• Journal of Power Electronics
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• 제17권3호
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• pp.725-732
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• 2017

This paper proposed a real-time, low-cost, fast transistor open-circuit fault diagnosis method for voltage-source inverter fed induction motors. A transistor open-circuit changes the symmetry of the inverter topology, leading to different similarities among three phase load currents. In this paper, dynamic time warping is proposed to describe the similarities among load currents. The proposed diagnosis is independent of the system model and needs no extra sensors or electrical circuits. Both simulation and experimental results show the high efficiency of the proposed fault diagnosis method.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2278-2288
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• 2017

Multilevel converter topologies are widely used in many applications. The cascaded H-bridge multilevel inverter (CHBMI), which is one of many multilevel converter topologies, has been introduced as a useful topology in high and medium power. However, it has a drawback to require a lot of switches. Therefore, the reliability of CHBMI is important factor for analyzing the performance. This paper presents a simple switch fault diagnosis method for single-phase CHBMI. There are two types of switch faults: open-fault and short-fault. In the open-fault, the body diode of faulty switch provides a freewheeling current path. However, when the short-fault occurs, the distortion of output current is different from that of the open-fault because it has an unavailable freewheeling current flow path due to a disconnection of fuse. The fault diagnosis method is based on the zero current time analysis according to zero-voltage switching states. Using the proposed method, it is possible to detect the location of faulty switch accurately. The PSIM simulation and experimental results show the effectiveness of proposed switch fault diagnosis method.

• 상하수도학회지
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• 제27권1호
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• pp.139-146
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• 2013

A process diagnosis method for membrane water treatment plant was developed using a constant flux membrane fouling model. This diagnosis method can be applied to a real-field membrane-based water treatment plant as an early alarming system for membrane fouling. The constant flux membrane fouling model was based on the simplest equation form to describe change in trans-membrane pressure (TMP) during the filtration cycle from a literature. The model was verified using a pilot-scale microfiltraton (MF) plant with two commercial MF membrane modules (72 m2 of membrane area). The predicted TMP data were produced using the model, where the modeling parameters were obtained by the least square method using the early plant data and modeling equations. The diagnosis was carried out by comparing the predicted TMP data (as baseline) and real plant data. As a result of the case study, the diagnsis method worked pretty well to predict the early points where fouling started to occur.

• 한국한의학연구원논문집
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• 제15권2호
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• pp.101-109
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• 2009

The Pulse diagnosis is in the boundary of the Four Examinations, and it is called 切診, or palpation. It has a great impact on people in reminding of the Traditional Medicine that it is probably the first thing that people think of when they hear about Traditional Medicine. Hu-Jun quoted in the Treasured Mirror of Eastern Medicine "東醫寶鑑" that the doctor finds out the deficiency and the excess of the meridian of the patiant through the pulse, and that it is of the utmost necessity to know the "deficiency and the excess" of the meridian to decide the formula (君臣佐使) of the herbal medicine and the acupuncture/moxibustion treatment. The research on the studies of pulse diagnosis have been concentrated on the origin, history, and the theory of the pulse diagnosis throughout the years; however, the number of research on the image from the classics on pulse diagnosis have been less. With this in mind, this paper was written to study more on the origin and the history of the pulse diagnosis as well as to study on the image of pulse diagnosis shown on the classics on Traditional Medicine in China and Korea. The history of the pulse diagnosis has its root on the attempt to find out what is happening inside the body through the indication of the small changes of the pulse that is shown on the outer boundaries of the body. There were various kinds of pulse diagnosis including "Three positions and nine indicators method" and "Carotid pulsation and wrist pulse method" in the ancient period, and wrist pulse-taking method became the most popular since the completion of studying on palpation by 初보. The image of the palpation helps the rudimentary practitioners of Traditional Medicine. They are divided into two large categories, which are the area of diagnosis and the shape of the pulse itself. The historical classics including the image of the pulse diagnosis can be found since the Song Dynasty of China. There are various kinds of image of pulse diagnosis in the classic such as "The picture of the hand meridian" from "脈訣指掌病式圖說", "The picture of the image of meridian" from "察病指南", "The picture of the Seven exterior and Eight interior" from "校正圖注脈訣", and "The picture of the six parts of meridian" from Treasured Mirror of Eastern Medicine "東醫寶鑑". The Treasured Mirror of Eastern Medicine "東醫寶鑑" have analyzed the basic theories and made up the standards of pulse diagnosis by establishing "The picture of the six parts of meridian" based on "The method of placing the viscera and bowels corresponding to cun-guan-qi, or the meridian".

• 항공우주기술
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• 제11권2호
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• pp.182-194
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• 2012

한정된 기간과 비용 하에 높은 신뢰도와 안전성을 갖는 엔진을 완성하기 위해서는 엔진 개발과 병행하여 엔진에 최적화된 진단시스템의 개발이 필요하다. 본 연구에서는 진단시스템의 개발방향을 정립하기 위하여 해외문헌을 바탕으로 엔진에서 발생 가능한 고장들, 상태진단을 위한 검사파라미터의 특성, 진단방법들(실시간 진단법, 사후 진단법, 사고원인 분석법, 파라미터 계통법, 시험진단법)을 고찰하였고, 엔진 개발단계 및 운용단계에서 수행해야할 진단관련 과제들을 제시하였으며, 해외의 액체로켓엔진 진단 사례를 정리하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.735-737
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• 2004

This paper proposes a method of fault diagnostics on switching mode power supply. When the error of switching mode power supply cannot be found when the conventional diagnostics is performed, this proposed method first performs diagnosis on the switching mode power supply strictly to judge the operating condition. This method analyzes the PWM wave which depends on the load change, to make sure the feedback control of the power supply to diagnosis the operation of the power supply system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.97-101
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• 2003

In this paper, we propose a new diagnosis method of DC/UC converter aging. The method is based on parasitic resister change with aging process. we apply to on-line diagnosis of DC/DC converter because of observing not a device but a system. We present the mathematical analysis and experimental study.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2183-2187
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• 2005

In this paper we propose a new fault detection and isolation (FDI) method for those faults of parameter change type. First, we design a residual generator based on the ${\delta}$-operator model of the plant by using the stable pseudo inverse system. Second, the parameter change is estimated by using the property of the block Hankel operator. Third, reliability with respect to stability is quantified. Fourth, the limitations for the meaningful diagnosis in our method are given. The numerical examples demonstrate the effectiveness of the proposed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.243-247
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• 1999

An electrolytic capacitor is widely used in a motor drive system. Therefore, the deterioration diagnosis of an electrolytic capacitor is needed of preventive maintenance of the system. In this paper, we propose a new diagnosis method for the electrolytic capacitor by using the system identification method, which presents the information about the capacitor's interna parameters in on-line operation an use fuzzy algorithm for the deterioration decision. We demonstrated the effectiveness of the proposed control scheme by using computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.339-343
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• 1990

This paper describes a neural-network-based methodology for providing a potential solution in the area of process fault diagnosis. The existing neural network for fault diagnosis learn fault node by using pairs of single-symptom-single-cause only. But in real plants, the effect of a fault propagates continuously from it's origin; different sensor values reflect this. In this paper, we suggest a new method which can handle the effect of symptom propagation. The proposed method can find the exact origin of the fault of which the symptom is propagated continuously with time.