• Journal of the Korean Society of Safety
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• v.37 no.2
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• pp.1-9
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• 2022

Most factories deal with toxic or flammable chemicals in their industrial processes. These hazardous substances pose a risk of leakage due to accidents, such as fire and explosion. In the event of chemical release, massive casualties and property damage can result; hence, quantitative risk prediction and assessment are necessary. Several methods are available for evaluating chemical dispersion in the atmosphere, and most analyses are considered neutral in dispersion models and under far-field wind condition. The foregoing assumption renders a model valid only after a considerable time has elapsed from the moment chemicals are released or dispersed from a source. Hence, an initial dispersion model is required to assess risk quantitatively and predict the extent of damage because the most dangerous locations are those near a leak source. In this study, the dispersion model for initial consequence analysis was developed with three-dimensional unsteady advective diffusion equation. In this expression, instantaneous leakage is assumed as a puff, and wind velocity is considered as a coordinate transform in the solution. To minimize the buoyant force, ethane is used as leaked fuel, and two different diffusion coefficients are introduced. The calculated concentration field with a molecular diffusion coefficient shows a moving circular iso-line in the horizontal plane. The maximum concentration decreases as time progresses and distance increases. In the case of using a coefficient for turbulent diffusion, the dispersion along the wind velocity direction is enhanced, and an elliptic iso-contour line is found. The result yielded by a widely used commercial program, ALOHA, was compared with the end point of the lower explosion limit. In the future, we plan to build a more accurate and general initial risk assessment model by considering the turbulence diffusion and buoyancy effect on dispersion.

• Journal of the Korean Institute of Gas
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• v.10 no.3 s.32
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• pp.48-53
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• 2006

In case of fire and explosion which resulted from LP gas release of LPG vessel retail store, the populated area such as apartment complex is supposed to be damaged either partially or totally. To estimate the damage of LP gas explosion, we conducted quantitative risk analysis procedure as has been recommended by AIChE/CCPS. For incident scenario selection, event tree analysis was proposed. TNT equivalent method, SAFER Trace v.8.0 and probit model were also used for consequence analysis. The various methods and analyses which were performed in this study are presented with the effect zones in the layout.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.745-754
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• 2012

The correlations between Large Early Release Frequency (LERF) and Early Fatality need to be investigated for risk-informed application and regulation. In Regulatory Guide (RG) -1.174, while there are decision-making criteria using the measures of Core Damage Frequency (CDF) and LERF, there are no specific criteria on LERF. Since there are both huge uncertainties and large costs needed in off-site consequence calculation, a LERF assessment methodology needs to be developed, and its correlation factor needs to be identified, for risk-informed decision-making. A new method for estimating off-site consequence has been presented and performed for assessing health effects caused by radioisotopes released from severe accidents of nuclear power plants in this study. The MACCS2 code is used for validating the source term quantitatively regarding health effects, depending on the release characteristics of radioisotopes during severe accidents. This study developed a method for identifying correlations between LERF and Early Fatality and validates the results of the model using the MACCS2 code. The results of this study may contribute to defining LERF and finding a measure for risk-informed regulations and risk-informed decision-making.

• Journal of the Korean Society of Safety
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• v.33 no.6
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• pp.102-114
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• 2018

The Railway Safety Management System is based on risk management and the basic purpose of risk management is safety management activities to prevent railway accidents and operational obstacles in advance. In order to manage risk, an acceptable risk standard must be established. This risk criterion is used to evaluate the railway risk with both frequency and severity. In the case of overseas railway or other industrial sectors, various factors are reflected in the main variables that constitute the occurrence frequency, but this is no the case in the domestic railway sector. In particular, the current risk assessment criteria in the railway sector remain at a level that exploits the incidents that have occurred in the past and the severity of the property damage and it dose not properly reflect complex and diverse environmental and situational changes in railway operations. Therefore, in this study, it is possible to calculate the potential occurrence of future events instead of occurrence frequency as a component of the risk assessment criteria, focusing on the High-Speed Railway. In addition to the property damage to the consequence, we suggest a rational methodology, development direction, and theoretical implications for constructing accurate and reasonable risk criteria including actual damage such as human injury and time loss.

