• Journal of Korean Society of Forest Science
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• v.103 no.4
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• pp.703-708
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• 2014

This study was conducted to investigate effects of soil amendments on survival rate and growth of seedlings in a semi-arid region, Mongolia. 2-year-old Populus sibirica and Ulmus pumila seedlings were planted in alkaline sandy soils and treated with 2 levels of nitrogen, elemental sulfur, artificial moisture retention and converted loess. After 4 months, the seedling survival rate of both species decreased as the amount of nitrogen increased. Nitrogen has been generally known to increase seedling survival rate and growth by supplying nutrients, however, reduced survival rate in this study might be affected by consequential increase in soil osmotic pressure, which was caused by excessive nitrogen fertilization. The root collar diameter (RCD) growth of both species increased significantly by the treatment of converted loess, and only RCD growth of P. sibirica increased by the artificial moisture retention treatment. Although P. sibirica is drought-tolerant, it is in the group of Populus spp. which requires a high capacity of available water. Conversely, the elemental sulfur treatment showed no effect on survival rate and RCD growth for both species due to the low oxidation of sulfur in arid soils. The extended monitoring of seedling growth and soil characteristics is required to elucidate the long-term effects of soil amendments in the semi-arid region, and the further studies are also needed to examine the appropriate amount of fertilizers for both species.

• Carbon letters
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• v.19
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• pp.40-46
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• 2016

Nitrogen-atom doped graphene oxide was considered to prevent the dissolution of polysulfide and to guarantee the enhanced redox reaction of sulfur for good cycle performance of lithium sulfur cells. In this study, we used urea as a nitrogen source due to its low cost and easy preparation. To find the optimum urea content, we tested three different ratios of urea to graphene oxide. The morphology of the composites was examined by field emission scanning electron microscope. Functional groups and bonding characterization were measured by X-ray photoelectron spectroscopy. Electrochemical properties were characterized by cyclic voltammetry in an organic electrolyte solution. Compared with thermally reduced graphene/sulfur (S) composite, nitrogen-doped graphene/S composites showed higher electroactivity and more stable capacity retention.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.11
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• pp.1524-1528
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• 2004

In order to determine the extent of change in nitrogen fractions and in vitro ruminal degradability of forage protein during ensilage and the influence on nitrogen utilization by sheep, orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) were ensiled in separate 120 L silos for 5, 21 and 56 days. With respect to nitrogen fractions, fraction 1 (buffer solution soluble nitrogen), fraction 2 (buffer solution insoluble nitrogen-neutral detergent insoluble nitrogen), fraction 3 (neutral detergent insoluble nitrogen-acid detergent insoluble nitrogen), and fraction 4 (acid detergent insoluble nitrogen) were determined. Fractions 1 and 2 accounted for more than 80% of total nitrogen in orchardgrass and 90% of that in alfalfa. The proportion of fraction 1 in orchardgrass increased from 33.0% at day 0 to 52.0% after day 56 of ensiling. In the case of alfalfa silage it was 41.7% and 62.9%, respectively. Seventy percent of this increase occurred within the first 5 days of ensiling. A similar change of in vitro ruminal degradability of total nitrogen was also observed in both forages. Nitrogen retention in sheep tended to decrease as the length of ensiling increased, with a significantly positive correlation between urinary nitrogen and fraction 1, and in vitro ruminal degradability of total nitrogen.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.175.1-175.1
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• 2011

A rotating activated bacillus contactor (RABC) process with a series of aerobic reactors was tested in pilot scale to treat digested liquid from an anaerobic digester treating swine wastewater and sewage sludge. The influent (digested liquid) for the RABC process showed C/N ratios less than 2 as a typical feature of effluent from anaerobic digesters. The pilot process, which consists of three 3 RABC reactors, four aerobic tanks and a sedimentation tank, was operated for 210 days with a hydraulic retention time of 20 days without pH and temperature control. Since the Bacillus-enriched aerobic reactors shows high efficiencies of nitrogen removal at low DO levels less than 1.0 mg/L, they were operated at reduced aeration intensities. With relatively low concentrations of organics in comparison with nitrogen concentrations, the RABC process tested in this study showed stable and high nitrogen and organics removal efficiencies over 80%. The nitrogen removal process tested in this study was proven to be an effective and operation-cost saving (lower aeration) method to remove nitrogen without adding external carbon sources to meet the optimum C/N ratio.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.195-206
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• 2014

