서 수십만 개의 물리적 서버로 구성되어 있어서 높은 수준의 데이터 전송이 가능한 네트워킹 기술이 필요하다. 이러한 네트워킹 기술은 또한 확장성과 고장 감내성 등이 필요하며 민첩성이 필요하다. 이를 위해 다양한 다중 경로를 이용하는 기법이 제안되었다. 하지만 주로 부하 균형을 위한 기법이나 임의적으로 경로를 선택하는 데 사용되었다. 본 논문에서는 소프트웨어 정의 네트워킹 기술을 이용하여 다중 경로를 구성하고 다중 경로를 이용하여 트래픽을 병렬 전송함으로써 빠른 전송속도를 가져오며, 확장성 문제를 해결하고 고장 발생 시에 감내할 수 있는 기술을 제안한다.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.498-508
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• 2021

Micro reactors are increasingly being considered for utilization as distributed power sources. Hence, the probabilistic safety assessment (PSA) of a direct supercritical-CO₂-cooled fast reactor, called micro modular reactor (MMR), was performed in this study; this reactor was developed using innovative design concepts. It adopted a modular design and passive safety systems to minimize site constraints. As the MMR is in its conceptual design phase, design weaknesses and valuable safety insights could be identified during PSA. Level 1 internal event PSA was carried out involving literature survey, system characterization, identification of initiating events, transient analyses, development of event trees and fault trees, and quantification. The initiating events and scenarios significantly contributing to core damage frequency (CDF) were determined to identify design weaknesses in MMR. The most significant initiating event category contributing to CDF was the transients with the power conversion system initially available category, owing to its relatively high occurrence frequency. Further, an importance analysis revealed that the safety of MMR can be significantly improved by improving the reliability of reactor trip and passive decay heat removal system operation. The findings presented in this paper are expected to contribute toward future applications of PSA for assessing unconventional nuclear reactors in their conceptual design phases.

• Steel and Composite Structures
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• 제39권4호
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• pp.353-366
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• 2021

Cored moment resisting stub column (CMSC) was previously developed by the features of adopting a core segment which remains mostly elastic and reduced column section (RCS) details around the ends to from a stable hysteretic behavior with large post-yield stiffness and considerable ductility. Several full-scale CMSC components with various length proportions of the RCSs with respect to overall lengths have been experimentally investigated through both far-field and near-fault cyclic loadings followed by fatigue tests. Test results verified that the proposed CMSC provided very ductile hysteretic responses with no strength degradation even beyond the occurrence of the local buckling at the side-segments. The effect of RCS lengths on the seismic performance of the CMSC was verified to relate with the levels of the deformation concentration at the member ends, the local buckling behavior and overall ductility. Estimation equations were established to notionally calculate the first-yield and ultimate strengths of the CMSC and validated by the measured responses. A numerical model of the CMSC was developed to accurately capture the hysteretic performance of the specimens, and was adopted to clarify the effect of the surrounding frame and to perform a parametric study to develop the estimation of the elastic stiffness.