• Structural Engineering and Mechanics
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• v.17 no.3_4
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• pp.527-537
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• 2004

Consequence-Based Engineering (CBE) is a new paradigm proposed by the Mid-America Earthquake Center (MAE) to guide evaluation and rehabilitation of building structures and networks in areas of low probability - high consequence earthquakes such as the central region of the U.S. The principal objective of CBE is to minimize consequences by prescribing appropriate intervention procedures for a broad range of structures and systems, in consultation with key decision makers. One possible intervention option for rehabilitating unreinforced masonry (URM) buildings, widely used for essential facilities in Mid-America, is passive energy dissipation (PED). After the CBE process is described, its application in the rehabilitation of vulnerable URM building construction in Mid-America is illustrated through the use of PED devices attached to flexible timber floor diaphragms. It is shown that PED's can be applied to URM buildings in situations where floor diaphragm flexibility can be controlled to reduce both out-of-plane and in-plane wall responses and damage. Reductions as high as 48% in roof displacement and acceleration can be achieved as demonstrated in studies reported below.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.42-49
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• 2011

To achieve the safety management of an industry by using practical consequence analysis, parameters affecting damage area and financial loss by gas release accident were analyzed at pressure vessels containing flammable gas. As a result, the total financial loss cost was largely effected by the business interruption cost, and it was considered for equipment type and materials, process properties, and circumstances. Also, the consequences of the financial loss must be practically used more than the consequences of the damage area in industry.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.4
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• pp.339-344
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• 2004

The purpose of this study was to evaluate neurosensory disturbance associated with implant surgery performed by implant practitioner (n=47) composed of trained oral surgeon, periodontist, prosthodontist. The incidence, type and duration of sensory disorder were investigated. Anatomical factor of the patient and experience of operator were also evaluated. The result revealed high incidence of inferior alveolar nerve damage (45%) regardless of experience of implant practitioner. The sensory disturbance sustained within 6 months for 61% of cases, which revealed almost normal recovery of nerve function. Initial neurologic sign after nerve damage was not coincide with their consequence of recovery. Half of the practitioners tried surgical intervention to the implants such as removing the fixture, partial unscrewing or re-implant shorter fixture, of which trial regarded as effective measure for 53% of cases. The result indicates that the objective method of sensory nerve evaluation should be introduced to the implant practitioners and the importance of informed consent for possibility of nerve damage in mandibular implant fixation.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.403-413
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• 2017

Residual axial capacity from numerical analysis was widely used as a critical indicator for damage assessment of reinforced concrete (RC) columns subjected to blast loads. However, the convergence of the numerical result was generally based on the displacement response, which might not necessarily generate the correct post-blast results in case that the strain softening behavior of concrete was considered. In this paper, two widely used concrete models are adopted for post-blast analysis of a RC column under blast loading, while the calculated results show a pathological mesh size dependence even though the displacement response is converged. As a consequence, a nonlocal integral formulation is implemented in a concrete damage model to ensure mesh size independent objectivity of the local and global responses. Two numerical examples, one to a RC column with strain softening response and the other one to a RC column with post-blast response, are conducted by the nonlocal damage model, and the results indicate that both the two cases obtain objective response in the post-peak stage.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.204-208
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• 2008

Casualties Damage from Smoke is very serious consequence. Especially, Damage from smoke in in the Subway Station is the terrible result. Smoke from the fire in the Subway Station that evacuation route on the path and the sight of refugees caused by serious traffic problems. Accordingly, A study on Smoke barriers of smoke systems take into considerations relate to effects depending on wind velocity speed of the piston effect come into the retarding effect of smoke control in smoke barriers. As a result of modeling, According to increasing of Velocity in the platform which installed smoke barriers were been on the increase spreading quantity of smoke in the right direction of upstairs however, In contrast spreading quantity of smoke in the left direction on the upstairs were been on the decrease.

• Journal of the Korean Society of Safety
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• v.8 no.2
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• pp.58-63
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• 1993

Recently, a large amount of flammable or explosive materials have been handled or stored in chemical industries. H the equipments fail or the materials release in consequence of operation errors, fire and explosion could occur to them. Thus, risk assessment using quantification of risks is very important when design of processes and modifications of installed processes are performed. The purpose of this study is to develop the program for fire and explosion index in order to quantify the expected damage of fire and explosion incidents in chemical plants, to identify equipment that would be likely to contribute to the creation or escalation of an incident, to comunicate the potential fire and explosion risk to management and to account of damage cost.