• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.7
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• pp.442-447
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• 2010

FPSO (Floating Production Strorage and Offloading) method for LNG industry is efficient and facile compared to onshore NG (Natural Gas) treatment facility. Five simple natural gas liquefaction cycles for FPSO are presented and simulated in this paper. SMR (Single Mixed Refrigerant) cycle, SNE (Single Nitrogen Expander) cycle, DNE (Double Nitrogen Expander) cycle, PNE (Precooled Nitrogen Expander) cycle, and PDNE (Precooled Double Nitrogen Expander) cycle are compared. Simple analysis results in this paper show that precooling process and adding an expander in the liquefaction cycle is an effective way to increase liquefaction efficiency.

• Transactions of Materials Processing
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• v.12 no.4
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• pp.284-289
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• 2003

The effects of nitrogen on the deformation behavior of duplex stainless steel have been studied. The variation of strength was correlated with the characteristic microstructures pertaining to nitrogen. Analysis based on Hall-fetch relation confirmed that nitrogen enhances phase-boundary strengthening effect. The evolution of dislocation structure, slip traces and misorientation distribution during deformation were also characterized to elucidate the effect of nitrogen on inelastic deformation mechanism. It has been verified in this study that the higher nitrogen content provides a dual-phase microstructure with smaller strength difference between austenite and ferrite resulting into the earlier transfer of inelastic deformation from austenite to ferrite.

• Korean journal of food and cookery science
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• v.12 no.3
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• pp.273-278
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• 1996

To investigate the main components of Korean traditional soy sauce for its typical taste, we compare the physicochemical properties of Korean traditional soy sauce and commercial soy sauce. The physicochemical analysis revealed that each components showed significant difference between Korean traditional soy sauce and commercial soy sauce. The significant characters for discrimination between Korean traditional soy sauce and commercial soy sauce were salt content, ammonia nitrogen content and total acidity (R$^2$=0.99). The components of Korean traditional soy sauce divided into 3 clusters, and each group is characterized as formol nitrogen, salt and total nitrogen content by cluster analysis. Main amino acids of Korean traditional soy sauce were alanine, glutamic acid, leucine and valine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.5
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• pp.711-717
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• 1994

This study was conducted to obtain accurate data on intake, apparent digestibility and nitrogen balance of dietary protein which the korean take in habitually. Subjects were 8 male college students, aged from 20 to 26, and maintained their menu and life pattern as usual during a 4-week study. The same amount of diet that the subjects had consumped, and feces and urine were collected and measured to extract their nitrogen content data by Kjeldahl method. From above data, the apparent digestibility and the body nitrogen balance were estimated by determining daily protein intake and excretion. The daily protein intake measured by Jjeldahil method was 88.3$\pm$ 0.9g(1.45/kg of body weight /day) which marked 8.3% higher than that estimatd by food analysis table. The proportional of animal protein against total protein intake was 50.4$\pm$ 2.3%. Daily fecal protein loss was 14.3$\pm$0.6g and the apparent digestibility was 83.8$\pm$ 0.7%. The urinary nitrogen excretion was 10.30$\pm$0.19g. The nitrogen balance considering nitrogen excretion from feces indicated positive balance of 1.06$\pm$0.20g.

• The Korean Journal of Ecology
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• v.10 no.4
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• pp.175-182
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• 1987

Soybeans(Glycine max Merr. cv. Kwanggyo), inoculated with Rhizobium japonicum 110 and then sand-cultured with nitrate gradients (0, 1, 3, 10 and 30mM KNO3). were studied on the growth analysis, nitrogen fixation and nitrogen economy during the growing period. The maxium values of total leaf area, biomass and nitrogen quantity were increased 139%, 122% and 161%, respectively with higher concentration of nitrate treatment. Nodulation showed significant linear correlation with leaf area growth for each treatment of nitrate concentration increased. The more nitrate concentration increased, the more distribution ratios of dry matter and nitrogen to nodule decreased, and the more T/R ratios, CGR and N content increased. On the other hand, F/C ratios and RGR showed little changes. The amounts of nitrogen fixation of soybean alloted to 0, 1, 3, 10 and 30mM nitrate treatments were 100, 46, 14, 0.1 and 0.004% for the total nitrogen assimilation, respectively. The nitrogen utility of soybean plant was smaller than that of other plants and ranged from 23 to 30 at varying nitrate gradients.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.189-196
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• 2009

Bacteria were isolated from roots of plants belonging to family Solanaceae and Gramineae, inhabited in Dokdo island. Fifty six endospore-forming bacteria grown on tryptic soy broth (TSB) agar medium and 23 nitrogen-fixing bacteria (NFB) grown on nitrogen free agar medium were isolated, respectively. The isolates were partially identified by analyzing the 16S rDNA and categorized into phylogenetic groups. The 16S rDNA sequences of each identified isolates were compared with sequences of each type strains to analyze phylogenetic relationship by phylogenetic tree. As a result, endospore-forming bacteria and nitrogen-fixing bacteria were classified into 4 and 6 lineage groups, respectively. Among these isolated, 18 were presumed to be novel species candidates based on the similarity (lower than 98%) analysis of the l6S rDNA sequences.

