• Plant Journal
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• v.11 no.4
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• pp.47-54
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• 2015

국내 플랜트 엔지니어링 및 건설 업체들의 수익성 악화가 지속됨에 따라 플랜트 원가 경쟁력 강화 및 생산성 향상에 대한 요구가 증대되고 있다. 본 논문에서는 ISO 도면으로부터 용접 포인트의 번호를 부여 하는 용접커팅플랜 작업과 용접이력관리를 위한 용접검사보고서 작성에 대하여 현행 프로세스를 분석하고 문제점을 도출하였다. 현행 프로세스에서는 수작업에 따른 생산성 저하와 현장변경요청 발생에 대한 검증의 어려움이 발생하여 전산화를 통하여 석유화학 플랜트 배관공사용 용접관리 프로세스를 개선하였다. 개선 효과의 검증을 위해 국내 석유화학 플랜트 건설 프로젝트를 대상으로 현장변경요청 발생률과 업무 생산성 향상에 대하여 개선 전후를 비교하였다. 개선된 프로세스를 적용하여 현장변경요청 발생률은 개선프로세스 적용 이전 대비 4.3%p 감소하였고, 업무 생산성은 개선프로세스 적용 이전 대비 생산성이 한 장당 0.13 시간 향상이 있음을 확인할 수 있었다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.87-92
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• 2006

This paper supplements shortcoming of radioactivity check by detecting defect of SWP weld zone using ultrasonic wave. Manufacture 2 stage robot detection systems that can follow weld bead of SWP by method to detect weld defects of SWP that shape of weld bead is complex for this as quantitative. Also, through signal processing ultrasonic wave defect signal system of GUI environment that can grasp easily existence availability of defect because do videotex compose. Ultrasonic wave signal of weld defects develops artificial intelligence style sightseeing system to enhance pattern recognition of weld defects and the classification rate using neural net. Classification of weld defects that do fan Planar defect and that do volume defect of by classify.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.4
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• pp.328-333
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• 2003

It has been widely recognized that the residual stress of the weldment affect the integrity of steel structures and cause an initiation of crack in the welded regions. Since the power plants adopt a variety of welding processes, it is necessary to know the distribution and magnitude of residual stresses. This paper has attempted to investigate the validity of the saw cutting method and the indentation method to measure the residual stresses in the steel plates. The residual stresses in the specimens of hot reheater pipes, cold reheater pipes and feed water lines in power plants were determined by the saw cutting method and the indentation method. The data were compared and reviewed for the validity of the methods.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.5
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• pp.307-313
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• 2015

Leak detection in a pipeline usually involves acoustic emission sensors such as contact type sensors. These contact type sensors pose difficulties for installation and cannot operate in areas having high temperature and radiation. Therefore, recently, many researchers have studied the leak detection phenomenon by using a camera. Leak detection by using a camera has the advantages of long distance monitoring and wide area surveillance. However, the conventional leak detection method by using difference images often mistakes the vibration of a structure for a leak. In this paper, we propose a method for steam leakage detection by using the moving average of difference images and histogram analysis. The proposed method can separate the leakage and the vibration of a structure. The working performance of the proposed method is verified by comparing with experimental results.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1044-1053
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• 2022

Time domain reflectometry (TDR) is a diagnostic technique to evaluate the physical integrity of cable and finds application in leak detection and localization of piping system. In this study, a cable-shaped leak detection sensor was proposed using the TDR technique for monitoring leakage detection of ship's engine room seawater piping system. The cable sensor was developed using a twisted pair arrangement and wound by an absorbent material. The availability and performance of the sensor for leak detection and localization were evaluated on a lab-scale pipeline set up. The developed sensor was installed onto the pipes and flanges of the lab-scale set up and various TDR waveforms were acquired and analyzed according to the dif erent variables including the number of twists and sheath thickness. The result indicated that the twisted cable sensor was able to produce clear and smooth signal as compared to the TDR sensor with a parallel arrangement. The optimal number of twist was determined to be above 10 per the unit length. The optimal diameter of sheath thickness that results in the desired sensitivity was determined to be ranging from 80% up to 120% of the diameter of the conductor. The linear regression analysis for estimation of leak localization was carried out to estimate the location of the leakage, and the result was a determination coefficient of 0.9998, indicating a positive relationship with the actual leakage point. The proposed TDR based leak detection method appears to be an effective method for monitoring leakage of ship's seawater piping system.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.330-330
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• 2010

