• Journal of Korean Society for Atmospheric Environment
• /
• v.23 no.2
• /
• pp.225-241
• /
• 2007

A closed flux chamber system was used for measuring major greenhouse gas (GHG) emission from tideland and/or wetland soils in estuarine area at Saemankum, Kunsan in southwestern Korea during from months of February to June 2006. Hourly averaged GHG soil emissions were measured two to three times a day during the ebb tide hours only. Site soils were analyzed for soil parameters (temperature, pH, total organic contents, N and C contents in soil) in the laboratory. Soil GHG fluxes were calculated based on the GHG concentration rate of change measured inside a closed chamber The analysis of GHG was conducted by using a Gas Chromatography (equipped with ECD/FID) at laboratory. Changes of daily, monthly GHGs' fluxes were examined. The relationships between the GHG emissions and soil chemical contents were also scrutinized with respect to gas production and consumption mechanism in the soil. Soil pH was pH $7.47{\pm}0.49$ in average over the experimental period. Organic matter contents in sample soil was $6.64{\pm}4.98\;g/kg$, and it shows relatively lower contents than those in agricultural soils in Kunsan area. Resulting from the soil chemistry data, soil nitrogen contents seem to affect GHG emission from the tidal land surface. The tidal soil was found to be either source or sink for the major GHG during the experimental periods. The annual average of $CH_{4}\;and\;CO_{2}$ fluxes were $0.13{\pm}0.86\;mg\;m^{-2}h^{-1}\;and\;5.83{\pm}138.73\;mg\;m^{-2}h^{-1}$, respectively, which will be as a source of these gases. However, $N_{2}O$ emission showed in negative flux, and the value was $-0.02{\pm}0.66\;mg\;m^{-2}h^{-1}$, and it implies tidal land surface act as a sink of $N_{2}O$. Over the experimental period, the absolute values of gas fluxes increased with soil temperature in general. Averages of the ambient gas concentration were $86.8{\pm}6.\;ppm$ in $CO_{2},\;1.63{\pm}0.34\;ppm\;in\;CH_{4},\;and\;0.59{\pm}0.15\;ppm\;in\;N_{2}O$, respectively. Generally, under the presence of gas emission from agricultural soils, decrease of gas emission will be observed as increase in ambient gas concentration. We, however, could not found significant correlation between the ambient concentrations and their emissions over the experimental period. There was no GHG compensation points existed in tide flat soil.

• Journal of Digital Convergence
• /
• v.10 no.10
• /
• pp.465-473
• /
• 2012

The mobile devices and cloud computing technology introduced new content services such as N-Screen service. The DRM techniques have been developed to support interoperability and multi-platform for new environment of content service. Nevertheless, it is still inconvenient for the consumers to purchase a new DRM-supported device or to migrate some purchased contents into new device due to the change of the subscription of service. Therefore, in this paper, cloud-based DRM model which is referred as DRMaaS (DRM-as-a-Service) model, is proposed to allow the consumer to freely use and move some DRM-protected contents in various smart devices regardless of subscription of service.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.23 no.4
• /
• pp.548-554
• /
• 1994

In order to observe the effects of the feeds mixed with the lard and two vegetable seed oils on the fatty acid compositions of serum lipkid and lipoprotein, the oils mixed with 2.5% lard and various levels of perilla oil and evening promrose oil were administered to the male rats of the Sprague-DAwley for 4 weeks. In the fatty acid compositions of serum lipid and serum lipoprotein fractions, as the content so f mixed perilla oil decreased and the contents of mixed evening primrose oil increased, n -3 PUFa (polyunsaturated fatty acid) contents and ratio of EPA/AA (eicisapentaenoiidacid/arachidonic acid) tended to decrease, but n-6 PUFA contents and ratio of AA/PUFA tended to increase. Fatty acid compositions of serum lipid and serum lipoprotein fractions were influenced from the fatty acid composition of the test lipids.

