• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.807-815
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• 2014

This study was performed using a laminar flow reactor that could replicate the combustion environment of pulverized coal in a blast furnace. Since a pulverized coal injection system was developed for iron making, the combustion characteristics of pulverized coal have been important in the iron and steel industry. The flame structure, particle temperature, and exhaust gas were investigated for different types of coal. The results of this study demonstrated that the combustion characteristics of coal are influenced by several properties of individual coals. In particular, the CO emission and volatile matter content of individual coals were found to have a strong influence on their combustion characteristics. Thus, this study found the properties of the coals to be significant and focused on the particle temperature and CO and $CO_2$ emissions.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.533-536
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• 2008

Recently, in Korea, there has been an increasing number of research papers published which are to improve durability of concrete, particularly by analyzing correlation between diffusivity of chloride and porosity/pore size distribution. In these studies, such test methods as mercury intrusion porosimetry(MIP), gas adsorption or image analysis method are used to analyze the microstructure of materials while MIP is most widely used for concrete. This study analyzes the results of porosity and pore size distribution of paste and concrete adding fly ash or blast furnace slag by using MIP equipment which is widely used for determining micro-porosity structure of cementitious materials. A variation in porosity and pore size distribution at the curing day 3, 7 and 28 has been observed by using MIP equipment for cement paste 35%, 40%, 45%, 50%, 55%, 60% of W/C when using $300kg/m^3$ of cement, 35%, 45%, 55% of W/C when replaced 60% with blast-furnace slag, and 35%, 45%, 55% of W/C when replaced 30% with fly ash. For long-term water cured normal OPC concrete and mixed concrete replaced 60% with blast-furnace slag powder, micro-structure of the sample has been analyzed by using MIP equipment when W/C indicated 40%, 45%, 50% respectively and the binder varied $300kg/m^3$, $350kg/m^3$, $400kg/m^3$, and $450kg/m^3$.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.1
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• pp.47-60
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• 2021

Hydrogen is a next-generation energy source, and according to the roadmap for activating the hydrogen economy, it is expected that industries to stably produce, store, and transport of hydrogen as well as the supply of hydrogen fuel cell vehicles will be made rapidly. Accordingly, safety measures for accidents of hydrogen vehicles in confined spaces such as tunnels are required. In this study, as part of a study to ensure the safety of hydrogen fuel cell vehicles in road tunnels, a basic investigation and research on the risk of fire and explosion due to gas leakage and hydrogen tank rupture among various hazards caused by hydrogen fuel cell vehicle accidents in tunnels was conducted. The following results were obtained. In the event of hydrogen fuel cell vehicle accidents, the gas release rate depends on the orifice diameter of TPRD, and when the gas is ignited, the maximum heat release rate reaches 3.22~51.36 MW (orifice diameter: 1~4 mm) depending on the orifice diameter but the duration times are short. Therefore, it was analyzed that there was little increase in risk due to fire. As the overpressure of the gas explosion was calculated by the equivalent TNT method, in the case of yield of VCE of 0.2 is applied, the safety threshold distance is analyzed to be about 35 m, and number of the equivalent fatalities are conservatively predicted to reach tens of people.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4950-4959
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• 2015

The importance of public infrastructures' protection against crash or blast loads has been emerging issue as structures are becoming bigger and population densities in downtown cities are growing up. However, there exists no sufficient study which considers the developments of protective building materials, that are essential for protective design and construction. To assess the protection performance and the applicability as protective materials of high performance fiber reinforced cementitious composites(HPFRCC), this study performed the impact tests with 40 mm gas-gun propelled projectile crash machine. From this study, it has observed that both high compressive strength of cement matrix and fiber reinforcement are beneficial for the improvement of impact resistance.

• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.32-37
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• 2012

The aim of this study is to evaluate the characteristics of explosion and flame velocity that can be utilized to factories where Mg-Al alloy metal powders are handled in the form of raw materials, products or by-product for similar dust explosion prevention and mitigation. Because the strength of the blast pressure is the result due to flame propagation, flame velocity in dust explosion can be utilized as a valuable information for damage prediction. An experimental investigation was carried out on the influences of content ratio of Mg-Al alloy (mean particle size distribution of 151 to 161 ${\mu}m$). And a model of flame propagation velocity based on the time to peak pressure and flame arrival time in dust explosion pressure, assuming the constant burning velocity, leads to a representation of flame velocity during dust explosion. As the results, the maximum flame velocity of Mg-Al(60:40 wt%), Mg-Al(50:50 wt%) and Mg-Al(40:60 wt%) was estimated 15.5, 18 and 15.2 m/s respectively, and also tend to change with content ratio of Mg-Al.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.450-457
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• 2017

