• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.357-364
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• 2018

Fly ash is a material used as a concrete admixture. When fly ash is used for concrete manufacturing, it is expected to improve the performance such as reduction of cement usage and increase of chemical resistance. However, fly ash have some problems such as unburned carbon content and amorphous film on the surface of fly ash particles. When concrete is manufactured using fly ash containing a large amount of unburned carbon, there is a problem that the slump is lowered due to adsorption of AE agent. In addition, the amorphous film on the surface of the particles prevents the reactive substances from leaching out of the fly ash. Therefore, a method of surface treatment of fly ash using plasma has been studied to remove such unburned carbon and amorphous films. However, plasma has the problem that $O_3$ is generated when $O_2$ is used as an active gas. $O_3$ is a harmful substance and adversely affects the health of the experimenter. In this study, the surface of fly ash was treatment by arc discharge. Experimental results show that the unburned carbon is removed when the surface of fly ash is treatment by arc discharge and the amorphous film was broken and the reactivity was improved. Therefore, it is considered that arc discharge can treatment the surface of fly ash and improve the quality of fly ash.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.293-298
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• 2006

There are many researches in progress on co-firing of coal and biomass to reduce carbon dioxide produced from the coal consumption. This study carried out 200 Kg/h combustion test furnace by mixing coal with timber. Coal was mixed with domestic and imported-wood around 10% to 20% based on input energy. For the mixed fuel, combustion temperature, unburned carbon and the composition of flue gas were analyzed. In addition, the tendency of slagging and fouling was examined using a probe. According to the result of the experiment, combustion temperature was depended on the kind of wood and mixing ratio. The unburned carbon loss was higher with increase of wood biomass mixing ratio, as a result, the total heat loss of furnace was slightly increased. The emission of NOx and SOx were decreased by $3{\sim}20%$ and $21{\sim}60%$ respectively. There are no difference of slagging and fouling tendency between biomass co-firing and coal burning only.

• The Korean Journal of Ecology
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• v.7 no.4
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• pp.203-207
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• 1984

This report is an investigation of the revegetation and secondary succession in the burned area of Mt. Sanseung in Taegu region. The forest fire took place in December, 1977. The survey was conducted eight times, -three times from October 1, 1983 to October 3, the same year and five times from August 10, 1984 to August 15, the same year. The floristic compositions in the sampled sites constituted 25 kinds of vascular plants and 21 kinds in the burned area and the unburned area respectively. The biological type in both the burned and unburned areas was H-D1-R5-e type, which is generally common to other areas (Taegu, Kyungpook, Chung Buk and Kangweon areas). In the burned area dominant species were Carex humilisvar. nana, Arundinella hirata and Quercus serrata and on the other hand, in the unburned area Pinus densiflora, Carex humilis var. nana, Rhododendron mucrfonulatum var. ciliatum and Quercus serrata. The species diversity diversity index(H) and eveness index(e) of the burned area were higher than those unburned area. Degree of succession (DS) was 650 in the burned area at the 6th years after the fires and 962 in the unburned area. THe vegetation of the burned area was slowly recovered as of 1984 compared with each other. According to the analysis of the soil preperties, pH, available phosphorus and exchangeable potassium were increased, but organic matter, total nitrogen and total organic carbon were decreased. It is assumed that these results were due to the forest fire.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.04a
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• pp.223-224
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• 1999

• Fire Science and Engineering
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• v.14 no.3
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• pp.13-18
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• 2000

The objective of the present work is to examine the cooling characteristics of water droplet on the unburned surface. The hot solid surface material used brass, carbon steel and copper at temperature ranging from 70 to $116^{\circ}$. the droplet size is from 2.4 mm to 3.0 mm. The CCD camera was used to record the evaporation histories of the droplets. and the evaporation time of the droplet on the hot solid surface could be determined by using frame-by-frame analysis of the video records. It is found that during the droplet evaporation process for copper the temperature remains nearly constant, whereas for carbon steel the temperature continuously decreases about $1^{\circ}$. During the droplet evaporation process on the hot solid surface, regardless of solid materials, nondimensional droplet volume decreases nondimensional evaporation time increases.

