• 한국구조물진단유지관리공학회 논문집
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• 제24권3호
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• pp.122-129
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• 2020

원자력발전소의 확률론적 지진취약도 분석을 수행하기 위해서는 실제 중대 사고를 표현할 수 있는 파괴모드와 파괴기준의 정의가 중요하다. 그러나 배관시스템의 내진설계기준은 소성붕괴로서 실제 한계상태인 누수를 표현하지 못하므로 중대 사고를 충분히 반영하지 못하고 있다. 따라서 신뢰성 있는 확률론적 지진취약도 분석을 위해서는 한계상태를 명확히 정의할 필요가 있다. 따라서 본 연구에서는 배관시스템의 취약부위인 SCH80 3인치 강재배관엘보의 한계상태를 누수로 정의하고 면내반복가력시험을 수행하였다. 또한 모멘트-변형각의 관계의 소산 에너지에 기반을 둔 손상도를 이용하여 강재배관엘보의 파괴기준을 정량화하고자 하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제11권3호
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• pp.123-131
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• 2007

본 연구에서는 등분포 하중을 받는 섬유 보강 복합재료 관의 좌굴 거동을 분석하였다. 등방성의 원통형 구조물의 경우, 좌굴 형상은 단면만 변형할 뿐 길이방향으로의 단면 형상은 일정한 2차원 좌굴이 발생하나, 섬유 보강 복합재료와 같은 이방성 재료로 구성된 원통형 구조물의 경우에는 길이 방향으로 단면의 형상이 변화하는 3차원 좌굴이 발생하게 된다, 또한 적층 구조물에서는 적층각의 변화에 따라 각 방향에 따른 재료의 강도가 변화하므로, 적층각의 변화는 구조물의 강도를 변화시킨다. 본 연구에서는 원통형 적층 구조물의 2차원 좌굴과 3차원 좌굴의 경계를 조사하고, 적층각 변화에 따른 섬유 보강 복합재료 관의 좌굴 강도를 평가하였다.

• 상하수도학회지
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• 제23권3호
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• pp.295-303
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• 2009

In the present study, a reliability analysis calculating the probability of system failure has been performed using cut set and results of numerical analysis for unsteady flow in pipe. Especially, the probability of system failure has been evaluated regarding the effect of valve closure which is a really important activity in operation of piping system. In spite of small amount of demand, it was found that fast valve closure can generate high probability of system failure. Furthermore, it was confirmed that surge tank can reduce the unsteady effects and probability of system failure in water distribution system. From the results, it was found that the unsteady flow has a significant effect on the probability of system failure Furthermore, it was able to find which pipe or cut set has high probability of system failure. So it could be used to determine which pipe or cut set has a priority of repair and replacement. Therefore, reliability analysis regarding unsteady flow has to be performed for the planning, designing, maintenance, and operation of piping system.

• Nuclear Engineering and Technology
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• 제46권2호
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• pp.225-234
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• 2014

Wall-thinned defects caused by accelerated corrosion due to fluid flow in the inner pipe appear in many structures of the secondary systems in nuclear power plants (NPPs) and are a major factor in degrading the integrity of pipes. Wall-thinned defects need to be managed not only when the NPP is under maintenance but also when the NPP is in normal operation. To this end, a test technique was developed in this study to detect such wall-thinned defects based on the temperature difference on the surface of a hot pipe using infrared (IR) thermography and a cooling device. Finite element analysis (FEA) was conducted to examine the tendency and experimental conditions for the cooling experiment. Based on the FEA results, the equipment was configured before the cooling experiment was conducted. The IR camera was then used to detect defects in the inner pipe of the pipe specimen that had artificially induced defects. The IR thermography developed in this study is expected to help resolve the issues related to the limitations of non-destructive inspection techniques that are currently conducted for NPP secondary systems and is expected to be very useful on the NPPs site.

• Smart Structures and Systems
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• 제33권5호
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• pp.375-383
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• 2024

Infrastructure facilities contain various pipe systems, which can be considerably damaged by external loads such as earthquakes. Therefore, structural health monitoring (SHM) and safety assessment of pipes are crucial. Digital twin technology for SHM of pipes is important in the industry. This study proposes a digital twin system that estimates the behavior, stress, and external load of real-scale pipes in real time under simultaneous seismic and external loads using a minimum number of sensors. Vibration tests were performed to construct the digital twin system, and a numerical model was developed that considered the dynamic characteristics of a target pipe. Moreover, a reduced-order modeling technique of a numerical model was applied to enhance its real-time performance. The digital twin system successfully estimated the response of the pipe at all points. Verification of the digital twin system was performed by comparing it with the experimental parameters of a real-scale pipe. The proposed digital twin system can help enhance SHM and system's maintenance.

• 한국구조물진단유지관리공학회지
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• 제20권3호
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• pp.60-66
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• 2016

• 한국측량학회:학술대회논문집
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• 한국측량학회 2003년도 추계학술발표회 논문집
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• pp.347-352
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• 2003

This study attempts to develop the management and control system of water pipe on the footing of database builded by the research on the pipe of water supply equipped over 48.809km within district of Hamyang-up by Hamyang-Gun, and to apply it to the work of self-governing body. And, since the structure and equipment of facilities of underground water supply pipe ate so complex, the maintenance and management of function of facilities are needed for long-term. This study has the purpose to build the database per self-governing body which can be connected with the future NGIS project, and to promote the efficiency of management and control of facilities and equipment.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.447-453
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• 2004

Various structural materials have been used in construction projects using stones, connotes, and steels materials. Among of these projects, concretes may use widely because concretes have high compressive strength, and comparatively easy maintenance and management. Reinforced concrete Buildings will be deteriorated as time passed. These problems will be accelerated by propagation of cracks. In order to manage such cracks, time, efforts and expense are required. In this study, leakages of fluorescence and adhesive material were investigated using glass sensors that were embedded in a model beam and column. In addition, currents in glass pipe sensor were observed to find leakage of liquid in glass pipes. Progressive cracks were generated by fracture of glass me sensor. In this investigation, a reinforcement clothing system was wrapped for a glass pipe sensor, The glass pipe sensor that can make control and reinforce cracks simultaneously.

• 상하수도학회지
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• 제20권1호
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• pp.35-43
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• 2006

Concerns related to protecting, identifying, and isolating of subsystems of a water distribution network have led to the realization of the increased importance of valves in the system. The most important purpose of valves in water distribution systems is to isolate a subsystem due to breakage, maintenance activities, or contamination. A subsystem called segment is isolated by the closure of adjacent valves. Minimizing the pipe failure impact, an efficient algorithm is required to identify adjacent valves quickly. In this paper, an algorithm to identify adjacent valves to be closed to isolate a subsystem from the remainder of a network when a pipe failure is presented. The algorithm is operated on a matrix called the valve location matrix containing the information of valve locations. An application to an existing water distribution system demonstrates the developed algorithm efficiently locates the adjacent valves for the isolation of a broken pipe.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.173.1-173
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• 2001

This paper proposes the methodology in image processing algorithm that estimates the pose of the pipe crawling robot. The pipe crawling robots are usually equipped with a lighting device and a camera on its head for monitoring and inspection purpose. The proposed methodology is using these devices without introducing the extra sensors and is based on the fact that the position and the intensity of the reflected light varies with the robot posture. The algorithm is divided into two parts, estimating the translation and rotation angle of the camera, followed by the actual pose estimation of the robot. To investigate the performance of the algorithm, the algorithm is applied to a sewage maintenance robot.