• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1817-1824
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• 2000

This study is carried out to investigate the discharge characteristics of PCDD/Fs from municipal solid waste(MSW) incinerator, According to the results measured at several air pollution control devices(APCDs), the largest amount of polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/Fs) are found at selective catalytic reduction (SCR) inlet. Therefore, it concludes that the electrostatic precipitator(EP) provides the appropriate condition for the formation of PCDD/Fs. The concentration of PCDD/Fs shows a large difference with the season. The concentration of PCDD/Fs in winter is higher than that of autumn, which suggests that the formation of PCDD/Fs is affected by the MSW components and the operation condition of municipal solid waste incinerator(MSWI).

• Nuclear Engineering and Technology
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• v.46 no.3
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• pp.431-438
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• 2014

The effect of various pH agents on the corrosion behavior of carbon steel was investigated under a simulated secondary water chemistry condition of a pressurized water reactor (PWR) in a laboratory, and the steel's corrosion performance was compared with the field data obtained from Uljin NPP unit 2 reactor. All tests were carried out at temperatures of $50^{\circ}C-250^{\circ}C$and pH of 8.5 - 10. The pH at a given temperature was controlled by adding different agents. Laboratory data indicate that the corrosion rate of carbon steel decreased as the pH increased under the test conditions and the highest corrosion rate was measured at $150^{\circ}C$. This high corrosion rate may be related to high dissolution and instability of Fe oxide ($Fe_3O_4$) at $150^{\circ}C$. It was also found that an addition of ethanolamine (ETA) to ammonia was more effectivefor anticorrosion than ammonia alone, and that mixed treatment reduced 50% of iron or more at pHs of 9.5 or higher, especially in the steam generator (SG) and the moisture separator & re-heater (MSR).

• KSBB Journal
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• v.30 no.3
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• pp.97-102
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• 2015

This study aimed to evaluate the potential plantgrowth promoting effects of potassium polyacrylate, a superabsorbent polymer, and Bacillus sp. SH1RP8, a family of plant-growth-promoting bacteria. Potassium polyacrylate was selected as the polymer for use due to its high molecular weight and its ability to retain and continuously supply moisture. Plant-growth-promoting rhizobacteria (PGPR) were isolated from the soil and applied to plants growing in dry environments, such as saline conditions. The moisture absorption and retention abilities of potassium polyacrylate were evaluated at a high temperature ($50^{\circ}C$) and in a dry condition, during which time the polymer showed a water retention potential of 19606.07% after 29 days. To overcome the reaming problem in the soil environment, natural polymers (such as cellulose) were mixed with the potassium acrylate. The shoot growths of Peucedanum japonicum Thunb and Arundo donax were significantly enhanced when treated with the mixture of the isolated rhizosphere bacterium SH1RP8 and potassium polyacrylate (63.5 and 124.3%, respectively).

• Journal of Radiation Industry
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• v.7 no.2_3
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• pp.171-176
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• 2013

In previous study, the novel nanosized curdlan-silica complex for a sustain-releasing effect was developed by using gamma-irradiation. It can be applicable to use in various sustainr-eleasing formulation in agriculture industry. This study was conducted to investigate its storage stability and environmental toxicity in an accelerated condition. The complex samples were treated with high temperature condition ($65^{\circ}C$) during 3 weeks, and then sustain-releasing property of complex was verified thereby using Ion Chromatography on a weekly basis. The morphology of the complex was characterized using scanning electron microscopy (SEM). Results of Ion Chromatography analysis showed that sample treated for 3 weeks was similar to sustain-releasing pattern of non-treatment sample. We verify concluded that the complex is able to keep its sustain-releasing property and sustained-releasing in 3 years. Also the formulation has no environmental toxicity.

• Ocean Systems Engineering
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• v.5 no.1
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• pp.1-19
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• 2015

The water jetting system for a jack-up spudcan requires the suitable design considering the platform/spudcan particulars, environments, and soil conditions, either the surficial clay or surficial sand. The usage of water jetting depends critically on soil conditions. The water jetting is usually used for the smooth and fast extraction of the spudcan in the surficial clay condition. It is also required for inserting spudcan up to the required depth in the surficial sand condition, which is investigated in this paper. Especially, it should be very careful to use the water jetting during an installation of spudcan in the surficial sand condition, because there is a risk of overturning accident related to the punch-through. Therefore, in this study, the effect of water jetting flow rate and time on the change of soil properties and penetration resistance is analyzed to better understand their interactions and correlations when inserting the spudcan with water jetting in surficial sand condition. For the investigation, a wind turbine installation jack-up rig (WTIJ) is selected as the target platform and the multi layered soil (surficial sand overlaying clays) is considered as the soil condition. The environmental loading and soil-structure interaction (SSI) analysis are performed by using CHARM3D and ANSYS. This kind of investigation and simulation is needed to decide the proper water jetting flow rate and time of spudcan for the given design condition.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.2 no.2
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• pp.109-114
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• 1998

