• Journal of the Korea Institute of Construction Safety
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• v.3 no.1
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• pp.18-24
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• 2020

The purpose of this study is to propose a system improvement plan to prevent ground sinking accidents. To do this, follow the procedure below. First, it defines terms that are used interchangeably, such as ground subsidence and ground depression. Second, analysis of the current status and cause of ground sink, and the analysis of the correlation between rainfall and ground sink causes, derives priority management causes. Third, we propose a system improvement plan for the cause of priority management. As a result, damage to underground pipes and inadequate underground works were identified as the cause of priority management, and two system improvement plans to manage them were proposed. The results of this study can be used as basic data for improving the system for more effective prevention of underground sink in the future.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.104-109
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• 2017

As the ground subsidence occurred at the center of Seoul area in 2014, the ground subsidence phenomenon was emerged as a social issue in Korea. Even so far, national and local governments and related experts have been making a lot of efforts to prevent ground subsidence phenomenon, but it is still happening all over the country. In this study, we chose 9 influence factors on which ground subsidence and derived weights using AHP(Analytic Hierarchy Process) method for ground subsidence risk analysis. And we analyze the risk of subsidence in ${\bigcirc}{\bigcirc}$city using GIS(Geographic Information System) analysis method and evaluate the potential risk.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.8
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• pp.718-727
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• 2016

Korean ground systems have started to be developed for mission control and payload data processing since 1990s. International technology cooperations were needed in the early development phase of ground system for science experiment satellite, LEO satellite and GEO satellite and then they have been developed as domestic own technology since acquiring early technology. Our country has developed total 14 ground systems until now, this paper suggests prospect and direction on ground system development in the base of such development experiences. Mission control system is needed to develop multi-satellite mission control system in the base of technology of re-configure, re-use and automation. Processing system is needed to acquire processing technology for kinds of payload sensor data and study inter-operation to integrate and use outputs which are processed between users. Finally, national ground system infrastructure is needed to operate kinds of lots of satellites at worldwide area.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.270-281
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• 2005

An especial attention for old tunnel safety is required on increasing of The various tunnel recently. Specially, the lining investigation method of the old tunnel will be able to presume condition of concrete lining indirectly. Because it is many restriction thought of environment and ground condition investigation method of tunnel lining rear. This study carried out section & convergence measurement of part which was deformed in tunnel lining. It had been observed for the change of tunnel behavior with a continuous measurement. It has been analyzed for a cause of tunnel deformation and inspected for the effect after a repair-reinforcement to tunnel compared with the effect before those by structure analysis. By establishing automatic measurement system after repair-reinforcement to tunnel, it would be accomplished to convergence measurement continually. As a result, it was observed that deflection and deformation of tunnel was convergent. but it should be followed to a continuous maintenance because of unstable ground condition, cause of inner tunnel, environment. The railroad tunnel which was executed a reinforcement of the tunnel lining must investigate the close condition of reinforcement lining and concrete lining.

• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.389-396
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• 2007

The Global Navigation Satellite System (GNSS) becomes more important and is applied to various systems. Recently, the Galileo navigation system is being developed in Europe. Also, other countries like China, Japan and India are developing the global/regional navigation satellite system. As various global/regional navigation satellite systems are used, the navigation ground system gets more important for using the navigation system reasonably and efficiently. According to this trend, the technology of GNSS Ground Station (GGS) is developing in many fields. The one of purposes for this study is to develop the high precision receiver for GNSS sensor station and to provide ground infrastructure for better performance services on navigation system. In this study, we consider the configuration of GNSS Ground Station and analyze function of Monitoring and Control subsystem which is a part of GNSS Ground Station. We propose Monitoring and Control subsystem which contains the navigation software for GNSS Ground System to monitor and control equipments in GNSS Ground Station, to spread the applied field of navigation system, and to provide improved navigation information to user.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.432-439
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• 2009

This research project was carried out to develop the technique to assess quantitatively and rapidly the stability of a tunnel by using the measured displacement at the tunnel construction site under excavation. To achieve this purpose, a critical strain concept was introduced and applied to an assessment of a tunnel under construction. The new technique calculates numerically the strains of the surrounding ground by using the measured displacements during excavation. A numerical practical system was developed based on the proposed analysis technique in this study. The feasibility of the developed analysis module was verified by incorporating the analysis results obtained by commercial programs into the developed analysis module. To verify the feasibility of the developed analysis module, analysis results of models both elastic and elasto-plastic grounds were investigated for the circular tunnel design. Then the measured displacements obtained in the field are utilized practically to assess the safety of tunnels using critical strain concept. It was verified that stress conditions of in-situ ground and ground material properties were accurately assessed by inputting the calculated displacement obtained by commercial program into this module for the elastic ground. However for the elasto-plastic ground, analysis module can reproduce the initial conditions more closely for the soft rock ground than for the weathered soil ground. The stability of tunnels evaluated with two types of strains, that is, the strains obtained by dividing the crown displacement into a tunnel size and the strains obtained by using the analysis module. From this study, it is confirmed that the critical strain concept can be fully adopted within the engineering judgment in practical tunnel problems and the developed module can be used as a reasonable tool for the assessment of the tunnel stability in the field.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.800-806
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• 2012

This paper proposes design and development of the Integrated Ground Support System (IGSS) for the flight test of the Unmanned Aerial Vehicle (UAV), which combines ground support and ground control. The integrated flight test of the UAV is a necessary procedure to validate the functionality of the Unmanned Aerial System (UAS). In order to execute cost-effective and systematic flight tests, the IGSS is regarded as an inevitable infrastructure of UAS for small laboratories. The proposed IGSS has functions of ground control, radio communication, power generation, transportation and the maintenance of the UAV.

• Earthquakes and Structures
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• v.7 no.6
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• pp.1283-1301
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• 2014

Ground motion modification is extensively used in seismic design of civil infrastructure, especially where few or no recorded ground motions representative of the design scenario are available. A site in Los Angeles, California is used as a study site and 28 ground motions consistent with the design earthquake scenario are selected. The suite of 28 ground motions is scaled and modified in the time domain (TD) and frequency domain (FD) before being used as input to a bilinear SDOF system. The median structural responses to the suites of scaled, TD-modified, and FD-modified motions, along with ratios of he modified-to-scaled responses, are investigated for SDOF systems with different periods, strength ratios, and post-yield stiffness ratios. Overall, little difference (less than 20%) is observed in the peak structural accelerations, velocities, and displacements; displacement ductility; and absolute accelerations caused by the TD-modified and FD-modified motions when compared to the responses caused by the scaled motions. The energy absorbed by the system when the modified motions are used as input is more than 20% greater than when scaled motions are used as input. The observed trends in the structural response are predominantly the result of changes in the ground motion characteristics caused by modification.

• 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.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.364-368
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• 2011

The super-speed tube train was introduced to increase the speed of ground transportation. It levitates magnetically and runs in a partial vacuum tube, which significantly reduces air resistance. However, strong magnetic force sufficient to propel the massive train can affect the infrastructure. The induced eddy current produces joule heat, and raises the inside temperature of the girder, which might lead to electrochemical corrosion on the girder, thereby weakening its durability. In this paper, the authors analyzed the magnetic flux and induced eddy current in the reinforced concrete girder by using three-dimensional FEM, particularly by varying the number of reinforcing steels of the upper flange of the girder to the condition of almost the same flexural strength and reinforcing steel amount.