• Journal of Korean Society on Water Environment
• /
• v.30 no.6
• /
• pp.665-672
• /
• 2014

Elemental cellular stoichiometry of natural phytoplankton communities was examined in six large dam reservoirs in the Han River system. Carbon (C) and nitrogen (N) contents of the phytoplankton-dominated seston from Lake Soyang was higher than that from other lakes. Phosphorus (P) content showed slight variations among six lakes in the range of $0.04{\sim}0.18{\mu}mol$ P mg $DW^{-1}$. The phosphorus concentrations of lake water showed obvious positive relationship with P and C contents of the phytoplankton-dominated seston. In all six lakes, N:P ratios and C:P ratios in the phytoplankton-dominated seston were more than 23 and 133 respectively, indicating the phytoplankton communities in six lakes have been exposed in phosphorus limited condition. The relative abundance of diatoms showed significant negative correlation with C, N, P contents of the phytoplankton-dominated seston and that of cyanobacteria showed significant positive correlation. Elemental stoichiometry of diatoms-dominated seston showed distinctive less content than that of cyanobacteria-dominated seston. The cellular N:P ratios of diatoms- and cyanobacteria-dominated seston indicate that both main classes of phytoplankton in six lakes are in phosphorus deficiency. Elemental stoichiometry of the phytoplankton-dominated seston in this study could be used for the further ecological stoichiometric studies in six lakes.

• Journal of Microbiology and Biotechnology
• /
• v.14 no.4
• /
• pp.877-880
• /
• 2004

In this study, we determined the content of chitooligosaccharides (COS) in Korean commercial salt-fermented shrimps by competitive direct enzyme-linked immunosorbent assays (cdELISAs), using anti-COS mixture (COSM) antibody and COSM horseradish peroxidase (HRP) conjugate. When COS6 was spiked into salt-fermented shrimps at the level of $10-300\mu{g/g,}$ the average recovery was $120\pm19%$ ($mean\pmS.D.$). The COS contents of the 92 samples of Korean commercial salt-fermented shrimps collected during February 2000 and August 2002 were $36.3\pm20.7\mug$ COS6 equivalent/g (expressed as "$\mug/g$" hereafter). Among the samples, the COS contents of yuk-jeot ( $40.3 \pm 22.5 \mug/g, n=27$) and buksaewoojeot ($40.2 \pm 21.6 \mug/g, n=5$) were higher than the others. The COS contents of salt-fermented shrimps produced at Gwangcheon ($47.1 \pm 20.7 \mug/g, n=18$) and Gomso ($44.1 \pm 21.8 \mug/g, n=6$) areas were higher than those produced at the other areas. This is the first report to determine COS of salt-fermented shrimps by cdELISA.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.2
• /
• pp.33-39
• /
• 2004

Sandblasting has recently been developed into a powder blasting technique for brittle materials. In this study, the machinability of $Si_3N_4$-hBN based machinable ceramics are evaluated for micro - pattern making processes using powder blasting. Material properties of the developed machinable ceramics according to the variation of h-BN contents give a good machinability to the ceramics. The effect of scanning times, the size of patterns and variation of BN contents on the erosion depth of samples without mask and samples with different mask patterns in powder blasting of $Si_3N_4$-hBN ceramics are investigated. The Parameters are the impact angle of $90^{\circ}$, the scanning times of nozzle up to 40, and the stand-off distances of 100mm The widths of masked pattern are 0.1mm 0.5mm and 1mm. The powder used is Alumina particles, WA#600. and the blasting pressure of powder is 0.2MPa. Through required experiments, the results are investigated and analyzed. As the results, the machinability of the developed ceramics increases as the BN contents in the ceramics.

