• Korean Journal of Microbiology
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• v.48 no.1
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• pp.42-47
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• 2012

Hydrothermal vents (HTV) provide special environments for evolution of lives independent on solar energy. HTV samples were gained from Tofua arc trench in Tonga, South Pacific. We investigated archaeal diversity enriched using combinations of various electron donors (yeast extract and $H_2$) and electron acceptors [Iron (III), elemental sulfur ($S^0$) and nitrate. PCR amplification was performed to detect archaeal 16S rRNA genes after the cultures were incubated $65^{\circ}C$ and $80^{\circ}C$ for 2 weeks. The cultures showing archaeal growth were transferred using the dilution-to-extinction method. 16S rRNA gene PCR-Denaturing Gradient Gel Electrophoresis was used to identify the enriched archaea in the highest dilutions where archaeal growth was observed. Most of cultured archaea belonged to genus of Thermococcus (T. alcaliphilius, T. litoralis, T. celer, T. barossii, T. thoreducens, T. coalescens) with 98-99% 16S rRNA gene similarities. Interestingly, archaeal growth was observed in the cultures with Iron (III) and nitrate as an electron acceptor. It was supposed that archaea might use the elemental sulfur generated from oxidation of the reducing agent, sulfide. To cultivate diverse archaea excluding Thermococcus, it would be required to use other reducing agents instead of sulfide.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.1
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• pp.20-29
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• 2004

Macrobenthos species-area relationship was investigated and empirical models were estimated to enable comparisons among species numbers of different sample size. The study aims to choose a way to predict cumulative relative species number (CRSN) in a given sample size Saemangeum, located in the west coast of South Korea, were visited in Apr., May and Aug.,2002 and a total of 261 biological samples from 87 stations were obtained by employing a quantitative sediment sampler, Smith-McIntyre grab and design of 3 replicates at each station. Relative species numbers (%) were baselined at sample size of 1000 $\textrm{cm}^2$ and the patterns of CRSN along the axis of sample size were measured and observed. In correlation analysis performed on a set of abiotic and biotic variables, log-transformed CRSN showed the only significant relationship with log-transformed density. Based on the result, three models, Log CRSN 2000, Log CRSN 3000 and Log CRSN were produced. The former two were devised to predict CRSN at 2000 and 3000 $\textrm{cm}^2$ respectively, and the latter at various sample sizes and samplers (all p-values were <0.001). Database from other studies (intertidal or subtidal macrofaunal samples from Kyonggi Bay and Saemangeum) were used to evaluate validity of the models. Observed CRSN below sample size of 3000 $\textrm{cm}^2$ fell under the range of 95% prediction interval and this was appeared to provide reliability of the models below that sample size.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.4
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• pp.372-380
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• 2015

In order to study the characteristics of physical environment in water column around the artificial upwelling structure, CTD and currents measurements were carried out along line observations. Before installation of artificial upwelling structure was installed, the stratification of water column existed 30m in water depth. After installation of artificial upwelling structure, however, stratification formation depth and strength changed depending on currents directions. It seems that the change of stratification has a close relation with upwelling of lower temperature water. After installing the artificial upwelling structure, the distributions of vertical flows were analyzed. Local upwelling and downwelling flows showed a distinct time and spacial changes. Local upwelling flows caused by artificial upwelling structure appeared 100 times larger than coastal upwelling in the South-East Sea of Korea. Upwelling flows generated by the artificial structure raised the high concentration of nutrients to upper layer from lower layer breaking stratification in the summer. Thus, upwelling structure plays an important role for vertical water circulation improving the food environments by increasing primary production.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.388-392
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• 1997

The random amplified polymorphic DNAs (RAPD) technique was used to characterize seven isolates of the green seaweed Ulvales collected from Songjeng, Haeundae, Jumunjin, Dadaepo and Wando in Korea. Total DNA was extracted by the LiCl extraction method from thalli of green seaweed. The extracted DNA (3 ng) in $25{\mu}\ell$ reaction volume was amplified by 45 cycles of the polymerase chain reaction with arbitrary primers. Thirty-four primers resulted in 1227 PCR products ranged 240 bp to 1.5 kb of both conserved and polymorphic bands. Genetic similarities of the seven isolates calculated by Jaccard's equation were ranged from $7\%\;to\;36\%$. Monostroma nitidum (Wando) was shown to be most distantly related with the others based on genetic similarity and did not produce the amplified band of 630 bp, common in Ulvales using primer OPB-01 (CATCCCCTG).

