• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.157-165
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• 2006

In February,2004, at International Maritime Organization (IMO), LONDON, a new international convention 'International Convention fur the Control and Management of Ship's Ballast Water and Sediment 2004' was adopted. It is called 'Ballast Water Management Convention (BWM)'. Ballast water means charged seawater or fresh water in ship's special tanks (ballast tank) to keep safety navigation and ship's maneuverability. However, from 1980, it was point out the serious problem for marine ecosystem and human life that ballast water includes harmful marine species (and small organisms) and these species are also discharged along with ballast water. These species were released with discharged ballast water in water areas, where species are different from discharged ballast water. The problem is that released species increase when released species are more powerful than native species and consequently, marine ecological system is destroyed in released water area. Authors have inspected the validity of the ballast water exchange using pumping-through method that is one of the methods of ballast water management. In this paper, the numerical simulation of the motion and density of the fluid at the time of exchange of the fluid in a 2-dimensional tank using the pumping-through method was carried out by using two different type numerical methods. One method is MPS method that is one of the particle methods. Other one is Finite Different Method (FDM). Authors were compared with result of two numerical method calculations and experiment result and reported some knowledge from these results.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.687-693
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• 2018

The active development of the global marine trade industries has been known to increase the inflows of marine invasive species and harmful organisms into the ecosystem, and the marine ecological disturbances. One of these invasive species, Ciona robusta, has now spread to the Korea Strait, the East Sea, and Jeju Island in connection with the climate change but not the Yellow Sea in Korea. Currently, the spread and distribution of C. robusta is increasingly damaging aquaculture and related facilities. Therefore, this study aims to identify the spread of C. robusta and potential habitats and to secure a data for the prevention of effective management measures due to climate change as well as damage the reduction in future through the prediction of spread. We used environmental variables in BioOracle. Also, the potential habitat and distribution of C. robusta was predicted using MaxEnt, a species distribution model. Two different RCP scenarios(4.5 and 8.5) were specified to predict the future distributions of C. robusta. The results showed that the biggest environmental factor affecting the distribution of C. robusta was the salinity as well as the highest distribution and potential habitats existent in the East Sea and around Jeju Island.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.63-68
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• 2009

Among various microscopic organisms producing photobiological hydrogen, cyanobacteria have long been recognized as the promising biological agents for hydrogen economy in 21 century. For photobiological production of hydrogen energy, marine unicellular $N_2$-fixing cyanobacteria have been evaluated as an ideal subgroup of Cyanophyceae. To develope the hydrogen production technology using unicellular $N_2$-fixing cyanobacteria, 3 important factors are pre-requisite: 1) isolation of the best strain from marine natural environment, 2) exploration on the strain-specific optimal conditions for the photobiological hydrogen production, and finally 3) application of the molecular genetic tools to improve the natural ability of the strain to produce hydrogen. Here we reviewed the recent research & development to commercialize photobiological hydrogen production technology, and suggest that intensive R&D during next 10-15 years should be imperative for the future Korean initiatives in the field of the photobiological hydrogen production technology using photosynthetic marine unicellular cyanobacterial strains.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.389-401
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• 2024

In recent decades, numerous instances of blockages have been reported in coastal nuclear power plants globally, leading to serious safety accidents such as power reduction, manual or automatic power loss, or shutdown of nuclear power units. Loss or shortage of cooling water may compromise the reliability of the cooling water system, thus threatening the operational safety of power plants and resulting in revenue reduction. This study provides a comprehensive review of the current state of cooling water system safety in coastal nuclear power plants worldwide and the common challenges they face, as well as the relevant research on cooling water system safety issues. The research overview and progress in investigation methods, outbreak mechanisms, prevention and control measures, and practical cases of blockages were summarized. Despite existing research, there are still many shortcomings regarding the pertinence, comprehensiveness and prospects of related research, and many problems urgently need to be solved. The most fundamental concern involves understanding the list of potential risks of blockages and their spatially distributed effects in surrounding waters. Furthermore, knowledge of the biological cycles and ecological habits of key organisms is essential for implementing risk prevention and control and for building a scientific and effective monitoring system.

