• 웰빙융합연구
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• 제6권3호
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• pp.19-23
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• 2023

Purpose: High concentrations of nitrogen exist in food wastewater, and when nitrogen is not properly treated and discharged, it can cause eutrophication in the aquatic ecosystem. Research design, data and methodology: In order to remove nitrogen using sodium hypochlorite, the BNCR tank was designed and installed in the step behind the biological treatment tank, and the data of pH, TOC, and T-N were collected after about a month of demonstration. Results: As a result of operating the BNCR tank, total nitrogen decreased by about 83% on average. The total nitrogen in the second sedimentation tank before going through the BNCR tank must be removed and finally discharged after nitrogen is removed above the legal standard of 60 mg/L. Conclusions: If BNCR tank is added to the process currently applied to nitrogen removal and operated, ammonia nitrogen can be removed more efficiently. However, the disadvantage is that nitric acid nitrogen and nitric acid nitrogen cannot be removed. If these disadvantages are supplemented and optimized in the future, it will be helpful for workplaces that are having difficulty removing nitrogen.

• Agricultural and Biosystems Engineering
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• 제7권1호
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• pp.18-26
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• 2006

In-field site-specific nitrogen (N) management increases crop yield, reduces N application to minimize the risk of nitrate contamination of ground water, and thus reduces farming cost. Real-time N sensing and fertilization is required for efficient N management. An 'on-the-go' site-specific N management system was developed and evaluated for the supplemental N application to com (Zea mays L.). This real-time N sensing and fertilization system monitored and assessed N fertilization needs using a vision-based spectral sensor and controlled the appropriate variable N rate according to N deficiency level estimated from spectral signature of crop canopies. Sensor inputs included ambient illumination, camera parameters, and image histogram of three spectral regions (red, green, and near-infrared). The real-time sensor-based supplemental N treatment improved crop N status and increased yield over most plots. The largest yield increase was achieved in plots with low initial N treatment combined with supplemental variable-rate application. Yield data for plots where N was applied the latest in the season resulted in a reduced impact on supplemental N. For plots with no supplemental N application, yield increased gradually with initial N treatment, but any N application more than 101 kg/ha had minimal impact on yield.

• 한국환경과학회지
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• 제26권1호
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• pp.119-131
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• 2017

This study evaluated the feasibility of recovering and recycling nitrogen (N) and phosphorus (P) from livestock excreta as struvite ($MgNH_4PO_4{\cdot}6H_2O$) in South Korea. Our experimental results showed that struvite precipitation was a very effective way to recover N and P from livestock excreta. Moreover, our study demonstrated that struvite precipitates from livestock excreta (SPL) contain higher concentrations of N, P, and magnesium (Mg) as compared to compost and liquid manure from livestock excreta. In addition, although SPL contain high concentrations of copper (Cu) and zinc (Zn), they meet the fertilizer criteria for concentrations of heavy metals. In South Korea, SPL cannot currently be used as a fertilizer due to legal constraints. Legal permission for SPL use would offer greater choice in livestock excreta management. In conclusion, recovery and recycling of N and P from livestock excreta as struvite can be an effective tool for managing nutrients in livestock excreta.

• 대한안전경영과학회지
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• 제4권2호
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• pp.209-221
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• 2002

Machinability improvement by the use of liquid nitrogen in cryogenic machining has been reported in various studies. This has been mostly attributed to the cooling effect of liquid nitrogen. However, No study has been found in discussion on whether liquid nitrogen possesses lubrication effect in cryogenic cutting. In machining tests, cryogenic machining reduced the force component in the feed direction, indicating that the chip slides on the tool rake face with lower friction. This study also found that the effectiveness of LN2 lubrication depends on the approach how LN2 is applied regarding cutting forces related.

• 한국정밀공학회지
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• 제25권1호
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• pp.92-98
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• 2008

The flame image observation and analysis has been investigated for combustion monitoring and management of the pulverized coal firing for thermal power plant, especially for lower nitrogen oxide generation and safer operation. We aimed at obtaining the relationship between burner flame image information and emissions of nitrogen oxide and unburned carbon in furnace utilizing the flame image processing methods, by which we quantitatively determine the conditions of combustion on the individual homers. Its feasibility test was undertaken with Samchonpo thermal power plant #4 unit which has 24 burners, through which the system was observed to be effective for evaluating the combustion conditions and continuous monitoring to prevent future loss of ignition.

