• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.26-33
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• 2004

This study presents a hazard assessment of the human body exposed to electic shock considering various parameters which affect severity of the electric shock. The present study has two research objectives; one is no analyze hazards of the human body by the elctric shock both on the ground and in the water. The other is to understand the mechnism of the electric shock. In order to achieve these objectives the hazard of shock is estimated by comparing with physiological effects of electric curren througn the human body according to variation of shock parameters of shock circuits. The shock parameters adopted in this paper consist of body resistance, resistance of protective equipment, ground resistance, shock duration, depth of gound surface layer, relection factor, permissible touch voltage, body current and body voltage. Besides, safety standard determining hazard degree of the human body is introduced. And hazard of the human body due to the electric shock is quantitatibely assessed in consideration of data obtained by the method suggested herein, and final results are presented and discussed.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.571-576
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• 2010

In this study, an application method of critical strains concept for tunnels' safety by using the values of measured displacements which are obtained in the field is discussed. The aim is to: (1) study on the engineering meanings of critical strains concept by reviewing the previous researches and application examples with measured displacement values; (2) study on the engineering reasonability of critical strains concept with the view point of a tunnel engineering and a geotechnical engineering; (3) study on the features of ground deformation due to tunneling and reciprocal relation between total displacement and measured displacement; (4) evaluate a tunnel safety by using domestic measurements collected in the field; and (5) re-evaluate the control criteria which were previously used in the field, with the view point of critical strains concept. Consequently, it was confirmed that critical strains in the ground has a reasonability and a possibility of unified or common concept with the view point of a tunnel engineering.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.6
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• pp.233-240
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• 2021

The stochastic method is applied to simulate strong ground motions at seismic stations of seven metropolises in South Korea, creating an earthquake scenario based on the causative fault of the 2016 Gyeongju earthquake. Input parameters are established according to what has been revealed so far for the causative fault of the Gyeongju earthquake, while the ratio of differences in response spectra between observed and simulated strong ground motions is assumed to be an adjustment factor. The calculations confirm the applicability and reproducibility of strong ground motion simulations based on the relatively small bias in response spectra between observed and simulated strong ground motions. Based on this result, strong ground motions by a scenario earthquake on the causative fault of the Gyeongju earthquake with moment magnitude 6.5 are simulated, assuming that the ratios of its fault length to width are 2:1, 3:1, and 4:1. The results are similar to those of the empirical Green's function method. Although actual site response factors of seismic stations should be supplemented later, the simulated strong ground motions can be used as input data for developing ground motion prediction equations and input data for calculating the design response spectra of major facilities in South Korea.

• Structural Engineering and Mechanics
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• v.81 no.2
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• pp.219-230
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• 2022

Due to the large number of railway bridges along China's high-speed railway (HSR) lines, which cover a wide area with many lines crossing the seismic zone, the possibility of a HSR train running over a bridge when an earthquake occurs is relatively high. Since the safety performance of the train will be threatened, it is necessary to study the safety of trains running over HSR bridges during earthquakes. However, ground motion (GM) is highly random and selecting the appropriate ground-motion intensity measures (IMs) for train running safety analysis is not trivial. To deal this problem, a model of a coupled train-bridge system under seismic excitation was established and 104 GM samples were selected to evaluate the correlation between 16 different IMs and train running safety over HSR bridges during earthquakes. The results show that spectral velocity (SvT₁) and displacement (SdT₁) at the fundamental period of the structure have good correlation with train running safety for medium-and long-period HSR bridges, and velocity spectrum intensity (VSI) and Housner intensity (HI) have good correlation for a wide range of structural periods. Overall, VSI and HI are the optimal IMs for safety analysis of trains running over HSR bridges during earthquakes. Finally, based on VSI and HI, the IM thresholds of an HSR bridge at different speed were analyzed.

• Earthquakes and Structures
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• v.14 no.4
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• pp.349-360
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• 2018

Reinforced concrete (RC) moment frames supported on two ground levels have been widely constructed in mountainous areas with medium to high seismicity in China. In order to investigate the seismic collapse behavior and risk, a scaled frame model was tested under constant axial load and reversed cyclic lateral load. Test results show that the failure can be induced by the development of story yielding at the first story above the upper ground. The strong column and weak beam mechanism can be well realized at stories below the upper ground. Numerical analysis model was developed and calibrated with the test results. Three pairs of six case study buildings considering various structural configurations were designed and analyzed, showing similar dynamic characteristics between frames on two ground levels and flat ground of each pair. Incremental dynamic analyses (IDA) were then conducted to obtain the seismic collapse fragility curves and collapse margin ratios of nine analysis cases designated based on the case study buildings, considering amplification of earthquake effect and strengthening measures. Analysis results indicate that the seismic collapse safety is mainly determined by the stories above the upper ground. The most probable collapse mechanism may be induced by the story yielding of the bottom story on the upper ground level. The use of tie beam and column strengthening can effectively enhance the seismic collapse safety of frames on two ground levels.

