• Journal of Korean Society of Disaster and Security
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• v.15 no.3
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• pp.1-14
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• 2022

Recently, the risk of water disasters are increasing due to climate change and the aging of river levees. Existing conventional river embankment inspections have many limitations due to the consumption of a lot of manpower and budget. Thus, it is necessary to establish a new monitoring and forecast/warning method for effective flood response. This study proposes the river levee health monitoring system by analyzing the relationship between river levee deformation and hydrological factors using Sentinel-1. The variance index calculated in this study was classified into 4 grades. And the levees collapse section was judged to be a high vulnerable point in which the variance rapidly increased based on the result of the rapid increase in soil moisture. In the future, it is expected that it will be possible to advance levee maintenance technology and improve national disaster management through the advancement of the existing levee management system and automated monitoring through the forensic method that combines remote technology.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.565-570
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• 2024

Recently, due to adjacent excavation work such as new buildings and common tunnel expansion concentrated around the urban railway, deformation of the underground box and tunnel structure of the urban railway built underground has occurred, and as a result, repair and reinforcement work is frequently carried. In addition, the subway is responsible for large-scale transportation, so ensuring the safety and drivability of underground structures is very important. Accordingly, an automated measurement system is being introduced to manage the safety of underground box structures. However, there is no analysis of structural damage vulnerabilities caused by subsidence or uplift of underground box structures. In this study, we aim to analyze damage vulnerabilities for safety monitoring of underground box structures. In addition, we intend to analyze major core monitoring locations by modeling underground box structures through numerical analysis. Therefore, we would like to suggest sensor installation locations and damage vulnerable areas for safety monitoring of underground box structures in the future.

• Journal of the Korean Geosynthetics Society
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• v.16 no.3
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• pp.1-10
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• 2017

Recently, one of the natural disasters, landslide is causing huge damage to people and properties. In order to minimize the damage caused by continuous landslide, a scientific management system is needed for technologies related to measurement and monitoring system. This study aims to establish a management system for landslide damage by prediction of slope failure. Ground behavior was predicted by surface ground deformation in case of slope failure, and the change in ground displacement was observed as slope surface. As a result, during the slope failure, the ground deformation has the collapse section, the after collapse precursor section, the acceleration section and the burst acceleration section. In all cases, increase in displacement with time was observed as a slope failure, and it is very important event of measurement and maintenance of risky slope. In the future, it can be used as basic data of slope management standard through continuous research. And it can contribute to reduction of landslide damage and activation of measurement industry.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.97-104
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• 1999

This case study has been prepared to provide the practical data about construction of temporary shoring facilities (i.e. braced sheet pile excavation) and to utilize the case study information effectively for design and construction of future facilities. This case study includes information such as 1) installing measurement devices to monitor the deformation of the sheet pile walls and the subsoil in the vicinity after establishing the criteria for the sheet pile deflection; 2) monitoring the actual movement of the temporary facility after setting up the survey control standard (due to the movement of the temporary facility) : 3) inspecting the suitability of the temporary facility construction: and 4) analyzing and studying the result of the tension test after installing ground anchors.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.31-34
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• 2002

A study on the method that can measure the internal strain of composite materials is performed to monitor the health status of composite structures. A fiber optic sensor was constructed using the total reflected extrinsic Fabry-Perot interferometer(TR-EFPI) probe with a broadband light source. Result obtained from electrical strain gage adhered on the aluminum beam specimen was compared with that from the fiber optic TR-EFPI sensor and showed a good agreement. It was found that fiber optic TR-EFPI sensor system was adequate for monitoring the strain and thus failure processes in the interior of composite materials.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.188-191
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• 2002

3-D orthogonal woven carbon/Al composites were fabricated using a pressure infiltration casting method. Especially, to minimize geometrical deformation of fiber pattern and $Al_4C_3$ formation, the process parameters of the minimum pressurizing force, melting temperature, delay and holding time of molten aluminum pressurizing was optimized through the PC-controlled monitoring system. Resonant ultrasound spectroscopy (RUS) was utilized to measure the effective elastic constants of 3-D orthogonal woven carbon/Al composites. The CTE measurement was conducted using strain gages in a heating oven.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.06a
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• pp.109-115
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• 2000

The spindle unit is core parts in high precision machine tools. Diverse static, dynamic and thermal charateristics of spindle unit are needed for special purpose of machine tools. Compromise between those charateristics will be done in concept design phase. High static stiffness at spindle nose may be very important performance for heavy cutting work. High dynamic stiffness is also useful to high precision and high speed machine tools. Improvement of thermal charateristics in spindle lead to high reliability of positioning accuracy. For high speed spindle structure, the design parameter such as, bearing span, diameter, bearing type and arrangement, preload, cooling and lubrication method should be in harmony.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.43-50
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• 2010

This study aims to analyze the structural safety by comparing deformation and equivalent stress of door with a stiffener or no stiffener when the door crashes against something in case of overturn. Three types are classified on the basis of the no stiffener model in the vehicle door. One is the type which has a stiffener. Another is the type which has no stiffener and the other is the type which has a hole in the stiffener. These three types are compared with each other by analyzing. This side door of vehicle is the automotive part about the kind of vehicle as Mercedes Benz E-Klasse scaled down as 1/18 times as the real size. The study model of vehicle door is modelled by CATIA program and it is analyzed by ANSYS.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.388-392
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• 1995

The Electronic Speckle Pattern Interferometry(ESPI) has been applied to many technical problems such as deformation and displacement measurement, strain visualization and surface roughness monitoring. Composite materials have various complicated characteristics depending on the ply materials,ply orientations,ply stacking sequences and boundary conditions. Therefore, it is difficult to analyze composite material. For efficient use of composit materials in engineering applications, the dynamic behavior such as, natural frequencies and modal patterns should be identified. This studying presents FEM results for the free vibration of symmetrically laminated composite as [30/-30/90] $_{s}$. The natural frequencies of laminated composite rectangular plates having the boundary condition(:2-edge clamped) are experimentally obtained. In order to demonstrate the validity of the experiment,FEM analysis using ANSYS was performed and natural frequencies experimentally obtained is compared with calculated by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.t.

• Structural Monitoring and Maintenance
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• v.5 no.2
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• pp.189-204
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• 2018

This paper examines the seismic responses of a reinforced concrete (RC) frame core-tube building with pre-pressed spring self-centering energy dissipation (PS-SCED) braces. The PS-SCED brace system consists of friction devices for energy dissipation, pre-pressed combination disc springs for self-centering and tube members as guiding elements. A constitutive model of self-centering flag-shaped hysteresis for PS-SCED brace is developed to better simulate the seismic responses of the RC frame core-tube building with PS-SCED braces, which is also verified by the tests of two braces under low cyclic reversed loading. Results indicate that the self-centering and energy dissipation capabilities are well predicted by the proposed constitutive model of the PS-SCED brace. The structure with PS-SCED braces presents similar peak story drift ratio, smaller peak acceleration, smaller base shear force and much smaller residual deformations as compared to the RC frame core-tube building with bucking-restrained braces (BRBs).