• The Korean Journal of Ecology
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• v.20 no.4
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• pp.259-264
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• 1997

To determine patterns of nitrogen (N) and phosphorus (P) change in foliage and twig we collected branch samples of 40-year-old Pinus rigida and Larix leptolepis plantations every month during the growing season of 1996 in Yangpyeong, Kyonggi-Do. Significant seasonal differences on N and P concentrations in foliage and twig were observed for both study species because of nutrient retranslocation. P. rigida and L. leptolepis retranslocated 40 and 37% of foliar N and 86 and 16% of foliar P, respectively. Twig N and P retranslocation rates of P. rigida and L. leptolepis were 114 and 25%, and 42 and 70%, respectively. There were no significant differences in foliar N retranslocation rates between P. rigida and L. leptolepis while P retranslocation rate in foliage of P. rigida was higher than that of L. leptolepis. Our results suggested that twigs were the main sinks for retranslocated nutrients from foliages of the both study species.

• Membrane Journal
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• v.9 no.1
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• pp.43-50
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• 1999

The effects of water vapor on the permeation rates of oxygen and nitrogen through poly sulfone hollow-fiber membrane were investigated. The permeation rates of both 02 and $O_2$ were decreased significantly owing to the presence of water vapor. The permeation rate of oxygen with 100% relative humidity was reduced by as much as 20%, while the permeation rate of nitrogen decreased by 14% at 30 "C and 3kgf/$cm^2$ of upstream pressure. The permeation rates of $O_2$ were declined monotonously with running time and arrived at steady state values by the presence of water vapor. However, those of $N_2$ increased tentatively and then decreased to the steady state.tate.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.263-271
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• 2018

The objective of this work was to analyze organic matter removal, nitrification, biomass growth and membrane fouling in a submerged flat-sheet membrane bioreactor, fed with synthetic wastewater, of similar composition to the effluents generated in a fish meal industry. After biomass acclimatization with saline conditions of 12 gNaCl/L and COD/N ratio of 15 in the bioreactor, results showed that the organic matter removal was higher than 90%, for all organic loading rates (0.8, 1, 1.33 and $2gCOD/L{\cdot}d$) and nitrogen loading rates (0.053, 0.067, 0.089 and $0.133gN/L{\cdot}d$) tested during the study. However, nitrification was only carried out with the lowest OLR ($0.8gCOD/L{\cdot}d$) and NLR ($0.053gN/L{\cdot}d$). An excessive concentration of organic matter in the wastewater appears as a limiting factor to this process' operating conditions, where nitrification values of 65% were reached, including nitrogen assimilation to produce biomass. The analysis of membrane fouling showed that the bio-cake formation at the membrane surface is the most impacting mechanism responsible of this phenomenon and it was demonstrated that organic and nitrogen loading rates variations affected membrane fouling rate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.918-924
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• 2020

This study investigated diurnal fasting and postprandial total ammonia nitrogen (TAN) excretion rates in juvenile Oplegnathus fasciatus (rock bream; mean body weight 45.8±1.1 g) at three temperatures (15, 20, and 25℃) in a recirculating system (three replicates). The fish were hand-fed twice daily (09:00 and 17:00 h) with commercial food (46.7% protein) until satiation. The results showed that the fasting and postprandial TAN excretion rates were temperature-dependent. The mean hourly rates were 7.7 (15℃), 10.2 (20℃), and 11.9 (25℃) mg kg fish-1 h-1 for fasting and 34.0 (15℃), 47.8 (20℃), and 60.2 (25℃) mg kg fish-1 h-1 for postprandial. At each temperature, two postprandial TAN excretion peaks were observed 2-4 h after feeding; the second peak was always higher. The TAN loss to nitrogen consumption ratio was 41.1-46.8 % and increased significantly with increasing temperature. Temperature affected fasting and postprandial TAN excretion in juvenile rock bream, providing insight for culture management.

