• 한국전기전자재료학회논문지
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• 제28권10호
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• pp.625-629
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• 2015

The second-generation HTS wire its YBCO coated conductor is widely used in the superconducting power apparatus. The YBCO coated conductor uses the normal-superconducting junction to increase the transport capacity of superconducting power apparatus when it is applied. The normal-superconducting junction can be a cause of reducing the stability of the superconducting power apparatus when a fault current is applied. Thus, in this study we have conducted the effect analysing normal-superconducting junction for the fault current using transport current and quench resistance. From the experimental results when a fault current is applied, the effect on the normal-superconducting junction is reduced the larger the amplitude of the fault current and is helpful to maintain the thermal stability of the HTS wire.

• 한국초전도ㆍ저온공학회논문지
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• 제9권3호
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• pp.46-51
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• 2007

The 22.9kV/630A superconducting fault current limiter (SFCL) is developed by the KEPRI-LSIS collaboration group. This resistive SFCL uses three pairs of conduction-cooled current leads. When the SFCL system is in the fault mode. the current flows 20 times more than the steady state. Therefore. it is important that the current lead is designed to have the thermal stability in order to minimize the heat input of the cold-end. This paper presents the design and performance results of a pair of conduction-cooled brass current leads considering both cases that the SFCL system operates at the steady state and the fault current.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.357-358
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• 2016

This paper presents a dynamic, electric-thermal model for a photovoltaic (PV) cell that combines electrical and thermal parameters. In this model, the irradiance and ambient temperature are used to calculate the PV cell temperature based on a five-layer thermal model. The cell temperature is then used in the electrical model to accurately adjust the PV cell output electrical characteristics and power. A custom experimental setup was built to test and verify the electrical and thermal characteristics of the PV cell and its surrounding layers. The electric-thermal model is validated using experimental data in realistic scenarios. This PV model can be scaled up and used to simulate PV systems in wide variety of applications, extreme environmental conditions, and fault conditions in real-time.

• 자원환경지질
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• 제42권6호
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• pp.609-618
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• 2009

지층 내에 발달한 고투수성 단층은 유체, 에너지, 그리고 용질이 이동하는데 있어서 중요한 역할을 하는 지질구조이다. 따라서 고투수성 단층 주변부에서는 지열수(혹은 온천), 지열 이상대, 그리고 금속 광상 등이 형성될 가능성이 크다. 단층의 구조에 따른 지하수 유동과 이에 따른 지층 내의 열적 상태를 확인하기 위해서 단층 구조가 다른 세 가지의 경우에 대해서 이차원 열-수리적 거동 모델링을 수행하였다. 모델링 결과로부터 세 가지 모든 단층 구조의 경우에서 단층의 투수율이 커지면 단층대에서의 지하수 용출 온도가 초기 온도 보다 높아지는 경향을 확인 할 수 있다. Peclet number 와 단층대에서의 용출온도의 상관관계 분석으로부터 상관계수($R^2$)가 0.98로 상당히 높은 것을 확인하였다. Peclet number가 1이상 일 때 단층대에서는 약 $32^{\circ}C$ 이상의 온도가 용출되며 이러한 경우에 단층대에서의 열흐름은 매질을 통한 전도 보다는 지하수에 의한 대류의 영향이 큰 것으로 판단된다.

• 한국초전도ㆍ저온공학회논문지
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• 제17권1호
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• pp.10-13
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• 2015

High-temperature superconducting coated conductors (HTS-CCs) are good candidates for resistive superconducting fault current limiter (RSFCL) applications. However, the high current density they can carry and their low thermal diffusivity expose them to the risk of thermal instability. In order to find the best compromise between stability and cost, it is important to study the heat transfer between HTS-CCs and the liquid nitrogen ($LN_2$) bath. This paper presents an experimental method to monitor in real-time the temperature of a quenched HTS-CC during a current pulse. The current and the associated voltage are measured, giving a precise knowledge of the amount of energy dissipated in the tape. These values are compared with an adiabatic numerical thermal model which takes into account heat capacity temperature dependence of the stabilizer and substrate. The result is a precise estimation of the heat transfer to the liquid nitrogen bath at each time step. Measurements were taken on a bare tape and have been repeated using increasing $Kapton^{(R)}$ insulation layers. The different heat exchange regimes can be clearly identified. This experimental method enables us to characterize the recooling process after a quench. Finally, suggestions are done to reduce the temperature increase of the tape, at a rated current and given limitation time, using different thermal insulation thicknesses.

• Nuclear Engineering and Technology
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• 제28권1호
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• pp.36-43
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• 1996

본 논문은 원자력발전소 열성능 감시 시스템의 PC기반 구현에 관한 연구 내용이다. 이 시스템은 열성능 감시와 진단을 플랜트 운전중에 실시간으로 수행할 수 있다. 고리 원전2호기를 목적호기로 원형 시스템을 구성하여 시험해 보았다. 원자력발전소의 열 주기 시스템은 대단히 복잡하고 구성 요소간에 상호 영향이 커서, 그 분석과 고장 진단에 어려움이 많다. 본 연구에서는 열 주기를 효율적으로 표현하고, 계산시간을 단축하기 위해 성능 진단 변수를 설정하였다. 비정상 상태에서의 진단 변수의 특성 패턴 변화를 인식하기 위해 자기학습 신경망의 일종인 퍼지아트맵을 이용하였다. 시험을 통해 이 알고리듬이 비정상 상태를 감지하고 고장 원인을 성공적으로 규명하는 것을 보였으며, 운전원의 편의를 위해 그래픽 사용자 인터페이스를 구축하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.67-69
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• 1992

This paper presents the new protective device which is developed specifically for use in oil filled distribution transformers. This device is mounted Inside of the transformer and connected between the secondary winding and the secondary bushings. It provides both fault and overload protection to the transformer, and visual warning of the existence of uneconomical loading conditions. It Is available in thermal/magnetic operating device depending upon fault duty required.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.32.1-32
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• 2002

The fault monitoring technique is presented for identifying the status of the agitator driving system in thermal reduction reactor. For identifying a fault such as bearing defect or clearance blocking, Wavelet transform (WT) is applied to vibration signals and features are extracted. For classification, the fuzzy ARTMAP is employed. With the features from WT, a single training epoch and a single learning iteration are sufficient for the fuzzy ARTMAP to classify the faults. The test results show the perfect classification though some features extracted from the test data are distorted against those in the training data

• 한국주조공학회지
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• 제10권5호
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• pp.399-407
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• 1990

The effect of thermal cycling and isothermal exposure on the high temperature microstructural stability of unidirectionally solidified $Al-CuAl_2$ eutectic composite has been studied. A coarsening procedures of lamellar eutectic structures were initiated at growth fault region because of diffusion through low angle boundary at this region. It was considered that thermally induced residual stresses produced by thermal cycling were high enough to increase the dislocation density in Al-rich matrix phase. However, it was also considered that dislocations generated by these high thermal stresses were annihilated at high temperature by stress relaxation. Consequently, the thermal cycling up to 1440 cycles between 20 and $520^{\circ}C$ did not affect the microstructural stability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.213-215
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• 1987

As a means of improving the reliability of the analog type controller for the thermal power plant, an efficient method is proposed, which is to place the hardware redundancy, i.e. a back-up controller with fault detecting capability. FTCS is implemented by using multi-processors and it is experimentally verified that the back-up controller takes over the role of the original controller, controlling the faulty loop.