하나로 노심에서 발생하는 열중성자를 감속재인 액체수소층을 통과시켜 냉중성자를 생산 하는 설비인 냉중성자원 시설은 초경량 합금, 신소재 및 DNA 구조연구 등의 첨단기술연구에 유용한 도구로 활용될 계획이며, 현재 원자력연구원에서는 냉중성자원 시설을 개발하여 제작 설치하였고, 이 장치들에 대해 기능시험을 수행하였다. 냉중성자원 시설계통에서 가스블랭킷계통은 수소의 외부누출을 방지하고, 진공용기를 포함한 수조내기기 내부로 공기 및 경수가 유입되지 않도록 하여 냉중성자원을 보호하기 위한 역할을 수행한다. 또한 가스블랭킷계통의 구성은 가스공급장치($N_2$ 및 He 가스 실린더로부터 가스공급 기능), 질소충압탱크, 진공박스, 수소박스, 밸브박스 및 각 구역별 독립 배관 등으로 되어있다. 이동식 진공배기장치는 가스블랭킷계통에서 사용하기 위해 특수하게 제작된 장치로서 진공계통과 수소계통의 초기충진 시 또는 계통배기 시 잔류가스를 제거하거나, 블랭킷가스의 오염검사를 위한 시료채취 기능 등을 수행할 수 있도록 되어있다. 본 논문에서는 냉중성자원장치 내의 수소계통 및 진공계통의 배관과 기기를 외기와 경수로부터 안전하게 격리시키기 위해서 제작설치 적용된 가스블랭킷계통에서 이동식 진공배기장치를 이용하여 잔류가스 제거방법과 각 가스블랭킷 영역으로부터 시료를 채취하여 수행된 산소농도 분석에 대해 기술하였다.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.2
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• pp.93-101
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• 2023

In this study, a deep learning algorithm was used to diagnose electric potential signals obtained through CIPS and DCVG, used indirect inspection methods to confirm the soundness of buried pipes. The deep learning algorithm consisted of CNN(Convolutional Neural Network) model for diagnosing the electric potential signal and Grad CAM(Gradient-weighted Class Activation Mapping) for showing the flaw prediction point. The CNN model for diagnosing electric potential signals classifies input data as normal/abnormal according to the presence or absence of flaw in the buried pipe, and for abnormal data, Grad CAM generates a heat map that visualizes the flaw prediction part of the buried pipe. The CIPS/DCVG signal and piping layout obtained from the 3D finite element model were used as input data for learning the CNN. The trained CNN classified the normal/abnormal data with 93% accuracy, and the Grad-CAM predicted flaws point with an average error of 2m. As a result, it confirmed that the electric potential signal of buried pipe can be diagnosed using a CNN-based deep learning algorithm.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.25-30
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• 2013

The periodic inspection of piping and pressure vessels welds in nuclear power plant has to provide reliable result related to weld flaws, such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these data. Specially, the amplitude of flaw response is used as basic parameter for flaw sizing and it may cause some deviation in length sizing result. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by the requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error. Therefore, the objective of this study is to compare and evaluate the ultrasonic amplitude difference between air filled and water filled pipe in nuclear power plant. Additionally, the accuracy of flaw sizing is estimated by comparing both conditions.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.1
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• pp.74-78
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• 2015

Nuclear power plant steam generator that is one of the main component has several thousands of thin tubes. And the steam generator tube is subject to damage because of the severe operation conditions such as the high temperature and pressure. Therefore periodic inspections are conducted to ensure the integrity of steam generator component. Hanul unit 3 also has been inspected in accordance with in-service inspection program and is scheduled to be replaced for exceeding the plugging rate which was recommended by manufacturer. During the steam generator replacement activity, we found several clustered porosity on inner surface of main feed water pipe. Additionally crack-like indications were found at weld interface between base material and weld of main feed water pipe. This paper describes the field experience and visual testing results for inner surface of main feed water pipes. The destructive test result had shown that these indications were porosities which were caused by manufacturing process not by operation service.

• Progress in Medical Physics
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• v.13 no.2
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• pp.90-97
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• 2002

The simulator which has a identical geometry with radiotherapy equipments, is a essential equipment to accomplish optimized radiotherapy plan through simulation by using diagnostic low energy X-ray. A Radiotherapy simulator has a combined technology from the therapeutic and diagnostic radiology and needs a periodical test for mechanical and optical properties, X-ray generator, image intensifier of simulator to keep the proper maintenance and radiation safety. Hence, tests were done and classified as i) mechanical and optical parameter for the gantry, collimator, and couch ii) key performance of the X-ray generator such as a kVp, mAs, and timer iii) performance of the image intensifier such as a resolution and contrast for three kinds of simulator, common use in clinic. The above result of tests will be applied to the acceptance test and periodical quality assurance procedure.