• 응용통계연구
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• 제24권3호
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• pp.515-521
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• 2011

이 논문에서는 수리가능한 시스템의 고장을 감지해서 수리 개시를 가능하게 하는 고장감지장치를 고려한 시스템 신뢰도 산출을 연구한다. 실제 상황에서 고장감지장치의 고장이 가능할 수 있는데 이는 시스템 고장의 미발견을 초래할 수 있고 시스템 신뢰도에 큰 영향을 주게 된다. 적절한 마코프 확률과정을 이용하여 감지장치의 고장이 가져오는 시스템 신뢰도에 대한 영향을 분석한다.

• 응용통계연구
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• 제26권1호
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• pp.111-118
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• 2013

이 논문에서는 고장감지장치(FDE)가 시스템 가용도에 미치는 영향을 연구한다. 주시스템(MS) 수리 도중에 고장이 발생한 FDE를 수리하기 위한 새로운 수리 정책을 고려한다. 이 논문의 주요 목적은 MS의 가용도를 계산하고 비교하는 데에 있다.

• 한국항공운항학회지
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• 제27권3호
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• pp.15-23
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• 2019

This paper contains analyses and development processes of the requirements to detect the possible intermittent failure in an old avionics backplane. Interconnections for signal transmission between electronic components, such as Pin-to-PCB, FPCB-to-FPCB, pin-to-FPCB, and pint-to-wire, were selected as the main cause of intermittent failure by analyzing target equipment and documents. The possibility of detecting intermittent failures occurring in the target equipment is verified by physics-of-failure analyses. In order to verify the occurrence of intermittent failures and their detectability, latching continuity circuit testers were manufactured and accelerated life tests were performed by applying temperature and vibration cycle in consideration of flight conditions. Through the above process, the detection requirements for the major intermittent failure in the target avionics backplane was developed.

• Communications for Statistical Applications and Methods
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• 제29권2호
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• pp.151-160
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• 2022

The total system is composed of the main system (MS) and the failure detection equipment (FDE) which detects failures of MS. The analysis of system reliability is performed when the failure of FDE is possible. Several repair policies are considered to determine the order of repair of failed systems, which are sequential repair (SQ), priority repair (PR), independent repair (ID), and simultaneous repair (SM). The states of MS-FDE systems are represented by Markov models according to repair policies and the main purpose of this paper is to derive the system availabilities of the Markov models. Analytical solutions of the stationary equations are derived for the Markov models and the system availabilities are immediately determined using the stationary solutions. A simple illustrative example is discussed for the comparison of availability values of the repair policies considered in this paper.

• 품질경영학회지
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• 제49권4호
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• pp.581-594
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• 2021

Purpose: The purpose of this study is to compare machine learning models for anomaly detection of mechanical facility equipment and suggest an anomaly detection system for mechanical facility equipment in subway stations. It helps to predict failures and plan the maintenance of facility. Ultimately it aims to improve the quality of facility equipment. Methods: The data collected from Daejeon Metropolitan Rapid Transit Corporation was used in this experiment. The experiment was performed using Python, Scikit-learn, tensorflow 2.0 for preprocessing and machine learning. Also it was conducted in two failure states of the equipment. We compared and analyzed five unsupervised machine learning models focused on model Long Short-Term Memory Variational Autoencoder(LSTM-VAE). Results: In both experiments, change in vibration and current data was observed when there is a defect. When the rotating body failure was happened, the magnitude of vibration has increased but current has decreased. In situation of axis alignment failure, both of vibration and current have increased. In addition, model LSTM-VAE showed superior accuracy than the other four base-line models. Conclusion: According to the results, model LSTM-VAE showed outstanding performance with more than 97% of accuracy in the experiments. Thus, the quality of mechanical facility equipment will be improved if the proposed anomaly detection system is established with this model used.

• 한국산업정보학회논문지
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• 제18권5호
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• pp.45-50
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• 2013

최근 시장이 확대되고 있는 SMART TV에는 다양한 기능을 위하여 내장형 카메라가 들어가게 된다. 하지만, 이로 인한 불량 또한 발생하게 되며, 특히 TV power up sequence 문제로 인한 내장형 카메라의 화면 무감 불량현상은 기존 검사장비에서 검출되기 힘든 특징을 가지고 있다. 이를 위해 오디오 쪽 컨트롤 신호를 재현할 수 있는 새로운 검사장비가 필요하지만, 시간과 많은 비용이 소요되며, 생산에 큰 영향을 준다. 본 논문에서는 이와 같은 문제점을 해결하고자 FPGA (Field Programmable Gate Array)를 활용한 불량 검출 장비를 개발하여 문제점을 빠르고 정확하게 검출하는 방법을 제시한다. 이를 통해 새로운 장비를 대체하는 비용 절감 효과와 기존 검출 테스트 시간을 약 20여초에서 10초미만으로 크게 단축시킴으로써 개발기간의 최소화 및 공정에 적용을 통한 불량률 감소를 이룰 수 있다.

• Journal of Information Processing Systems
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• 제18권6호
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• pp.822-829
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• 2022

According to existing study into the remote fault diagnosis procedure, the current diagnostic approach has an imperfect decision model, which only supports communication in a close distance. An Internet of Things (IoT)-based remote fault diagnostic approach for wind power equipment is created to address this issue and expand the communication distance of fault diagnosis. Specifically, a decision model for active power coordination is built with the mechanical energy storage of power generation equipment with a remote diagnosis mode set by decision tree algorithms. These models help calculate the failure frequency of bearings in power generation equipment, summarize the characteristics of failure types and detect the operation status of wind power equipment through IoT. In addition, they can also generate the point inspection data and evaluate the equipment status. The findings demonstrate that the average communication distances of the designed remote diagnosis method and the other two remote diagnosis methods are 587.46 m, 435.61 m, and 454.32 m, respectively, indicating its application value.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.173-174
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• 2023

In this paper, we introduce a model for detecting Personal Protective Equipment (PPE) using YOLO (You Only Look Once), an object detection neural network. PPE is used to maintain a safe working environment, and proper use of PPE protects workers' safety and health. However, failure to wear PPE or wearing it improperly can cause serious safety issues. Therefore, a PPE detection system is crucial in industrial settings.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.36-41
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• 2008

Fault detection and diagnosis(FDD) system is beneficial in equipment management by providing the operator with tools which can help find out a failure of the system. An experimental study has been performed on fault detection and diagnosis method for a water chiller. Bayes classifier, which is one of classical pattern classifiers, is adopted in deciding whether fault occurred or not. FDD algorithm can detect refrigerant leak failure, when 20% amount of charged refrigerant for normal operation leaks from the water chiller. The refrigerant leak failure caused COP reduction by 6.7% compared with normal operation performance. When two kinds of faults, such as a decrease in the mass flow rate of cooling water and temperature sensor fault of cooling water inlet, are detected, COP is a little decreased by these faults.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.581-583
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• 2021

코로나19의 펜데믹 현상으로 인하여 모바일 서비스의 활용 비중이 높아지고 있다. 그러나, 대부분의 모바일 장비에 대한 이상 현상을 장비의 알람 중심으로 인지하므로, 복잡한 장애가 발생할 경우에 직관적으로 장비의 문제 판별하기 어려운 한계가 발생한다. 이를 보완하기 위해서 본 연구에서는 장비의 알람과 성능 정보를 조합하여 직관적으로 문제를 인지할 수 있도록 RRCF 알고리즘을 활용하여 Anomaly Score 생성하였으며, 과거 장애 이력을 97% 검출하는 효과를 검증하였다.