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.4
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• pp.139-151
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• 2017

The habitat preference of roe deers(Capreolus pygargus) in Jeju island, South Korea was analyzed by using their occurrence probability in MaxEnt model in this study. Totally 490 surveying data were gathered and 15 environmental variables were chosen for the model in which 6 variables out of 15 ones were filtered and finally removed because of there being higher correlation(over 0.7 in correlation coefficient). According to the modeling, roe deers were known to prefer the area ranging from 200 to 700 meter and over 1,500 meter in sea level, where there were not many dominant tree and/or dominant vegetation with low density so that understory vegetation can grow well with plentiful sunlight and can be used as a food of herbivore like roe deers. Otherwise, the region ranging from 700 to 1,500 meter was mostly covered with high density vegetation which cut off sunlight trying to penetrate through the dominant vegetation. It can cause a lower density of vegetation on surface, which can not attract to roe deers.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.273-281
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• 2014

We conducted the weekly monitoring (December 2012~April 2013) to evaluate the temporal variation and identification of Stephanodiscus spp. that are generally dominant during winter in the Yeongsan River. Phytoplankton species were identified and counted using the optical microscope and scanning electron microscope (SEM). Phytoplankton in the river were grouped into 6 classes (bacillariophyceae, chlorophyceae, cryptophyceae, cyanophyceae, dinophyceae, euglenophyceae), 30 genus and 41 species. Phytoplankton composition showed high abundance of diatoms in winter and Aulacoseira sp., Cyclotella sp. and Stephanodiscus spp. were dominant. Among the species, Stephanodiscus spp. was relatively abundant compared to other diatom species. Stephanodiscus spp. appeared from December 2012 to April 2013 and their abundance peaked in January. Abundance of diatoms especially peaked ($21,080cells\;mL^{-1}$) in January 15, 2013 when Stephanodiscus spp. also bloomed ($20,560cells\;mL^{-1}$). The abundances of Stephanodiscus spp. were gradually decreased from March and reached as low as $60cells\;mL^{-1}$ in April 26. Cyclostephanos (C. invisitatus), Cyclotella (C. meneghiniana), Discostella (D. pseudostelligera, D. woltereckii) and Stephanodiscus (S. hantzschii, S. minutulus, S. parvus) were classified in the circular diatoms. Abundance of S. hantzschii was extremely high compared to S. minutulus and S. parvus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.5
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• pp.554-559
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• 2011

To measure the proximate composition and mineral content of laver Porphyra yezoensis, we collected 30 raw and 30 dried laver from the major production area of the south coast of Korea (Busan, Goheung, Haenam, Wando). The approximate composition of a 100 g edible portion of raw laver was $89.9{\pm}1.4$ g moisture, $3.7{\pm}1.0$ g protein, $0.5{\pm}0.2$ g lipids, $2.1{\pm}1.8$ g carbohydrate and $3.9{\pm}0.6$ g ash. The approximate composition of a 100 g portion of dried laver was $8.9{\pm}1.6$ g moisture, $31.5{\pm}6.5$ g protein, $1.9{\pm}0.3$ g lipids, $48.4{\pm}6.5$ g carbohydrate and $9.3{\pm}1.1$ g ash. No clear regional variation in laver composition was observed. The mineral content of laver was expressed as dry weight. The mean macro mineral content per 100 g portion of raw laver was (in descending order): K ($1,979{\pm}863.0$ mg), Na ($1,063.2{\pm}498.8$ mg), P ($658.7{\pm}101.8$ mg), Mg ($432.3{\pm}83.5$ mg) and Ca ($394.2{\pm}136.5$ mg). In comparison, the mean micro mineral content of raw laver was (in descending order): Fe ($243.72{\pm}154.75\;{\mu}g/g$), Zn ($72.76{\pm}30.61\;{\mu}g/g$), Mn ($41.53{\pm}15.33\;{\mu}g/g$), Cu ($4.16{\pm}1.66\;{\mu}g/g$) and Ni ($0.43{\pm}0.70\;{\mu}g/g$) No clear regional variation in the mineral content of laver was observed; however, raw laver contained a higher mineral content than dried laver.

