• Corrosion Science and Technology
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• v.19 no.6
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• pp.281-287
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• 2020

Chloride ion is one of the most important corrosive agents in atmospheric corrosion, especially in marine environments. It has high adsorption rate and increases the conductivity of electrolytes. Since chloride ions affect the protective properties and the surface composition of the corrosion product, they increase the corrosion rate. A low level of chloride ions leads to uniform corrosion, whereas a high level of chloride ions may induce localized corrosion. However, higher solution temperatures tend to increase the corrosion rate by enhancing the migration of oxygen in the solution. This work focused on the effect of NaCl concentration and temperature on galvanic corrosion between A516Gr.55 carbon steel and AA7075T6 aluminum alloys. When AA7075T6 aluminum alloy was galvanically coupled to A516Gr.55 carbon steel, AA7075T6 was severely corroded regardless of NaCl concentration and solution temperature, unlike the corrosion properties of single specimen. The combined effect of surface treatment involving carbon steel and aluminum alloy on corrosion behavior was also discussed.

• Carbon letters
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• v.9 no.2
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• pp.108-114
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• 2008

We have demonstrated the feasibility of using electrospinning method to fabricate long and continuous composite nanofiber sheets of polyacrylonitrile (PAN) incorporated with zinc oxide (ZnO). Such PAN/ZnO composite nanofiber sheets represent an important step toward utilizing carbon nanofibers (CNFs) as materials to achieve remarkably enhanced physico-chemical properties. In an attempt to derive these advantages, we have used a variety of techniques such as field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high resolution X-ray diffraction (HR-XRD) to obtain quantitative data on the materials. The CNFs produced are in the diameter range of 100 to 350 nm after carbonization at $1000^{\circ}C$. Electrical conductivity of the random CNFs was increased by increasing the concentration of ZnO. A dramatic improvement in porosity and specific surface area of the CNFs was a clear evidence of the novelty of the method used. This study indicated that the optimal ZnO concentration of 3 wt% is enough to produce CNFs having enhanced electrical and physico-chemical properties.

• Particle and aerosol research
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• v.5 no.2
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• pp.45-52
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• 2009

Black carbon, which is a by-product of combustion of fossil fuel and biomass burning, is the component that imposes the largest uncertainty on quantifying aerosol climate effect. The direct, indirect and semi-direct climate effects of black carbon depend on its state of the mixing with other water-soluble aerosol components. The process that transforms hydrophobic externally mixed black carbon particles into hygroscopic internally mixed ones is called "aging". In most climate models, simple parameterizations for the aging time scale are used instead of solving detailed dynamics equations on the aging process due to the computation cost. In this study, a new parameterization for the black carbon aging time scale due to condensation and coagulation is presented as a function of the concentration of hygroscopic atmospheric components and the black carbon particle size. It is shown that the black carbon aging time scale due to condensation of sulfuric acid vapors varies to a large extent depending on the sulfuric acid concentration and the black carbon particle size. This result indicates that the constant aging time scale values suggested in the literature cannot be directly applied to a global scale modeling. The aging time scale due to coagulation with internally mixed aerosol particles shows an even stronger dependency on particle size, which implies that the use of a particle-size-independent aging time scale may lead to a large error when the aging is dominated by coagulation.

• Journal of Environmental Science International
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• v.13 no.10
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• pp.911-919
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• 2004

The purpose of this research was evaluated economical effect to apply alternative external carbon source. Conventional activated sludge process in municipal wastewater treatment plant was adapted and introduced to Biological nutrient removal processes to meet the newly enforced effluent quality standard for nutrient removal in Korea. Low $COD/NH_4^+-N$ ratio and higher nutrient concentration of influent characteristics force to inject external carbon source for denitrifying recycled nitrate. In the most case, methanol was used as external carbon source. But Methanol is expensive and very dangerous in handling. So we could find cheaper and safer external carbon source substituted methanol in last study. This alternative external carbon source is named RCS(recoverd carbon source) and a by-product of fine chemical product at chemical plant. When RCS was applied real municipal wastewater treatment plant, average $55\~65\%$ of T-N removal efficiency, 8.8mg/l of effluent T-N concentration, 11.3mg/l of effleunt COD concentration were obtained without effluent COD increase as against used methanol. To apply RCS in municipal wastewater treatment plant obtain approximately $\74.5%$ expenditure cost reduction in comparison with methanol dosage cost.

• KSBB Journal
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• v.9 no.4
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• pp.428-435
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• 1994

Cell growth and production of ${\alpha}$-amylase, acetic acid and lactic acid were investigated in Bacillus amyloliquefaciens(ATCC 23350) flask culture with various carbon sources. Maximum dry cell density increased with increase in initial maltose concentration. Maximum dry cell density was the highest(1.4g/$\ell$) at 10g/$\ell$ of initial glucose concentration. With 10g/$\ell$ of initial glucose concentration, maximum specific cell growth rate was obtained. Among the various carbon sources maximum ${\alpha}$-amylase production was obtained with 149 unit/ml at 20g/$\ell$ of initial maltose concentration. With 5g/$\ell$ of initial maltose concentration, maximum ${\alpha}$-amylase production rate was obtained. By increasing carbon source concentration, acetic acid formation decreased. Acetic acid formation was higher in glucose than in maltose. By increasing carbon source concentration, lactic acid formation increased. Lactic acid formation was higher in maltose than in glucose.

