• Journal of Environmental Analysis, Health and Toxicology
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• v.21 no.4
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• pp.220-228
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• 2018

$PM_{2.5}$-bound mercury (PBM) was monitored at weekly intervals for three years (from 2014 to 2016) at an urban (Seoul) and rural site (Baengnyeong) in South Korea. The average PBM concentrations in $PM_{2.5}$ samples over the entire sampling period were $12{\pm}11pg/m^3$ and $36{\pm}34pg/m^3$ for Baengnyeong and Seoul, respectively. Seasonal differences were pronounced, with concentrations being highest in winter due to local meteorological conditions (high gas-particle coefficient due to low temperature and low mixing layer height in winter) as well as seasonal factors, such as coal combustion for heating purposes in China. In Baengnyeong, the significant positive correlation of PBM with $PM_{2.5}$, air pollutants, and heavy metals suggested that coal combustion in China might be the most important source of ambient mercury in Korea. In winter, no correlation of PBM with $PM_{2.5}$, air pollutants, and heavy metals was seen in Seoul. Furthermore, Seoul showed higher $PBM/PM_{2.5}$ and $Pb/PM_{2.5}$ ratios in winter due to the strong atmospheric oxidation-reduction reaction conditions as well as local and regional PBM sources. We conclude that immediate attention must be given to addressing PBM levels in Korea, including considering it as a key component of future air quality monitoring activities and mitigation measures.

• Clean Technology
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• v.29 no.4
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• pp.288-296
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• 2023

Coal is abundantly available compared to other energy sources and is used as a versatile energy resource worldwide. To address the environmental issues stemming from conventional coal utilization, efforts are underway to develop clean coal utilization technologies, with IGCC technology being a notable example. In IGCC plants, coal is subjected to a CMD process where both drying and pulverization are achieved by supplying hot air. However, if the temperature of the supplied hot air is excessively high, it can lead to devolatilization and spontaneous combustion, thereby compromising the stable operation of the CMD process. This study aimed to measure the devolatilization and spontaneous combustion temperatures of different types of bituminous coal, and to explore their correlations with the characteristics of the coals. Six coal types exhibited devolatilization between 350 and 400 ℃, while three coal types showed devolatilization at temperatures exceeding 400 ℃. Spontaneous combustion ℃curred in one coal type below 100 ℃, six coal types between 100 and 150 ℃, and two coal types above 150 ℃. The measured initiation temperatures were compared with the coal characteristics including the oxygen, moisture, Fe₂O₃, and CaO content, the H/C ratio, and the O/C ratio to establish correlations. Regression analysis was used to calculate the regression coefficients and determination coefficients for each ignition temperature. It was found that 52.44% of the FC/VM data significantly influenced the volatile matter ignition temperature, and 59.10% of the Fe₂O₃ data significantly affected the spontaneous combustionignition temperature.

• Fire Science and Engineering
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• v.20 no.1 s.61
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• pp.43-49
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• 2006

In this paper, we are studied on the temperature characteristics and fire progress of an incandescent electric lamp at 220V/100W. In the case of stationary state, the ignition possibility of the incandescent electric lamp due to the heat generation was low because the temperature was measured at $161.9^{\circ}C$ the temperature was increased at $538.1^{\circ}C$ in the airtight chamber, but it does not generated the fire because the oxygen was not exist in the airtight chamber. When the lamp is broken, the filament of lamp was melted in the air. The gas of lamp interior spurted to the weakest part by external flame. Thus, the incandescent electric lamp is high possibility of fire when oxygens from airtight space. Also, it is known that the possibility of ignition is very high if combustion materials(sawdust) exists on surrounding. These experimental results will be utilized for the data in the investigation electrical fire cause.

• Environmental Engineering Research
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• v.14 no.3
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• pp.158-163
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• 2009

It is difficult for a burner to achieve an increase in combustibility and a reduction of NOx emission, simultaneously. The reason is because thermal NOx could be reduced at low temperature, while the combustibility should be decreased. To solve this problem, an externally oscillated staging burner was developed, and experiment was conducted according to effective parameters. The combustibility could be improved through the accelerated transfer of heat, mass and momentum obtained by external oscillation. Also, NO is reduced by the decrease of residence time of burning gas in the local highest-temperature spot, which is decreased by the external oscillation and fuel staging. Experiments on variables were conducted to determine the reference flame, and the flame generating the lowest NO concentration was selected. The conditions of reference flame were oscillation frequency 250 Hz, sound pressure 1 VPP, and air ratio 1.1, and NO and CO concentrations were 1ppm and 20 ppm, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.95-95
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• 2010

An apparatus for generating flames and more particularly the microwave plasma burner for generating high-temperature large-volume plasma flame was presented. The plasma burner was composed of micvrowave transmission lines, a field applicator, discharge tube, coal and gas supply systems, and a reactor. The plasma burner is operated by injecting coal powders into a 2.45 GHz microwave plasma torch and by mixing the resultant gaseous hydrogen and carbon compounds with plasma-forming gas. We in this work used air, oxygen, steam, and their mixtures as a discharge gas or oxidant gas. The microwave plasma torch can instantaneously vaporize and decompose the hydrogen and carbon containing fuels. It was observed that the flame volume of the burner was more than 50 times that of the torch plasma. The preliminary experiments were carried out by measuring the temperature profiles of flames along the radial and axial directions. We also investigated the characteristics for coal combustion and gasification by analyzing the byproducts from the exit of reactor. As expected, various byproducts such as hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, etc. were detected. It is expected that such burner cab be applied to coal gasification, hydrocarbon reforming, industrial boiler of power plants, etc.

