• Nuclear Engineering and Technology
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• 제55권2호
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• pp.493-505
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• 2023

Comprehensive condition monitoring of large industry systems such as nuclear power plants (NPPs) is essential for safety and maintenance. In this study, we developed novel system-scale diagnostic technology based on deep-learning and IR thermography that can efficiently and cost-effectively classify system conditions using compact Raspberry Pi and IR sensors. This diagnostic technology can identify the presence of an abnormality or accident in whole system, and when an accident occurs, the type of accident and the location of the abnormality can be identified in real-time. For technology development, the experiment for the thermal image measurement and performance validation of major components at each accident condition of NPPs was conducted using a thermal-hydraulic integral effect test facility with compact infrared sensor modules. These thermal images were used for training of deep-learning model, convolutional neural networks (CNN), which is effective for image processing. As a result, a proposed novel diagnostic was developed that can perform diagnosis of components, whole system and accident classification using thermal images. The optimal model was derived based on the modern CNN model and performed prompt and accurate condition monitoring of component and whole system diagnosis, and accident classification. This diagnostic technology is expected to be applied to comprehensive condition monitoring of nuclear power plants for safety.

• Nuclear Engineering and Technology
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• 제49권3호
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• pp.632-637
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• 2017

Even though the potential for an accident in nuclear power plants is very low, multiple emergency plans are necessary because the impact of such an accident to the public is enormous. One of these emergency plans involves a robotic system for investigating accidents under conditions of high radiation and contaminated air. To develop a robot suitable for operation in a nuclear power plant, we focused on eliminating the three major obstacles that challenge robots in such conditions: the disconnection of radio communication, falling on uneven floors, and loss of localization. To solve the radio problem, a Wi-Fi extender was used in radio shadow areas. To reinforce the walking, we developed two- and four-leg convertible walking, a floor adaptive foot, a roly-poly defensive falling design, and automatic standing recovery after falling methods were developed. To allow the robot to determine its location in the containment building, a bar code landmark reading method was chosen. When a severe accident occurs, this robot will be useful for accident condition monitoring. We also anticipate the robot can serve as a workman aid in a high radiation area during normal operations.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.360-363
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• 2009

변압기 누설전류 통합 감시 장치는 변압기 중성선에 흐르는 누설전류를 검출하여 실시간으로 모니터링이 가능한 장치로, 지정 값 이상의 누설전류가 검출되면 관리자에게 경보함으로써 전기적인 사고를 사전에 예방할 수 있다. 본 논문에서는 변압기 누설전류 통합 감시장치에 대해 설명하고, 국내 현재 설비상황 및 실제 사고 사례를 통해 변압기 누설전류 통합 강시장치의 필요성에 대해 설명하였다.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.803-816
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• 2014

Defense-in-depth is a fundamental safety principle for the design and operation of nuclear power plants. Despite its general appeal, defense-in-depth is not without its drawbacks, which include its potential for concealing the occurrence of hazardous states in a system, and more generally rendering the latter more opaque for its operators and managers, thus resulting in safety blind spots. This in turn translates into a shrinking of the time window available for operators to identify an unfolding hazardous condition or situation and intervene to abate it. To prevent this drawback from materializing, we propose in this work a novel safety principle termed "observability-in-depth". We characterize it as the set of provisions technical, operational, and organizational designed to enable the monitoring and identification of emerging hazardous conditions and accident pathogens in real-time and over different time-scales. Observability-in-depth also requires the monitoring of conditions of all safety barriers that implement defense-in-depth; and in so doing it supports sensemaking of identified hazardous conditions, and the understanding of potential accident sequences that might follow (how they can propagate). Observability-in-depth is thus an information-centric principle, and its importance in accident prevention is in the value of the information it provides and actions or safety interventions it spurs. We examine several "event reports" from the U.S. Nuclear Regulatory Commission database, which illustrate specific instances of violation of the observability-in-depth safety principle and the consequences that followed (e.g., unmonitored releases and loss of containments). We also revisit the Three Mile Island accident in light of the proposed principle, and identify causes and consequences of the lack of observability-in-depth related to this accident sequence. We illustrate both the benefits of adopting the observability-in-depth safety principle and the adverse consequences when this principle is violated or not implemented. This work constitutes a first step in the development of the observability-in-depth safety principle, and we hope this effort invites other researchers and safety professionals to further explore and develop this principle and its implementation.

• 한국산학기술학회논문지
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• 제13권9호
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• pp.4186-4192
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• 2012

풍력발전기가 경제적, 환경적 요인에 따라 대형화, 해상화 되고 있어 접근이 어렵고, 부품 및 유지보수 비용이 증가하고 있다. 풍력발전기 상태 모니터링을 통하여 고장 요소를 최소화 하고, 고장 시 2차 사고를 예방하여 운영유지 및 보수비용을 낮추고 신뢰성을 증가시켜야 한다. 본 논문에서는 IEC 61400-25-2에서 표준으로 추진하는 풍력발전기 모니터링에 적합한 센서 중 실제 풍력발전기 상태 모니터링에 필요한 온도, 습도, 전압, 전류, 풍향, 풍속 센서를 ZigBee 무선 통신 소자와 결합하여 무선 센서노드를 구성하고 이를 이용한 간단한 네트워크를 통하여 센서 신호를 전송한다. 각 무선 센서노드에서 전송되는 신호는 라우터를 통하여 중앙 모니터링 터미널에 전송한다. 또한 LabVIEW로 신호를 수집 및 처리하고, TCP/IP 통신 변환을 통해 인터넷 환경이면 언제 어디서든지 사용자 및 관리자가 모니터링 할 수 있도록 한다.