• Journal of Life Science
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• v.26 no.11
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• pp.1308-1312
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• 2016

Heavy metals such as gallium (Ga) cause serious physiological damage to exposed organisms, mostly of aquatic species. Ga one of the inter-metallic, transition elements increasingly being used in making high-speed semiconductors, such as Ga arsenide. The purposes of this study were to investigate the effects of Ga on acute toxicity, serum biochemical changes, and erythrocyte morphological changes in the blood stream of goldfish (Carassius auratus). Median lethal concentrations were determined in acute tests. The 96 hr $LC_{50}$ value was 9.15 mg/ml. Goldfish were exposed to different Ga concentrations (2.0, 4.0, and 8.0 mg/ml) for 30 days to assess its toxic effects. The results indicate that the measured serum biochemistry parameters (including glucose, blood urea nitrogen, creatinine, cholesterol, and triglyceride) of the Ga-exposed fish groups differed significantly from the untreated fish group. In addition, a change in the erythrocytes' morphology at a high concentration (8.0 mg/ml) of Ga exposure shows respiratory problems. Our results suggest that 2.0 mg/ml is proposed as a biologically safe concentration that can be used for establishing tentative water quality criteria concerning the same-size goldfish.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.9-16
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• 2013

An experiment was conducted to evaluate the biochemical adverse effect of increased carbon dioxide in seawater on marine polychaete, Perinereis aibuhitensis. We measured the available energy reserves, Ea (total carbohydrate, protein, and lipid content) and the energy consumption, Ec (electron transport activity) of Perinereis aibuhitensis exposed for 7-d to a range of $CO_2$ concentration such as 0.39 (control =390 ppmv), 3.03 (=3,030 ppmv), 10.3 (=10,300 ppmv), and 30.1 (=30,100 ppmv) $CO_2$ mM, respectively. The cellular energy allocation (CEA) methodology was used to assess the adverse effects of toxic stress on the energy budget of the test organisms. The results of a decrease in CEA effect of increased carbon dioxide in seawater from all individual in Ea and Ec. Increase of carbon dioxide reduced pH in seawater, significantly. The chemical changes in sea- water caused by increasing $pCO_2$ might cause stresses to test organisms and changes in the cellular energy allocations. Results of this study can be used to understand the possible influence of $CO_2$ concentration increased by the leakage from sub-sea bed storage sites as well as fossil fuel combustion on marine organisms.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.382-388
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• 2015

Eleven protease-producing bacteria were isolated from the organisms' external shells and the inorganic materials collected from intertidal zone of Jeju Island, Republic of Korea. The samples were diluted serially, inoculated on Zobell agar plates with 1% skim milk and incubated at $20^{\circ}C$. Clear zone forming colonies were selected as protease-producing bacteria and each strain was identified based on the phylogenetic analysis with their 16S rDNA sequences. Strains JJM125, JJM129, YG47 and YG49 belong to the marine bacterial genus Pseudoalteromonas; strain JJM122 belong to the genus Microbulbifer; strains YG51, YG52, YG62 and YG63 belong to the genus Vibrio; and strain YG65 belong to genus Bacillus. Hence, the present study suggests that these protease producing bacteria could be further used to develop new varieties of protease with various biotechnological applications.

• Journal of Aquaculture
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• v.11 no.4
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• pp.449-455
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• 1998

The small size food organism(under the size 150${\mu}m$) is needed as food for early stage of marine fish larvae of small mouse (e.g the group of grouper). This study was investigated to develop a method for copepod Apocyclops sp. culture in combination with the rotifer B. rachionus for stable culture of copepod species and harvest of various size food organisms. The culture conditions as temperature, salinity, culture volume, photo period, culture preiod and observation interval were 25${\circ}C$, 22ppt, 40ml, all dark except to observation time, 16 days and every two day during the experimental period, respectively. The Tetraselmis suecica was used as the food for the two testing orgtanisms. After every two day counting, theses two organisms were transferred to fresh culture tanks with Tetraselmis suecica of $7{\times}10^5$cells/ml. In the mixed culture of B. rotundiformis and A. sp., growth of rotifer was suppressed by mixed culture with A. sp. whereas the growth of copepod Apocyclops was promoted in the mixed culture with rotifer B. rotundiformis (the maximum density was 22 individuals/ml through the 16 culture days). Moreover, the number of copepod nauplius were promoted about 2 times in the mixed culture compared to the numbers in single species culture. With this combination culture, the havested two food organisms of variable sizes. This size variation of food organisms was useful tools for larval rearing of small mouse marine fish larvae and next step food organism size of post hatched larvae.

