• 한국인터넷방송통신학회논문지
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• 제22권5호
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• pp.111-116
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• 2022

전동기 소손의 원인으로는 과부하, 결상, 구속, 층간단락, 권선의 지락, 순간과전압의 유입, 회전자가 고정자에 닿는 경우 등 절연파괴로 이어져 고장 또는 전기 사고로 이어지고 있다. 따라서 기기 고장은 기기의 보수/수리에 필요한 비용에 의한 손실뿐만 아니라, 전동기가 포함된 공정 자체를 멈추기 때문에 공정 정지에 따른 생산성 저하에 의한 막대한 경제적 손실을 초래한다. 전동기의 고장을 진단하기 위한 현재의 기술의 수준은 진동, 열, 전력분석 방식을 이용하고 있지만, 고장에 따른 상당 부분의 시간이 진행되어야 문제점을 분석할 수 있는 한계점을 가지고 있다. 따라서 본 논문에서는 이러한 문제점을 해결하고자 DC AMP 신호를 이용하여 절연저항을 측정하는 장치 및 알고리즘을 산업용 전동기에 적용하여 절연저항 상태값을 추종하여 기존방식에서 해결되지 못한 전동기의 열화 및 고장 진단을 제안한다.

• Composites Research
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• 제35권2호
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• pp.61-68
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• 2022

복합재료는 비강도, 비강성 및 내부식성 등이 우수하여 항공우주산업뿐만 아니라 다양한 산업에서 사용되고 있다. 그러나 복합재료는 충격에 취약하고 이러한 충격은 복합 재료 내부의 균열 형성과 균열 성장으로 이어져 구조 파단의 원인이 된다. 본 논문에서는 음향 방출 신호 및 유한요소해석(Finite element analysis, FEA)을 이용하여 복합재 적층판의 Mode I 파괴 모드의 특성을 분석하였다. DCB 시험은 탄소/에폭시 적층판의 Mode I 파괴 특성을 분석하기 위하여 수행되었고 시편의 파괴에 의해서 발생되는 탄성파를 측정하기 위하여 시편에 음향 방출 센서를 부착하였다. 누적 음향 방출 에너지와 균열 선단 위치의 관계를 이용하여 시편의 파괴 인성(Fracture toughness, G_I)을 계산하였다. 계산된 파괴 인성 값을 유한요소모델에 적용하여 해석을 수행하였고 하중-변위 곡선 및 균열 길이-변위 곡선을 통하여 DCB 시험 결과와 비교/분석하였다. 유한요소해석 및 DCB 시험의 결과가 잘 일치함을 보였다.

• 한국안전학회지
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• 제38권2호
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• pp.104-111
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• 2023

Rolling stock maintenance, which focuses on preventive maintenance, is typically implemented considering the potential harm that may be inflicted to passengers in the event of failure. The cost of preventive maintenance throughout the life cycle of a rolling stock is 60%-75% of the initial purchase cost. Therefore, ensuring stability and reducing maintenance costs are essential in terms of economy. In particular, private railroad operators must reduce government support budget by effectively utilizing railroad resources and reducing maintenance costs. Accordingly, this study analyzes the reliability characteristics of components using field data. Moreover, it resolves the problem of determining an economical replacement interval considering the timing of scrapping railroad vehicles. The procedure for determining the optimal replacement interval involves five steps. According to the decision model, the optimal replacement interval for the onboard signal device components of the "A" line train is calculated using field data, such as failure data, preventive maintenance cost, and failure maintenance cost. The field data analysis indicates that the mileage meter is 9 years, which is less than the designed durability of 15 years. Furthermore, a life cycle in which the phase signal has few failures is found to be the same as the actual durability of 15 years.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2004년도 정기학술대회
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• pp.183-190
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• 2004

Found important components in terms of frequency in the assembly (but not in terms of money). Component 39*** was most important. The failure mode was N69(no light on warning signal the cause of the failure was C15(bad connection). Formed a population for each component. Performed reliability and warranty cost analyses At the component level. At the subsystem level. At the system level. **They don'l trust the warranty cost analysis.** Reliability improvement. Among all the subsystems front \ulcorner subsystem is most vulnerable (among other things due to the large number of components in it), especially components 39*** and 28***.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1996년도 추계학술발표회논문집
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• pp.122-124
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• 1996

This paper describes a diagnosis of distribution cable splices by analysis of ultrasonic signals which are generated by partial discharge. A method of ultrasonic signal was used to detect internal defects in distribution cable splices. It is possible that analysis of ultrasonic signal predicts failure by partial discharge generated in distribution cable splices.

• 한국안전학회지
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• 제14권3호
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• pp.146-154
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• 1999

The feasibility of using AE for monitoring mechanical failure in concrete structures has been tested. Specifically, the relationship between the fracture and the characteristics of AE signal is theoretically and experimentally investigated. The experimental results manifest that the high sensitivity of AE signal to the fracture of concrete structure makes it a good choice as sensor for monitoring concrete structure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.27-29
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• 2006

In this paper, we propose a new method of automatic white balance which is one of the image signal processing techniques. Our method is conceptually based on gray world assumption. However, while previous methods generate linear results as multiplying pixel values by a gain, our method generates non-linear results using the feature of B-Spline curves. The two merits of deriving non-linear results are preventing AWB failure from transforming strong color of high level into wrong color and well preserving original contrast of an input image.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.301-307
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• 1995

A monitoring technique of spindle fairure should be investirated prior to researcs of fairure diagnosis. This work is about monitoring of unbalanced shaft and defected bearings. The major work is done via experiments and the vibration signal is analysed means of power spectrum technique, and root mean squqre, peak-to-peak. Relationship is quantitatively investigated between defects and these monitoring paramenters.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.476-482
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• 2009

A signal equipment improvement project for the existing facility ATS to ATP is under construction in Kyung-Bu and Ho-Nam commercial line including 400 rolling stocks. But there was a concern for the interface between KTX OBCS and ATP from the beginning of the project. At present, this is the front burner event. This paper introduces interface checking and predicted failure point between KTX OBCS and ATP improvement system. Through this measure the optimal installation of the ATP will be possible. The study was made under maintenance efficiency including reliability because the KTX signal equipment must qualify the above condition.

• 한국정밀공학회지
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• 제14권12호
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• pp.48-55
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• 1997

A useful method to detect tool breakage suing neural network of cutting force signal is porposed and implemented in a basic cutting process. Cutting signal is gathered by tool dynamometer and normalized as a preprocessing. The cutting force signal level is continually monitored and compared with the predefined level. The neural network has been trained normalized sample data of the normal operation and cata-strophic tool failure using backpropagation learning process. The develop[ed system is verified to be very effective in real-time usage with minor modification in conventional cutting processes.