• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.97-107
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• 2013

Culverts are structures constructed across river levees. Since river levees are to be constructed continuously, constructions of culvert are known to reduce the stability of river levees. In order to establish an effective inspection system of culverts, a visual inspection system using checklists and smart phone was recommended in this paper. It was determined that the recommended visual inspection checklist is applicable in establishing the investment priority based on the culvert's repair plan establishment, repair and precision safety inspection.

• Journal of Cadastre & Land InformatiX
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• v.49 no.1
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• pp.85-101
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• 2019

Recently, thank to the popularization of light-weight drone through the significant developments in computer technologies as well as the advanced automated procedures in photogrammetry, Unmanned Aircraft Systems have led to a growing interest in industry as a whole. Documentation, maintenance, and restoration projects of large scaled cultural property would required accurate 3D phenomenon modeling and efficient visual inspection methods. The object of this study verify on the accuracies achieved of 3D phenomenon reconstruction as well as on the validity of the preservation, maintenance and restoration of large scaled cultural property by UAS photogrammetry. The test object is cltural heritage(treasure 1324) that is the rock-carved standing Bodhisattva in Soraesan Mountain, Siheung, documented in Goryeo Period(918-1392). This standing Bodhisattva has of particular interests since it's size is largest stone Buddha carved in a rock wall and is wearing a lotus shaped crown that is decorated with arabesque patterns. The positioning accuracy of UAS photogrammetry were compared with non-target total station survey results on the check points after creating 3D phenomenal models in real world coordinates system from photos, and also the quantified informations documented by Culture Heritage Administration were compared with UAS on the bodhisattva image of thin lines. Especially, tests the validity of UAS photogrammetry as a alternative method of visual inspection methods. In particular, we examined the effectiveness of the two techniques as well as the relative fluctuation of rock surface for about 2 years through superposition analysis of 3D points cloud models produced by both UAS image analysis and ground laser scanning techniques. Comparison studies and experimental results prove the accuracy and efficient of UAS photogrammetry in 3D phenomenon modeling, maintenance and restoration for various large-sized Cultural Heritage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.59-66
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• 2019

Small bridges carry out only general inspections based on visual inspection. The Bridges with more than 30 years of public use need to be decided on whether or not they will be reconstruction according to aging. However, there are some situations that need to be determined only by appearance condition, which is insufficient in terms of safety maintenance. In this paper, the condition evaluation and the load carrying capacity evaluation were carried out for aged small bridges. A comparison of the evaluation results was conducted to examine the appropriateness of the maintenance related to the decision making of the reconstruction. As a result of reviewing, two of the bridges showed that there are no abnormality in the safety of the state evaluation, but the load capacity were insufficient. Thus evaluation the safety and performing the reconstruction decision of aged small bridges by visual inspection alone with may cause problems. Therefore, it is necessary to carry out additional research on the ambient measurement and load carrying capacity evaluation for the maintenance of the bridges, and to supplement it through application of the bridge management system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.275-276
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• 2021

In the construction industry, many of the inspection activities have been conducted by experts' eyes. The inspection performance of this kind of method is highly influenced by experience and knowledge of the expert. The experts who have fluent experience may show better inspection performance than the novice. The problem is the deficiency of experts in the near future due to the acceleration of retirement of the aging expert. Eye-tracking technology can be a solution to effectively educate the novice through transferring the knowledge of an expert and to advance the inspection activities using experts' eyes. This study, as an initial step to suggest the solution, (1) figured out the state of the art of eye-tracking technology, (2) reviewed the previous research to improve the inspection in construction using experts' eye, (3) explored the potential of the application area of eye-tracking technology, and (4) established the framework to develop the advanced inspection method in two application area which are construction site safety management and infrastructure performance measurement.

• Journal of KIBIM
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• v.3 no.3
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• pp.1-8
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• 2013

In general, a two-dimensional platform were used to manage the structural inspection information. But we performed a study on utilizing 3D model to input and display the information of structure inspection. Coarse and Fine model of structure were used to input the information. 3D model combined with database built from record plan and field inspections data and rating will provide more intuitive and effective environment for inspectors in bridge maintenance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.30-39
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• 2023