• Journal of The Korean Society of Grassland and Forage Science
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• v.20 no.2
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• pp.131-138
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• 2000

This experiment was carried out during the period from September, 1997 to October, 1998 to determine the effect of fermented saw-dust pig manure (FSP) application on the herbage production on a mixed pasture in the Cheju brown volcanic ash soil. Split plot design (main plot: 3 nitrogen application levels of 0, 150 and 300 kgiha; sub plot: 4 pig sawdust manure levels of 0, 3, 6 and 12 tonha) was used. Plant height and dry matter yield increased significantly with an increase of nitrogen and FSP level. There was no difference in the botanical composition of grasses as affected by FSP application level, but herbage yields of grass species were increased by nitrogen application compared to that without nitrogen application. Botanical composition of white clover decreased with an increase of nitrogen application, but increased with an increase of FSP application level. Percentages of weeds were not affected by application rates of chemical nitrogen fertilizer and swine manure in the mixed species pasture. Nitrogen, phosphorus, and potassium contents of species in the pasture significantly increased with increasing application rates of nitrogen fertilizer. In conclusion, it would be an optimum to apply 150 kgha of inorganic chemical fertilizer and plus either 3 or 6 toniha of fermented swine manure with sawdust for optimum production of mixed pasture on Cheju Island. (Key words : Herbage production, Botanical composition, Morphology, Plant mineral contents)

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.32-40
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• 2006

The nitrogen (N) absorption and partition of the rice plants are important indicators that can be used to improve the N use efficiency (NUE) of the plants. Improving the plant NUE can help to avoid nutrient waste that may cause environmental pollution. To investigate the N absorption and partition of the rice plants, Hwaseongbyeo (Japonica) and Dasanbyeo (indica/japonica) were applied with N fertilizers at the rates of 60, 120, and 180 kg N per ha in paddy field. Also micro plots of $0.81m^2$ were established inside each plot for application of $^{15}N-labeled$ fertilizer. The differences in N utilization of the rice plants were associated with the total N absorption and partitioning after the heading stage. In the grain filling period, the increase of nitrogen content in the total and leaf blades of Dasanbyeo was higher than that of Hwaseongbyeo. Soil N was the main contributor for the increase of total N of Dasanbyeo during the grain filling period. The N fertilizer uptake rate of Hwaseongbyeo rapidly increased with the increment of N fertilization rate. In Dasanbyeo, N fertilizer uptakes were similar under all rates and times of N application. From heading stage to harvest, Dasanbyeo continued accumulating nitrogen, whereas Hwaseongbyeo had small changes. In conclusion, the difference in nitrogen absorption and partition after heading of the two cultivars was caused by the ability of Dasanbyeo to accumulate and remobilize soil nitrogen to the grains during the grain filling period.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.1
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• pp.14-20
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• 2006

In this study, the feasibility of simultaneous removal of organic materials and nitrogen in the waste-water from fisheries processing plant was evaluated using entrapped mixed microbial cell technique(EMMC) process. The experiment was performed using activated sludge from municipal sewage treatment plant which was immobilized with gel matrix by cellulose triacetate. It was found that the stable operation at the treatment system which is composed of anoxic and oxic tank, was possible when the organic and nitrogen loading rates were increased stepwise. The organic and nitrogen loading rates were applied from 0.65 to $1.72kgCOD/m^3/d$ and from 0.119 to $0.317kgT-N/m^3$ with four steps, respectively. The maximum nitrogen loading rate which could satisfy the regulated effluent standard of nitrogen concentration, was $0.3kgT-N/m^3/d$. The removal efficiency of total nitrogen was decreased apparently as increasing nitrogen loading rates, whereas the removal efficiency of ammonium nitrogen was effective at the all tested nitrogen loading rates. Therefore, it was concluded that nitrification was efficient at the system. Nitrate removal efficiency ranged from 98.62% to 99.51%, whereas the nitrification efficiency at the oxic tank ranged 94.0% to 96.9% at the tested loading rates. The removal efficiencies of chemical oxygen demand(COD) and those of total nitrogen at the entire system ranged from 94.2% to 96.6% and 73.4% to 83.4%, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.108-115
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• 2002