Immobilization of anaerobic ammonium oxidizing bacteria has been studied to enhance the biomass retention of the slowly growing bacteria and the process stability. The purpose of this study was to compare the nitrogen removal efficiency of granular and immobilized anammox bacteria with poly vinyl alcohol and alginate. The specific anammox activity of the granular, homoginized and immobilized anammox bacteria were $0.016{\pm}0.0002gN/gVSS/d$, $0.011{\pm}0.001gN/gVSS/d$ and $0.007{\pm}0.0005gN/gVSS/d$, respectively. Although the activity decreased to 43.7 % of the original one due to low pH and $O_2$ exposure during the homogination and the immobilization, it was rapidly recovered within 7 days in the following continuous culture. When synthetic T-N concentrations of 100, 200, 400, 800 mg/L were fed, the immobilized anammox bacteria showed higher nitrogen removal efficiencies at all operational conditions than those of granular anammox bacteria. When the sludge retention time was shorten below 30.7 days and the reject water was fed, the nitrite removal efficiency of the granular anammox bacteria dropped to 8 % of the initial value, while that of the immobilized anammox bacteria was maintained over 95 % of the initial one. The immobilization with poly vinyl alcohol and alginate would be a feasible method to improve the performance and stability of the anammox process.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.5
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• pp.659-665
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• 2000

A nitrogen (N) balance trial was conducted to examine the effect of N deprivation on subsequent N retention, blood urea nitrogen (BUN) and IGF-I levels and the ratio of IGF binding protein (IGFBP)-3 to IGFBP-l and -2. Pigs in treatment (T) 1 were given diet A (2.39% N) and those in T2 and T3 were given diet B (1.31% N) and excreta were collected (period 1 (P1)). Pigs in T1 continued to receive diet A while diets for T2 and T3 were changed to diets A and C (2.74% N), respectively. The excreta were collected for two more periods (P2 and P3). During P1, pigs in T2 and T3 retained 50% less N (p<0.001) than those in T1. However, pigs provided T2 (p<0.01) and T3 (p<0.05) retained more N than those assigned to T1 during P2. Pigs in T3 tended to retain more (p=0.10) N than those receiving T2 for the same period. The BUN values were lower (p<0.05) for pigs assigned to T2 and T3 than T1 during P1 and P2. Both IGF-I and IGFBP ratios of pigs assigned to T1 were higher (p<0.05) than those given T2 and T3 during P1 but no differences were found during P2 and P3.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.967-973
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• 2000

A metabolism trial was conducted with 28 Najdi rams allocated into seven dietary groups to evaluate the effect of dietary inclusion of Salicornia bigelovii Torr biomass on nutrient digestibility, rumina I fluid metabolites and nitrogen and mineral balances. Either the stems (ST) or spikes (SP) of this seawater-irrigated halophyte were incorporated into complete diets at rates of 0, 10, 20 and 30% levels, replacing equal amounts of rhodesgrass hay in a ground mixed control diet. Digestibility of DM, OM, EE, NFE and fecal and urinary nitrogen were not affected by increased level of ST in the diet. As level of ST increased from 0 to 20% in the diets, CP digestibility and nitrogen retention approached their maximum (p<0.01), whereas CF digestibility reached its minimum (p<0.01). On the other hand, except for EE, digestion of all nutrients and nitrogen retention were linearly depressed (p<0.01) as SP increased in the diets from 10 to 30% level. Concentration of ammonia-N, total VFA and pH values in the rumen fluid were lower (p<0.01) with the ST- or SP-fed diets than with the control diet. Increasing level of ST or SP in the diet was associated with an increase (p<0.01) in the proportion of acetate and a decline (p<0.01) in molar percentage of propionate in the ruminal fluid. Sodium absorption increased (p<0.01) with increased ST and SP in the diets up to the 10 and 20% level, respectively, followed by constant absorption values up to the 30% level. When the level of ST in the diet gradually increased to 30%, a concomitant increased (p<0:01) in Ca and P absorption were obvious; whereas, increased level of SP in the diets from 0 to 30% resulted in noticeable (p<0.01) depression in Ca and P apparent absorption.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.206-215
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• 2007