• Journal of Sensor Science and Technology
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• v.29 no.6
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• pp.382-387
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• 2020

Hydrogen (H₂) is considered as a new clean energy resource for replacing petroleum because it produces only H₂O after the combustion process. However, owing to its explosive nature, it is extremely important to detect H₂ gas in the ambient atmosphere. This has triggered the development of H₂ gas sensors. 2-dimensional (2D) graphene has emerged as one of the most promising candidates for chemical sensors in various industries. In particular, graphene exhibits outstanding potential in chemoresistive gas sensors for the detection of diverse harmful gases and the control of indoor air quality. Graphene-based chemoresistive gas sensors have attracted tremendous attention owing to their promising properties such as room temperature operation, effective gas adsorption, and high flexibility and transparency. Pristine graphene exhibits good sensitivity to NO₂ gas at room temperature and relatively low sensitivity to H₂ gas. Thus, research to control the selectivity of graphene gas sensors and improve the sensitivity to H₂ gas has been performed. Noble metal decoration and metal oxide decoration on the surface of graphene are the most favored approaches for effectively controlling the selectivity of graphene gas sensors. Herein, we introduce several strategies that enhance the sensitivity of graphene gas sensors to H₂ gas.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• Journal of ILASS-Korea
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• v.22 no.4
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• pp.210-217
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• 2017

A gasoline direct injection engine has an intake air temperature can be lowered by the fuel vaporization in the combustion chamber increase the volume efficiency is high compression ratio. Therefore, study for injection rate and characteristics which influence mixture formation in combustion chamber is important. Movement of the injector needle has a direct effect on the injection of the fuel, such as formation of cavitation, the fuel injection rate, etc. Therefore, recent studies on the dynamic characteristics of the injector considering the movement of the needle have been reported, but it takes a lot of time and cost to experimentally confirm the movement of the needle inside the injector. In this study, AMESim, a commercial 1-D code, and Star-CCM+, a 3-D CFD code, were used to predict the dynamic performance of the injector with needle motion. In order to predict the movement of the needle under the high pressure, the result of the surface pressure distribution according to the movement of the needle was derived by using the morphing technique of flow analysis. In addition, we predicted the injection rate of the injector considering the movement of the needle in conjunction with the 1-D code. The injection rate of the injector was measured by the BOSCH's method and the results were similar to those of the simulation results. This method can predict the injection rate and injection characteristics and this result is expected to be used to predict the performance of gasoline direct injection engines with low cost and time in the future.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.403-412
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• 2006

The effect of a wall temperature on the soot deposition process from a diffusion flame to a solid wall was investigated in a microgravity environment to attain in-situ observations of the process. The fuel for the flames was an ethylene ($C_2H_4$). The surrounding oxygen concentration was 35% with surrounding air temperatures of $T_a=600K$. In the study, three different wall temperatures. $T_w$=300, 600, 800K, were selected as major test conditions. Laser extinction was adopted to determine the soot volume fraction distribution between the flame and burner wall. The experimental results showed that the maximum soot volume fractions at $T_w$=300, 800 K were $8.8{\times}10^{-6},\;9.2{\times}10^{-6}$, respectively. However, amount of soot deposition on wall surface was decreased because of lower temperature gradient near the wall with increasing wall temperature. A numerical simulation was also performed to understand the motion of soot particles in the flame and the characteristics of the soot deposition to the wall. The results from the numerical simulation successfully predicted the differences in the motion of soot particles by different wall temperature near the burner surface and are in good agreement with observed soot behavior that is, the 'soot line', in microgravity.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1134-1144
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• 2018

Cetane Number is one of the quality standard for diesel, which assesses the compatibility of ignition quality of diesel compression in diesel engines. Cetane number must be upper 52 to keep the recent diesel quality standards. It is known that if cetane number is high, there will be shorter ignition delay periods than being lower. On the other hands, if cetane number is too high that exceeds the quality standard, there will increase the air pollution and decrease of the fuel efficiency because incomplete combustion. In South Korea, various methods are being used to measure the cetane number such as cetane number that used CFR engine, cetane index from calculate density and distillation temperature and derived cetane number to make up for CFR engine that ignition delay in high temperature is implemented. In this study will be conducted by collecting the diesel from the major oil companies, and try to analyze the correlation between the different methods of cetane number with various factors. At the results of this study, it was shown that the cetane index is high then cetane engine and derived cetane number. therefore it will be necessary to additional research for out of cetane number quality standards.