• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.102-106
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• 2002

The Act on Safety Management of Social Assets was established on 1995 and revised on 1999 to relieve maintenance cost of managing offices. The provision for load bearing test before opening was deleted and the number of load bearing test after opening was reduced in the Revised Act on 1999. The effect of revision is the main concern in this study. 176 technical reports on load bearing test of long span bridges are analyzed. The results show that various structural defects are inherent in recent bridges constructed since 1995. So the preservation of provisions deleted in original act is needed up to now.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.131-140
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• 2003

An accident involving a boiler can result in a disaster since it handles high-pressurized steam so that it may cause an explosion. Therefore, the boiler is very susceptible to industrial accidents. This thesis aimed to develop counter-plans to prevent industrial accidents involved the boiler. At first after collecting accident cases involving boilers, a survey on the trait of them was carried out. Ant on the other hand a qualitative analysis was conducted to draw out hazardous components in the boiler itself and their inherent relative importance was assessed. Through this procedure, 'negligence of unsafe condition' was noted as the major cause for unsafe acts whereas 'fault in work procedure' for unsafe condition. In the meanwhile, results of a hazard analysis using FMEA technique ranked gas safety devices, a switch preventing gas from under-pressurization, protect relays high. In particular, it was pointed out that the water feeding and steam subsystem has more components in hazard than other subsystems. Considering these analyses results, counter-plans to improve safety management was suggested also.

• Nuclear Engineering and Technology
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• v.45 no.5
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• pp.573-580
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• 2013

The combined effects of reactivity coefficients, along with other core nuclear characteristics, determine reactor core behavior in normal operation and accident conditions. The Power Coefficient of Reactivity (PCR) is an aggregate indicator representing the change in reactor core reactivity per unit change in reactor power. It is an integral quantity which captures the contributions of the fuel temperature, coolant void, and coolant temperature reactivity feedbacks. All nuclear reactor designs provide a balance between their inherent nuclear characteristics and the engineered reactivity control features, to ensure that changes in reactivity under all operating conditions are maintained within a safe range. The $CANDU^{(R)}$ reactor design takes advantage of its inherent nuclear characteristics, namely a small magnitude of reactivity coefficients, minimal excess reactivity, and very long prompt neutron lifetime, to mitigate the demand on the engineered systems for controlling reactivity and responding to accidents. In particular, CANDU reactors have always taken advantage of the small value of the PCR associated with their design characteristics, such that the overall design and safety characteristics of the reactor are not sensitive to the value of the PCR. For other reactor design concepts a PCR which is both large and negative is an important aspect in the design of their engineered systems for controlling reactivity. It will be demonstrated that during Loss of Regulation Control (LORC) and Large Break Loss of Coolant Accident (LBLOCA) events, the impact of variations in power coefficient, including a hypothesized larger than estimated PCR, has no safety-significance for CANDU reactor design. Since the CANDU 6 PCR is small, variations in the range of values for PCR on the performance or safety of the reactor are not significant.

• Journal of IKEEE
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• v.16 no.2
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• pp.145-152
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• 2012

This paper is the Software Hazard Analysis (SWHA) which will study the managerial process and the technical methode and techniques inherent in the performance of software safety task within the Military Aircraft System Safety program. This SWHA identifies potential hazardous effects on the software intensive systems and provides a comprehensive and qualitative assessment of the software safety. The purpose of this paper is to identify safety critical functions of software in Military A/C. The identified software hazards associated with the design or function will be evaluated for risks and operational constraint to further improve the software design requirement, analysis and testing efforts for safety critical software. This common SWHA, the first time analysis in KOREA, was review all avionics OFP(Operational Flight Program), and focus only on software segments which are safety critical. This paper provides a important understanding between the customer and developer as to how the software safety for the Military A/C will be accomplished. It will also provide the current best solution which may as one consider the necessary step in establishing a credible and cost-effective software safety program.

• Fire Science and Engineering
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• v.24 no.3
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• pp.45-51
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• 2010

The objective of this study to analyse the cause and pattern of failing to use in Self Contained Breathing Apparatus using by government regulation for producer and client. Regulation for producer is related to legal and institution of safety inspectiontest of SCBA. Rregulation for client is preventive maintenance. Improving fail in use of SCBA are following. First, expansion of ad hoc collection inspection and safety checking is required. Second, the strict application of the law for monitoring and auditing disposal procedure in low performance SCBA is required.