Large dams, which are critical infrastructures for disaster prevention, are exposed to various risks such as aging, floods, and earthquakes. Better dam safety inspection and diagnosis using digital transformation technologies are needed. Traditional visual inspection methods by human inspectors have several limitations, including many inaccessible areas, danger of working at heights, and know-how based subjective inspections. In this study, drone photogrammetry was performed on two large dams to evaluate the applicability of digital data-based dam safety inspection and propose a data management methodology for continuous use. High-quality 3D digital models with GSD (ground sampling distance) within 2.5 cm/pixel were generated by flat double grid missions and manual photography methods, despite reservoir water surface and electromagnetic interferences, and severe altitude differences ranging from 42 m to 99.9 m of dam heights. Geometry profiles of the as-built conditions were easily extracted from the generated 3D mesh models, orthomosaic images, and digital surface models. The effectiveness of monitoring dam deformation by photogrammetry was confirmed. Cracks and deterioration of dam concrete structures, such as spillways and intake towers, were detected and visualized efficiently using the digital 3D models. This can be used for safe inspection of inaccessible areas and avoiding risky tasks at heights. Furthermore, a methodology for mapping the inspection result onto the 3D digital model and structuring a relational database for managing deterioration information history was proposed. As a result of measuring the labor and time required for safety inspection at the SYG Dam spillway, the drone photogrammetry method was found to have a 48% productivity improvement effect compared to the conventional manpower visual inspection method. The drone photogrammetry-based dam safety inspection is considered very effective in improving work productivity and data reliability.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.3
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• pp.179-186
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• 2021

In general, the daily safety inspection activities, which investigate damages in structures and measures the size of the damage, have been relied heavily on the visual inspection so far. Since the probe of the condition and performance of facilities by such personnel is often dependent on the subjective judgment of the investigator, the consistency and repeatability of the probing results may reduce. Particularly, damage located in a difficult-to-reach place depends mainly on experience with the naked eye, and an unsafe method using a ladder has mainly applied when necessary. Therefore, in this study, we tried to propose a way of using images that can reduce the deviation between safety inspection investigators, enhance objectivity, and improve the safety of workers. In this study, we have applied homographic transformation as a method of correcting the image. As a result of analyzing the size of the damage in the corrected image of the test subject, it confirms that the accuracy of measuring the magnitude of the damage can satisfy the target levels of 5.0mm and 0.005m², the target accuracy levels. As a result of the field verification test to which the proposed image correction technique applied, the coefficient of variation of the crack length in the structure decreased from 5.4~7.0% to 0.072~0.12%, and that of the damaged area from 10.9% to 1.6%. It confirms that the measurement accuracy is improved. Therefore, it is expected that this study on the image utilization technique in safety inspection activities can increase the accuracy of damage measurement and improve the reliability of the safety inspection reports and exterior survey drawings.

• JOURNAL OF ELECTRICAL WORLD
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• s.443
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• pp.29-34
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• 2013

• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.186-187
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• 2016

본 논문에서는 평소 사람이 접근하기 어려워 점검이 힘들었던 대형구조물에 대하여 드론을 활용한 안전점검의 활용 가능성을 기획하였으며, 지상에서 식별하기 힘들거나 육안만으로 찾기 힘든 구조물을 근접 촬영하고 열화상 카메라를 이용해 구조물의 상태를 정밀 점검하고자 한다. 국내 최초로 드론을 활용하여 정밀 안전진단에 활용 가능한지에 대한 검토와 일반 안전진단과의 차별성 및 비교를 통해 향후 드론에 미치는 영향을 검토하고자 한다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1760-1761
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• 2011

원자력발전기술원은 발전정지 관련계통 제어케비넷 내에 장착된 제어용 기기들의 다중화 설계변경 활동을 지원하고 관련 기기의 배선상태 등의 육안점검을 통해 취약성 여부를 최종 확인하기 위하여 국내 Westinghouse형 원전 계측제어 케비넷 점검을 수행하였다. 또한 관련 설계변경에 대한 신뢰도평가 기술지원도 함께 수행하여 해당 설계변경이 설비의 신뢰도 향상에 효과가 있는지를 정량적으로 평가하고자 하였다. 이에 따라 원자로냉각재펌프(RCP, Reactor Coolant Pump) 제어 채널의 다중화 개선에 대하여 설계변경 전후의 기기 배열 변화에 따른 계통 신뢰도 변화를 대표유형 기기의 고장률에 근거하여 분석하였다. 고장수목을 이용하여 설계변경 전후의 RCP 고장정지로 인한 발전정지를 유발하는 고장조합을 도출하고, 고장정지 확률 변화를 정량화 하였다. 또한 기기 보호 측면에서 펌프 보호를 위한 신호를 출력하지 못하는 경우를 정량화하여 이를 비교하였다.