• 한국해양학회지
• /
• v.19 no.1
• /
• pp.1-10
• /
• 1984

an analysis of stomach contents of skipjack tuna Katsuwonus pelamis and plankton samples collected during troll fishing operations showed that the abundance of some dominant organisms in tuna stomachs was related to their abundance in the plankton. Fish larvae mainly pilchards, Nyctiphanes australis, brachyuran and other decapod larvae and calanoid copepods are important food item for skipjack. The copepods Undinula vulgaris and Nannocalanus minor occurred consistently throughout the survey period in both stomach contents and plankton samples. U. vulgaris appeared to be a preferred food considering its high percentage composition in tuna stomachs compared with its low percentage composition in the plankton. Temora turbinata and N. minor may also serve as important food items for skipjack. The largest catches of the fish were made in January and February when plankton organisms were composed dominantly of N. australis, copepods and brachyuran larvae. The main stomach contents during this period were N. australis and brachyuran larvae.

• Ocean and Polar Research
• /
• v.38 no.1
• /
• pp.35-46
• /
• 2016

To understand the diet of chaetognaths, the gut content and fatty acid trophic makers (FATMs) of Sagitta crassa and S. nagae, which are the most predominant species of chaetognath in the Yellow Sea, were analyzed. Gut contents of the two species examined by microscopic analysis revealed that copepods are the major components of the diet (> 70% of gut contents) and there was no significant changes in the gut contents of two species collected in spring and summer season. Although 16:0, 20:5(n-3) (Eicosapentaenoic acid) and 22:6(n-3) (Docosahexanoic acid), which are known as phytoplankton FA markers, were the most dominant among the fatty acids in both chaetognath species, the detection of copepod FA markers, 20:1(n-9) (Gadoleic acid) and 22:1(n-11) (Cetoleic acid), provided evidence that their food sources include copepods. These results suggest that S. crassa and S. nagae are carnivores and mainly feed on copepods in the Yellow Sea.

• Elastomers and Composites
• /
• v.44 no.3
• /
• pp.308-314
• /
• 2009

The acrylic rubber was synthesized by emulsion polymerization using n-butyl acrylate, n-butyl methacrylate, acrylonitrile, glycidylmethacrylate, and allyl methacrylate. When the contents of acrylonitrile were increased at fixed amount of crosslinking monomers, the Tg of polymers was increased with the contents of acrylonitrile, Mooney viscosity, hardness, and tensile strength also were increased. But the elongation was decreased due to the reduction of chain flexibility. The addition of the monomer for crosslinking, glycidylmethacrylate whose Tg is $56^{\circ}C$ resulted in the increased Tg of the polymer, and increased Mooney viscosity, hardness, and tensile strength, but the elongation at break was decreased with the glycidylmethacrylate contents. It was shown that this phenominon was attributed to the increment of crosslinking density by glycidylmethacrylate through the measurement of rheometer.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.3
• /
• pp.210-221
• /
• 2008

The mesoscale environmental surveys were conducted between $5^{\circ}N\;and\;17^{\circ}N$ mainly along the $131.5^{\circ}W$ meridian from 1997 to 2002 to investigate controlling factors of carbon and nitrogen contents in bottom sediments. Sediments of the study area showed zonal distribution pattern depending on latitudinal position and can be classified into four types; calcareous ooze($5{\sim}6^{\circ}N$), siliceous sediments($8{\sim}12^{\circ}N$), pelagic red clay($16{\sim}17^{\circ}N$), and mixed sediments($7^{\circ}N$). Inorganic carbon(IC) contents varied depending on water depth and carbonate compensation depth(CCD). Carbonate materials were well preserved in the low latitude region, where water depths are shallower than CCD. In contrast, the higher latitude region dominated by siliceous sediment and pelagic red clays has low productivity in water column as well as the water depths deeper than CCD. Thus, most of carbonate materials were dissolved, which resulted in IC contents of less than 0.05% in the sediments. Organic carbon(OC) and total nitrogen contents(TN) in siliceous sediments were higher than in pelagic red clay sediments simply because of higher primary productivity in the siliceous sediment dominated area. The contents of OC and TN were lower in the calcareous ooze than in the siliceous sediments. It is attributed to the high input of calcareous material to the bottom due to relatively shallow water depth of the area, which diluted organic matter contents in the sediment. Overall results indicated that water depth relative to CCD, primary production in water column, and sedimentation rate largely controls the large-scale distribution of carbon and nitrogen contents in the study area.