• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.30-31
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• 2016

As the treatments of many kinds of explosive objects increase recently, it is in the trend that explosion accidents increase. Thus, many studies on HPFRCC (High-performance Fiber-reinforced Cement Composites) whose ductility is enhanced are being conducted actively in order to minimize the damages from explosion accidents. However, HPFRCC, the self-shrinkage of HPFRCC is on the rise as a problem since it becomes ultra-high strengthened by using low W/B. Thus, in this study, it is intended to evaluate the capacity for reducing the self-shrinkage of HPFRCC depending on some changes of ERCO(Emulsified Refined Cooking Oil) replacement ratio and the fiber replacement ratio between some short steel fibers (SS) and some long organic fibers (OL). As a result, it was found that some excellent effects are exerted since the self-shrinkage was reduced a lot as the ERCO replacement ratio increases and the fiber replacement ratio of SS rather than OL increases.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.481-483
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• 2015

Multi-dimensionality in the inner working of core-collapse supernovae has long been considered one of the most important ingredients to understand the explosion mechanism. We perform a series of numerical experiments to explore how rotation impacts the 3-dimensional hydrodynamics of core-collapse supernova. We employ a light-bulb scheme to trigger explosions and a three-species neutrino leakage scheme to treat deleptonization effects and neutrino losses from the neutron star interior. We find that the rotation can help the onset of neutrino-driven explosions for models in which the initial angular momentum is matched to that obtained from recent stellar evolutionary calculations (${\sim}0.3-3rad\;s^{-1}$ at the center). For models with larger initial angular momenta, a shock surface deforms to be oblate due to larger centrifugal force. This makes a gain region, in which matter gains energy from neutrinos, more concentrated around the equatorial plane. As a result, the preferred direction of the explosion in 3-dimensional rotating models is perpendicular to the spin axis, which is in sharp contrast to the polar explosions around the axis that are often obtained from 2-dimensional simulations.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.499-505
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• 2005

Underwater explosion shock response analysis of a nonlinear double resiliently mounted equipment on a MIL-S-901D Large floating Shock Platform(LFSP) was carried out using LS-DYNA3D/USA. As a nonlinear double resiliently mounted equipment, real main engine module of naval ship was considered, where the engine, bearing, and base frame including sound enclosure were treated as rigid bodies with six degrees of freedom. The nonlinear effects of resilient mounts on its shock response characteristics were examined, and the usefulness of our suggested method was also confirmed comparing with calculation results by the equipment maker.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1611-1614
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• 2010

The explosion of a nuclear weapon radiates a gamma-ray in the form of a transient pulse. If the gamma-ray introduces to semiconductor devices, much Electron-Hole Pairs(EHPs) are generated in depletion region of the devices[7]. as a consequence of that, high photocurrent is created and causes upset, latchup and burnout of semiconductor devices[8]. This phenomenon is known for Transient Radiation Effects on Electronics(TREE), also called dose-rate effects. In this paper 3D structure of inverter and NAND gate device was designed and transient pulse gamma-ray was modeled. So simulation for transient radiation effect on inverter and NAND gate was accomplished and mechanism for upset and latchup was analyzed.

• Explosives and Blasting
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• v.40 no.3
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• pp.19-32
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• 2022

Hydrogen is a fuel having the highest energy compared with other common fuels. This means hydrogen is a clean energy source for the future. However, using hydrogen as a fuel has implication regarding carrier and storage issues, as hydrogen is highly inflammable and unstable gas susceptible to explosion. Explosions resulting from hydrogen-air mixtures have already been encountered and well documented in research experiments. However, there are still large gaps in this research field as the use of numerical tools and field experiments are required to fully understand the safety measures necessary to prevent hydrogen explosions. The purpose of this present study is to develop and simulate 3D numerical modelling of an existing hydrogen gas station in Jeonju by using handheld LiDAR and Ansys AUTODYN, as well as the processing of point cloud scans and use of cloud dataset to develop FEM 3D meshed model for the numerical simulation to predict peak-over pressures. The results show that the Lidar scanning technique combined with the ANSYS AUTODYN can help to determine the safety distance and as well as construct, simulate and predict the peak over-pressures for hydrogen refueling station explosions.

• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.68-74
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• 2008

Measurements were performed to investigate the effects on flame and pressure development by varying locations of multiple obstacles in a top-venting explosion chamber. The chamber dimension was 1000 mm in height with a $700\;{\times}\;700\;mm^2$ cross-section and a rectangular vent area of $700\;{\times}\;700\;mm^2$. Three different multiple obstacles with blockage ratio of 30% were used by changing from 200 mm, 500 mm to 800 mm in heights within the chamber. Temporally resolved flame front images were recorded by a high speed camera to investigate the interaction between the propagating flame and the obstacles. The results showed that the triangular bar caused the fastest flame developments at given times whereas the lowest was obtained with the cylindrical bar. It was also found that local flame displacement speeds of different obstacles were sensitive to the locations of obstacles. The local speed becomes larger in going from 200 mm, to 500 mm and to 800 mm in heights. The obstacles in height of 800 mm yielded the highest overpressure whereas the lowest was in height of 200 mm.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.85-99
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• 2024

As the proliferation of hydrogen electric vehicles accelerates, there is observed diversification in hydrogen refueling station models. This diversification raises safety concerns for different types of stations. This study conducted a quantitative risk assessment of a multi-vehicle hydrogen station, capable of simultaneously refueling cars, buses, and trucks. Utilizing Gexcon's Effects&Riskcurves Software, scenarios of fire and explosion due to hydrogen leaks were assessed. The study calculated the impact distances from radiative heat and explosion overpressure, and measured risks to nearby buildings and populations. The largest impact distance was from fires and explosions at dispensers and high-pressure storage units. High-pressure storage contributes most significantly to personal and societal risk. The study suggests that conservative safety distances and proper protective measures for these facilities can minimize human and material damage in the event of a hydrogen leak.

• Journal of Welding and Joining
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• v.16 no.5
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• pp.93-99
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• 1998

Effects of gas formers of MgCO$_3$, CaCO$_3$ and Li$_2$CO$_3$ on the spattering phenomena were investigated for non-shielded flux cored arc welding. Spattering phenomena were pictured using high speed camera as a speed of 3000 frames per sec. As experimental results, spattering modes were classified into 4 types. The modes were spattering by arc force, gas explosion, short circuit and pore escape. The amount of spatters by arc force was 30%, gas blowing force was 40%, short circuit 10%, pore escape was 10% and others were 10%. When Li$_2$CO$_3$ was added, the amount of spatters was largest, and it decreased in the order of CaCO$_3$ and MgCO$_3$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.422-426
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• 2012

Transient radiation is emitted during a nuclear explosion. Transient radiation causes a fatal error in the CMOS circuit as a Upset and Latch-up. In this paper, transient radiation NMOS, PMOS, INVERTER SPICE model was proposed on the basisi of transient radiation effects analysis using TCAD(Technology Computer Aided Design). Photocurrent generated from the MOSFET internal PN junction was expressed to the current source and Latch-up phenomenon in the INVERTER was expressed to parasitic thyristor for the transient radiation SPICE model. For example, the proposed transient radiation SPICE model was applied to CMOS NAND circuit. SPICE simulated characteristics were similar to the TCAD simulation results. Simulation time was reduced to 120 times compared to TCAD simulation.

• Korean Security Journal
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• no.2
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• pp.83-98
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• 1999

The LPG station's explosion at Bucheon city was a major accident which with rare frequency of occurrence but large damage effect. Therefore, to prevent similar accident in the future from LPG chargings stations which located at inner urban area, it needs to identify the damage effects of such facilities by comparing theoretically quantities risks-PHAST. The BLEVE effects from the accident showed similar level in case of heat flux, however, the over pressure level reflected at reduced distance. The structure damage to the nearby area showed comparatively large reduction of concrete strength and shape changes through by heat effect while the overpressure effect was small.