• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.3
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• pp.9-17
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• 2002

This Study is to investigate 8 composite propellants including Butacene and ${Bi_2}{O_3}$ by Shotgun/RQ Bomb test. Burning rate and mechanical properity are known to be major factors in determining the deflagrability of propellant. Propellant including over 5.5% Butacene(Ferrocene grafted HTPB) burned out over 135 m/s of impact velocity during Shotgun/RQ Bomb test. It was blown that Butacene was very sensitive material under high velocity impact. In the test results, propellants under 25mm/s in burning rate at 1500 psia could meet the requirements for IM of UN Test Series 7c(ii). Propellant deflagrabillity depends on burning rate at performance in the results of the present.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.29-29
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• 2000

추진제의 폭연 특성을 실험실 규모로 측정하는 시험방법으로 NAWC에서 개발한 BIC (Ballistic Impact Chamber) 시험과 SNPE에서 개발한 Shotgun/RQ Bomb 시험이 있다. SNPE에서는 화약과 추진제가 UNO 위험등급 분류체계에서 1.6급수(우연한 개시나 반응의 전환 가능성이 거의 없는 매우 둔감한 물질)로 분류되는 기준을 UN Test Series 7c(ii)에 탄속 150m/s에서 dP/dt가 15MPa 이내로 규정하고 있다.(중략)

• Journal of Hydrogen and New Energy
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• v.35 no.4
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• pp.415-427
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• 2024

Explosion experiments were conducted using a rectangular concrete structure filled with hydrogen-air mixture (29.0%). In addition, the effect of ignition location on explosion was investigated. The impact on overpressure and flame was increased with the increasing distance of the ignition source from the vent. Importantly, depending on the ignition location the incident pressure was up to 24.4 times higher, while the reflected pressure was 8.7 times higher. Additionally, a maximum external overpressure of 30.01 kPa was measured at a distance of 2.4 m from the vent, predicting damage to humans at the injury level (1% fatality probability). Whereas, no significant damage would occur at a distance of 7.4 m or more from the vent.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.468-475
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• 2019

An end-line flame arrester allows free venting in combination with flame protection for vertical vent applications. End-line flame arresters are employed in various fields, especially in shipping. In flame arresters, springs are essential parts because the spring load and the spring's elasticity determine the hood opening moment. In addition, the spring has to work under a high-temperature condition because of the burning gas flame. Therefore, it is necessary to analyze the mechanical load and elasticity of the spring when the flame starts to appear. Based on simulations of the working process of a specific end-line flame arrester, a thermal and structural analysis of the spring is performed. A three-dimensional model of a burned spring is built using computational fluid dynamics (CFD) simulation. Results of the CFD analysis are input into a finite element method simulation to analyze the spring structure. The research team focused on three cases of spring loads: 43, 93, and 56 kg, correspondingly, at 150 mm of spring deflection. Consequently, the spring load was reduced by 10 kg after 5 min under a $1,000^{\circ}C$ heat condition. The simulation results can be used to predict and estimate the spring's load and elasticity at the burning time variation. Moreover, the obtained outcome can provide the industry with references to optimize the design of the spring as well as that of the flame arrester.

• Journal of Korean Society of Forest Science
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• v.111 no.2
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• pp.242-250
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• 2022

Here we aimed to date the year and season of the resin collection from Korean red pines at Worak mountain and investigate the natural healing ability of the wounds using the tree-ring analysis technique. We determined the dating of the resin collection based on the synchronization between the ring-width time series from the wound surface of the experimental trees and the local master chronology, which is the mean time series from the sound surface on the opposite side of the wounds. For the dating of resin collection, we selected thirteen Korean red pines with resin wounds. For the investigation on the annual healing ability of the wounds, we sampled three dead trees out of 13 trees as disks. Through the comparison of the individual ring-width time series from the wounds with the local master chronology, it was verified that the resin collection was undertaken between the spring of 1962 and the autumn of 1975. The mean healing length of the wounds was 15.8 cm over the preceding 42 years, making their annual mean healing 0.38 cm. Through our study we successfully verified the healing ability of the wounded Korean red pines for the resin collection as well as the undocumented resin collection history.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.307-310
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• 2005