• Journal of Navigation and Port Research
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• v.41 no.4
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• pp.195-206
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• 2017

In situ capping technology for marine sediment pollution control has never been applied in South Korea. In this study a pilot project for the capping was carried out in Busan N Harbor. Pipeline and clamshell capping technologies were implemented for the pollution control. Changes of capping shapes, sediment contamination, and the time and costs required for the two constructions were compared. Both the pipeline and clamshell technologies were found to satisfy the target thickness of 50 cm on average. However, the pipeline method did not operate sensitively in terms of change of the sea floor topography, resulting in an uneven shape and a thickness. Organic carbon and ignition loss quite decreased after the pipeline or the clamshell capping while pH showed no significant change. Organic and residual fraction of Cd, Ni, and Zn in the sediments appeared to decrease after all cappings. The pipeline method took a construction time four times as much as the clamshell method. The clamshell method was demonstrated to reduce the construction cost by about 40% compared with the pipeline method. However, a monitoring for all the parameters needs to be conducted at least two years in order to better evaluate an efficiency of the pollution control by these capping constructions.

• Korean Journal of Environmental Biology
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• v.39 no.1
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• pp.19-31
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• 2021

We investigated the distribution characteristics of mussels (Mytilus coruscus) growing in the Geomundo sea area by water depth. The research was also conducted to identify the surrounding benthic organisms. Mussels showed high density and low obesity in low water depths. The lower the density, the higher the obesity level appeared in deeper water. The morphological characteristics also appeared to increase as the water depth deepened. In addition, the shell length and total weight were more strongly correlated at a depth of 12 m than at 2 m. The total weight by the growth of the shell length and shell height was affected by the water depth. The analysis showed that the density and biomass of the algae inhabiting the surroundings decreased somewhat as the water depth increased. In benthic animals, the number of mussels tended to decrease slightly at the point where oysters dominated, at a depth of 2 m. Conversely, the number of oysters tended to decrease in deeper water dominated by mussels. Thus, the spatial competition between oysters and mussels was affected by the water depth. Also, mussels did not appear in areas where large algae flourished, suggesting that the survival of mussels was affected by the presence or absence of large algae.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.200-210
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• 2007

Phytoplankton community was investigated in Asan Bay, South Korea. Samples were collected at 5 stations along Asan Bay axis during wet season from June to August, 2006. In June and July, salinity decreased especially at inside stations. Nutrients were high in June and July, however, decreased in August. We observed the community of phytoplankton including diatoms(62.8%), dinoflagellates(17.3%), cryptophytes(14.8%), euglenophytes(1.0%), cyanophytes (0.9%), chlorophytes(0.4%), and some of unidentified taxa(2.8%) during summer 2006 in Asan Bay. In June, dinoflagellates (mainly Prorocentrum sp.(29.6%)) were dominated, accounting for about 43.5% of total cell number, whereas in July and August diatoms (mainly Leptocylindrus sp.(21.4%), Chaetoceros sp.(27.6%)) were dominated occupying 69.1% and 89.9%, respectively. The results suggest that freshwater inputs affected phytoplankton community in the Asan Bay ecosystem.