• Journal of Korea Water Resources Association
• /
• v.42 no.8
• /
• pp.631-641
• /
• 2009

Transport of nitrous oxide and treated waste water was investigated in an estuary receiving treated waste water. Seasonal change of water quality were also observed to assure origins of $N_2O$ and to estimate the influence of treated waste water on $N_2O$ production in the survey area. Based on nitrous oxide concentration profiles in the survey area, discharged treated waste water were traced, which flowed upstream at the flood tide and downstream at the ebb tide with concentration maxima. It is assumed that nitrous oxide discharged from treated waste water is transported to the survey area with partial and vertical mixture. To determine the production of $N_2O$ in survey area, flux at each sampling sites were calculated and 25% of the produced $N_2O$ was originated from treated waste water in result. The remaining percentage of the production was also assumed to be the discharge from the sediment layers.

• Journal of Korea Water Resources Association
• /
• v.32 no.4
• /
• pp.501-510
• /
• 1999

Stream and groundwater qualities of small agricultural watershed in Kangwon Probince, Korea were monitored 1 to 2 years, and the relationships between stream and groundwater qualities and seasonal water quality changes analyzed. Flooded paddy fields influenced groundwater level and quality during rice culture. The differences between groundwater levels during rice culture and non-culture spans were between 0.8 and 2.91 m. Seasonal changes of total nitrogen and nitrate nitrogen concentrations of stream and groundwater were very similar and groundwater quality was thought to have a profound impact on stream quality of the research watersheds. Suspended solids and BOD maintained the first degree stream water quality throughout the monitoring period except for a few and short flooding spans. The concentrations of total phosphorus and total bacteria of both waters showed wide variations and any seasonal trends were not observed. Long-term monitoring studies on small rural watersheds were recommended to understand the pattern of both stream and groundwater quality changes with respect to land use, season and cultural practice, and to apply the results to develop effective water quality management policies for large river and domestic water supply systems.

• Microbiology and Biotechnology Letters
• /
• v.20 no.6
• /
• pp.668-676
• /
• 1992

For the purpose of optimizing poly-l3-hydroxybutyrate (PHB) production from Alcaligenes eutrophus, two-stage fed-batch culture was adopted. In this system, specifk growth rate was maximized during the first stage whereas specific production rate was maximized during the second stage. The optimal concentrations of glucose and ammonium chloride were 16.6 and 0.54 g/I in the growth stage and 20.0 and 0.07 g/l in the production stage, respectively. Proportional feedback control considering time lag was suggested for PHB production process and a simulator was developed for real-time control purpose.

• Korean Journal of Ecology and Environment
• /
• v.48 no.3
• /
• pp.147-152
• /
• 2015

Nitrogen (N) loading from domestic, agricultural and industrial sources can lead to excessive growth of macrophytes or phytoplankton in aquatic environment. Many studies have used nitrogen stable isotope ratios to identify anthropogenic nitrogen in aquatic systems as a useful method for studying nitrogen cycle. In this study to evaluate the precision and accuracy of Kjeldahl processes, two reference materials (IAEA-NO-3, N-1) were analyzed repeatedly. Measured the ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values of IAEA-NO-3 and IAEA-N-1 were $4.7{\pm}0.2$‰ and $0.4{\pm}0.3$‰, respectively, which are within recommended values of analytical uncertainties. Also, we investigated spatial patterns of ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ in effluent plumes from a waste water treatment plant in Han River, Korea. ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values are enriched at downstream areas of water treatment plant suggesting that dissolved nitrogen in effluent plumes should be one of the main N sources in those areas. The current study clarifies the reliability of Kjeldahl analytical method and the usefulness of stable isotopic techniques to trace the contamination source of dissolved nitrogen such as nitrate and ammonia.

• Electrical & Electronic Materials
• /
• v.7 no.5
• /
• pp.397-402
• /
• 1994

기계적 합금화방법을 이용 실온에서 철분말의 질화물을 얻을 수 있다. 이때 얻어진 준안정 철질화물은 질소농도가 14.9[at. %N]이하에서는 bcc 구조의 과포화 고용체가, 그리고 19.4[at. %N]이상에서는 고온상인 hcp 구조임을 확인할 수 있었다. 또한 bcc상의 Fe원자당 Volume은 문헌에 보고된 N-martensite의 것보다 작은 값을 나타내었다. 제조된 철질화물의 실온 포화 자화값은 질소농도가 증가함에 따라 감소하였으며, 이 결과는 bct 구조의 철질화물에서 질소농도가 증가함에 따라 자화값이 증가하는 것과 대조적이었다.

