• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2135-2146
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• 2011

The rail surface irregularity is generated severely by train braking effect in the section of station. The braking force increases slip rate and friction factors caused by wheel-rail contact points. It brings rail surface irregularity as well. In this study, interactions between wheel and rail were investigated using rolling contact fatigue theory and mechanism of rail degradation through fracture mechanics. For the more, the Von-Mises stress occurred on the rail due to the interaction between wheel and rail was analyzed using 3-D finite element method. The amounts of surface irregularity of rail were measured according to accumulated passing tonnage in urban railway in fields. Therefore, the maintenance of rail should be separated by running and braking sections to prevent RCF defects.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.505-508
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• 1999

In this study, weight loss, ESDD, surface conductivity and leakage current were measured at the different saline solutions by salt fog method. The magnitude of leakage current was higher at higher conductivity of 2 S/m saline water, but weight loss ESDD and surface conductivity which are indices of degradation were lower. This is considered that the current includes mainly ohmic component which doesn\`t contribute to surface degradation. In addition, it is shown that FFT could be useful in measuring initial transition from hydrophobic to hydrophilic surface.

• 방사선산업학회지
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• 제12권4호
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• pp.333-336
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• 2018

Natural lacquer was cured at room temperature at a relative humidity of 60% at $27^{\circ}C$ to obtain a lacquer film. Photolysis of lacquer was investigated by irradiating 1~75 kGy of gamma ray to this lacquer film. No significant changes were observed in the range of 1~10 kGy radiation. As the radiation doses were increased, the white spots were increased in the scanning electron microscope photographs. The increase of the white dots of the lacquer surface shows that the lacquer is degradation by radiation. As a result of IR spectral analysis of the lacquer surface with increasing irradiation dose, there was no significant change in $3,445cm^{-1}$ hydroxide group, $2,900cm^{-1}$ hydrocarbon group, and $993cm^{-1}$ triene group. However, the $1,745cm^{-1}$ carbonyl group was found to increase, and the $1,715cm^{-1}$ unsaturated hydrocarbon group and the $1,463cm^{-1}$ methylene group showed a tendency to decrease.

• Advances in materials Research
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• 제2권1호
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• pp.65-75
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• 2013

Heterogeneous photocatalysis is a rapidly developing field in environmental engineering. It has a great potential to cope with the increasing pollution in the air. The addition of a photocatalyst to ordinary building materials such as tiles, concrete, paints, creates environmental friendly materials by which air pollution or pollution of the surface itself can be controlled and diminished. This work reports the results of the laboratory research, especially carried out towards air purifying action and self-cleaning measurements. In particular the research was focused on the study of the photocatalytic behavior of industrially prepared tiles produced starting from commercial micro-sized $TiO_2$. Air purification action has been investigated through NOx degradation tests. On the contrary, the degradation of pollution at the surface, also called as self-cleaning action, is verified by the degradation of two different organic dyes: Rhodamine B (red color) and Metanil yellow (yellow).

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.109-112
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• 2000

Long chain fatty acids (LCFA) are potential inhibitors of bacteria involved in anaerobic digestion because of their surface activity. Precipitation of long-chain fatty acids with iron can improve the anaerobic degradation due to their precipitation and reducing surface properties. Degradation of stearic acid was improved in the presence of iron (II). The methane production was increased 1.6 times as compared to control. Iron-containing soil was applied for degradation of vegetable oil as model case. The methane production was increased 1.5 times as compared to control. Yield of methane production was 0.09 and 0.06L/g COD in experiment and control respectively. Optimum COD/Fe ratio was found 20 mg/mg. Iron (II) can be produced in the treatment system from iron (III) hydroxide or iron containing minerals.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.57-60
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• 2000

In this paper, study on the properties of the thermal degradated epoxy resin which is used in indoor insulation apparatus is performed to investigate the problems of the decreasing insulation characteristics and crack in the indoor insulation apparatus. As a parameter of variation, SEM, contact angle, surface resistivity, relative dielectric constant and weight loss are measured. As the results of the above measurements, the contact angle and surface resistivity of the epoxy resin has increased to 200$^{\circ}C$ in but at the above 200$^{\circ}C$ the values have decreased. The relative dielectric constants the thermal treated samples have increased on with the temperature increase. We find the volatile components of the epoxy resin compound has disappeared during thermal degradation by SEM. The insulation properties of the epoxy resin have increased by the 200$^{\circ}C$ but decreased in the above 200$^{\circ}C$.