• The Korean Journal of Ecology
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• v.19 no.5
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• pp.417-430
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• 1996

This study was conducted to investigate the developmental process of plant community during the secondary succession and the dynamics of soil properties in the burned and unburned areas of Mt. Ch’oly-san. Owing to the forest fire occurred on April, 1989, the red pine(Pinus densiflora) forest and its floor vegetation were burned down. The floristic composition of burned and unburned areas were composed of 53 and 49 species of vascular plants, respectively. The dominant species based on SDR4 of the burned sites were lespedeza cyrtobotrya (89.62), Miscanthus sinensis var. purpurascens (62.50), and Carex humilis (58.73), Quercus serrata (43.33). In contrast, Pinus densiflora (83.56), Lespedeza cyrtobotrya (55.57), Miscanthus sinensis var. purpurascens (51.88) and Carex humilis (50.41) were dominant in the unburned area. The biological spectra showed the $H-D_1-R_5-e$ type in both the burned and unburned areas. The indices of similarity ($CC_S$) between the two areas were 0.74. Degree of succession (DS) was 604 in the burned area and 802 in the unburned area. From these facts, it is assumed that the succession is rapidly progressing because of the recovery of vegetation. The species diversity ($\={H}$) and evenness index(C) in the burned and unburned areas were 0.15 and 0.18, respectively. Red pine tree did not resprout after scorch by the forest fire, but Lespedeza, Quercus, Rhododendron, Albizzia, and Zanthoxylum resprouted from the roots and trunks after the forest fire. It seems that these species are the fire-resistant species. Soil properties such as soil pH, content of organic matter, available phosphous, total nitrogen, tatal carbon, exchangeable potssium, sodium, calcium, and magnesium increased due to forest fire. These results suggest the intensity of forest fire in the study area was relatively weak. Monthly changes of soil properties were of little significance except for some cases.

• The Korean Journal of Ecology
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• v.10 no.3
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• pp.129-138
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• 1987

In a red pine (Pinus densiflora) forest, changes of pH, electric conductivity, total carbon, total nitrogen, available phosphate and available potassium in soil and runoff have been studied at intervals for 1 year after early spring fire. Phytimasses of herb and shrub were measured following the current and the subsequent year. The pH, E.C., total nitrogen and phosphate of soil in burned site wee 1.1, 1.5, 1.6 and 2.0 times higher than in unburned site, respectively. But potassium showed no significant difference. A rise in pH, E.C., and total nitrogen in burned site were maintained throught the study period while phosphate maintained 4 months after the fire. The E.C., total carbon, $NO_2-N$ and $NH_4-N$ of runoff in burned site were 1.3, 1.3, 1.3 and 29.0 times higher than in unburned site, respectively, while $NO_3-N$ in unburned site was 4 times higher than in burned site. In burned site, phytomasses of herb and shrub were 148 and 33% of unburned site in a current year and 107 and 51% in a subsequent year, respectively. The considerable amount of increase in soil nutrient after the fire was conserved by the uptake of the fast regrowing plants and by the immobilization of $NH_4=N$.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.60-66
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• 2004

Increased energy costs have placed demands for improved combustion efficiency, high equipment availability, low maintenance and safe operation. Simultaneously low NOx modification, installed due to stricter environmental legislations, require very careful combustion management. The flame diagnostics system has been developed specially to meet these requirements. We aimed at gaining the relationship between burner flame image and emissions such as NOx and unburned carbon in furnace by utilizing the image processing method. For the first step of development, its possibility test was undertaken with bench furnace. The test proceeded to the second step with pilot furnace, the system was observed to be effective for evaluating the combustion conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.499-502
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• 2003

Increase energy costs have placed demands for improved combustion efficiency, high equipment availability, low maintenance and safe operation. Simultaneously low NOx modification, installed due to stricter environmental legislation, require very careful combustion management. We aimed at gaining the relationship between burner flame image and emissions such as NOx and unburned carbon in furnace by utilizing the image processing method. For the first step of development, its possibility test was undertaken with bench furnace. The test proceeded to the second step with pilot furnace, the system was observed to be effective for evaluating the combustion conditions. By using this technology, it is possible to perform continuous monitoring of the combustion conditions and instant detection of individual changes for each burner to prevent future loss of ignition.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.1-7
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• 2003

This paper proposes a method to detect misfired cylinders by the exhaust pressure ascent rate. The misfire is generated by faults of electric system or faults of fuel delivery system. It is one of the abnormal combustions. Therefore, it increases the unburned hydrocarbon and the carbon monoxide and affects a bad influence to the 3-way catalyst. The misfire causes to decrease the power of the engine and increase the consumption of the fuel. Early detection and correction of the misfired cylinders can prevent these unusual phenomena. The misfired cylinders can be detected by the comparison of exhaust pressure ascent rate during each cycle. The exhaust pressure ascent rate is defined as pressure rise per time. Our experimental results showed that the proposed method is effective in the detection of the misfired cylinders on a gasoline engine regardless loads and revolutions of the engine.