• Analytical Science and Technology
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• v.25 no.6
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• pp.421-428
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• 2012

In this study, PCDD/PCDFs, PAHs and PCBs in wastes from metal, plastic and wastewater treatment facilities were analyzed. The concentrations of PCDD/PCDFs ranged from 7.37~432.20 ng-TEQ/kg in fly ash, 0.51~855.01 ng-TEQ/kg in incinerated ash and 0.37~385.81 ng-TEQ/kg in dust. Dioxin content was lower, compared to data in foreign countries. PAHs concentration was in the range of 0.0075~2.9225 mg/kg for process sludge and 0.0035~1.6716 mg/kg for wastewater sludge, which satisfied all of the two standards (Nap, Ant, B(a)F:4/0.8, Phen, B(a)A:5/1, Flt:10/2.5, B(a)P:4.5/0.9) of the Marine Environment Management Act. PAHs concentration in process sludge and wastewater sludge were slightly lower than those abroad. According to the analysis of seven types of PCBs (in comparison with the first standard, 0.15 mg/kg), concentration was found in the range of 0.0~0.65 mg/kg, while PCB-52, PCB-101, PCB-138, PCB-153 and PCB-180 isomers were detected in excessive value in some machine oil and hydraulic fluid.

• Journal of Aquaculture
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• v.19 no.4
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• pp.310-314
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• 2006

This study was carried out to investigate grazing of brackish water cyclopoid copepod Paracyclopina nana on four microalgae species (Tetraselmis suecica, Isochrysis galbana, Phaeodactylum tricornutum and Dunaliella tertiolecta) and different food concentrations raging from 5 to 55 ng chl a/ml. The grazing of P. nana was examined by the analysis of decreased number of microalgae and chlorophyll a content in rearing water and pigment content in the gut of P. nana. The maximum content of decreased chlorophyll a and gut pigment in P. nana varied with microalgae species and concentrations. It appeared at the food concentration 30 ng chl a/ml in T. suecica, 40 ng chl a/ml in I. galnaba and D. tertiolecta, and 45 ng chl a/ml in P. tricornutum, respectively. The grazing rate of a P. nana per hour also varied with different microalgae species and concentrations. The maximum grazing rate per hour of P. nana fed T. suecica with 39.3 ng chl a/ml was the highest with 0.63 ng chl a/h, but lowest with 0.52 ng chl a/h. From these results, it can be concluded that T. suecica is the best species among four microalgae species for the mass culture of P. nana and daily optimum food concentration of P. nana is $25{\sim}39$ ng chl a (approximately $10{\sim}15{\times}10^4$ cells).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.1
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• pp.25-32
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• 2014

Offshore wind power structures are subject to coastal hydrodynamic loading such as wind and wave loads. A considerable number of turbines have been installed in Europe, but so far none in Korea. Interest in offshore wind energy is growing in Korea, and it is expected that projects will reach the design stage in the near future. This paper discusses the level of structural reliability implied by the design rules of ABS(2010, 2013) and IEC(2009). Metocean conditions in 4 Korean seas(Gunsan, HeMOSU 1, Mokpo, Jeju) were used in the calibrations to calculate the aerodynamic and hydrodynamic loads as well as the structural responses of the typical designs of offshore wind turbines. Due to the higher variability of the wind and wave climate in hurricane-prone areas, applying IEC strength design criteria in combination with Korea west sea conditions could result in a design with much lower reliability index than what is anticipated from a design in European waters. To achieve the same level of safety as those in European waters, application of ABS 100 year design standards are recommended. Level-1 reliability-based design suitable for the Korean sea state conditions should be introduced because the IEC standards does not consider the typhoon effects in depth and the ABS standards is a WSD design method. In addition, the design equation should be established based on the statistical characteristics of the wind and wave loads of the Korean sea areas.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.1
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• pp.16-24
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• 2014

Long-term measured wind data are absolutely necessary to estimate extreme offshore wind speed. However, it is almost impossible to collect offshore wind measured data. Therefore, typhoon simulation is widely used to analyze offshore wind conditions. In this paper, 74 typhoons which affected the western sea of Korea during 1978-2012(35 years) were simulated using Holland(1980) model. The results showed that 49.02 m/s maximum wind speed affected by BOLAVEN(1215) at 100 m heights of HeMOSU-1 (Herald of Meteorological and Oceanographic Special Unit - 1) was the biggest wind speed for 35 years. Meanwhile, estimated wind speeds were compared with observed data for MUIFA, BOLAVEN, SANBA at HeMOSU-1. And to estimate extreme wind speed having return periods, extreme analysis was conducted by assuming 35 annual maximum wind speed at four site(HeMOSU-1, Gunsan, Mokpo and Jeju) in western sea of the Korean Peninsular to be Gumbel distribution. As a results, extreme wind speed having 50-year return period was 50 m/s, that of 100-year was 54.92 m/s at 100 m heights, respectively. The maximum wind speed by BOLAVEN could be considered as a extreme winds having 50-year return period.

