• Journal of Environmental Science International
• /
• v.4 no.5
• /
• pp.509-516
• /
• 1995

The treatment performances of anaerobic-aerobic activated sludge process were investigated under various operation conditions. The treatment system proposed in this study gave a relatively stable performance against hourly change of the flow rate and showed a satisfactory removal of nitrogen and phosphorus compounds under experimental conditions. The recycle ratio of mixed liquor from aerobic to anaerobic region and peak coefficient primarily controlled the extent of nitrogen removal. The recycle ratio had the optimum values which were determined by the microbial activities of nitrification and denitrification. The behavior of the treatment unit could be simulated by using the kinetic equations and reactor models which considered the treatment units as complete mixing tanks.

• Journal of Environmental Science International
• /
• v.4 no.5
• /
• pp.123-123
• /
• 1995

The treatment performances of anaerobic-aerobic activated sludge process were investigated under various operation conditions. The treatment system proposed in this study gave a relatively stable performance against hourly change of the flow rate and showed a satisfactory removal of nitrogen and phosphorus compounds under experimental conditions. The recycle ratio of mixed liquor from aerobic to anaerobic region and peak coefficient primarily controlled the extent of nitrogen removal. The recycle ratio had the optimum values which were determined by the microbial activities of nitrification and denitrification. The behavior of the treatment unit could be simulated by using the kinetic equations and reactor models which considered the treatment units as complete mixing tanks.

• Journal of the Korean institute of surface engineering
• /
• v.27 no.3
• /
• pp.143-148
• /
• 1994

Effects of process variables of HCD ion plating on the film composition of Ti(C, N) were analyzed. The mole ratio of carbon to nitrogen and that of non-metal to titanium in the film primarily depend on the partial pressure ratio of ($C-2H_2$/ $N_2$) and total reactive gas pressure, respectively. The amount of nonmetallic com-ponents increases in nonlinear fashion as the total gas pressure due to the different reactivity of $C-2H_2$ and $N_2$ gases with Ti. The nonmetallic components was saturated dwith nitrogen when the nitrogen gas was more than 60% of total reactive gas. These two process variables could be related systematically using the concept of effective pressure in which the difference of reactivity of each gas was normalized.

• Journal of Korean Society on Water Environment
• /
• v.24 no.4
• /
• pp.499-503
• /
• 2008

In order to control the non-point source pollution, a vegetative filter strips (VFS) was set up and the site-monitoring was performed. The objective of this study is to investigate the influence of the plant coverage on treatment efficiency of total nitrogen (T-N) and total phosphorus (T-P) using vegetative filter strips. According to the results, it seemed that the treatment efficiencies of T-N and T-P were closely related with the plant coverage ratio. The results showed that treatment efficiency of T-P average 50% at higher than 50% of the plant coverage and 20~23% at lower than 50% of the plant coverage. Also, the treatment efficiency of T-N increased with the increase of the plant coverage ratio.

• Journal of Environmental Science International
• /
• v.21 no.3
• /
• pp.383-390
• /
• 2012

For the cost-effective biological nitrogen removal (BNR) process whose characteristics of influent have low COD/N ratios, the automatic control system for the addition of external carbon based on oxidation-reduction potential (ORP) data in an anoxic reactor has been developed. In this study, it was carried out with a pilot-scale Bardenpho process which was consisted of anoxic 1, aerobic 1, aerobic 2, anoxic 2, aerobic 3 tank and clarifier. Firstly, the correlation coefficient ($R^2$) of the dosage of external carbon source and ORP value was about 0.97. Consequently, the automatic control system using ORP showed that the dosage of external carbon source was decreased by about 20% compared with a stable dosage of 75 mg/L based on the COD/N ratio of the anoxic influent.

• Journal of Ecology and Environment
• /
• v.42 no.4
• /
• pp.278-284
• /
• 2018

Plant functional traits have been shown to be useful to understand how and why ecosystems and their components vary across environmental heterogeneity or gradients. This study investigated how plant functional (leaf) traits vary according to an elevation-associated environmental gradient. Environmental gradients (mean annual temperature and precipitation) were quantified, and leaf traits (leaf area, specific leaf area, leaf nitrogen, leaf phosphorus, leaf carbon, and leaf C/N ratio) of the understory woody plant species Acer pseudosieboldianum were examined across an elevational gradient ranging from 600 to 1200 m in a Baegunsan Mountain in Gwangyang-si, Jeollanam-do, South Korea. The results showed that mean annual temperature and precipitation decreased and increased along with elevation, respectively. Leaf area of the plant species decreased slightly with increasing elevation, while specific leaf area did not differ significantly. Leaf nutrients (nitrogen, phosphorus, and carbon concentrations) were higher at high elevations, but leaf C/N ratio decreased with elevation.

• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.58.2-58.2
• /
• 2020

We present a method for determining the abundance ratio of nitrogen to iron ([N/Fe]) from low-resolution (R~2000) stellar spectra from large spectroscopic surveys such as Sloan Digital Sky Survey (SDSS) and Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). The basic idea of the method is to match a grid of synthetic spectra with an observed spectrum in the CN band region around 3883 Å. To calibrate our estimate of [N/Fe], we make use of the giants observed in Apache Point Observatory Galaxy Evolution Experiment (APOGEE), which are also observed in the SDSS. This method will be applied to the Galactic halo stars to determine [N/Fe], and the measured nitrogen abundance ratios will be used to investigate the C-N anti-correlation, which is observed in globular clusters, to trace their origin with their kinematic properties.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.6 no.2
• /
• pp.63-70
• /
• 2001

Changes in concentrations of dissolved oxygen, ammonia, nitrate, pH, Fe and Mn were monitored from the laboratory incubation of an benthic chamber. The extent of sedimentary organic carbon and nitrogen decomposition was quantified by applying the concentration data to the chemical reaction equations of early diagenesis. The patterns of the concentration changes, observed during the 237 hr long incubation experiment, made it possible to divide the entire experiment period into four characteristic sub-periods (0-9 hr, 9-45 hr, 45-141hr, 141-237 hr). C/N ratio, estimated for each sub-period, was 6.63, 1.49, 0.81 and 0.02, respectively. This sequential decrease in C/N ratio suggests that during the incubation experiment dissolved nitrogen species diffuse more out of the sediment than dissolved carbon species. Greater diffusion of nitrogen indicates the preferential decomposition of organic nitrogen during early diagenesis of sedimentary organic matter. Comparison of the concentration data (sedimentary organic carbon and nitrogen, porewater organic carbon and ammonia)between the sediment pre and post incubation also indicates the preferential decomposition of nitrogen during early diagenesis of sedimentary organic matter.

• Journal of the Korean Magnetics Society
• /
• v.3 no.2
• /
• pp.87-93
• /
• 1993

Iron nitride (Fe-N) magnetic thin films were deposited using a DC magnetron sputtering system. Microstructures and magnetic properties were examined as a function of deposition power and nitrogen gas input ratio. The nitrogen content in the film was found to be the major factor determining the microstructure and the magnetic properties. The films deposited at low nitrogen input ratios have an $\alpha$-Fe structure of which the lattice is expanded due to the nitrogen atoms incorporated at the interstitial sites. As the nitrogen content in the film increases, the degree of lat-tice expansion increases and the value of saturation magnetization decreases linearly. The films with a high degree of lattice expansion give very low values of coercivity, which is attributed to the disturbance of colunmar growth and the decrease of surface roughness. Further increase in the nitrogen input ratio causes the phase transfonnation from $\alpha$-Fe to $Fe_{2-3}N$, resulting in the marked reduction in the saturation magnetization. The phase transformation occurs when, regardless of deposition conditions, the nitrogen content reaches at 15 at.% and the lattice is expanded by 5%.

• KSBB Journal
• /
• v.24 no.3
• /
• pp.296-302
• /
• 2009

This paper was investigated the research regarding the effects of several factors such as initial ammonium nitrogen concentration, aeration rate. biomass amount and C/N ratio on nitrification process using synthetic wastewater and activated sludge obtained from wastewater treatment facility. As a result, in high ammonium nitrogen concentration above 100 mg/L, the pH of wastewater was dropped to pH 6.8. The increases of initial ammonium nitrogen concentration, aeration rate and initial biomass amount were linearly enhanced the removal rate of ammonium nitrogen. In the condition of C/N ratio of 0 to 3, high ammonium nitrogen removal rate was obtained.