• Journal of the Korean Society of Safety
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• v.34 no.3
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• pp.8-14
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• 2019

Many electrical socket-outlet fire accidents take place not only in homes but in the offices each year. The causes are mostly faulty constructions, managerial problems and carelessness. Construction and managerial flaws can be resolved by regular or special inspections, but carelessness is not solvable through inspections. Such carelessness can be related to the consumption capacity of electrical socket-outlets presently, the rated current of electrical socket-outlets is based on 16A. However, even at 16A, the heat generated in the insulator of an electrical socket-outlet varies due to such factors as part damage and environmental conditions of use. To explore this situation, the study conducted an experiment to analyze thermal relationship by applying 10A, 20A, and 30A currents. To secure reliability, the study employed thermal analysis simulation and compared the thermal relationship in the same current value. The experimental and simulation values were found to be similar and therefore, diverse current values were replaced with the simulation. At 30A, the temperature was found to rise to at least $169.9^{\circ}C$ which had worked as a sufficient amount of energy to bring the insulation aging of insulator.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.88-93
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• 2003

The Process Safety Management (PSM) by the Law of Industry, Safety and Health has been performed for preventing major accidents of chemical plants since 1996. In terms of preventing chemical accidents more precisely, it is essential to develop a tool for quantitative risk assessment. For this, KOSHA (Korea Occupational Safety and Health Agency) developed an Integrated Risk Management System (IRMS). The system is designed to assimilate data on chemical plant hazards from external database, to integrate these data with location information(topographic and demographic), and to make them user-friendly accessible. The system consists of several main functions: display of five major Korean petrochemical complex layout display of equipment layout with its information utilizing the external database, zonation of the hazard effected area with consequence analyses, the most probable accident scenario generation, accident/incident database and calculation of frequency of accident using equipment reliability database, etc. The highlight of IRMS is to provide the risk contours using GIS(Geographical Information System) technology. IRMS is intended to manage hazardous installation more systematically and effectively, to reduce the number of accident remarkably, further minimizing production loss in the plant. The system is now under application to about 500 PSM sites as well as and emergency authorities in Korea by KOSHA (Korea Occupational Safety and Health Agency)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2267-2273
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• 2009

In this paper, in order to monitor and manage an electrical risk factor like as leakage current, load current, and arc-fault, a real time monitoring and management system being operated in the ubiquitous environment was developed, and a plan of construction of an electrical safety grid using the system was proposed. For confirmation of usefulness and reliability of the proposed safety system and grid, the developed intelligent panels were applied to 28 Korean traditional houses in Jeonjoo city, and the grid including the panels was operated. If the proposed National Electrical Safety Grid is completely constructed in the houses of general electrical users, the Grid will have an effect on that a main manager on electrical safety transfers from management system by general people to real-time management system by expert. As a result, the electrical fires caused by an over-load, an arc-fault, and an earth-fault will be prevented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.199-206
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• 2019

Recently, an expansion of safety facilities has been widely applied to effectively manage the safety of train operation due to increase of the high-speed section of the general railway and the introduction of high-speed train. Accordingly, performance improvement, upgrading and high reliability of existing safety devices are required. the dragging detector, one of the safety devices, is an analogue system that consists of closed circuit with an electric current flows and operates when the closed circuit is opened by the impact of the dragging object. Such method has unreasonable problem that should be replaced after being detected. It is need to replace with an automatic return type dragging detector which is easy to maintain. In addition, it is necessary to develop a dragging detector that applicable to general railway and urban railway including high-speed railway, in accordance with the speeding up and densification of trains, although it is currently applied only to high-speed railway. In this paper, we propose an automatic return type dragging detector which has versatility and excellent maintainability with digital sensor and real time monitoring.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.120-125
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• 2015

This research aims to increase the reliability and reproducibility of the ambient cycling test by properly making corrections to the test procedure. The vessel (106 L) is initially filled with 70 L of water and horizontally placed on a balance. The pressure range inside the vessel varies from 2.5 to 25.9 MPa at the frequency of 6 cycles per minute. After reviewing the results, there was a temperature difference of approximately $10^{\circ}C$ between the air pocket and the water, and the upper part of the liner faced a repeated temperature change of $40^{\circ}C$. It is possible for the aluminum liner of the composite vessel to be damaged by such a sharp change in temperature. Additionally, as a result, no pass having anything to do with the purpose of the test would occur. Therefore, it is suggested that the air pocket be completely removed.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.50-59
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• 2021

The need for risk based safety management has been highlighted in accordance with the growth of aviation industry and public interest in aviation safety. Maintenance, Repair and Overhaul (MRO) in aviation industry is defined to guarantee the safety and reliability. Therefore, state's Civil Airworthiness Authority (CAA) has established safety oversight system dedicated for the development of a healthy MRO industry. The study proposed a risk based oversight system considering Korean environment. Based on literature review including analysis of International Civil Aviation Organization guidance and advance system, we identified two organization risks. Organization complexity can be evaluated in accordance with how large the organization is and how complicated the service they provide are. Organization profile is the organization's characteristic related with safety. This study contributes to improving the process of identifying risk of organization and focusing surveillance capabilities on risk areas for efficient management of CAA's resources.