The effects of long-term fertilization on soil properties and nutrient availability are not well documented for cassava cultivation in Vietnam. In 1990, a field research plots were established with 12 treatments to test the effect of different rates of nitrogen (N), phosphorus (P) and potassium (K) on soil properties in Acrisols at Thai Nguyen University in Northern Vietnam. In 1999, composite soil samples (0 to 20cm depth) were collected from eight selected plots for measurements of nutrient supply rates by ion exchange membrane probes and for growing corn and canola in a growth chamber with and without added lime. Generally, long-term nitrogen (N) fertilization increased available N supply rates but decreased available potassium (K) and magnesium (Mg). Long-term phosphorus(P) applications increased canola N, calcium (Ca) and Mg uptake. Canola P uptake increased with increased P rates only when lime was added. Long-term K applications increased canola N, K, Ca, Mg uptake but only significantly increased corn N uptake. Liming significantly increased uptake of N, P, K, Ca, Mg and S for both corn and canola. However, N $H_{4-}$N, K and Mg soil supply rates were reduced when lime was added, due to competition between Ca from the added lime and other nutrients.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.14-25
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• 2006

Response of grain yield and milled-rice protein content to nitrogen (N) rates at various growth stages is critical for quantifying real-time and real-amount of applied N requirement for target grain yield and protein content. An experiment including 10 N rate treatments at transplanting, tillering and panicle initiation stages with four rice cultivars in 2003, 6 N treatments with two rice cultivars in 2004 and 2005 was conducted. Increase of N rates at PIS significantly increased both grain yield and milled-rice protein content but increase of N rates at tillering stage significantly increased grain yield but not milledrice protein content. Therefore, high grain yield and low milled-rice protein content would be difficult to obtain only by adjusting N rates at PIS. Internal N use efficiency (INUE) was 60.5 kg grain/kg N accumulation on an average over N treatments, cultivars, and experimental years, showing considerable reduction especially at high shoot N accumulation in the experimental year of low sunshine duration. Milled-rice protein content tended to increase almost linearly with increasing shoot N accumulation, but it revealed big variation even at the same shoot N accumulation at harvest. Milled-rice protein content decreased with increasing INUE. N accumulation in the milled rice increased at an almost constant proportion of 45.5 percent of the shoot N accumulated at harvest, showing slight decresing proportion with the increasing shoot N accumulation.

• Journal of The Korean Society of Grassland and Forage Science
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• v.10 no.2
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• pp.102-109
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• 1990

This experiment was carried out to study the effect of pure mineral nitrogen fertilizing on dry matter yield of grassland and the advisable mineral nitrogen amounts in long duration under practical conditions at the "Federal Institute for Agriculture in the Alps" in Austria. The application rates were 0, 30, 60,90 and 120 kg N/ha/cut, the cutting regimes 3-, 4-, 5- and 6-cuts/year. In order to explain the nitrogen-profitability were determined that 1 kg pure mineral nitrogen have to produce 8 - 16 kg DM/kg N in dependence on cutting regimes and requiring of nitrogen efficiencies. The results were as follows: 1. With only PK-fertilizaing average dry matter yields from 4.0 to 7.6 tons per ha and year were obtained. 2. Within all applied cutting regimes 60 kg min. Nlhalgrowth have proved to be the most efficient application rate witn 13 - 24 kg DM/kg N in dependent of cutting regimes. Comapred with only PK-treatment the DM yields increased by 3.9 - 4.7 t/ ha nad year. 3. By the sigmaformed process of Input-Output curve the highest marginal yield (the "most efficient" Ndressing rate) per ha and year was calculated: 152 kg N at 3-cut regimes, 204 kg N at 4-cut regimes, 220 kg N at 5-cut regimes and 240 kg N/ha/year at 6-cut regimes. 4. With required efficiencies of 16 and 12 kg DM/kg N 240 - 300 kg N per ha and year respectively would have to be applied at 3-cut regimes; with required efficiencies of 12 and 10 kg DM/kg N at 4-cut regimes the appropriate figures ranged from 320 to 420 kg N/ha and year, at 5- and 6-cut regimes and efficiencies of 10 and 8 kg DM/kg N results of 360 - 460 kg N and 380 - 500 kg N respectively were obtained. 5. At the relatively dry location Piber the highest dressing rates were needed in order to obtain the efficiencies from 8 to 16 kg DM/kg N, about 30 - 60 kg N/ha/year more than at the relatively moist location Admont.ist location Admont.