• Explosives and Blasting
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• v.17 no.4
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• pp.67-88
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• 1999

Ground settlements induced by tunnel excavation cause the foundations of the neighboring superstructures to deform. An expert system called NESASS was developed to analyze the structural safety of such superstructures. NESASS predicts the trend of ground settlements to be resulted from tunnel excavation and carries out a safety analysis for superstructures on the basis of the predicted ground settlements. Using neural network techniques, NESASS learns a data base consisting of the measured ground settlements collected from numerous actual fields and infers a settlement trend at the field of interest. NESASS calculates the magnitudes of angular distortion, deflection ratio, and differential settlement of the structure and, in turn, determines the safety of the structure. In addition, NESASS predicts the patterns of cracks to be formed on the structure using Dulacskas model for crack evaluation. In this study, the ground settlements measured from the Seoul subway construction sites were collected and sorted with respect to the major factors influencing ground settlement. Subsequently, a database of ground settlement due to tunnel excavation was built. A parametric study was performed to verify the reliability of the proposed neural network structure. A comparison of the ground settlement trends predicted by NESASS with the measured ones indicates that NESASS leads to reasonable predictions. An examples is presented in this paper where NESASS is used to evaluate the safety of a structure subject to deformation due to tunnel excavation near to the structure.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.195-197
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• 2007

This paper presents experimental results on the safety of persons due to a ground fault in 22.9 kV-Y distribution system In order to evaluate the touch voltages due to internal ground faults in a step down transformer based on the newly prescribed KS C IEC 60364 standard series, the verification tests in a 22.9 kV multi-grounded neutral system were carried out From the experimental results, it was found that there will be significant potential rise jeopardizing LV equipment insulation in case of separate grounding between HV and LV system and the effective measures against hazardous touch voltages due to a IN side ground fault in the common grounding system between HV and LV system are proposed. As a consequence, it was found that the equipotential bonding is an important prerequisite for the effectiveness of the protective measures for the safety of persons in the common ground system between 22.9 kV-Y and low-voltage grounding system.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.229-236
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• 2022

In this study, a model experiment and field experiment was conducted to introduce the optimal tensile force when constructing a non-open cut tunnel according to the ground conditions of sandy soil. CMR (Concrete Modular Roof) method is economical because of the high precision and excellent durability, and corrosion resistance, and the inserted parts can be used as the main structure of a tunnel. In addition the CMR method has a stable advantage in interconnection because the concrete beam is press-fitted compared to the NTR (New Tubular Roof) method, and the need for quality control can be minimized. The ground conditions were corrected by adjusting the relative density of sandy soil during the construction of non-open cut tunnels, and after introducing various tensile forces, the surface settlement according to excavation was measured, and the optimal tensile force was derived. As a result of the experiment, the amount of settlement according to the relative density was found to be minor. Furthermore, analysis of each tensile force based on loose ground conditions resulted in an average decrease of approximately 22% in maximum settlement when the force was increased by 0.8 kN per segment. Considering these results, it is indicated that more than 2.0 kN tensile force per segment is recommended for settlement of the upper ground.

• Journal of Advanced Navigation Technology
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• v.19 no.1
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• pp.41-47
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• 2015

Recently, it is actively under study for the implementation of advance surface movement ground control systems (A-SMGCS) level IV in Korea. To ensure the safety of the A-SMGCS system needs the safety assessment, and Eurocontrol is encouraged to perform the functional hazard assessment, preliminary system safety assessment, and system safety assessment to the safety assessment of A-SMGCS. In this paper, we identify the hazard of A-SMGCS through a functional hazard assessment. Therefore, we will identify 29 types of hazard for the A-SMGCS level IV and serve as important data to evaluate the severity of each hazard.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.10
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• pp.54-59
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• 2015

In this paper, we evaluate safety of grounding system which is designed according to IEC standards. Safety assessment of construction site and grounding system of building is needed before construction for the safety of human in building. Until now, in case of domestic field, design of grounding system is proceeded based on methods which are proposed in IEEE Std. 80. In other words, it is not in the situation that grounding system is designed based on IEC standards. Therefore, we propose a method which designs grounding system and evaluates safety of it according to IEC standards. We measure ground resistance of construction site using measuring equipment of ground resistance. Using this value, soil structure and ground resistivity are obtained through program analysis. CDEGS program of SES company is used for simulation analysis.