• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.124-129
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• 2010

When a phenolic resin is carbonized by the leakage current flowing along its surface, the carbonization pattern is one of the most important factors to determine its carbonization characteristics. However, the typical carbonization pattern of a phenolic resin is too complicated to be analyzed by conventional Euclidean geometry. In most cases, such a complicated shape shows a fractal structure. It is possible, therefore, to examine the characteristics of the carbonization pattern regarding a given phenolic resin. In order to quantitatively investigate the carbonization pattern of the phenolic resin carbonized by a leakage current, in this paper, the fractal dimension of the carbonization pattern has been calculated as a function of the magnitude of a leakage current and the distance between two electrodes. For reliability of calculation, the correlation function as well as the box counting method has been used to calculate the fractal dimension. According to the result of calculation, the fractal dimension increases as the current increases at the constant electrode gap distance. However, there is no significant relation between the fractal dimension and the electrode gap distance at a constant current.

• Carbon letters
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• v.1 no.3_4
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• pp.158-164
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• 2001

It is well known that the fabrication process of carbon/carbon composites is very complex. Above all, the carbonization process have major effect on the morphology development of carbon matrix. Carbon/carbon composites of 4-directional fiber preform were fabricated using the coal tar based pitch as a matrix precursor in this study. According to carbonization pressure of 1 bar, 100 bar, 600 bar, and 900 bar, morphological changes of cokes and matrix of composites were discussed. As the carbonization pressure increased to 600 bar, the flow pattern morphology of bulk mesophse was well developed. On the contrary, mosaic pattern morphology was found in case of 900 bar of carbonization pressure. It is confirmed that the carbonization pressure have profound effect on the degree of graphitization and crystal size of carbon matrix. Even in the highly densified carbon/carbon composites, large voids were still found in the matrix pocket region.

• Fire Science and Engineering
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• v.32 no.5
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• pp.15-21
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• 2018

This study examined the growth characteristics and carbonization pattern when a fire occurs due to a flammable liquid sprinkled on a vinyl floor. When acetone was sprinkled on a floor, the flame reached its peak in approximately 0.2 s after it was ignited. The lower part of the flame showed a laminar pattern while the upper part showed a turbulent pattern. The pattern showed a turbulent pattern and generated white smoke. The combustion completed floor surface showed carbonization of a dim pore pattern. In the case of benzene, an intense flame was formed in approximately 0.6 s after ignition. The flame length was measured to be approximately 50 mm. When the flame became weak, a significant amount of black smoke was generated due to incomplete combustion. The combustion completed floor surface showed carbonization of a pour pattern and splash pattern. In the case of alcohol, an intense flame was formed in approximately 1.1 s after ignition. In addition, the depth of carbonization was significant where the flammable liquid was collected and a trace of carbonization was observed at the boundary of the flow path of the flammable liquid.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.3
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• pp.332-337
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• 2008

We analyzed carbonization pattern and crystal structure of polyvinyl chloride wire by thermal stress. Copper that is oxidized at normal temperature is a reddish brown. If under the thermal stress range of 500 to 700 [$^{\circ}C$], carbonization and exfoliation occurrence. Section structure of electric wire is same as arrangement of particle in metallograph analysis. But, as thermal stress increases, size of particle is enlarged. Electric wire displays elongation structure in SEM image analysis and elongation structure collapses when receive thermal stress at 300 [$^{\circ}C$]. In EDX analysis, we get the spectra of CuL, CuK, OK, and ClK. FT-IR analysis was shown new spectra with in range of $1,440{\sim}1,430\;[cm^{-1}]$, 1,340 [$cm^{-1}$], 1,240 [$cm^{-1}$].

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2121_2122
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• 2009

In this paper, we analyzed carbonization pattern of Ligth Emitting Diode(LED) lamp that become burnout by outside flame. Surface side can know that void is formed greatly than central part in section analysis of electric wire that is carbonized by outside flame. Chared globe displayed special quality that lump of abnormal carbonization falls was formed, and becomes melting among carbonization process. The LED resistance of forward direction is about 1.74 [$M{\Omega}$], and backward resistance is about 140 [$M{\Omega}$]. We can know progress direction of flame through measurement of the LED resistance.

