• Journal of the Korea Society for Simulation
• /
• v.26 no.3
• /
• pp.1-11
• /
• 2017

Blast injuries in a compartment are investigated, and the effects of obstacles on blast injury are particularly analyzed by comparing injuries in the compartments with or without protruding obstacles inside. Even if blast pressure profile tends to be complicated in a confined space unlike in open field, it can be obtained in a relatively short time by using some empirical fast running models for simple confined spaces. However, a finite element method should be employed to obtain blast pressure profiles in a case with obstacles in confined spaces, because the obstacles heavily disturb blast waves. On the other hand, Axelsson SDOF(Single degree of freedom) model and ASII(Adjusted severity of injury index) injury level are employed to estimate blast injury in compartments, because the usual pressure-impulse injury criterion based on the ideal Friedlander waves in open the field cannot be applied to personnel in a confined space due to complexity of blast waves inside. In cases with obstacles, chest wall velocity was reduced by 26 to 76 percent(%) and the personnel injury in the compartment caused by blast was also reduced.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.6
• /
• pp.355-362
• /
• 2021

Various blast pressure calculation methods have been developed for predicting the explosion pressure of vapor cloud explosions. Empirical methods include the TNT equivalent method, and multi-energy method. The multi-energy method uses a charge strength that considers environmental factors. Although the Kinsella guideline was provided to determine the charge strength, there are limitations such as guidelines related to ignition sources. In this study, we proposed an improved charge strength guideline, by subdividing the ignition source intensity and expanding the type classification through literature analysis. To verify the improved charge strength guideline, and to compare it with the result obtained using the Kinsella guideline, four vapor cloud explosion cases which could be used to estimate the actual blast pressure were investigated. As a result, it was confirmed that the Kinsella guidelines showed an inaccurate, that is, wider pressure than the actual estimated blast pressure. However, the improved charge strength guideline enabled the selection of the intensity of the ignition source, and more subdivided types through the expansion of classification, hence it was possible to calculate the blast pressure relatively close to that of the actual case.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.1
• /
• pp.1-8
• /
• 2021

Vapor cloud explosions show different characteristics from that caused by ordinary TNT explosives and their loading effect is similar to pressure waves. Typical methods used for blast pressure calculations are the TNT-equivalent method and multi-energy method. The TNT-equivalent method is based on shock waves, similar to a detonation phenomenon, and multi-energy method is based on pressure waves, similar to a deflagration phenomenon. This study was conducted to derive an appropriate blast pressure by applying various plant explosion cases. SDOF analysis and nonlinear dynamic analysis were performed to compare the degree of deformation and damage of the selected structural members for the explosion cases. The results indicated that the multi-energy method was more exact than the TNT-equivalent method in predicting the blast pressure of vapor cloud explosions. The blast pressure of vapor cloud explosion in plants can be more accurately calculated by assuming the charge strength of multi-energy method as 7 or 8.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.6
• /
• pp.551-555
• /
• 2014

In this paper, framework of weapon effects calculator for hardened targets is presented. Fast running time, validation and easy expandibility are required for weaponeering tools, and these requirements were met by using of physics-based fast-running models or semi-empirical equations for damage prediction and penetrations, and modular architecture. Key concepts and outputs, required functions and corresponding use cases were presented.

• Korea and Global Affairs
• /
• v.1 no.2
• /
• pp.33-84
• /
• 2017

This study deals with President Park Chung-hee's greed for dominance and oppression during the Yushin Regime in the 1970's and consists of case studies related to anti-democracy of the National Council for Unification Subject, illegality of President's emergency rule and oppression in the process of putting down Buma Uprising. The National Council for Unification Subject was an organization for presidential selection and institutionalized by the enactment of Yushin constitution. Emergency rule was carried into effect as a means to repressing college students and forces out of office for the president's long-term seizure of power. And Buma Uprising rose against violence in resistance to the Yushin regime and president Park Chung-hee's greed for dominance and oppression. These case analyses applied the aspects of causal relationship(birth and fall of Yushin Regime), legal system(Yushin constitution and president's emergency rule) and behavior(President Park's greed for dominance and oppression) for this study. The National Council for Unification Subject institutionalized through Yushin constitution and the Yushin regime formed by emergency rule enabled President Park to cling to long-term seizure of power by means of greed for dominance and oppression. After all, his failure to keep the spirit of the time and stepping stone for democratic constitutional government triggered Buma Uprising, a kind of anti-Establishment movement, and caused the fall of the Yushin regime.

• Journal of the Korean Institute of Gas
• /
• v.27 no.4
• /
• pp.56-61
• /
• 2023

The plant is an important facility as a infrastructure, and ensuring safety against possible accidents such as gas leaks and explosions must be considered in the design. However, there is little study on explosion pressure in plants for reasons such as economic feasibility, and overpressure data on this field is insufficient. In this study, an experimental design plan considering the explosion scenario that may occur in the plant was presented, and the explosion pressure was confirmed through an explosion experiment. Hydrogen-methane mixed gas was used as a combustible material, and the effect of confinement and congestion on overpressure was studied. The effect of overlapping pressure waves during deflagration and the turbulence effect by congested pipes are discussed. The results of this study can be used as input data in various safety designs.

• Computational Structural Engineering
• /
• v.25 no.3
• /
• pp.28-31
• /
• 2012

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.544-548
• /
• 2007

In general, final width of hot strip should be accomplished in this stage because width reduction of strip hardly appears during typical finishing mill. However, it is difficult to control the width of strip in the roughing mill process as the horizontal rolling of strip is subsequently performed after the vertical rolling. It is therefore important to obtain the deformation rolling direction on strip width to minimize the width spread of strip during horizontal rolling after vertical rolling. Generally there is Sizing press type and Edger-roll type. The width reduction process in sizing press has small amount of width spread compared with the edger. However, productivity by the sizing press process is much lower than those of the edger. In this study, sizing press and Edger-roll process parameters in a sheet rolling mill were set at specified values and the effect of the change in these parameters on product quality and process performance were evaluated.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.4
• /
• pp.207-214
• /
• 2022

A prediction model is proposed for a blast load acting on a column component because of an external explosion. The model can predict the pressure-time histories acting on a column using the fitting curves established from a database composed of finite-element (FE) analysis results. To this end, 70 numerical simulations using the commercial software AUTODYN were performed by changing the column width. To confirm the performance of the proposed model, pressure-time histories estimated from an existing empirical formula and the proposed model were compared based on the FE analysis results. It was verified that the proposed model can more precisely predict the pressure-time histories compared with the existing model.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.33 no.5
• /
• pp.339-349
• /
• 2020

Double-leaf blast-resistant doors consisting of steel box and slab are application-specific structures installed at the entrances of protective facilities. In these structural systems, certain spacing is provided between the door and wall. However, variation in the boundary condition and structural behavior due to this spacing are not properly considered in the explosion analysis and design. In this study, the structural response and failure behavior based on two variables such as the spacing and blast pressure were analyzed using the finite element method. The results revealed that the two variables affected the overall structural behavior such as the maximum and permanent deflections. The degree of contact due to collision between the door and wall and the impact force applied to the door varied according to the spacing. Hence, the shear-failure behavior of the concrete slab was affected by this impact force. Doors with spacing of less than 10 mm were vulnerable to shear failure, and the case of approximately 15-mm spacing was more reasonable for increasing the flexural performance. For further study, tests and numerical research on the structural behavior are needed by considering other variables such as specifications of the structural members and details of the slab shear design.