• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.668-675
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• 2019

Fine dust in air pollutants is recognized as one of the most serious social environmental problems. Most of the NOx is generated in a combustion process such as that of a coal-fired power plant, and therefore efficient elimination of the NOx from the coal-fired power plants is needed. This study investigates the removal efficiency of using $TiO_2$, a photocatalyst, to remove NOx by Selective Catalytic Reduction (SCR). To evaluate the NOx removal efficiency, $TiO_2$ catalyst and phosphate binder were mixed on the surface of the $Al_2O_3$ substrate with the exothermic agent, and the substrate was heat-treated. The NOx removal efficiency of the catalysts was evaluated according to the temperature, and XRD, SEM, TG-DTA and BET analyzes were performed to investigate the physicochemical properties of the catalysts. NOx removal efficiency was 58.7%~65.9% at 20min, 63.7~66.0% at 30min with temperature change according to time($250^{\circ}C{\sim}500^{\circ}C$). The $TiO_2$ used in the SCR for NOx removal is judged to have the most efficient removal efficiency at $300^{\circ}C$.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.37-43
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• 2019

This research studied production of lightweight filling production for sink hole restoration utilizing various industrial by-products(2kinds of fly ash, petro-cokes CFBC ash, blast furnace slag fine particle). For this purpose, the mixed raw material properties(compressive strength) behaviors according to the blending ratio of industrial by-products were examined by applying the experimental design method and statistical analysis was performed using the commercial program MINITAB. Compressive strengths of industrial by-products were strongly dependent on blast furnace slag powder. Compressive strength(3days aging) was 3~11MPa depending on the amount of blast furnace slag powder used. The use of CFBC fly ash was evaluated to have the least effect on compressive strength. In addition, the compressive strength and the coefficient of permeability were measured by preparing foamed concrete for the experimental batch 1 condition in the mixture experimental design. In this case, the bulk density is 0.9 to 1.0, the apparent porosity is 30 to 50%, the compressive strength(3days old) is 1 to 2MPa, and the permeability coefficient is $10^{-2}$ to $10^{-3}cm/sec$.

• Journal of the Korean GEO-environmental Society
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• v.22 no.3
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• pp.5-13
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• 2021

Due to population growth and industrial development, the amount of industrial waste is increasing every year. In particular, in a thermal power plant using finely divided coal, a large amount of coal ash is generated after combustion of the coal. Among them, fly ash is recycled as a raw material for cement production and concrete admixture, but about 20% is not utilized and is landfilled. Due to the continuous reclamation of such a large amount of coal ash, it is required to find a correct treatment and recycling plan for the coal ash due to problems of saturation of the landfill site and environmental damage such as soil and water pollution. In recent years, the use of a fluid embankment material that can exhibit an appropriate strength without requiring a compaction operation is increasing. The fluid embankment material is a stable treated soil formed by mixing solidifying materials such as water and cement with soil, which is the main material, and has high fluidity before hardening, so compaction work is not required. In addition, after hardening, it is used for backfilling or filling in places where compaction is difficult because higher strength and earth pressure reduction effect can be obtained compared to general soil. In this study, the possibility of use of fluidized soil using high water content cohesive soil and coal ash is considered. And it is intended to examine the flow characteristics, strength, and bearing capacity characteristics of the material, and to investigate the effect of reducing the earth pressure when applied to an underground burial.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.582-587
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• 2022

Biphasic solvents are attracting attention as energy-reducing solvents for capturing CO₂ from flue gas in combustion process. In this study, considering diethylenetriamine (DETA) and diethylethanolamine (DEEA) mixed solvents, one of the biphasic solvents by blending of two types of amines, the CO₂ absorption rates of DETA and DEEA was measured by wetted wall column. The effects of DETA and DEEA concentrations and operating temperature on the overall mass transfer coefficient were investigated. As a result, the overall mass transfer coefficient was proportional to the DETA concentration. However, in the case of the DEEA concentration, the effect was small and when the concentration was exceeded, the overall mass transfer coefficient decreased. The DETA aqueous solution showed little change in the overall mass transfer coefficient with the operating temperature, whereas the DEEA aqueous solution increased the overall mass transfer coefficient with the operating temperature. As a result of obtaining the observed reaction rate constant under the pseudo-first-order reaction assumption, it was found that the observed reaction rate constant in DETA aqueous solution was proportional to the DETA concentration, but DEEA did not fit the pseudo-first-order reaction assumption.