• Journal of Platform Technology
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• 제6권4호
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• pp.41-48
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• 2018

영유아 관련 사고는 빈번하게 발생하고 있으며 초동 조치가 원활하지 않을 경우 더 큰 사고로 이어질 수 있다. 신속한 초동 조치를 위해서는 적절한 모니터링 시스템이 요구되며, 아동의 생체 상태에 대한 정확한 모니터링과 긴급한 상황 발생에 대해서 즉각적인 통보가 가능한 시스템의 구축이 필요하다. 최근 IoT 기술의 발전과 더불어 다양한 형태의 센서들이 초소형으로 개발되고 있으며 스마트 폰의 발전과 더불어 스마트 폰과의 연계된 웨어러블 디바이스의 개발이 가속화 되고 있다. 이러한 웨어러블 디바이스를 사용하여 영유아 사고의 위험을 줄이고 사고 발생시 신속한 대응이 가능해 진다. 본 논문에서는 영유아 상태에 대한 모니터링이 가능한 웨어러블 시스템을 제안하고 영유아 사고를 예방하기 위한 서비스를 제시한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.425-430
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• 2008

To verify the system performance of portable AE leak diagnosis system which can measure with moving conditions, AE activities such as RMS voltage level, AE signal trend, leak rate degree according to AE database, FFT spectrum were measured during operation on total 11 valves of the secondary system in nuclear power plant. AE activities were recorded and analyzed from various operating conditions including different temperature, type of valve, pressure difference, valve size and fluid. The results of this field study are utilized to select the type of sensors, the frequency band for filtering and thereby to improve the signal-to-noise ratio for diagnosis for diagnosis or monitoring of valves in operation. As the final result of application study above, portable type leak diagnosis system by AE was developed. The outcome of the study can be definitely applied as a means of the diagnosis or monitoring system for energy saving and prevention of accident for power plant valve. The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18 ". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.

• 한국안전학회지
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• 제28권5호
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• pp.78-82
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• 2013

The purpose of this study is to review the labor force partitpation rate and work environment characteristics of female workers to provide basic information for establishment and implementation of effective policies related to accident prevention and workers health protection for female workers. It was analyzed employment status, work environment and injuries and illnesses based on economic activity census results, compensation of industrial injury and the second working condition survey. According to economic activity census results, female labor force participation rate has been steadily increased, whereas male labor force participation rate has been decreased since 1970. Industrial accident rate has been declined in male workers but that in female workers has been steadily increased even though male workers were higher accident rate than female workers. It was evaluated that female workers are vulnerable to industrial injuries and illnesses in the aspect of their working environment and employment status. Also, Substantial differences between female and male workers in occupational exposure patterns, occupational disease and occupational environments were observed. Therefore it was recommended that special care programs for female workers such as a specialized monitoring and management program should be introduced in the near future.

• 한국정보통신학회논문지
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• 제20권1호
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• pp.200-206
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• 2016

수배전반 전기사고 사전 예방을 위해 전기 관리자가 시간과 장소에 구애받지 않고 전력설비의 상태를 실시간으로 감시할 수 있는 시스템 개발이 필요하다. 본 논문에서는 사물인터넷 기반 수배전반 상태 모니터링 시스템을 제안한다. 제안된 시스템은 기존 수배전반 및 제어반 등에 설치하여 수배전반 및 제어반의 상태정보와 제어정보를 인터넷망과 연결된 클라우드 서버와 근거리 무선통신망으로 실시간 전송된다. 관리자는 관리자 단말기를 통해 언제, 어디서나 상태정보 모니터링을 신속하고 용이하게 관리할 수 있으며, 수배전반 상태정보의 성능평가 결과 판정기준 ${\pm}5%$ 이내 오차범위 내의 측정결과를 얻었다.

• 한국구조물진단유지관리공학회 논문집
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• 제14권5호
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• pp.72-78
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• 2010

CFRP보강공법은 구조물에 내하력을 증가시키기 위해 사용되고 있으며 실제 교량에 적용빈도가 높고 연구 활용성에 대한 기대가 큰 공법이다. CFRP로 보강된 콘크리트 구조물은 외부에 에폭시 등으로 접착된 CFRP로 인하여 휨파괴 및 전단파괴 외에 부착파괴가 추가적으로 발생하게 되며 이러한 부착파괴가 전체거동을 지배하게 되는 경우가 대부분이며, 취성파괴를 유발하게 된다. 따라서 이러한 CFRP 부착파괴에 대한 모니터링은 매우 중요한 의미를 갖는다. 본 논문에서는 국부적인 손상 파악에 유리한 PZT센서를 이용한 임피던스 기반 손상검색 방법을 사용하여 콘크리트 균열과 CFRP 부착파괴 모니터링에 대한 적용가능성을 검증해 보았다.