• 전기학회논문지
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• 제61권7호
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• pp.923-927
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• 2012

This paper studies a busbar design of high power HVDC converter. In order to design a electrical busbar, we need to consider electrical, mechanical and environmental condition. In this papre, we focus on the electrical design in terms of temperaure and currnet. Busbar conductor can be damaged to burn due to the temperature and fault current of busbar. In this paper, Busbar design of Jindo-Jeju HVDC #2 System that will start operate in 2012 is considered.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1057-1058
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• 2007

This paper proposes an alternative vibration detection method in a squirrel-cage induction motor using flux sensors. The air-gap flux will be changed when mechanical vibration occurs by bearing fault as well as broken rotor bar and air-gap eccentricity. For detecting those flux variations due to vibration, search coils are installed at stator slots. The induction motor with 380 [V], 7.5 [kW], 4 [Poles], 1,760 [rpm] ratings is used. Magnitudes and distortion of the induced voltage from flux sensors are used to discriminate faulted types. As a result, the flux sensor has been proven to be useful for vibration detection. It is compared to the result with vibration sensor as well.

• Nuclear Engineering and Technology
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• 제36권2호
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• pp.184-195
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• 2004

The multi-tasking feature of digital I&C equipment could increase risk concentration because the I&C equipment affects the actuation of the safety functions in several ways. Anticipated Transient without Scram (ATWS) is a typical case of safety function failure in nuclear power plants. In a conventional analysis, mechanical failures are treated as the main contributors of the ATWS. This paper quantitatively presents the probability of the ATWS based on a fault tree analysis of a Korea Standard Nuclear Power Plant is also presented. An analysis of the digital equipment in the digital plant protection system. The results show that the digital system severely affects the ATWS frequency. We also present the results of a sensitivity study, which show the effects of the important factors, and discuss the dependency between human operator failure and digital equipment failure.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.115-121
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• 2001

The wear test has been performed to evaluate the wear mechanism of steam generator (SG) tube materials against ferritic stainless steel in water environment. The wear rates of SG tube materials depend on the change of mechanical properties between contact surfaces during wear test. From the subsurface hardness test, Inconel 690 is more work-hardened than Inconel 600 even though these materials have similar hardness values before the wear test. Main cause is due to the difference of stacking fault energy with the chromium content. In water environment, wear mechanism is closely related with the continuous formation and fracture of deformation layers at the contact surfaces.

• 한국기계가공학회지
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• 제20권12호
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• pp.107-112
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• 2021

The usage of electric-powered components consisting of several electrical and mechanical parts is continuously increasing in automobiles. Therefore, continuous assessment of the reliability and quality of these electric-powered parts is crucial. In this study, a noise and vibration measurement system for testing and evaluating the different electric-powered parts of automobiles was designed. Further, an FFT analysis was performed on some electric-powered steering assembly test equipment. In the FFT analysis of the noise and vibration signals for each essential fault part, the vibration FFT analysis was significantly compared with the noise analysis. The results showed that the vibration FFT analysis was more effective in determining the reliability and quality of the electric-powered parts.

• Applied Microscopy
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• 제50권
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• pp.19.1-19.9
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• 2020

Deformation twinning, one of the major deformation modes in a crystalline material, has typically been analyzed using generalized planar fault energy (GPFE) curves. Despite the significance of these curves in understanding the twin nucleation and its effect on the mechanical properties of crystals, their experimental validity is lacking. In this comparative study based on the first-principles calculation, molecular dynamics simulation, and quantitative in-situ tensile testing of Al nanowires inside a transmission electron microscopy system, we present both a theoretical and an experimental approach that enable the measurement of a part of the twin formation energy of the perfect Al crystal. The proposed experimental method is also regarded as an indirect but quantitative means for validating the GPFE theory.