• The Korean Journal of Ecology
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• 제26권2호
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• pp.71-74
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• 2003

Effects of nitrogen addition on the growth of Indigofera pseudo-tinctoria (Leguminosae) in the waste landfill site was investigated. Nitrogen fertilization in the nitrogen poor soils of waste landfill may influence the growth of nitrogen fixing plants beneficially or detrimentally. When I. pseudo-tinctoria was fertilized with three different levels of nitrogen, the coverage of plants treated with 46 g N/$m^2$ and 460 g N/$m^2$ was significantly less than that of plants treated with 23 g N/$m^2$. The growth rates of plant height treated with 46 g N/$m^2$ and 460 g N/$m^2$ were significantly less than those of plants treated with 23 g N/$m^2$. The growth rates of plant diameter treated with 46 g N/$m^2$ and 460 g N/$m^2$ were significantly less than those of plants treated with 23 g N/$m^2$. Dry weights of whole plants in control sites were higher than those of all the others nitrogen treatment sites. Nodule numbers were higher in control plants than those of plants in all the other nitrogen treatment sites. It is suggested that nitrogen fertilizer addition over 23 g N/$m^2$ affect the growth of some nitrogen fixing plants, such as I. pseudo-tinctoria, negatively.

• 한국환경보건학회지
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• 제46권6호
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• pp.646-654
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• 2020

Objectives: Users of parks or children's play facilities have pointed to pets' bowel movements as the most serious problem when using them. In prior studies, a very low detection rate of parasites (eggs) in sand flooring materials has been found. Even though feces have been identified, no parasites (eggs) have been detected. Method: A standard solution of nitrate nitrogen was used to verify the reliability of a new nitrogen analysis method. The linearity, precision, and accuracy of the nitrate nitrogen analysis method were verified. Using this method, the pollution distribution of the sand flooring material and the degree of pollution at each point were investigated. Results: As a result of the verification of the nitrogen analysis method, the linearity was found to be good at r2=0.999 when distilled water is mixed in a standard substance solution. The standard substance additive solution r2=0.968 was found to be good. Precision represented 0.01 to 0.06% RSD for peak height. The recovery rate was 92.4 to 104.0 percent, indicating high accuracy. According to the same method of analysis, the flooring material sand at a general amusement facility with the largest number of concealed spaces was nitrate nitrogen 6.1 times higher than at the entrance of the playground. Also, in a comparison between clean sand and sandy flooring, the average nitrogen concentration of the sand flooring material was 24.4-167 times higher than pure sand. Conclusions: As such, no parasites (eggs) were detected at all points under investigation, but the sand flooring was exposed to animal fecal contamination. Therefore, the management of nitrogenous components should allow accurate identification of animal fecal contamination so that the timing of sand replacement can be managed hygienically and safely.

• 한국수산과학회지
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• 제47권5호
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• pp.622-629
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• 2014

This study induced biological denitrification and nitrification via a biofiltration process with the view of removing nitrogen from land-based fish farm effluent. To achieve this, we operated an aquaculture nitrogen-removal system that includes a denitrification and nitrification reactor [working volume 40 L, flow rate 64.8 L, HRT (hydraulic retention time) 14.8 h, HRT considering recycling of NOx 7.4 h]. In the continuous process, the nitrification rate of ammonium nitrogen exceeded 90% at a steady state and the denitrification efficiency exceeded 80% with recycling to a pre-anoxic reactor. In addition, the pH in the final effluent was lower with a low influent water alkalinity averaging 100 mg/L (as $CaCO_3$). For effective denitrification reactions, carbon must be supplied via particulate organic matter (POM) hydrolysis because of the low C/N (carbon/nitrogen) ratio in the water.

• 한국폐기물자원순환학회지
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• 제35권7호
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• pp.647-652
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• 2018

The emission of nitrogen oxides has a great environmental impact. It leads to Los Angeles type smog, and it recently has attracted attention as a source of ultrafine dust. The main sources of nitrogen oxides are internal combustion engines and industrial boilers. These emission sources are processes that are essential for human industrial activities, so the regulation of original use is impossible. Therefore, special control methods should be applied to reduce NOx emissions into the atmosphere. In this study, we investigated how the supply of ER and urea influences the removal of nitrogen oxides from SRF combustion boilers. Experimental results show that the removal efficiency of nitrogen oxides can be up to 80% under the conditions of ER 2.0 and a urea feed of 0.5 LPM.

• 한국응용과학기술학회지
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• 제22권1호
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• pp.62-70
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• 2005

Step-feed process for biological nitrogen removal were analyzed numerically for the each unit and final total nitrogen(TN) effluent by water quality management(WQM) model and the results were compared data from these wastewater treatment plants. No bugs and logic error were occurred during simulation work. All of the simulation results tried to two times were obtained and both results were almost same as this model has become good reappearance. It was concluded that most of nitrogen removal occurred in the first oxic tank. Thus the controlling of the first anoxic tank may be more important in term of nitrogen removal. Also each unit of simulation result was kept good relationship with that of measured data. Accordingly this WQM model has good reliance. Finally, WQM model can predict final TN effluent within ${\pm}6.0mg/{\ell}$.