• Ocean and Polar Research
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• v.28 no.1
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• pp.1-12
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• 2006

Analyses of sedimentological and geochemical parameters from two radiocarbon-dated sediment cores (JM98-845-PC and JM98-818-PC) retrieved from the central part of Isfjorden, Svalbard, in the Arctic Sea, reveal detailed paleoclimatic and paleoceanographic histories over the last 15,000 radiocarbon years. The overconsolidated diamicton at the base of core JM98-845-PC is supposed to be a basal till deposited beneath pounding glacier that had advanced during the LGM (Last Glacial Maximum). Deglaciation of the fjord commenced after the glacial maximum, marked by the deposition of interlaminated sand and mud in the ice-proximal zone by subglacial meltwater discharge, and prevailed between 13,700 and 10,800 yr B.P. with enriched-terrigenous organic materials. A return to colder conditions occurred at around 10,800 yr B.P. with a drop in TOC content, which is probably coincident with the Younger Dryas event in the North Atlantic region. At this time, an abrupt decrease of TOC content as well as an increase in C/N ratio suggests enhanced terrigenous input due to the glacial readvance. A climatic optimum is recognized between 8,395 and 2,442 yr B.P., coinciding with 'a mid-Holocene climatic optimum' in Northern Hemisphere sites (e.g., the Laurentide Ice sheet). During this time, as the sea ice receded from the fjord, enhanced primary productivity occurred in open marine conditions, resulting in the deposition of organic-enriched pebbly mud with evidence of TOC maxima and C/N ratio minima in sediments. Fast ice also disappeared from the coast, providing the maximum of IRD (ice-rafted debris) input. Around 2,442 yr B.p. (the onset of Neoglacial), pebbly mud, characterized by a decrease in TOC content, reflects the formation of more extensive sea ice and fast ice, which might cause decreased primary productivity in the surface water, as evidenced by a decrease in TOC content. Our results provide evidence of climatic change on the Svalbard fjords that helps to refine the existence and timing of late Pleistocene and Holocene millennial-scale climatic events in the Northern Hemisphere.

• Analytical Science and Technology
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• v.24 no.4
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• pp.310-318
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• 2011

The collection of atmospheric $PM_{10}$ and $PM_{2.5}$ particle samples was made at Gosan site of Jeju Island, which is one of the most representative background sites in Korea. Their chemical compositions have been analyzed to explore the pollution characteristics and emission sources. The mass concentrations of $PM_{10}$ and $PM_{2.5}$ particles were $37.6{\pm}20.1$ and $22.9{\pm}14.3{\mu}g/m^3$, respectively, with the content of $PM_{2.5}$ to $PM_{10}$ as 61%. The $PM_{2.5}/PM_{10}$ ratios of nss-$SO_4^{2-}$, $NO_3^-$, and $NH_4^+$ were 0.94, 0.56, 1.02, respectively, indicating that these components were distributed mostly in the fine fractions. Based on the factor analysis, it was found that the compositions of fine particles were mainly influenced by anthropogenic sources, followed by soil or marine sources. The results of the backward trajectory analysis indicate that the concentrations of nss-$SO_4^{2-}$, $NO_3^-$, $NH_4^+$, nss-$Ca^{2+}$, and Pb were high when the air parcels moved from the China continent, while relatively low with the air parcels coming from North Pacific Ocean and/or East Sea.

• Ocean and Polar Research
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• v.26 no.2
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• pp.287-298
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• 2004