• Ocean and Polar Research
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• 제24권1호
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• pp.47-53
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• 2002

To evaluate the effect of reed population on the distribution and activities of microorganisms, vertical distribution of heterotrophic bacteria, degradation rate of cellulose, extracellular aminopeptidase activity (APA) and metabolic diversity based on GN2 Microlog plate were measured at two salt marsh stations in Hogok-ri, Namyang Bay, west coast of Korea. The number of heterotrophic bacteria at station 1 (reed population inhabited area) showed 2 to 6 times higher than that of station 2 (exposed area) with exception in the surface layer. Cellulose degradation rates in station 1 showed more than 50%. month-I and higher than that of station 2 (10.2 to 38.4%. $month^{-1}$). Yet the APA at two stations did not show difference except surface layer and suggested that APA might not be a significant factor in degrading marsh plant debris. Lipid class compounds, cell wall polymers and L-alanine were widely used by microorganisms. The number and activities of bacterial populations especially concerned in plant debris degradation seemed to be stimulated by the reed communities.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.71-74
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• 2001

The conventional tracking testing as IEC-60587 is widely used In surface aging measurement of outside insulator because those testing can carry out very short time in Lab testing. Also IEC-60587 testing is able to offer the standard judgement of relative degradation level of outside HV machine. Therefore it is very useful method compare to previous conventional tracking testing method and effective Lab testing method. But surface discharges(SD) have very complex characteristics of discharge pattern so it is required estimation research to development of precise analysis method. In recent, the study of IIR-camera is carrying out discover of temperature of power equipment through condition diagnosis and system development of degradation diagnosis. In this study, SD occurred from IEC-60587 is measured with partial temperature distribution in real time, the degradation grade of SD is analyzed through produced patterns in IEC-60587 according to applied time.

• 한국세라믹학회지
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• 제27권2호
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• pp.226-232
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• 1990

The degradation phenomena and thermal stability of 2.5Y-TZP at low-temperature were studied by means of XRD, Raman spectra and microstructural analysis. The degradation of heat-treated 2.5Y-TZP at 20$0^{\circ}C$-20hr in air was observed on the TZP surface, be caused by the cracks generated from tlongrightarrowm transformation, and the cracks was propagated inside the polycrystalline body. The ZrO2 grain boundaries and grains near the crack were revealed as if these were diffused and dissolved. And it was also observed mlongrightarrowt transformation as the degraded TZP was refired at 140$0^{\circ}C$, and it was thought to be the fact that the moisture in atmosphere during the aging process contributed to the degradation. The thermal stability of 2.5Y-TZP was improved dramatically with an addition of 3w/o CeO2 or a provision of high Y2O3 concentration on the TZP surface.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.57-60
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• 2000

In this paper, study on the properties of the thermal degradated epoxy resin which is used in indoor insulation apparatus is performed to investigate the problems of the decreasing insulation characteristics and crack in the indoor insulation apparatus. As a parameter of variation, SEM, contact angle, surface resistivity, relative dielectric constant and weight loss are measured. As the results of the above measurements, the contact angle and surface resistivity of the epoxy resin has increased to 200$^{\circ}C$ in but at the above 200$^{\circ}C$ the values have decreased. The relative dielectric constants the thermal treated samples have increased on with the temperature increase. We find the volatile components of the epoxy resin compound has disappeared during thermal degradation by SEM. The insulation properties of the epoxy resin have increased by the 200$^{\circ}C$ but decreased in the above 200$^{\circ}C$.