• International Journal of Safety
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• v.11 no.2
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• pp.10-14
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• 2012

Recently, the combined power plants are refocused rapidly as a replaceable energy system of the nuclear power plant. The large turbine is revolved highly at 1800~3600 rpm. Thus, the turbine speed should be monitored with mechanical and electrical method for a safety. The electrical cutoff valve which blocks the flow channel with the electrical signal is with a built in. The aim of this study is to develop a manufacturing technology through by the localization of a solenoid actuated directional control valve. Especially the results show performances of the solenoid valve by the experiments and modeling and the reliability estimation. Applied load port pressure was changed rapidly on the form of a quadratic curve over time. And in the cases of square waveform when 0~100 V and 20~120 V input voltage, it was driven on a stable state until 13.4 Hz and 16.6 Hz, respectively. We think that this study will give useful data for the electricity safety system of the combined power plant gas turbine.

• Journal of Radiation Protection and Research
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• v.29 no.1
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• pp.41-48
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• 2004

A safety assessment code, called SAGE (Safety Assessment Groundwater Evaluation), has been developed to describe post-closure radionuclide releases and potential radiological doses for low- and intermediate-level radioactive waste (LILW) disposal in an engineered vault facility in Korea. The conceptual model implemented in the code is focused on the release of radionuclide from a gradually degrading engineered barrier system to an underlying unsaturated zone, thence to a saturated groundwater zone. The radionuclide transport equations are solved by spatially discretizing the disposal system into a series of compartments. Mass transfer between compartments is by diffusion/dispersion and advection. In all compartments, radionuclides ate decayed either as a single-member chain or as multi-member chains. The biosphere is represented as a set of steady-state, radionuclide-specific pathway dose conversion factors that are multiplied by the appropriate release rate from the far field for each pathway. The code has the capability to treat input parameters either deterministically or probabilistically. Parameter input is achieved through a user-friendly Graphical User Interface. An application is presented, which is compared against safety assessment results from the other computer codes, to benchmark the reliability of system-level conceptual modeling of the code.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.513-519
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• 2006

As a very important part in development of the protocol, verifications for developed protocol specification are complementary techniques that are used to increase the level of confidence in the system functions by their specifications. Using the informal method for specifying the protocol, some ambiguity may be contained therein. This indwelling ambiguity in control systems can cause the occurrence of accidents, especially in the case of safety-critical systems. To clear the vagueness contained in the designed protocol, we use the LTS (Labeled Transition System) model to design the protocol for railway signaling. And then, we verify the safety and the liveness properties formally through the model checking method. The modal ${\mu}$-calculus, which is an expressive method of temporal logic, has been applied to the model checking method. We verify the safety and liveness properties of Korean standard protocol for railway signaling systems. To perform automatic verification of the safety and liveness properties of the designed protocol, a communication verification tool is implemented. The developed tools are implemented by C++ language under Windows XP. It is expected to increase the safety and reliability of communication protocol for signaling systems by using the developed communication verification tool.

• Journal of the Korean Society of Safety
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• v.33 no.6
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• pp.50-57
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• 2018

The purpose of this study is to evaluate the practical application of the self consolidating concrete for the steel concrete pannel (SCP) in module LNG storage tank proposed in the previous research. We evaluated the physical properties and filling performance of developed concrete for the SCP module. First, a slump flow test was conducted to evaluate the performance of the proposed guidelines for the filling test. As a result, all of the concrete used showed satisfactory performance. Based on the results of the previous study, it was found that the reliability of the required time measured by the $T_{500}$ test and the rheometer results measured before and after pumping was 0.94 which means the separation and blocking should not occur. The L-box test and the U-box test were conducted before and after pumping. All of the guidelines suggested showed satisfactory performance. SCP module for LNG storage tanks was fabricated on actual size scale to evaluate the practical application at the final site. As a result, it was confirmed that satisfactory filling performance was obtained in all the specimens.