• 한국정밀공학회지
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• 제13권10호
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• pp.112-122
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• 1996

In order to monitior machine tool condition and diagnose alarm states due to electrical and mechanical faults, and expert system using diagnostic parameters of NC machine tools was developed. A model-based knowledge base was constructed via searching and comparing procedures of diagnostic parameters and state parameters of the machine tool. Diagnostic monitoring results generate through a successive type inference engine were graphically displayed on the screen of the console. The validity and reliability of the expert system was rcrified on a vertical machining center equipped with FANUC OMC through a series of experiments.

• 한국전기전자재료학회논문지
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• 제24권1호
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• pp.52-56
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• 2011

The ongoing Superconducting Fault Current Limiter(SFCL) development mainly has focused on the application of commercializaton and power system through combining with normal-conducting device, moving away from current-limiting method, which is solely dependant on the existing superconductor. Compared to the structural development above, on the other hand, the research on applying superconducting current-limiting element to SFCL, the heart of SFCL, still has a lot left to do, apart form traditional resistive type SFCL. In this study, we looked into the current limiting characteristic of SFCL using core and coil. YBCO coated conductor with stainless steel stabilizer layer was verified by the excellent of current-limiting element of the resistive type SFCL that has a high Jc and index as well as being superior in mechanical property. Also, we study temperature characteristics and resistance characteristics, max voltage, response time and current-limiting ability that can be an indicator as current-limiting element while applying to superconducting current-limiting element caused by variation of winding direction, winding ratio of SFCL using core and coil.

• 한국전산구조공학회논문집
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• 제13권2호
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• pp.257-270
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• 2000

본 연구는 결함을 지닌 구조체의 거시적인 역학적 거동을 손상역학이론에 근거하여 해석할 수 있는 손상모델을 개발하고 이를 손상을 입은 구조체에 적용하여 손상된 구조체의 전체거동을 해석적으로 규명하는데 그 목적이 있다. 이를 위하여 수정된 2차손상텐서를 이용하였으며, 유효응력을 통해서 산정된 손상응력을 절점에 작용하는 추가의 하중 항으로 고려할 수 있고 균열면의 성질을 반영할 수 있는 유한요소해석 알고리즘을 개발하였다. 개발된 알고리즘은 실험치 및 횡등방성 이론에 의한 이론치와의 비교·검증을 통하여 그 신뢰성을 검토하였다. 선형탄성 가정 하에서 균열을 지닌 구조체에 개발된 알고리즘을 적용하여 해석한 결과, 균열의 방향과 균열군에 따른 손상된 구조체의 거동을 정량적으로 추정할 수 있었다. 개발된 모델을 균열이 존재하는 암반의 굴착문제와 파쇄대를 지니고 있는 지하구조체 문제에 적용해 본 결과, 손상으로 인해 야기되는 구조체의 전체 거동상의 차이를 규명할 수 있었다.

• 한국전자통신학회논문지
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• 제12권2호
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• pp.315-324
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• 2017

분산전원이 도입된 스마트 그리드는 기존 전력망의 문제들뿐만 아니라, 새로운 전기적 현상에 기인한 보호 협조 문제 등 다수의 문제들을 새롭게 제기한다. EMTP 기반의 해석 방법은 계통구성의 유연성과 편리성을 가지지만 설계 및 해석결과의 불확실성 때문에 실험적 검증이 요구된다. 반면에 실증 시스템은 상당한 경제적, 공간적 건설비용 요구, 계통구성 제약 때문에 대규모 계통에 대한 정확한 고장 관측이 어렵고 스마트 그리드의 분산, 자율적, 적응제어 전략의 실증도 쉽지 않다. 따라서 본 연구에서는 최소의 경제적, 공간적 비용하에서 22.9kV 스마트 그리드의 외란에 대한 전기적인 현상들과 분산, 자율적 적응제어 전략을 안전하고 자유롭게 실험, 관측할 수 있는 MEMS의 소형화 기술을 이용한 마이크로 스마트 그리드 시뮬레이터 설계를 위한 기초이론을 연구한다.