• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3620-3630
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• 2022

The diagnosis of abnormalities in a nuclear power plant is essential to maintain power plant safety. When an abnormal event occurs, the operator diagnoses the event and selects the appropriate abnormal operating procedures and sub-procedures to implement the necessary measures. To support this, abnormality diagnosis systems using data-driven methods such as artificial neural networks and convolutional neural networks have been developed. However, data-driven models cannot always guarantee an accurate diagnosis because they cannot simulate all possible abnormal events. Therefore, abnormality diagnosis systems should be able to detect their own potential misdiagnosis. This paper proposes a rulebased diagnostic validation algorithm using a previously developed two-stage diagnosis model in abnormal situations. We analyzed the diagnostic results of the sub-procedure stage when the first diagnostic results were inaccurate and derived a rule to filter the inconsistent sub-procedure diagnostic results, which may be inaccurate diagnoses. In a case study, two abnormality diagnosis models were built using gated recurrent units and long short-term memory cells, and consistency checks on the diagnostic results from both models were performed to detect any inconsistencies. Based on this, a re-diagnosis was performed to select the label of the second-best value in the first diagnosis, after which the diagnosis accuracy increased. That is, the model proposed in this study made it possible to detect diagnostic failures by the developed consistency check of the sub-procedure diagnostic results. The consistency check process has the advantage that the operator can review the results and increase the diagnosis success rate by performing additional re-diagnoses. The developed model is expected to have increased applicability as an operator support system in terms of selecting the appropriate AOPs and sub-procedures with re-diagnosis, thereby further increasing abnormal event diagnostic accuracy.

• 한국IT서비스학회지
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• 제17권4호
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• pp.75-83
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• 2018

Enterprises need to monitor systems for reliable IT service operations to quickly detect and respond to events affecting the service, thereby preventing failures. Events in non-critical systems can be seen as a precursor to critical system incidents. Therefore, event relationship analysis in the operation of IT services can proactively recognize and prevent faults by identifying non-critical events and their relationships with incidents. This study used the Recurrent Neural Network and Long Short Term Memory techniques to create a model to analyze event relationships in a system and to verify which models are suitable for analyzing event relationships. Verification has shown that both models are capable of analyzing event relationships and that RNN models are more suitable than LSTM models. Based on the pattern of events occurring, this model is expected to support the prediction of the next occurrence of events and help identify the root cause of incidents to help prevent failures and improve the quality of IT services.

• 천문학회보
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• 제42권1호
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• pp.36.1-36.1
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• 2017

A major goal of the proposed Korean Neutrino Detector and Telescope is to detect neutrino burst from core-collapse supernova (SN) explosions in the Milky Way, which will provide an unprecedented opportunity to look into the core of an exploding massive star. Detection with high statistics would give important information for the explosion physics. It can also detect neutrino signals from SN events in the Local Group and trigger alert of the event for the astronomical community. In this talk, I will review the SN rates of the Milky Way and the Local Group, and will discuss the implications for the proposed neutrino telescope.

• 한국멀티미디어학회논문지
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• 제16권6호
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• pp.667-677
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• 2013

소셜 네트워크 서비스의 인기가 증가하면서 현재 이슈가 되는 정보를 추출하거나 증상 등을 추적하는 분석연구가 활발히 진행되고 있다. 특히 트위터에서는 트윗을 통해 이벤트 현상에 대한 반응과 사용자의 개인적인 상태 등이 잘 반영되어 트윗을 센서로 적용한 이벤트 추출이 가능하다. 최근에는 지진과 같은 재난 이벤트뿐만 아니라 사회 전반적으로 관심을 갖고 있는 질환이나 질병에 대한 사회적 신호가 질병의 확산을 조기에 감지하는데 도움을 주고 있다. 논문에서는 감기를 대상 이벤트로 지정하여 트위터로부터 수집한 정보를 감기 신호라는 사회적 신호로 간주하고 분석하였다. 추출된 감기 신호의 신뢰성을 확인하기 위해 감기 확산의 환경적 요인으로 알려진 세 가지 기후 요소와 기상청에서 제공하는 감기 기상지수와의 상관분석을 통해 변수들 사이의 상관관계를 파악한다.

• 한국콘텐츠학회논문지
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• 제10권12호
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• pp.101-108
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• 2010

센서네트워크에서 노드의 에너지 제약 특성을 고려하여 군집 이벤트를 위한 에너지 효율적인 탐지 기법에 대한 다양한 연구들이 진행되고 있다. 기존에 제안된 군집 이벤트 탐지 기법들은 이벤트를 탐지한 센서 중 군집의 경계에 위치한 노드의 정보만을 추출하여 기지국으로 전송하는 방식을 취한다. 하지만 군집 이벤트의 범위가 넓어지고 센서의 배포 밀도가 높아지면 이벤트 경계에 위치한 노드들의 수 또한 증가하여 많은 전송 비용을 필요로 한다. 본 논문에서는 이벤트 경계 노드들의 정보를 압축/요약하여 나타낼 수 있는 인-네트워크 최소 경계 다각형을 이용한 에너지 효율적인 군집 이벤트 탐지 기법을 제안한다. 제안하는 기법은 대규모 센서 네트워크 환경에서 MBP 생성기법을 통해 군집 이벤트의 경계 정보를 표현한다. 제안하는 기법의 우수성을 보이기 위해 제안하는 기법과 기존 기법과의 성능평가를 수행하였다. 성능평가 결과, 최대 92%이상의 정확도를 유지하며 80.13% 에너지 소모량이 감소하였다.