• The Korean Journal of Ecology
• /
• v.27 no.4
• /
• pp.199-210
• /
• 2004

Effects of nitrogen and phosphorus fertilization on seasonal changes of nutrient content in tree components, and retranslocation N and P in foliage and twig were determined in adjacent 41-year-old plantations of Pinus rigida Miller and Larix kaempferi Gordon on a similar soil in Yangpyeong, Gyeonggi Province. In general, foliage N and P concentrations of L kaempferi were significantly higher than current and 1-year-old foliages of P. rigida. N and P concentrations were higher in foliage than in twigs for both tree species. However, there were no significant differences in foliage and twig N and P concentrations with ages. Significant seasonal differences in foliage and twig N and P concentrations were observed for both tree species because of nutrient retranslocation. Foliage nutrient concentrations were highest in the mid-growing season and lowest in autumn, whereas twig nutrient concnetrations have gradually increased since July. These seasonal trends indicated nutrient retranslocation from foliage into twigs before foliage senescence. However, there were no significant changes in foliage and twig nutrient retranslocation, and no consistent patterns in foliage and twig nutrient retranslocation following N and P fertilizer additions. No significant changes in nutrient retranslocation between different foliage and twig ages were observed following fertilization.

• Korean Journal of Remote Sensing
• /
• v.38 no.2
• /
• pp.215-222
• /
• 2022

In this study, the effect of wavelength range and absorption cross-section used to retrieve nitrogen dioxide (NO₂) vertical column density (VCD) from Pandora was analyzed using Differential Optical Absorption Spectroscopy (DOAS). During the GEMS Map of the Air Pollution (GMAP) 2020 campaign, data from direct sunlight observation with Pandora instrument in Seosan was used, and NO₂ VCD was retrieved under four conditions. The average NO₂ VCD under the four conditions ranged from 1.22×10¹⁶~1.38×10¹⁶ molec. cm^-2, with a maximum difference of 0.16×10¹⁶ molec. cm^-2 between each condition. The fitting error averaged 3.19~9.59%, showing an error within 10% in all cases, and the RMS was 5.11×10^-3~7.16×10^-3 molec. cm^-2. The retrieved NO₂ VCD using 4 conditions shows a slope in the range of 0.98 to 1.09 and correlation of 0.96 to 0.98 in comparison with Pandonia Global Network (PGN).

• Journal of Aquaculture
• /
• v.7 no.3
• /
• pp.177-187
• /
• 1994

The objective of the present study were to evaluate nitrification characteristics and determine optimum treatment conditions of three phase fluidized bed reactor for recycling water treatment of aquaculture. When the loading rates were 2.739-0.086kg $COD/m^3/day$ and 1.575-0.128kg $NH_4\;^+-N/m^3/day$, COD and ammonia removal efficiencies were $56.3-94.7\%\;and\; 67.3­92.6\%$, respectively. The maximum removal rates of COD and ammonia were 1200mg/l/day and 488mg/l/day, respectively. Ammonia removal rates were more than $90\%$ beyond 1hr HRT. The ammoniaremoval efficiency was sensitive to the variation of media concentration and air flowrate.

• Journal of Conservation Science
• /
• v.27 no.2
• /
• pp.231-241
• /
• 2011

Anoxia Treatment using inert gas like nitrogen and argon has been used to eradicate insects successfully in museums as alternative of methyl bromide and toxic insecticide. Killing efficacy of insect for anoxia treatment is depend on species of insects, oxygen concentration, temperature, relative humidity and gas. It is possible to kill museum insects which are most tolerant in anoxia environment, within 1 month below 0.03% of oxygen concentration in temperature $15{\sim}25^{\circ}C$ and relative humidity 40~60% of museum environment. And various systems like bag, tent, bubble and chamber depending on size and quantity of objects, are used.

• Korean Journal of Soil Science and Fertilizer
• /
• v.6 no.4
• /
• pp.213-219
• /
• 1973

Effects of three slow-release nitrogen fertilizers (Sulfur-coated urea, (SCU) Jin Hae Chemical Co. Korea(JHC); Tennessee Valley Authority. U.S.A(TVA); METAP, Japan) on the yield and nitrogen uptake of IR667 (Suwon 213) were investigated comparing with urea split application under the field condition with early and usual saeson cultivation. 1. SCU(JHC) was not superior than urea split application in yield and nitrogen nutrition due to early release of nitrogen. 2. SCU(TVA) outyielded urea split by 10% showed always highest nitrogen content in straw and most balanced relative cumulative curve of nitrogen uptake or dry matter yield. 3. At ear formation stage SCU(TVA) showed specially high nitrogen content which was highly correlated with number of grain per $m^2$ of field. 4. Only SCU(TVA) showed one peak curve of nitrogen uptake rate at ear formation stage while others showed two peak pattern. 5. nitrogen fertilizer recovery of slow-release fertilizers was higher than urea split in early season cultivation and SCU (TVA) (46.0) was higher but SCU(JHC) (38.9) was similar in compare with urea split(37.1) in usual season cultivation. 6. Most promising slow-release nitrogen to match plant requirement seems to be one mixed of various slow-release fertilizers having different release pattern.