• 조명전기설비학회논문지
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• 제30권3호
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• pp.46-52
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• 2016

When a fault occurs on a transmission line, it is important to identify the fault location as speedily as possible for improvement of the power supply reliability. Generally, distance to fault location is estimated by off line from the recorded data. Conventional fault recorder uses the fault data at one end. This paper deals with the design of an advanced fault recorder for enhancement accuracy of the fault distance estimation and fast detection a fault occurrence position. The major emphasis of the paper will be on the description of the hardware and software of the fault recorder. The fault locator algorithm utilizes a GPS time-synchronized the fault data at both ends. The fault data is transmitted to the other side substation through communication. The advanced fault locator includes a Power module, MPU(Main Processing Unit) module, ADPU(Analog Digital Processing Unit) module, and SIU(Signal Interface Unit) modules. The MMI firmware and software of an advanced fault recording device was implemented.

• 대한전기학회논문지:전력기술부문A
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• 제52권12호
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• pp.675-683
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• 2003

This paper describes the correction strategy of an overcurrent relay applied in the linked line for interconnecting wind farm with utility power networks in order to improve the capability of a fault detection. The fault current measured in a relaying point might vary according to the fault conditions. Generally, the current of the line to line fault or the line to ground fault in the linked line is much higher than the set value of protective relay due to the large fault level. However, when the high impedance fault occurs in the linked line, we can't detect it by conventional set value because its fault level may be lower than the generating capacity of wind farm. And, the protective relay with conventional set value may generate a trip signal for the insertion of wind turbine generators due to the large transient characteristics. In order to solve above problems and improve protective relaying algorithms applied in the linked line, we propose a new correction strategy of the protective relay in the linked line. The presented method can detect the high impedance fault which can't be detected by conventional relay set value and may prevent the mis-operation of protective relay caused by the insertion of wind farm.

• 대한전기학회논문지:전력기술부문A
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• 제52권3호
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• pp.151-157
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• 2003

Wind farm interconnected with grid can supply the power into a power network not only the normal conditions, but also the fault conditions of distribution network. If the fault happened in the distribution power line with wind fm, the fault current level measured in a relaying point might be lower than that of distribution network without wind turbine generator due to the contribution of wind farm. Consequently, it may be difficult to detect the fault happened in the distribution network connected with wind generator This paper describes the effect of the interconnected wind turbine generators on protective relaying of distribution power lines and detection of the fault occurred in a power line network. Simulation results shows that the current level of fault happened in the power line with wind farm depends on the fault impedance, the fault location. the output of wind farm. and the load condition of distribution network.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.513-518
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• 1998

In this paper, a robust fault-tolerant control scheme for robot manipulators overcoming actuator failures is presented. The joint(or actuator) fault considered in this paper is the free-swinging joint failure and causes the loss of torque on a joint. The presented fault-tolerant control framework includes a normal control with normal(non-failed) operation, a fault detection and a fault-tolerant control to achieve task completion. For both no uncertainty case and uncertainty case, a stable normal con-troller and an on-line fault detection scheme are presented. After the detection and identification of joint failures, the robot manipulator becomes the underactuated robot system with failed actuators. A robust adaptive control scheme of robot manipulators with the detected failed-actuators using the brakes equipped at the failed(passive) joints is proposed in the presence of parametric uncertainty and external disturbances. To illustrate the feasibility and validity of the proposed fault-tolerant control scheme, simulation results for a three-link planar robot arm with a failed joint are presented.

• 제어로봇시스템학회논문지
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• 제5권1호
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• pp.16-24
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• 1999

본 논문은 불확정 시스템의 견실한 이상검출기법의 적용을 위한 실시간 이상검출기법에 대하여 다루며 대상 시스템은 산업용보일러 시스템이다. 본 논문에서 기술된 이상검출기법은 Kwon (1994) 등에 의하여 이미 제시된바 있는 견실한 이상검출기법의 오프라인 배치 처리 알고리즘을 실시간 적용을 위해 확장된 것이며 모델링 오차에 의한 불확실성, 비선형 시스템을 특정 동작점에서 선형화 하는 과정에서 발생하는 선형화 오차, 잡음 등을 고려하였고, 보일러 시스템을 대상으로 한 모의 실험을 통해 본 알고리즘의 우수성을 보였다.

• 설비공학논문집
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• 제13권8호
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• pp.787-795
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• 2001

An experimentation on the on-line fault detection and diagnosis(FDD) system has been performed with HVAC system in he experimental building constructed inside the large scale environmental chamber. Personal computer with a home-made FDD program by pattern recognition method utilizing artificial neural network was connected on-line via Ether-net TCP/IP to the supervisory control server for HVAC system. The FDD program monitored the HVAC system by 1 minuted interval. The results showed that he FDD program detected the sudden or abrupt faults such s those in fans, sensors and heater, etc.

• 한국안전학회지
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• 제27권3호
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• pp.20-27
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• 2012

Mechanical seals are one of main components of high speed centrifugal pumps. So, it is very important to detect the faults (scratch, notch, indentation, wear) of mechanical seals since the damage of seal can cause a critical failures or accidents of machinery system. In the past, many researchers mainly performed to detect the seal fault using the time signals measured from sensors. Recently, studies are focused on the development of on-line real time monitoring system. But study on the feature parameters used for fault detection of mechanical seals has a little been performed. In this paper, we showed feature parameters extracted from accelerated and acoustic signals by using the discrete wavelet transform (DWT), alpha coefficient, statistical parameters. And also verified the possibility for fault detection of mechanical seal.

• 대한전자공학회논문지SD
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• 제46권9호
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• pp.14-24
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• 2009

System on panel 프레임 버퍼를 위한 메모리 셀 어레이와 주변회로가 설계되었다. 또한, system on panel 공정의 낮은 yield를 극복하기 위해, 블럭 단위의 parallel test 방안이 제안되었다. 기존의 메모리 테스트 보다 빠르게 fault detection이 가능하며, 다양한 embedded memory나 일반 SRAM 테스트 분야에도 적용 가능하다. 또한 기존의 다양한 test vector pattern이 그대로 적용될 수 있어 fault coverage가 높고, 최근의 추세인 hierarchical bit line과 divided word line 구조에도 적용될 수 있다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2007년도 추계학술논문발표회 논문집
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• pp.205-210
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• 2007

This study on the prevention of electric fire. Generally the electric fire is caused by break or disconnection of the power line, short circuit and poor contact, arcing fault ect. In these causes, this paper is studied on the detection of poor contact and arcing fault. The arcing fault is caused by poor contact mainly. The arcing fault can occurs a electric fire by interaction of flammable gas and materials and it can be caused of tracking and carbonization. These phenomenons is also caused of electric fire. Therefore this paper is studied on the detection of arcing fault and poor contact.

• 대한전기학회논문지:전력기술부문A
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• 제51권8호
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• pp.371-378
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• 2002

This paper presents the rapid and accurate algorithm for fault detection and location estimation in the transmission line. This algorithm uses wavelet transform for fault detection and harmonics elimination and utilizes least square error method for fault impedance estimation. Wavelet transform decomposes fault signals into high frequence component Dl and low frequence component A3. The former is used for fault phase detection and fault types classification and the latter is used for harmonics elimination. After fault detection, an adaptive data window technique using LSE estimates fault impedance. It can find a optimal data window length and estimate fault impedance rapidly, because it changes the length according to the fault disturbance. To prove the performance of the algorithm, the authors test relaying signals obtained from EMTP simulation. Test results show that the proposed algorithm estimates fault location within a half cycle after fault irrelevant to fault types and various fault conditions.