• Transactions on Electrical and Electronic Materials
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• v.2 no.2
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• pp.5-15
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• 2001

The experiment established optimal conditions for over-carbonization. With the use of the electron microscopy and X-ray phase analysis the regularities of carbon deposit formation in process of methane and propane pyrolysis on the zeolites, Kazakhstan natural clays, chrome and bauxite sludge containing metal oxides of iron subgroup, have been studied. In process of over-carbonization the trivalent iron was reduced to metal form. In addition, the carbon tubes of divers morphology had been impregnated with ultra-dispersed metal particles. The kinetic parameters of carbon formation in process of methane decomposition on the zeolite - CoO mixture surface were investigated by method of thermo-gravimetric analysis. The morphology and structure of formed carbon fibrils, with the metal particles fixed at their ends, have been investigated, the formation of branched carbon fibrils pattern, so called octopus, being found. Also, the walnut shells and grape kernel carbonization, their immobilization by the cells of selective absorption of heavy metal and sulfur dioxide ions have been studied. The example of metal-carbon composites used as adsorbents for wastewater purification, C$_3$- C$_4$ hydrocarbon cracking catalysts and refractory materials with improved properties have been considered.

• Fire Science and Engineering
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• v.34 no.4
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• pp.101-106
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• 2020

This study analyzed flame growth characteristics and carbonization patterns when floor materials were burned vertically using a needle flame produced for this study. It was found that PVC flooring was fire retardant and the area under direct flame contracted inward. Vertical combustion causes solidification in the form of a lump at the bottom and also generates soot in a pattern that progresses upwards. This study found that laminated flooring exhibited no fire retarding characteristics and that the laminated layer of its upper surface was destroyed by fire, causing irregular delamination. The carbonization ranges at the left and right sides were determined to be symmetrical. A vertical combustion test of a sample carpet showed that it exhibited no fire-retarding characteristics. It was observed that if heat accumulated in the carpet, the flame formed an ascending air current, and that when flammable materials were present around the flame, they further accelerated the diffusion of the flame. The carbonization pattern at the carpet surface exposed to direct flame revealed that the carpet surface had melted and had flown downwards and that many tiny holes formed on it.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.161-167
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• 2009

Organic insulating materials which are utilized as insulating materials for the low voltage show unique carbonization characteristics when they are carbonized by a leakage current. Therefore the use of the carbonization characteristics makes it possible to examine the electrical fire which is caused by a leakage current flowing on the surface of the organic insulating material. In order to understand such carbonization characteristics, in this paper, experiments have been done to carbonize typical organic insulating materials such as phenol resin, PVC, and acrylic resin, and the carbonization patterns and the IR absorption spectrum of specimens have been analyzed. According to the analysis of the carbonization patterns, the phenol resin shows the so-called 'spider-leg' carbonization pattern due to a thermosetting property. In contrast to the phenol resin, the thermoplastic property makes it difficult to observe a clear carbonization pattern to verify carbonizing causes on the surfaces of PVC and acrylic resins. In this case, the IR absorption spectrum can be analyzed to examine the specimen carbonized by a leakage current. The analysis result shows that absorption peaks appear at the wave numbers of $3,400[cm^{-1}]$ and $1,618[cm^{-1}]$, which can be an important factor to verify the carbonizing causes.

• 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.

• Fire Science and Engineering
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• v.33 no.6
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• pp.120-125
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• 2019

A real-scale combustion test was conducted on a vinyl flooring in a divided space, with 50 mL of an inflammable liquid sprayed on it. The combustion behavior of the vinyl flooring was studied in real time, and the carbonization patterns of the surface and cross-sections of the carbonized vinyl floor were analyzed. When the flame ignited by gasoline reached its peak, a continuously flaming region, intermittent flaming region, plume region, etc., were formed. The combustion of 50 mL gasoline on vinyl flooring took 26 s, and a halo pattern was observed. This test involved spraying kerosene evenly on the vinyl flooring and attempting to ignite the flooring using a gas torch, which failed. After the combustion of the vinyl flooring was complete, its carbonized range was measured to be 600 mm in length and 380 mm in width, and the carbonized area was 1000 ㎟. Heat transformed the coated layer of surface of the carbonized vinyl flooring into a carbonized layer, which became harder. The analysis of cross-section of the boundary surface of the carbonized vinyl flooring using a stereoscopic microscope showed that the vinyl flooring was bubbling, and that the white boundary layer at the bottom of the coated layer had disappeared.