The induction of crassulacean acid metabolism(CAM) characterized by day/night acid fluctuation was investigated in leaves from 10 days exposure to elevated $CO_2$ concentration(1,000 ${\mu}L\;L^{-1}CO_2).$ For Pereskia aculeata, have $C_3-like$ gas exchange pattern in well watered condition and shift into CAM-like in water stress, showed a more typical CAM-like diurnal acid fluctuation. Whereas the massive diurnal fluctuation of acidity in typical CAM of Kalanchoe rosea was declined. The effect of short-term exposure to various concentrations of $CO_2$ on titratable acidity in P. aculeata and K. rosea was also investigated. To investigate the response of various $CO_2$ concentrations, four different $CO_2$ levels(350, 700, 1,000 and 1,500 ${\mu}L\;L^{-1})$ were imposed for 24hr and measured the titratable acidity at 06:00, when the acidity was maximum, and 14:00, when the acidity was minimum. The accumulation of acid in P. aculeata was enhanced markedly by higher concentration of $CO_2,$ while the level of acidity in f rosea did not highly respond to $CO_2.$ A notable difference between P. aculeata and K. rosea was the response of de-acidification to a higher concentration of $CO_2$ Increasing with $CO_2,$ the degree of do-acidification of P. auleata was increased while that of K. rosea was depressed.

• Environmental Engineering Research
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• v.19 no.1
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• pp.59-66
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• 2014

The aim of this study was to assess the effect of pre-aeration on sludge solubilization and the behaviors of nitrogen, dissolved sulfide, sulfate, and siloxane. The results of this study showed that soluble chemical oxygen demand in sewage sludge could be increased through pre-aeration. The pre-aeration process resulted in a higher methane yield compared to the anaerobic condition (blank). The pre-aeration of sewage sludge, therefore, was shown to be an effective method for enhancing the digestibility of the sewage sludge. In addition, this result confirms that the pre-aeration of sewage sludge prior to its anaerobic digestion accelerates the growth of methanogenic bacteria. Removal rates for $NH_3$-N and T-N increased simultaneously during pre-aeration, indicating simultaneous nitrification and denitrification. The siloxane concentration in sewage sludge decreased by 40% after 96 hr of pre-aeration; in contrast, the sulfide concentration in sewage sludge did not change. Therefore, pre-aeration can be employed as an efficient treatment option to achieve higher methane yield and lower siloxane concentration in sewage sludge. In addition, reduction of nitrogen loading by pre-aeration can reduce operating costs to achieve better effluent water quality in wastewater treatment plant and benefit the anaerobic process by minimizing the toxic effect of ammonia.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1183-1190
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• 2007

A metabolic uncoupler, 3,3',4',5-tetrachlorosalicylanilide (TCS), was used to reduce excess sludge production in biological wastewater treatment processes. Batch experiments confirmed that 0.4 mg/l of TCS reduced the aerobic growth yield of activated sludge by over 60%. However, the growth yield remained virtually constant even at the increased concentrations of TCS when cultivations were carried out under the anoxic condition. Reduction of sludge production yield was confirmed in a laboratory-scale anoxic-oxic process operated for 6 months. However, it was found that ammonia oxidation efficiency was reduced by as much as 77% in the presence of 0.8 mg/l of TCS in the batch culture. Similar results were also obtained through batch inhibition tests with activated sludges and by bioluminescence assays using a recombinant Nitrosomonas europaea (pMJ217). Because of this inhibitory effect of TCS on nitrification, the TCS-fed continuous system failed to remove ammonia in the influent. When TCS feeding was stopped, the nitrification yield of the process was resumed. Therefore, it seems to be necessary to assess the nitrogen content of wastewater if TCS is used for reducing sludge generation.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.305-316
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• 2007

Free field ground motion during earthquake is significantly affected by the local soil conditions and it is essential for the seismic design to perform the site specific ground response analysis. So, Round Robin Test (RRT) on ground response analysis was performed for three sites in Korea. A total of 12 teams presented the results of ground response analysis with used input soil properties based on own judgement. In this paper, the results of one dimensional equivalent linear analysis presented by 11 teams were compared to evaluate the effect of input soil properties on ground response analysis. Additionally, 4 influence factors on ground response analysis, that is shear wave velocity of soil layer, nonlinear dynamic deformational characteristics, bedrock depth and bedrock velocity were studied for assumed simple soil conditions.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.947-952
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• 1996

The effect of fluctuating temperature on the respiration of vegetables has been investigated. Spinach was selected as the experimental material because of its high respiratory activity and kept under the condition that temperature changed alternately at low and high levels every 4 hours. The low-high level temperature combination was set in $1-10^{\circ}C,{\;}1-20^{\circ}C{\;}and{\;}1-30^{\circ}C$. Respiration was evaluated in terms of quantity of $CO_2$ evolved from spinach. The evolution rate of $CO_2$ was determined by a change in its concentration. The evaluation rate of $CO_2$ followed closely the temperature change. In the temperature combinations at $1-10^{\circ}C{\;}and{\;}1-20^{\circ}C$, the relationship between $CO_2$ evolution rate and temperature was found to be able to express by Arrhenius law, while at $1-30^{\circ}C$, it did not obey the law.