• 한국콘텐츠학회논문지
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• 제18권7호
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• pp.449-458
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• 2018

소셜 네트워크 서비스의 사용량이 증가함에 따라 오프라인에서 발생한 이벤트 정보가 더욱 빠르게 확산되고 있다. 이에 따라 소셜 데이터를 분석하여 이벤트를 검출하기 위한 연구들이 진행되고 있다. 본 논문에서는 소셜 네트워크 환경에서 사용자 관심도를 고려한 그래프 기반 이벤트 검출 기법을 제안한다. 제안하는 기법은 사용자들이 게시한 글을 분석하여 키워드 그래프를 구축한다. 사용자의 소셜 행위로부터 관심도를 계산하고 관심도의 변화를 고려하여 이벤트 판별에 이용한다. 따라서 의미 없이 반복 게시되어 이벤트로 검출된 결과를 제거하고 결과의 신뢰성을 향상시킬 수 있다. 제안하는 이벤트 검출 기법의 우수성을 입증하기 위해 다양한 성능평가를 수행한다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.157-161
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• 2009

In recent years, there is a remarkable progress in ICTs (Information and Communication Technologies), and then many attempts to apply ICTs to other industries are being made. In the field of disaster managements, ICTs such as RFID (Radio Frequency IDentification) and USN (Ubiquitous Sensor Network) are used to provide safe environments. Actually, various types of early warning systems using USN are now widely used to monitor natural disasters such as floods, landslides and earthquakes, and also to detect human-caused disasters such as fires, explosions and collapses. These early warning systems issue alarms rapidly when a disaster is detected or an event exceeds prescribed thresholds, and furthermore deliver alarm messages to disaster managers and citizens. In general, these systems consist of a number of various sensors and measure real-time stream data, which requires an efficient and rapid data processing technique. In this study, an event-driven architecture (EDA) is presented to collect event effectively and to provide an alert rapidly. A publish/subscribe event processing method to process simple event is introduced. Additionally, a complex event processing (CEP) technique is introduced to process complex data from various sensors and to provide prompt and reasonable decision supports when many disasters happen simultaneously. A basic concept of CEP technique is presented and the advantages of the technique in disaster management are also discussed. Then, how the main processing methods of CEP such as aggregation, correlation, and filtering can be applied to disaster management is considered. Finally, an example of flood forecasting and early alarm system in which CEP is incorporated is presented It is found that the CEP based on the EDA will provide an efficient early warning method when disaster happens.

• Journal of Information Processing Systems
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• 제8권2호
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• pp.213-240
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• 2012

Safety critical systems, real time systems, and event-based systems have a complex set of events and their own interdependency, which makes them difficult to test ma Safety critic Safety critical systems, real time systems, and event-based systems have a complex set of events and their own interdependency, which makes them difficult to test manually. In order to cut down on costs, save time, and increase reliability, the model based testing approach is the best solution. Such an approach does not require applications or codes prior to generating test cases, so it leads to the early detection of faults, which helps in reducing the development time. Several model-based testing approaches have used different UML models but very few works have been reported to show the generation of test cases that use events. Test cases that use events are an apt choice for these types of systems. However, these works have considered events that happen at a user interface level in a system while other events that happen in a system are not considered. Such works have limited applications in testing the GUI of a system. In this paper, a novel model-based testing approach is presented using business events, state events, and control events that have been captured directly from requirement specifications. The proposed approach documents events in event templates and then builds an event-flow model and a fault model for a system. Test coverage criterion and an algorithm are designed using these models to generate event sequence based test scenarios and test cases. Unlike other event based approaches, our approach is able to detect the proposed faults in a system. A prototype tool is developed to automate and evaluate the applicability of the entire process. Results have shown that the proposed approach and supportive tool is able to successfully derive test scenarios and test cases from the requirement specifications of safety critical systems, real time systems, and event based systems.

• 융합보안논문지
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• 제18권3호
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• pp.77-85
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• 2018

제어시스템은 공공 네트워크와의 통신망 융합에 따라 다양한 루트를 통해 정보유출 및 변조 등의 위협이 제어시스템에서도 그대로 나타날 수 있다. 최근 다양한 보안에 대한 이슈와 새로운 공격기법에 의한 침해 사례가 다변화됨에 따라서, 단순히 차단 및 확인 등의 학습을 통해 정보를 데이터베이스화하는 보안 시스템으로는 새로운 형태의 위협에는 대처하기 힘들어지고 있다. 현재 제어시스템에서는 이처럼 외부에서 내부로의 위협에 치중하여 보안 시스템을 운용하고 있으며, 보안 접근 권한을 가진 내부자에 의한 보안위협 탐지에 대해서는 미비한 실정이다. 이에 따라 본 연구에서는 NSA에서 발표한 "Spotting the Adversary with Windows Event Log Monitoring"의 주요 Event Log 목록을 토대로 중요도 분석을 실시하였다. 그 결과 제어시스템에 내부자 위협탐지를 위한 Event Log의 중요도 여부를 알 수 있었으며, 분석결과를 바탕으로 이 분야의 연구에 기여할 수 있을 것으로 판단된다.

• Journal of Astronomy and Space Sciences
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• 제20권3호
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• pp.227-238
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• 2003

Spacecraft mission planning functions including event prediction, mission scheduling, command planning, and ground track display have been developed for the KOMPSAT-2 mission operations. Integrated event prediction functions including satellite orbital events, user requested imaging events, and satellite operational events have been implemented. Mission scheduling functions have been realized to detect the mission conflicts considering the user specified constraints and resources, A conflict free mission scheduling result is mapped into the spacecraft command sequences in the command planning functions. The command sequences are directly linked to the spacecraft operations using eXtensible Markup Language(XML) for command transmission. Ground track display shows the satellite ground trace and mission activities on a digitized world map with zoom capability.