• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.320-330
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• 2008

For twenty-nine aquatic insect taxa common to mountain headwater streams in central Korean peninsula, body length-dry mass and -ash free dry mass relationships were developed by using a natural log transformed power function. Most of the predicted mass at length of this study was rather similar to those of other studies. Taxa with higher predicted mass at length than predicted by others tend to have soft exoskeleton and move by stretching and contracting their body. Ash rate in average was 10% of dry mass and was not significantly different among functional feeding groups.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.799-809
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• 2018

This study was performed to compare the physicochemical characteristics between imported dry-cured Hams from black and white pigs available in the domestic market. The black dry-cured hams contain higher moisture and ash contents than that of white hams, whereas the black dry-cured hams had lower fat contents than that of the black ones (p < 0.05). The hams from black ones had lower lightness ($L^*$) and yellowness ($b^*$) values than those from the white ones (p < 0.05). Moreover, the pH values and salt contents of the hams from the black ones were higher than those from the white ones (p < 0.05). Moreover, the black ones had a higher water holding capacity (WHC) than that of the white ones (p < 0.05). The thiobarbituric acid reactive substances (TBARS) values of the black ones were lower than those of the white ham samples (p < 0.05). For texture profile analysis, hardness, gumminess, chewiness, cohesiveness and shear force values were significantly lower in the black ones than in the white samples (p < 0.05). Saturated fatty acids in the white ones were higher than in the black ones, whereas unsaturated fatty acids in the black ones were higher (p < 0.05). Free amino acids such as aspartic acid and glutamic acid in the black ones were higher than in the white ones (p < 0.05). The shrinkage of muscle fiber was stronger in the white ones. Considering the meat quality parameters of ham, the black ones showed a superior meat quality. In general, this research can be used as fundamental information for the mass production of dry-cured hams in Korea.

• Animal cells and systems
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• v.7 no.4
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• pp.289-294
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• 2003

To quantify nutrient loading from emergent macrophytes through leaching in the littoral zones of Paldang Reservoir, we conducted incubation experiments using leaf litter of the emergent macrophyte, Zizaniz latifolia. To separate the leaching process from microbial decay, we used $HgCl_2$ to suppress microbial activity during the experiment. We measured electric conductivity, absorbance at 280nm, total nitrogen and dissolved inorganic nitrogen, total phosphorus and soluble reactive phosphorus, Na, K, Mg and Ca amounts in leaf litter and in water. In addition, we examined the effects of water temperature and ion concentrations of ambient water on the leaching process. A total of 6% of the initial ash-free dry mass of leaf litter was lost due to leaching during incubation (four days). Electric conductivity and A280 continued to increase and saturate during the incubation. To compare reaching rates of different nutrients, we fitted leaching dynamics with a hyperbolic saturation function [Y=AㆍX/(B+X)]. From these fittings, we found that ratios of leaching amounts to nutrient concentration in the litter were in the order of K > Na > Mg > P > Ca > N. Leaching from leaf litter of Z. latifolia was dependent on water temperature while it was not related with ion concentrations in the ambient water. Our results suggest that the leaching process of nutrients, especially phosphorus, from aquatic macrophytes provides considerable contribution to the eutrophication of the Paldang Reservoir ecosystem.

• Korean Journal of Ecology and Environment
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• v.48 no.4
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• pp.280-286
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• 2015

Life cycles of Sweltsa illiesi and S. lepnevae were determined from a headwater stream in Mt. Jumbong. Identification of nymphs was done by using DNA barcoding. Nymphs begin to have species specific color pattern on their head several months prior to adult emergence and differ in the form of the third antennal segment. Two species appear to have similar semivoltine life cycles in this stream, beginning to hatch from June and finishing adult emergence about 701 days later. The combined annual mean biomass in ash free dry mass (AFDM) was estimated as $96mg\;AFDM\;m^{-2}$. The combined annual secondary production were 373 mg and $297mg\;AFDM\;m^{-2}\;yr^{-1}$, calculated by using size frequency method and increment summation method respectively.

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.1013-1023
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• 2003

This study was performed to improve water quality of stream by applying hydraulic structures (weir and river bed material) made of porous concrete. The physical and chemical characteristics of porous concrete were measured to estimate application possibility of it in hydraulic structures and it was considered as a proper material for the hydraulic structures. In the results of comparison for the component of matters attached on the hydraulic structures made of porous and ordinary concrete, DW (dry weight) amount attached on porous concrete was 1.6 times higher than that on ordinary concrete under the condition of the same flow rate but influence by flow rate (difference of 10 times) was not shown. Therefore, we could understand that the material of media was more important in DW amount than flow rate. The rate of AFDM (ash free dry mass) to DW also was more at porous concrete than at ordinary concrete. Especially, the high rates of nitrogen and phosphorous in matters attached on porous concrete verify that they were removed by assimilation, adsorption and metabolism of periphyton. The removal percentage of SS, BOD, COD, T-N and T-P by hydraulic structures applying porous concrete compared with ordinary concrete was increased by 34.6%, 36.9%, 33.9%, 18.3% and 21.6%, respectively. Therefore, applying porous concrete to hydraulic structure is expected to contribute to improvement of stream water quality.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.2
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• pp.149-154
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• 1994

The hardness of kelp(Laminaria japonica) blade is a major deterrent to mass consumption in spite of its value as food. For improvement of kelp products as a special product of 'Donghae', the effect of additives on softening of kelp blade was studied. Kelp was composed of $34.74\%$ ash, $50.5\%$ carbohydrates, $4.81\%$ lipids and $9.98\%$ proteins on a dry weight basis. Glutamic and Aspartic acid are the principal free amino acids with percentage compositions of $2340mg\%\;and\;1650mg\%$ respectively of the $4719mg\%$ of total free amino acids. The softening effects of acetic acid and commercial mixed polyphosphate are more effective than that of monosodium carbonate. Boiling for more than 1hr was necessary for adequate softness of kelp blade in $0.3\%$ acetic acid solution. But, the kelp blade were softened more satisfactorily to 0.165kg/mm for only 30 min boiling in $0.2\%$ phosphate solution, and it is equal to boiling in $0.3\%$ acetic acid for 1hr.