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.460-470
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• 2017

Mussels are major fouling organisms causing serious technical and economic problems. In this study, antifouling activity towards mussel was found in three compounds isolated from a marine bacterium associated with the sea anemone Haliplanella sp. This bacterial strain, called PE2, was identified as Vibrio alginolyticus using morphology, biochemical tests, and phylogenetic analysis based on sequences of 16S rRNA and four housekeeping genes (rpoD, gyrB, rctB, and toxR). Three small-molecule compounds (indole, 3-formylindole, and cyclo (Pro-Leu)) were purified from the ethyl acetate extract of V. alginolyticus PE2 using column chromatography techniques. They all significantly inhibited byssal thread production of the green mussel Perna viridis, with $EC_{50}$ values of $24.45{\mu}g/ml$ for indole, $50.07{\mu}g/ml$ for 3-formylindole, and $49.24{\mu}g/ml$ for cyclo (Pro-Leu). Previous research on the antifouling activity of metabolites from marine bacteria towards mussels is scarce. Indole, 3-formylindole and cyclo (Pro-Leu) also exhibited antifouling activity against settlement of the barnacle Balanus albicostatus ($EC_{50}$ values of 8.84, 0.43, and $11.35{\mu}g/ml$, respectively) and the marine bacterium Pseudomonas sp. ($EC_{50}$ values of 42.68, 69.68, and $39.05{\mu}g/ml$, respectively). These results suggested that the three compounds are potentially useful for environmentally friendly mussel control and/or the development of new antifouling additives that are effective against several biofoulers.

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.232-241
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• 1998

Fatty acid compositions of 35 species of marine invertebrates (13 species of Bivalvia, 10 species of Gastropoda, 4 species of Cephalopoda, 4 species of Crustacea, 2 species of Ascidacea, 2 species of Holothuroidea) were studied using gas-liquid chromatography. Total lipids in all samples were very low, ranging from $0.24\%$ to $1.96\%$. The prominent fatty acids were 16:0, 20:5 (n-3), 22:6 (n-3), 18:0, 16:1 (n-7), 20:4 (n-6), 18:1 (n-9) and 18:1 (n-7) in the majority of marine invertebrates. Polyunsaturated fatty acid (PUFA) was the richest fatty acid group in all invertebrates, accounting for $55.3\pm6.70\%$ of total fatty acids (TFA), followed by saturated $(26.2\pm4.33\%)$ and monounsaturated fatty acid $(18.5\pm5.87\% )$. No correlation was found between total lipid content and each fatty acid group. Cephalopoda contained the highest level of n-3 PUFA $(54.6\pm5.17\%)$, while Holothuroidea and Gastropoda contained the lowest level of n-3 PUFA, accounting for $26.5\pm4.44\%$ and $28.4\pm4.04\%$, respectively. Bivalvia and Ascidacea are plankton feeders, which were rich in 20:5 (n-3) and 22:6 (n-3). Carnivorous species of Cephalopoda were prominently rich in 22:6 (n-3), ranging from $26.7\%$ to $46.1\%$ of the TFA. However, some species of Gastropoda are seaweed feeder (herbivorous), which contained high level of 20:4 (n-6) compared to plankton feeder and carnivorous species. In addition, blue and red colored sea cucumbers, and turban shells with and without apophyses belong to the same species, but they live in different habitats. These organisms were found to have different fatty acid compositions. Therefore, fatty acid compositions of these invertebrates might be affected by their different environments, particularly their diet.