As a part of Korea Deep Ocean Study program, we investigated the distribution of planktonic protists in the upper 200 m of the northeast Pacific from $5^{\circ}N$ to $17^{\circ}N$, along $131^{\circ}30'W$. Area of divergence was formed at $9^{\circ}N$ which is boundaries of the north equatorial counter current (NECC) and the north equatorial current (NEC) during this cruise. Chlorophyll-a concentration was higher in NECC than in NEC area. Pico chl-a(<$2\;{\mu}m$) to total chl-a accounted for average 89% in the study area. The contribution of pico chl-a to total chl-a was relatively high in NEC area than in NECC area. Biomass of planktonic protists, ranging from 635.3 to $1077.3\;mgC\;m^{-2}$(average $810\;mgC\;m^{-2}$), was most enhanced in NECC area and showed distinct latitudinal variation. Biomass of HNF ranged from 88.7 to $208.3\;mgC\;m^{-2}$ and comprised 15% of planktonic protists. Biomass of ciliates ranged from 123.6 to $393.0\;mgC\;m^{-2}$ and comprised 25% of planktonic protists. Biomass of HDF ranged from 407.2 to $607.8\;mgC\;m^{-2}$ and comprised 60% of planktonic protists. HDF was the most dominant component in both NECC and NEC areas. Nano-protist biomass accounted for more than 50% of total protists in the both areas. The contribution of nanoprotist to total protists biomass was relatively higher in NEC area than in NECC. The biomass of planktonic protists was significantly correlated with phytoplankton biomass in this study area. The size structure of phytoplankton biomass coincided with that of planktonic protists. This suggested that the structure of the planktonic protists community and the microbial food web were dependent on the size structure of the phytoplankton biomass. However, biomass and size structure of planktonic protist communities might be significantly influenced by physical characteristics of the water column and food concentration in this study area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.245-251
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• 1998

A 10-week feeding experiment was conducted to determine the influence of several minerals from dietary mineral premix on growth and body composition in juvenile Korean rockfish. Three replicate groups of fish Initially averaging 4.2 g were fed one of the ten experimental diets. Korean rockfish muscle and casein as protein sources were used in the basal diet, and deleted one of each mineral (P, Ca, Zn, Mg, Fe, K, Mn, Se or all) in the control mineral premix, Weight gain, feed efficiency and nutrient retention in fish fed the diet not containing mineral premix were significantly lower than those in fish fed other diets (P<0.01). Weight gain in fish fed the diets deleted each mineral (P, Ca, Zn, Hg, Fe, K, Mn or Se) was lower than that of control diet (P<0.01), Feed efficiency and protein retention in fish fed the diets deleted each of P, Ca, Zn or Mn were lower than those ot control diet (P<0.01). Daily feed intake and lipid retention were not affected by dietary mineral premixes ( P>0.01). Proximate analysis and mineral contents in the whole body, muscle, liver or bone of fish fed the diets deleted each mineral were not different to control diet ( P>0.01). The data obtained in this study indicate that each of the P, Ca, Zn, Mg, Fe, K, Mn or Se is essential for normal growth of Korean rockfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.252-258
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• 1998

A feeding experiment was conducted to investigate the effects of deletion of P, Ca, Zn, Mg, Fe, K, Mn, or Se from mineral premix in the diets containing $40\%$ fish meal on growth performance of juvenile Korean rockfish. Three replicate groups of the fish initially averaging 5.4 g were fed the experimental diets deleted one ot each mineral (P, Ca, Zn, Mg, Fe, K, Mn, Se or all) in the mineral premix for 9 weeks. A basal diet with fish meal ($40\%$), meat meal ($9\%$), soybean meal ($5\%$), corngluten meal ($3\%$), and leather meal ($3\%$) as protein sources were included. Weight gain in fish fed diets deleted Ca, Zn, K, or Se was lower than that of control diet ( P<0.05). Daily feed intake, condition factor, hepatosomatic index and liver chemical composition were not affected by dietary mineral premixes (P>0.05). Apparent skeletal deformities were not observed in the diets deleted each mineral, The data obtained in this study indicate that each of the Ca, Zn, K, or Se should be added in the diet contained $40\%$ fish meal for normal growth of Korean rockfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.290-294
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• 1999

An 18-week growth trial was conducted in flow-through aquarium system to investigate the effects of several additives in formulated diets on the growth and body composition of juvenile abalone (Haliotis discus hannai). Four replicate groups of abalone averaging 150 mg were fed one of four isonitrogenous ($33.8\%$) and isolipidic ($5.8\%$) diets containing $5\%$ squid meal, $0.5\%$ attractant, $1\%$ herb or $0.5\%$ lecithin. In addition, these formulated diets were compared to commercial diet. Survival rate and shell growth of abalone were not significantly affected by the different dietary additives and commercial diet (P>0.1). Body weight gain of abalone fed the diet containing herb was higher than those of abalone fed the diets containing squid meal or lecithin and commercial diet (P<0.1). Moisture, protein, lipid and ash contents of soft body were not influenced by dietary additives and commercial diet (P>0.1). The results suggest that herb as additive in this formulated diet can improve weight gain of abalone.