• Fire Science and Engineering
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• v.26 no.3
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• pp.35-39
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• 2012

This paper analyzes the combustion diffusion pattern when a water purifier is artificially ignited outside and inside in order to provide data to examine the cause of fire of a water purifier damaged by fire. The analysis result of the combustion diffusion pattern of a water purifier shows that the combustion diffused at a higher speed when it was ignited inside the purifier than when ignited outside. It took approximately 360 seconds for the water purifier to be half-burned when ignited on the outside, and approximately 180 seconds when ignited from inside. That is, it is thought that the internal combustion speed is higher because the internal ignition causes the generated heat to be accumulated and radiated instantly. It was observed that the water purifier damaged by fire caused by external ignition showed a uniform carbonization pattern and the carbide burned down at the bottom were gradually deposited. The water purifier damaged by internal ignition showed a relatively clear boundary of carbonized surface, which formed a V-pattern. The difference in the combustion patterns presents an objective base from which to determine where the fire started. By the time the purifier was half-burned by fire, the built-in fuse had not melted and the power supply protection device did not operate. In addition, as was found in the case of the fuse damaged by a general fire, carbonization occurred at the metal holder, and it is thought that this fact may be used as a basis from which to determine the cause of a fire.

• Clean Technology
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• v.29 no.2
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• pp.102-108
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• 2023

This study applied a hydrothermal carbonization (HTC) method to carbonize sewage sludge in order to satisfy the criteria of the Waste Management Act for recycled products and to explore the possibility of recycling sludge into modification blocks. Cement was mixed with carbonized sludge generated at the optimal temperature and reaction time during HTC. After that, the compressive strengths of the modification blocks were measured by conducting both a performance and leaching test. The results of the leaching test showed that heavy metals were not detected, and the specific gravity and absorption rates were less than 1.7 and 10%, respectively, indicating that all species satisfied the criteria. The results of the compressive strength test showed that a mixing ratio of 5% and 7% with cement cured for 28 days satisfied the criteria of A, B, and C type blocks but a mixing ratio of 3% with cement did not satisfy the criteria of A type blocks after 28 days. However, after additional curing for 42 days, the mixing ratio of 3% also satisfied the A type block criteria. Therefore, the optimal mixing ratio of carbonized sludge and cement was considered to be between 3% and 5% and confirmed that the modified blocks could be utilized as aggregates.

• 보존과학연구
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• s.22
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• pp.115-132
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• 2001

No. 3 Tomb of Bogam-ri, in Naju City, Chollanam-do Province, was a site excavated and inspected from 1996 to 1998 and had a various grave forms, including jar-coffins, stone-chambers and stone-cists. Although most of the metal artifacts excavated from it were severely corroded, we could implement microstructure investigation by collecting samples from the iron axes, iron coffin-nails and iron clamps in which the metal parts were remained. The metal structures were inspected by using metallographic microscope and SEM, and fine components analysis was implemented by ICP. To examine the hardness differences in accordance with the structure distribution, we measured the hardness by structures with Vickers hardness testing machine. As a result of the metal structure inspection, most of them were pure iron, ferrite, and also pearlite, cementite and widmannstaten structures were displayed. We could confirm carbonization was formed on the surface of the iron axes-B, iron coffin-nails-B, and iron clamps-A. There was no carbonization in the rest of the artifacts, and it is not certain that whether the carbonized parts were peeled off through extreme corrosion or they were not carbonized when they were made. In the particular part of a blade, the quality of the material was strengthened through processing. Due to the processing re-grain was caused and fine grain particles were formed. As a result of the ICP component analysis, there were no addition atoms because pure irons were used as materials. In the mean time, No. 17 jar-coffin where the iron axes-A are excavated, is chronologically ordered as from the late-fourth century to the mid-fifth century, and No. 1 and No. 2 stone chambers, where the rest of the artifacts were excavated, as the early-sixth century. It was difficult to relate the periodic differences with the manufacture technique artifacts which we inspected because there were no distinct characteristics of the manufacture technique of the metal structures and it is impossible to conclude the artifacts and sites are at the same period although their periods are different.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.208-213
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• 2018

Epitaxial ($11{\bar{2}}0$) a-plane GaN films were grown on a ($1{\bar{1}}02$) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient $H_2/NH_3$ mixture gas at $1140^{\circ}C$ after carbonization by the pyrolysis in ambient $H_2$ at $1100^{\circ}C$. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ${\omega}-2{\theta}$ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After $Ar^+$ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.

