• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.21-28
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• 2022

The TMD has a simple structure than other vibration control devices and shows excellent control performance for the simple harmonic vibration generated in the structure. However, the vibration control range is narrower than other control devices, making it vulnerable to vibration cycles caused by unexpected external loads. The ETMD developed in this study consisted of Mass with electromagnets. Therefore when supplying a current, the magnetic field is formed to increase the friction force with the friction plate, thereby instantaneously controlling the behavior of the Mass. The experiment was conducted to compare the control performance of the control device by installing the ETMD developed for control performance evaluation in the center of the model simple beam bridge to forced excitation at 3.02 Hz where the maximum bending displacement occurs. As a result of the experiment, ETMD exhibited excellent control performance with a maximum bending displacement attenuation rate of 57.51%.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.2
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• pp.95-102
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• 2005

Delaying and objection for the construction of storage spent-fuel disposal has prompted to consider expanding on-site storage of spent reactor fuel since it can eliminate the need for costly and difficult shipping and control of the spent fuel completely under the direction of the owner-utility. The dry storage unit developed in Canada can accommodate Korea heavy water reactor fuel elements and become a candidate for the Korean market. In this paper, finite element analysis were carried out in order to investigate the structural behavior of the nuclear spent fuel dry storage system, which is subjected to impact loads such as collision of a truck load and dropping of flask under the irregular operation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.97-102
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• 2018

Conventional PSC I type girders were adversely affected by the self - weight of concrete, anchorage, prestressing. In order to overcome this problem, PSC girder was constructed with a hollow in the web and developed a hollow web PSC type I girder which is applicable to 50 - 70m span by multistage stressing and then actually long span hollow web PSC girder bridge was constructed. In this study, the results of Static Load Test and the Finite Element Analysis of the hollow web PSC I girder bridges were compared and analyzed, and the Load Carrying Capacity and safety of PSC girder bridges were evaluated. The Static Load Test and the numerical analysis results of this bridge showed similar tendency and the behavior of the hollow web PSC I girder was well simulated. The entire girders of the bridges had sufficient Load Carrying Capacity under the live load design condition and the bridges satisfied the safety and confirmed the appropriateness of the construction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.95-102
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• 2007

It needs to Prevent damage as aging shotcrete itself exists as a dangerous component to comuting vehicles or infrastructure due to scaling, spaling, and loosening. However, it is hard to make an approach owing to a steep slope and high work, and there has been indicated a limit that it is difficult to grasp the internal condition of shotcrete on the surface. This study aimed to research internal defects that cannot be observed from the surface, by measuring a subtle thermal transfer on the shotcrete surface by using infrared thermography for overcoming such a technical limit. As a result of conducting an inspection through an analysis on measured data and fieldwork using an endoscope camera, it was impossible to accurately determine the wet part because of an excessive coating of shotcrete, yet, This study is proposed effictively extract a void part of the inside with non-destructive and non-touching method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.25-34
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• 2015

Proposed equation is used many time in calculation of concrete compressive strength using the non-destructive testing at precision safety diagnosis. Most of proposed equation is suggested in abroad and have an error to estimate concrete compressive strength in the domestic. Therefor, proposed equation is low reliability to estimate concrete compressive and it has a significant effect in reliability of precision safety diagnosis. Nevertheless, It is possible to increase the reliability through a number of experiments from this problem that occurs in some localized part. This paper is proposed assessment formula of reliability related core compressive strength to increase the reliability. It is verified that reliability of proposed assessment formula is useful by probabilistic techniques. It is compared with each graphs of concrete compressive strength of proposed equation. It has been found that the present methods are very efficient.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.65-91
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• 1999

More than 6 years passed until GPR was introduced to our country. GPR method is now widely used in construction site because of its various applicability, convenient handling and low cost. We discussed the characteristics and limits of GPR method with various case study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.48-54
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• 2015

In this study, we propose an innovative lateral force distribution building system between tall buildings by utilizing the difference of moment of inertia, resulting the reduction of lateral displacement and the lateral forces in terms of an alternative for the dense human and increased cost of lands in highly integrated city area. A successive collapse prevention means by providing additional bearing plate between connections is proposed. In addition to that, a more economical vibration reduction is expected due to the suggested tuned mass damper on the surface of spacial structure. In the considered verification examples, reduced drifts at the top location of the building systems are validated against static wind pressure loads and static earthquake loads. The suggested hybrid building system will improve the safety and reliability of the new or existing building system in terms of more than 30% reduced drift and vibration through the development of convergence of tall buildings and spatial structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.42-51
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• 2018

Verticality problem during the installation process in offshore wind turbine substructures could degrade the safety of the whole structures. Therefore, in this paper, the design of vertically adjustable transition piece(T.P.), using a PS anchor and grout of anchor socket in concrete gravity based substructure(G.B.S.), was proposed. T.P. was designed for 5MW offshore wind trubine and can adjust up to $0.5^{\circ}$ in verticality, occurred during installation. The design plan for each members and design procedure for T.P. was proposed. Then based on the proposed design, actual design targeting sea of Jeju-island was carried out. Finally, by use of non-linear 3D Finite Element Analysis(F.E.A.), evaluation of design was performed. As a result of evaluation, by checking load transfer mechanism and stress of T.P, proposed design was considered safe up to $0.5^{\circ}$ of adjustment.

• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.665-676
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• 2021

As the number of deteriorated buildings increases, the importance of safety diagnosis and maintenance of buildings has been rising. Existing visual investigations and building safety diagnosis objectivity and reliability are poor due to their reliance on the subjective judgment of the examiner. Therefore, this study presented the limitations of the previously conducted appearance investigation and proposed 3D Point Cloud data to increase the accuracy of existing detailed inspection data. In addition, this study conducted a calculation of an objective building safety grade using a Deep-Neural Network(DNN) structure. The DNN structure is generated using the existing detailed inspection data and precise safety diagnosis data, and the safety grade is calculated after applying the state evaluation data obtained using a 3D Point Cloud model. This proposed process was applied to 10 deteriorated buildings through the case study, and achieved a time reduction of about 50% compared to a conventional manual safety diagnosis based on the same building area. Subsequently, in this study, the accuracy of the safety grade calculation process was verified by comparing the safety grade result value with the existing value, and a DNN with a high accuracy of about 90% was constructed. This is expected to improve economic feasibility in the future by increasing the reliability of calculated safety ratings of old buildings, saving money and time compared to existing technologies.

• Journal of Korean Society for Geospatial Information Science
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• v.3 no.2 s.6
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• pp.151-158
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• 1995

Change detection, image differencing technique, is the most widely used in a variety of image environments. The digital terrain model and digital images have the same data structure. This study applied digital terrain model and change detection technique for inspecting the deflection of the structure. Authors make digital terrain model from triangular irregular network(TIN) by leveling data and suggest to possibility recognize modification part and volumes by digital terrain model and change detection technique. Authors can reduce testing materials and man power, and displayed his modification part.