This study is to develop high quality floor mortar which can be applied in construction sites using EXFG(Expansive admixdure Flue Gas desulfurization gypsum). First, as the substitution rate of ALS(Aluminum Slag) increased, the flow is increased proportionally. EXFG showed a tendency to decrease with increasing substitution rate. Also, in the case of the setting time of 5% of ALS replacement rate, the setting time of Plain compared to EXFG was decreased by 5~20%. The compressive strength increased with the ALS replacement ratio at 0%, 5% and the EXFG replacement ratio at 1%. The strength was increased when the ALS replacement ratio was more than 10%. In the case of ALS replacement rate of 0% and 5%, drying shrinkage compared to plain was decreased by about 10~25% regardless of EXFG replacement rate.

• Journal of the Korean Institute of Gas
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• v.4 no.4 s.12
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• pp.50-57
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• 2000

Past accidents have shown that vapor cloud explosions are the predominant cause of the largest losses in the chemical and petrochemical industries due to the generation of significant overpressures. Prediction of such overpressure is of great concern and a knowledge of the likely overpressure is needed for the design of equipment, safety cases and emergency planning. For these reasons, risk assessment for vapor cloud explosion is crucial and this assessment can be carried out using the different models including TNT-Equivalency, TNO Hemispherical, TNO Multi-Energy and CFD models. Accordingly, in this paper, the published VCE prediction models are reviewed to provide a critical comparison of the different models used for the quantification of explosion hazards, in terms of the fundamental assumptions employed, and their predictive accuracy

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.55-62
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• 2015

An importance of infrastructures' protection against crash or blast loading has been an emerging issue as structures are becoming much bigger and population densities in downtown are growing up. However, there exists no such a standard to evaluate the protection performance of construction material itself. Prior to building standards for protection assessment techniques, this study performed gas-gun propelled projectile impact tests with series of contact-type monitoring systems to investigate the applicability of each sensing type. Through the impact tests, failure modes and protection performances of both normal concrete and UHPC (Ultra High Performance Concrete) reinforced by steel fibers were also evaluated. The results showed that LVDT could be applicable for the impact test among contact-type sensors and UHPC with fibers had a remarkable potential to improve protection against impact loading.

• Korean Journal of Agricultural Science
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• v.51 no.2
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• pp.227-238
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• 2024

Methane (CH₄) is an important greenhouse gas, with a short-term greenhouse effect 80-fold that of carbon dioxide. Blast furnace slag used as a base ingredient for silicate fertilizer, and contained Fe³⁺, which acts as reduction of CH₄ emissions in flooded rice paddy. This study was evaluated the effects of the silicate fertilizer with different rates of the iron slag on CH₄ emissions and rice growth. In this study, the SF 0.0% was applied with silicate fertilizer containing 0.0% of the iron slag, while the SF 2.5% and SF 5.0% were treated with silicate fertilizer containing 2.5 and 5.0%, respectively. The CH₄ emissions during rice cropping period were assessed using a closed-chamber method and then determined by Gas chromatography. The CH₄ fluxes were reduced by 17% (SF 0.0%), 17% (SF 2.5%), and 8% (SF 5.0%) compared to the treatment with only-inorganic fertilization (control). Conversely, rice grain yield increased by 15 - 30% compared to the control owing to the improvement of soil quality by silicate fertilization. In particular, soil pH, available phosphorus and available silicic acid content were increased with the increase in the iron slag rates from 0.0 to 5.0%. These contributed to a significant increase in rice growth such as 1,000-grains weight and percentage of filled grains. Consequently, these findings were indicated that the application of silicate fertilizer containing 2.5 - 5.0% of iron slag would be the most effective in both CH₄ reduction and rice growth.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.8-15
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• 2014

The ablation characteristics of graphite nozzle throat insert is analyzed for the use in solid rocket propulsion system. The propulsion system is composed of three types of conventional nozzles, such as De-Laval type, blast tube type, and submerged type. Various kinds of propellants are used in the thirteen kinds of propulsion system that has different shapes of each other. Total thirty seven tests are performed. From the results of the analysis, it is found that the ablation rate is higher for the higher average chamber pressure and the higher concentration of oxidizing species in combustion gas.