• Carbon letters
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• v.15 no.1
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• pp.25-31
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• 2014

A microstructure analysis is carried out to optimize the process parameters of a randomly oriented discrete length hybrid carbon fiber reinforced carbon matrix composite. The composite is fabricated by moulding of a slurry into a preform, followed by hot-pressing and carbonization. Heating rates of 0.1, 0.2, 0.3, 0.5, 1, and $3.3^{\circ}C/min$ and pressures of 5, 10, 15, and 20 MPa are applied during hot-pressing. Matrix precursor to reinforcement weight ratios of 70:30, 50:50, and 30:70 are also considered. A microstructure analysis of the carbon/carbon compacts is performed for each variant. Higher heating rates give bloated compacts whereas low heating rates give bloating-free, fine microstructure compacts. The compacts fabricated at higher pressure have displayed side oozing of molten pitch and discrete length carbon fibers. The microstructure of the compacts fabricated at low pressure shows a lack of densification. The compacts with low matrix precursor to reinforcement weight ratios have insufficient bonding agent to bind the reinforcement whereas the higher matrix precursor to reinforcement weight ratio results in a plaster-like structure. Based on the microstructure analysis, a heating rate of $0.2^{\circ}C/min$, pressure of 15 MPa, and a matrix precursor to reinforcement ratio of 50:50 are found to be optimum w.r.t attaining bloating-free densification and processing time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.346-348
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• 2022

A monitoring system was constructed to identify the cause of occurrence based on data on the analysis of the ignition factors of fermentation heat generated from loading waste. Universal Middleware was used to provide a real-time run-time environment for the configuration and speed of scenarios for each type of fire early warning. It is necessary to dynamically recognize the loading height and pressure of the loading waste, the drying of wood, batteries, and plastic waste, which are representative compositional wastes, and the carbonization changes on the surface. Therefore, this IoT situation recognition platform for analyzing low-temperature-fired fire possibility data was dynamically configured and presented.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.29-30
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• 2023

Wood is a construction material that has the advantages of carbon dioxide storage ability, noise reflection, and eco-friendliness. In order to use wood for a long time, you must use wood-specific paint, which is called oil stain. Oil stain improves water resistance and moisture resistance, but has the disadvantage of being weak against fire. This is because the oil contained in the oil stain causes a chemical reaction, and this chemical reaction causes the oil stain to spontaneously ignite, igniting nearby combustible materials and causing frequent fires. To improve this, in this study, different flame retardants were mixed and added to oil stain to produce functional oil stain. In addition, we would like to apply it to wood to check glow time and carbonization area. As a result of the experiment, it shows the best performance when mixed at 30(15 + 15)(%) and added to oil stain. The remaining burn time is satisfied from 10% for all samples, and the carbonized area is satisfied when it is 30%.

• Journal of environmental and Sanitary engineering
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• v.17 no.2
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• pp.48-54
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• 2002

In this study, the physical properties of coal-based(bituminous, anthracite·bituminous) activated carbon were compared with those of four different commercial activated carbon used for water treatment. In case of bituminous coal and blend coal, the results of SEM analysis indicated that more pore was extended and shaped in activation process than carbonization process. The results of BET analysis indicated that specific surface area of P Co. activated carbon was larger than the others, and C Co. activated carbon, S Co. activated carbon and anthracite + bituminous was similar. Therefore, adsorption capacities and breakthrough time of anthracite + bituminous regarded similar to C Co. activated carbon.

• Environmental Engineering Research
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• v.22 no.4
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• pp.384-392
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• 2017

Mango shell (MS) and mango shell activated carbon (MSAC) was used to adsorb crude oil from water at various experimental conditions. The MSAC was prepared by carbonization at $450^{\circ}C$ and chemical activation using strong $H_3PO_4$ acid. The adsorbents were characterized with Fourier Transform Infrared spectroscopy. Investigations carried out included the effects of parametric variations of different adsorbate dose, adsorbent dose, time, temperature, pH and mixing speed on the adsorption of crude oil. The equilibrium isotherm for the adsorption process was determined using Langmuir, Freundlich, Temkin and Dubinin Radushkevich isotherm models. Temkin isotherm was found to fit the equilibrium data reasonably well than others. The result demonstrated that MSAC was more effective for crude oil adsorption than raw mango shell. Optimum conditions were also presented. The enhanced effect from activation was justified statistically using Analysis of Variance and Bonferroni-Holm Posthoc significance test. The pseudo first order kinetics gave a better fit for crude oil adsorption with both MS and MSAC.

• Korean Journal of Agricultural Science
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• v.36 no.1
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• pp.19-25
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• 2009

This study was carried for recycling laminated PB and MDF of disused furniture. PB and MDF particles taken from disused furniture were heat-treated at $250^{\circ}C$ and four levels of treatment time, 2, 4, 6 and 8 hours. The recycled boards were made with heat-treated particles after milling and screening with 100 mesh. The bending strength of the recycled boards were lower than that of virgin boards while their anti-swelling efficiency were much improved. Their formaldehyde emissivity were very low. Thus it was concluded that the recylcled boards are prospective environment-friendly material for interial consturction.