• Journal of Marine Life Science
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• v.8 no.2
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• pp.121-127
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• 2023

The study was performed in order to understand the association between organic matter content in the sediments and the distribution of macrobenthos in the intertidal zone of the Muan bay. The sediment samples obtained from 21 sampling sites in August 2019 were analyzed for sediment composition and organic matter content (Ignition loss; IL and Total organic carbon; TOC). Further the macro benthos was sorted and enumerated. The sediments of inner area of bay has coarser composition where mouth part of bay, the sediments were predominantly silty. The highest organic matter content (both of IL and TOC) was measured at station 10 located near the Mokpo area while the lowest values was measured at station 20 adjacent to the north side of the bay. The 4 most abundant species accounted for more than 10% of all specimens were Assiminea sp., Musculista senhousia, Cerithideopsilla cingulate and Heteromastus filiformis. The maximum number of species and density were observed at station 10. Cluster analysis and non-metric multidimensional scaling (MDS) allow identification of four benthic assemblages based on species abundance. The correlation analysis revealed that there was a significant difference (p<0.05) in the density with TOC. Based on the analysis; it was found that the distribution of macrobenthos varied with the differences in sediment composition and organic matter content.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.281-284
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• 2004

본 연구에서는 분무열분해 공정에 의해 폐산용액으로부터 평균입도 100nm 이하의 나노 분말을 제조하였다. 용액 내의 Fe 성분의 농도가 20 g/$\iota$로부터 200 g/$\iota$로 증가됨에 따라 생성된 분말의 입도는 30 nm로부터 60 nm 까지 점점 증가하는 반면 입도분포는 더욱 불규칙하게 나타나고 있었다. 또한 용액 내의 농도 증가에 따라 $NiFe_2O_4$ 상의 생성비율이 현저히 증가하고 있었으며, 입자들의 비표면적은 현저히 감소하였다. 공기압력이 $1 kg/cm^2$까지는 분말의 평균입도는 80$\~$100 nm로 공기압력의 증가에 따라 분말들의 평균입도는 현저한 변화를 나타내지 않았으며, 생성된 상들의 비율의 현저한 변화도 나타나지 않았다. 공기압력이 $3kg/cm^2$로 증가하는 경우에는 평균입도가 약 70 nm로 감소하였으며 $NiFe_2O_4$의 생성비율도 감소하였다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.923-931
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• 2005

A study was carried out to identify the major causes of sediments pollution in the Paldang Lake in the vicinity of Gyeongan river. Samples from 40 sites were collected and analyzed to characterize the regional distributions of grain size, organic matter contents, and concentrations of T-N, T-P and heavy metals. contaminations. The mean grain size(Mz) ranged from sand type(Mz, $1{\sim}3\;{\phi}$) where Bukhan River and Namhan River converges at a high flow rate to silt type(Mz, $5{\sim}10\;{\phi}$) at the downstream of Gyeongancheon and Paldang lake, reflecting the water circulation in the area. Except sampling point St. 36 near the wetland, the determination coefficient($r^2$) of Mz and organic matter(LOI) was 0.88, showing that more organic matters are concentrated inside finer sediments. The concentrations of T-N and T-P in sediments were higher in the area at which Mz and organic matters are also higher. High concentrations of T-P analyzed in the sediments, ranging from $216{\sim}1,623\;{\mu}g/g$ (Avg. $769\;{\mu}g/g$) could be considered as a critical level. Adsorbed-P and NAI-P, which are easily released to the surrounding environments when physico-chemical characteristics of sediments are changed, was found to be around 20%, which was showed by the result of fractionated-P. Moreover, Principle Component Analysis(PCA), showed that high concentrations of T-N, T-P, organophilic metals (Cd, Cu, Pb, Zn) are distributed in the areas where high organic matter contents and fine grain-sized sediments are found. However, results of $I'_{geo}$ (Geoaccumulation Index) that considers the grain size of sediments showed that heavy metal concentrations in the lake was low enough to be considered as Class 1 indicating the relative degree of pollution was less than zero.

• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.369-372
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• 1990

Although the measurement of oil globule size distribution is necessary to detect the process of demulsification, the reasonable methodology for its measurement has not been suggested because the solution of soymilk contains insoluble soybean particle and the protein to interfere with the detection of oil globule or oil content. The oil globule size distribution was measured by the homogeneous suspension and cumulative method under gravitational force or centrifugal force, which were modified with Stokes' low. The geometric mean diameter of oil globules in this soymilk was $033{\mu}m\;and\;031{\mu}m$ under gravitational method and centrifugal method, respectively. The differences of oil globule size distribution in the solutions emulsified by different pressures were detected by this method. The mean diameter of the solutions treated at higher pressure was shifted to smaller size and the distribution pattern of the solutions at higher pressure became more compact around the mean diameter.

• Cement
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• s.49
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• pp.26-30
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• 1972

• Cement Symposium
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• no.6
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• pp.49-61
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• 1978

• Cement Symposium
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• no.27
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• pp.31-41
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• 2000

• 레미콘
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• no.12 s.10
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• pp.38-44
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• 1986

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.103-111
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• 2011

This study examined rheological properties of blast furnace slag and ash paste that are widely used as cement concrete for mineral admixture in current. In that way rheological properties of the paste of mineral admixture only was examined. The result of this study were as follow: In order to analyze that the rheological properties of the mineral admixture only, fine particles were produced with grinding machine to 3 particle sizes. These powders in general from the result of comparison with and analysis of rheological properties and the coefficient n and De values. The result that ash powder was higher in plastic viscosity and yield stress than Slag powder, and with the same n value, ash powder showed higher plastic viscosity and yield stress than Slag powder. But Slag powder in particle size distribution showed a sensitive tendency on changing in rheological properties.

• 한국해양학회지
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• v.30 no.1
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• pp.1-12
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• 1995

The modal analysis was carried out for the total of 216 subface sediments of southern continental shelf of Korean peninsula. Sandy mud or muddy sand distributed in the range of 70∼100 m water depth revealed the bimodal type (sand and mud components). The relations of textural parameters obtained from every modal were consistent with those of shallow marine sediments. The characteristics of sand component between bimodal were as follows: (1) the distributions of mean grain size, sorting, shell content were repeatedly distributed like the directions of depth contour lines. (2) Sand component was composed of medium to fine sand (Mz, 1-3$\psi$) containing many shell fragments, a few pebbles, and iron-stained quartz. (3) The surface of quartz revealed the concordial breakage and V-shaped features formed at high energy environment. (4) In CM-pattern, sand component was plotted in rolling and bottom suspension area. These characteristics imply that sand component probably derives from shoreface sediments deposited at the beach environment.