• Journal of Nutrition and Health
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• v.44 no.4
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• pp.338-343
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• 2011

This study assessed the current EAR, RDA, and AMDR for protein, which were set in 2005 and revised in 2010 as the DRIs for Koreans. A classical approach to establish the EAR for protein has been the nitrogen balance method. This method has practical limitations and problems in statistical analysis by giving over estimations of nitrogen balance. Thus, the present EAR for protein might be lower than the true requirement. Recent reevaluations of nitrogen balance studies by bilinear regression analysis and the IAAO method have indicated that the EAR of 0.66 g/kg bw/d should be increased by 39% to give 0.92 g/kg bw/d. The AMDR for protein in the Korean DRIs was set at 7-10%, which covers almost the entire population's protein intake. Since the 5th percentile of Korean protein intake is close to 10% of energy and due to the beneficial effects of protein beyond the maintenance of nitrogen equilibrium, the lower range of 7% needs to be increased up to 10%. For practical meal arrangement, 15% of energy as protein, which is close to the average protein intake of Koreans, seems to be proper, although the value is almost two times the EAR.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.198-203
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• 2003

The effects of salmon carcasses on forest and stream ecosystems were determined by nitrogen stable isotope analysis in natural streams in Hokkaido, Northern Japan, where numerous chum salmon (Oncoryhncus keta) were migrated upstream ITom ocean to spawn in autumn. The leaves and soils surrounding riparian forest and stream dwelling invertebrates were collected before and after migration. The nitrogen stable isotope ratio $({\delta}^{15}N)$ of riparian vegetation (Salix spp.) were different depending on the presence of salmon and distance from the stream. The $({\delta}^{15}N)$ of stream dwelling invertebrates were different between salmon present and absent stream. This difference was tested using the experiment channel by implanting salmon carcasses. The nitrogen stable isotope ratio of epilithic algae and leaf shredding animals were nearly 3 higher in the salmon implanted treatment suggesting that around 20％ of salmon derived nitrogen was uptake either in algae and leaf shredding invertebrates. These results suggest that the salmon carcasses effects not only on stream primary production but also on primary consumers, which decompose leaves fertilized with nitrogen from carcasses.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.1
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• pp.107-117
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• 2004

Hourly monitoring data from Saemangeum estuary, which is expected to become freshwater, was analyzed to evaluate the water quality characteristics. Higher algal growth at spring season than winter influenced the high ratio of organic nitrogen to total nitrogen and concentration of chemical oxygen demand (COD). About 87.9％ and 59.7％ of organic nitrogen was observed at winter season and spring season, respectively. Daily salinity analysis at the mouth of two main rivers demonstrated that the Dongjin in river was more influenced by tidal effect and showed higher variation than the Mankyung river. The ratio of nitrogen to phosphorus (N/P ratio) was different with site (estuary versus sea area) and season (winter versus spring) remarkably. The N/P ratio was highest (32.74 ∼ 43.93) at estuary in winter and was lowest (1.78 ∼ 3.06) at sea in spring. The high N/P ratio at estuary area implies that phosphorus can be the limiting nutrient factor for algal growth as in general freshwater river, therefore, water quality management practice considering river characteristics rather might be needed in the Saemangeum estuary. The Saemangeum project is nationally recognized for its environmental issues, and especially water quality concern is a critical factor to make policy decision and further assessment with continued monitoring is strongly recommended.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.262-268
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• 2019

BACKGROUND: To investigate mineralization characteristics of organic resources in the soil, five materials (rice straw, cow manure sawdust compost, microorganism compost, mixed oil-cake, and amino acid fertilizer) were treated according to the nitrogen content, and an indoor incubation experiment was conducted for 128 days. The results of this analysis were applied to determine the nitrogen mineralization pattern of these organic resources. METHODS AND RESULTS: During the constant temperature incubation period, the nitrogen net mineralization rate of the organic resources was the highest in the amino acid fertilizer with the highest nitrogen content, and the lowest in the rice straw with the lowest nitrogen content. A positive correlation (0.96) was observed between the potential nitrogen mineralization rate and total nitrogen content. The mineralization rate constant, k, was negatively correlated with the organic matter (-0.96) and carbon content (-0.97). The nitrogen mineralization rate during the first cropping season, as estimated by the model, was 6.6%, 11.6%, 30.9%, 70.7%, and 81.0% for the rice straw, the cow manure sawdust compost, the microorganism compost, the mixed oil-cake, and the amino acid fertilizer, respectively. CONCLUSION: The nitrogen mineralization rate varies depending on the type of organic resources or the nitrogen content; thus, it can be used as an index for determining the nitrogen supply characteristics of the organic resource. Organic resources such as compost with low nitrogen content or those undergoing fermentation contain organic nitrogen. Organic nitrogen is stabilized during the composting process. Therefore, as the nitrogen mineralization rate of these resources is lower than that of non-fermented organic resources, it is desirable to use the fermented organic materials only to improve soil physical properties rather than to supply nutrients for the required amount of fertilizer.