The objective of this study was to establish the optimal system operating strategies for nitrogen and phosphorus removal through model simulation system built for advanced wastewater treatment targeting on simultaneous temporal/special phase isolation BNR process. The simulation system was built with unit process modules using object modules in GPS-X code. The system was well verified by field experiment data. Simulation study was carried out to investigate performance response to design and operation parameters, i.e. hydraulic retention time (HRT), solids retention time (SRT), and cycle time. The process operated at HRTs of 10~15 hours, longer SRTs, and cycle time of 2 hours showed optimal removal of nitrogen. The HRTs of 10~15 hours, SRTs of 20~25 days, and longer cycle time was optimal for phosphorus removal. Both simulation and field studies showed that optimal operating strategies satisfying both the best nitrogen and phosphorus removals include HRTs ranged 10~15 hours, SRTs ranged 20~25 days, and cycle times of 4~8 hours. The simulation system with modularization of generalized components in BNR processes was, therefore, believed to be a powerful tool for establishing optimal strategies of advanced wastewater treatment.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.5
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• pp.702-705
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• 2003

Forest by-product silage (FPS) comprised of foliage, shrubs, and wild grasses was prepared to examine feeding value as sole roughage source for spotted (sika) deer. This diet was compared with imported oak leaf hay (OLH) and a commercial mixed ration (CMR) in digestion balance trials with spotted deer. Dry matter intake was highest (p<0.05) on the OLH, whereas intakes of the FPS and CMR were similar (p>0.05). Digestibility of dry matter was highest (p<0.05) for CMR. Digestibility of crude protein was highest in CMR and lowest in OLH and there were significant differences (p<0.05) among diets. Average daily gain, digestible dry matter intake and digestibility of crude fiber did not differ significantly among diets. Nitrogen intake, urinary and digestible nitrogen were highest (p<0.05) in CMR. However, nitrogen retention was not significantly different. Consequently, FPS is a good roughage source for deer having high digestibility, dry matter intake and availability of nitrogen.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.1
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• pp.33-41
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• 1988

In a study about minerals cycling in grassland agro-ecosystem, investigation on relations among two minerals, potassium(K) and magnesium(Mg), and nitrogen(N) was performed. Four kinds of diets different in K and N levels were fed to four goats with a Latin-square method and $2{\times}2$ factorial design. As the basal diet, press cake silage prepared from Italian ryegrass was used because of its uniformity and comparatively low mineral concentrations. Supplementation of K and N were made using potassium bicarbonate and urea. In the experiment, it was clearly shown that high K concentration in the forage crops is the main reason of the low utilization of Mg in ruminant animals. However, high nitrogen intake resulted in the increase of magnesium retention, urinary potassium excretion, water intake and volume of urine and in the decreases of potassium intake minus urinary potassium excretion. The results of high nitrogen intake seemed to be produced in the following order;increase of urine, increase of water intake, increase of urinary potassium excretion, and decrease of intake minus urinary potassium excretion. The amount of potassium intake minus urinary potassium excretion had significantly close relationships with magnesium utilization and serum magnesium concentration. As a conclusion, higher nitrogen intake by ruminants seemed to be preferable for magnesium utilization through increased water intake and urinary potassium excretion, if the sufficient drinking water could be supplied to ruminants.