• Proceedings of the KIEE Conference
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• 2007.04b
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• pp.91-94
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• 2007

The increased use of underground power distribution as opposed to overhead lines contributes to the aesthetics of the downtown areas. But there is an inherent risk of accidental electrocution should there be damage to the insulation of the cable because of heavy rain. Should a pedestrian make contact with this cable indirectly, via a man hole cover, electrocution could result. In this paper, we analyse electrical shock accident and checking results in this low-voltage handhole.

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.75-80
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• 1996

This paper presents a study on characteristics and safety for human body in ELF electric and magnetic fields using statistical method. The magnetic fields from a power line can be computed given a knowledge of the currents, voltage and geometry of the line. In this paper, a statistical method for predicting the magnetic fields given the inherent indetermination of the currents is presented. But the electric field is calculated given a knowledge of the voltage and geometry of the line. The effect of unexpected fluctuations in current is modeled by the Monte Carlo simulation. The suggested method is applied to the 345kV and 765kV transmission line system, the result shows that the maximum electric and magnetic field intensity is 6.8627kV/m and 284mG in 345kV system, 2. 5590kV/m and 35mG in 765kV system, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.241-247
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• 2011

Marine casualties of vessel are said to be in most case caused by human error, but it would be valid for the assumption that the ship is built with high quality and then should be acceptable to the safety standards. It means that the inherent characteristics of a ship should be the first consideration on the safety of ship. Therefore it is basically necessary for navigator to grasp the inherent stability of his ship and ensure that the ship complies with the minimum statutory standards of stability. This study is to realize the stability of the Korean offshore large purseiner varying with loading conditions by the inclining data and some calculations. The author compared the stability of the ship with IMO criteria and domestic rule, and proposed some improvement for the safety of the ship. The results are summarized as follows ; The values of GM of the ship according to the loading condition in navigation satisfy both of the IMO criteria and the domestic rule, but in case of the area under the GZ curves between the heel angles of $30^{\circ}$ and $40^{\circ}$, and the heel angle occuring the maximum righting lever not satisfy the IMO rule at the fishing ground departure and arrival conditions in the haul in net situation. The initial metacentric height of the ship is very large, but the range of stability and the occurring angle of the maximum GZ are very small, so even small inclining can bring about the beam end. The best method of improvement for that is to increase the freeboard of the model among the variables.

• Nuclear Engineering and Technology
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• v.39 no.4
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• pp.257-272
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• 2007

Supercritical water-cooled reactors (SCWRs) are recognized as a Generation IV reactor concept. The Super LWR is a pressure-vessel type thermal spectrum SCWR with downward-flow water rods and is currently under study at the University of Tokyo. This paper reviews Super LWR safety. The fundamental requirement for the Super LWR, which has a once-through coolant cycle, is the core coolant flow rate rather than the coolant inventory. Key safety characteristics of the Super LWR inhere in the design features and have been identified through a series of safety analyses. Although loss-of-flow is the most important abnormality, fuel rod heat-up is mitigated by the "heat sink" and "water source" effects of the water rods. Response of the reactor power against pressurization events is mild due to a small change in the average coolant density and flow stagnation of the once-through coolant cycle. These mild responses against transients and also reactivity feedbacks provide good inherent safety against anticipated-transient-without-scram (ATWS) events without alternative actions. Initiation of an automatic depressurization system provides effective heat removal from the fuel rods. An "in-vessel accumulator" effect of the reactor vessel top dome enhances the fuel rod cooling. This effect enlarges the safety margin for large LOCA.

• Safety and Health at Work
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• v.12 no.3
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• pp.416-420
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• 2021

Hazardous area classification design is required to reduce the explosion risk in process plants. Among the international design guidelines, only IEC 60079-10-1 proposes a new type of zone, namely zone 2 NE, to prevent explosion hazards. We studied how to meet the zone 2 NE grade for a facility handling hydrogen gas, which is considered as most dangerous among explosive gases. Zone 2 NE can be achieved considering the grade of release, as well as the availability and effectiveness of ventilation, which are factors indicative of the facility condition and its surroundings. In the present study, we demonstrate that zone 2 NE can be achieved when the degree of ventilation is high by accessing temperature, pressure, and size of leak hole. The release characteristic can be derived by substituting the process condition of the hydrogen gas facility. The equations are summarized considering relation of the operating temperature, operating pressure, and size of leak hole. Through this relationship, the non-hazardous condition can be realized from the perspective of inherent safety by the combination of each parameter before the initial design of the hydrogen gas facility.