• Journal of the Korean Institute of Gas
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• v.26 no.6
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• pp.24-29
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• 2022

This paper is a purpose to Analyze and study the failure examples for a engine oil leakage of camshaft bearing seal, poor contact by computer connector fin damage and vaporizer inferiority on LPG automotive. The first example, when the researcher disassembled the cylinder head of engine to establish the cause for oil leakage, he confirmed the engine oil leakage by damaged between the engine intake camshaft bearing and seal part. The second example, the connector fin of power source line that control the starting of a car supplied with engine computer. As a result, it found the fact that the engine operation stopped because of cutting of the power source by connector fin damage. The third example, it verified the engine incongruity phe cutting of the power source by connector fin damage. The third example, it verified the engine incongruity phenomenon as thd gas didn't flow the vaporizer by foreign substance deposit. Finally, it supplied a small quantity gas from vaporizer to mix. As the computer controlling mix opening condition supplied a air as opening signal, the air and fuel became rarefied state. it knew that the engine didn't produce prpper power. Therefore, a car have to throughtly inspect not in order to arise the failure symptoms.

• Clean Technology
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• v.29 no.4
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• pp.305-312
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• 2023

Due to the strengthening of environmental requirements, aging denitrification facilities need to improve their performance. The present study aims to suggest the possibility of improving performance using computational analysis techniques. This involved modifying both the geometric design and the operating conditions, including the flow path shape of the equipment such as the inlet guide vane and the curved diffusing part, and the flow control of the ammonia injection nozzle. The conditions presented in this study were compared with existing operating conditions in terms of the flow uniformity, the NH₃/NO molar ratio of the mixed gas flowing into the catalyst layer, and the total pressure drop of the facility. The flow field applied in the computational analysis ranged from the outlet of the economizer in the combustion furnace to the inlet of the air preheater, the full domain of the denitrification facility. The performances were derived by solving the flow fields using ANSYS-Fluent and the injection amount of ammonia was adjusted for each nozzle using Design Xplorer. Compared to the denitrification performances of the equipment currently in operation, the conditions proposed in this study showed an improvement in the flow uniformity and NH₃/NO composition ratio by 45.1% and 8.7%, respectively, but the total pressure drop increased by 1.24%.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.53-63
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• 2024

Adopting an engine igniter with high efficiency and ignition performance is essential for reliable operation of liquid rocket engines. In this study, we developed a spark torch igniter for a 450 N-scale methane-oxygen liquid rocket engine by conducting numerical analyses, igniter manufacturing and validation. Specifically, we conducted a parametric study for maximizing the enthalpy at the igniter exit, specifically by adjusting the mass flow rate, nozzle area ratio, fuel-oxidizer mixture ratio, and the igniter length-to-diameter. The heat transferred via the igniter nozzle exit was computed using 3-dimensional numerical simulations. We also manufactured and tested the igniter based on a deduced design to confirm ignition performance of the designed spark torch igniter. The igniter developed through this study could contribute to the development of practical propulsion systems such as upper-stage engines of small launch vehicles.

• 한국석유지질학회:학술대회논문집
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• autumn
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• pp.28-46
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• 2001

Natural gas is a mixture of hydrocarbon gases and impurities such as nitrogen, hydrogen sulfide, and carbon dioxide and a clean energy producing no pollution materials for combustion. Currently, the demand of the natural gas is rapidly increasing due to worldwide environmental problems. According to Hubbert's study in the past, the natural gas was predicted as rapidly depleted resources, and then the results led to high gas price and limitation of usage during 1980s. Afterward, the study of natural gas resources based on geology identified the additional natural gas resources that were not considered in Hubbert's study. They are unconventional gas, additional resources in the existed reservoirs, and natural gas in deep subsurface areas. Such additional resouces made the future of natural gas bright and pormised low and stable gas price in the future. Deep natural gas is defined as the gas existing at or below 15,000ft$(4,752{\cal}m)$ in depth from the surface. According to the study from the U.S. Geological Survey(USGS) in 1995, 1,412 TCF of technically recoverable natural gas was remained to be discovered or developed in the onshore of United States. A significant part of that resource base, 114 TCF, exists at deep sedimentary basins, and it shows wide distribution with various geological environments. In 1995, the deep gas contributed to $6.7\% of total supply amount of natural gas in the United States and is expected to be $18.7\% by 201.5. However, the development of the deep gas is a high risky business due to expensive investment and high portion of dry holes, although it is developed. Thus, for developing the deep gas economically, it is necessary to overcome many technical challenges. In this paper, for increasing success rate of the deep gas, 1) geologic and compositional characteristics, and production cost have been analyzed according to depth, 2) technical problems related to deep gas production have been summarized, and 3) finally future study areas for increasing application of the deep gas have been suggested. For reference, this paper was written based on the study results from USGS and Gas Research Institute(GRI), for the United States is doing the most active R&D in the deep gas area, and thus, has many reliable data.