• Journal of Environmental Science International
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• v.23 no.11
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• pp.1827-1833
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• 2014

This study has been carried out to present the valuation system of soil carbon sequestration potentials of soil in accordance with the new climate change scenarios(RCP). For that, by analyzing variation of soil carbon of the each type of agricultural land use, it aims to develop technology to increase the amount of carbon emissions and sequestration. Among the factors which affects the estimation of determining the soil carbon model and influence power after the measurement on soil organic carbon, under the center of a causal relationship between the explanatory variables this study were investigated. Chemical fertilizers (NPK) decreased with increasing the amount of soil organic carbon and as with the first experimental results, when cultivating rice than pepper, the fact that soil organic carbon content increased has been found out. The higher the carbon dioxide concentration, the higher the amount of organic carbon in the soil and this result is reliable under a 10% significance level. On the other hand, soil organic carbon, humus carbon and hot water extractable carbon has been found out that was not affected the soils depth, sames as the result of the first year. The higher concentration of carbon dioxide, the higher carbon content of humus and hot water extractable carbon content. According to IPCC 2006 Guidelines and the new climate change scenario RCP 4.5 and the measurement results of the total amount of soil organic carbon to the crops due to abnormal climate weather, 1% increase in atmospheric carbon dioxide concentration was found to be small when compared to the growing rate of increasing 0.01058% of organic carbon in the soil.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E1
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• pp.11-20
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• 2003

To characterize airborne particulate carbon and its temporal variation in the heavily industrialized metropolitan city, Seoul in South Korea, aerosol sampling was performed from 1986 to 1996. Correlation coefficients of elemental carbon (EC) and organic carbon (OC) with mass concentration of fine particles ($\underline{\leq}$2.1 ${\mu}m$) are 0.73 and 0.51, respectively. EC concentrations of the fine particle mode are 10.1, 5.9, 4.5, and 7.4 ${\mu}g\;m^{-3}$ in winter, spring, summer, and autumn, respectively. On the other hand, OC concentration shows maximum value in winter and followed by autumn, summer, and spring. A seasonal peak in the ratio of OC to EC in fine particles was observed during the summer photochemical season from June to August. Concentrations of EC and OC in Asian dust storm events are generally higher than in non- Asian dust storm events except in 1990. The difference of EC concentrations between Asian dust storm periods and non-Asian dust storm periods are much larger than those of OC concentrations. There are slight increases of EC concentration between 1987 and 1990 and a gradual decrease between 1990 and 1996.

• Journal of the Korea Furniture Society
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• v.22 no.1
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• pp.13-17
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• 2011

Recently, interest in indoor air quality is increasing. Especially, radon radioactivity among the indoor air is a well-known risk factor for lung cancer because of ionizing radiation in the form of ${\alpha}$-particles. This study was carried out to investigate effect of black charcoal and activated carbon for reduction of radon radiation that emitted from building materials. Black charcoal and activated carbon were used as a barrier which was against the infiltration of radon. The source of radon was gypsum board. Two types of charcoal barrier were powder- and board-type with 5 mm, 10 mm thickness respectively. The method for this determination is evaluated radon concentration in chamber. The measurements were performed with radon detector, SARAD3120. Results of this study are as following: Black charcoal and activated carbon confirmed the highly efficient barrier. Radon concentration was reduced from 72% to 85% as compared the control chamber. Radon reduction capability, however, was no difference as barrier's types. Results obtained in ventilation condition, radon concentration shows 5.93 pCi/L on average in the closed condition and shows 2.69 pCi/L in the opened condition.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.323-330
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• 2009

Efficiency of a fuel cell is determined by the generated water. If water is not removed sufficiently, water will be accumulated at GDL, which causes flooding. Therefore, water control is regarded as a crucial factor to sustain fuel ell performance. In this study, PTFE coating on the surface of carbon paper was carried out to establish optimum process for hydrophobic treatment of GDL. Carbon paper was immersed at different concentrations of nano-sized PTFE coating solution. Their characteristics were analyzed systematically by FE-SEM, water contact angle, cyclic voltamogam, XRD and FT-IR. The quantitative correlation between the amount of coated-PTFE on a carbon paper and concentration of coating solution was carefully investigated. It is suggested that the amount of PTFE-coating on a carbon paper can be managed by means of controling concentration of coating solution.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.1-7
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• 2013

This study was to examine growth, carbon and nitrogen responses in foliage following forest fertilization in a red pine stand. Two types of fertilizer (N:P:K=113:150:37 kg $ha^{-1}$; P:K=150:37 kg $ha^{-1}$) were applied on late April 2011. Growth, carbon and nitrogen responses of foliage were monitored 3 times (July, September, November) after fertilization. Morphological growth responses (dry mass, leaf area, specific leaf area) with foliage age were not significantly (P > 0.05) affected by fertilizer application, while needle dry mass and leaf area of July were significantly lower in current-year-old than in one-year-old or two-year-old needles of September or November. Carbon concentration and content in foliage was little affected by fertilizer application compared with sampling month or needle age, while the NPK fertilizer produced high nitrogen concentration and content of foliage. The results indicate that nitrogen concentration and content in foliage may serve as an indicator of the nitrogen status by fertilization in a red pine stand.