This Study was performed for the Insensitive Munition Technology Program contract between Roxel and ADD. Two Slow Coo-off(SCO) tests and One fast Cook-off(FCO) test have been made based on MIL-STD-2105C. SCO and FCO tests were made in order to evaluate the behaviour of the hybrid rocker motor with insensitive igniter and two types of propellants of which burning rates were 9.8 mm/s and 21.2 mm/s @ 7 MPa each other. The Reaction level of the two rocker motors to SCO test was classified as type IV and that of FCO test was classified as type V.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.369-374
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• 2010

This paper presents a numerical investigation of the Deflagration to Detonation Transition (DDT) of flame acceleration by a shock wave in combustible gas mixture. A model consisting of the reactive compressible Navier-Stokes equations is used. The effects of viscosity, thermal conduction, species diffusion, and chemical reactions are included. Using this model, the generation of hot spots by repeated shock and flame interaction in front and back of flame and the change of detonation occurrence by various shock intensities (Ms=1.1, 1.2, 1.3) are studied. The simulations show that as the incident shock intensity increases, the Richtmyer-Meshkov (RM) instability becomes stronger and DDT occurrence time is reduced.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.957-964
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• 2010

The deflagration-to-detonation transition (DDT) causes a strong pressure wave that can adversely affect surrounding structures. The pressure generated by multiple detonative pulses is strong enough to cause metal surface erosion and chipping of the edges of bulk structures. In this study, we investigate the damage caused by the DDT phenomenon and perform hydrocode simulations to evaluate the structural damage caused to a metallic pulverized-coal injector used in a pulverized-coal-oxygen combustion furnace. The experimental conditions are selected in order to accurately model the damage caused to metal injectors that are exposed to multiple DDT pulses.

• Fire Science and Engineering
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• v.12 no.2
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• pp.43-59
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• 1998

It was studied a compared estimation of the fire risk of the three kinds of the interior materials, such as a resist carpet, a resist-after-treatment plywood and sofa leather. Toxic gases, CO, CO2, NOx, SO2, HCN, HCI were detected during the combustion of the samples. A resist-carpet was more combustible than the resist-after-treatment plywood and sofa leather in the combustion characteristics and has a blow-up-combustion of combustion in all the samples. The generation of CO reached the lethal doses in minute after the combustion was begun. NOx and So2 were detected not more than each of the lethal doses, while HCN was detected in the carpet 20.6 times than the sofa leather, and 4.6 times than the resist-after-treatment plywood. HCI was detected in the carpet 4.48 times than the sofa leather and 2.47 times than the resist-after-treatment plywood. It is conclusion that the carpet was the highest in the fire risk among the three kinds of the interior materials.

• Journal of the Korean Institute of Gas
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• v.16 no.1
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• pp.8-14
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• 2012

Hydrogen is considered to be the most important future energy carrier in many applications reducing significantly greenhouse gas emissions, but the explosion safety issues associated with hydrogen applications need to be investigated and fully understood to be applicable as the carrier. The risk associated with a explosion depends on an understanding of the impacts of the explosion, particularly the pressure-time history during the explosion. This work provides the effects of explosion parameters, such as specific heat ratio of burned and unburned gas, equilibrium maximum explosion pressure, and burning velocity, on the pressure-time history with flame growth model. The pressure-time history is dominantly depending on the burning velocity and equilibrium maximum explosion pressure of hydrogen-air mixture. The pressure rise rate increase with the burning velocity and equilibrium maximum explosion pressure. The specific heat ratio of unburned gas has more effect on the final explosion pressure increase rate than initial explosion pressure increase rate. However, the specific heat ratio of burned gas has more influence on initial explosion pressure increase rate. The flame speeds are obtained by fitting the experimental data sets. The flame speeds for hydrogen in air based on our experimental data is very low, making a transition from deflagration to detonation in a confined space unlikely under these conditions.