• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 추계학술발표회
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• pp.197-205
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• 2007

국내에서 가축분뇨를 폐기물의 해양배출에 관한 현황 및 정부와 업계의 입장을 살펴보고, 정부(해양수산 및 농림부)와 업계(대한양돈협회 및 해양배출협회) 간의 갈등을 해결하는 대책을 검토하였다.

• 한국수산과학회지
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• 제30권6호
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• pp.929-935
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• 1997

The total energy of fish movement and the maximum burst swimming speed were estimated and formulated in accordance with body length and water temperature for several species in fisheries by empirical methods and also by using published results. Under the assumption of swimming energy reserve of a fish at the initial rest state, the swimming endurance of fish with different body lengths, swimming speeds and angular velocity was calculated using the relevant equations under similar conditions in tank experiments as well as natural conditions in field. Relative swimming energy efficiency or the transition swimming speed between red and white muscle for energy consumption was represented as a trigonometric function of swimming speed ratio. Therefore, this model does closely approach the actual swimming abilities and their limits especially in relation to the fishing gear operation and allow for the greater vitality of the wild fish in the fields.

• Fisheries and Aquatic Sciences
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• 제15권3호
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• pp.259-263
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• 2012

To isolate an alginate-degrading bacterium, we conducted a single colony isolation using a solid medium containing alginate as the sole carbon source. A marine bacterium Y-4 capable of degrading alginate was isolated from seawater. The strain was identified to be Pseudoalteromonas sp., based on morphological, biochemical, 16S rDNA homology, and phylogenetic analyses. Moreover, Pseudoalteromonas sp. Y-4 exhibited alginate lyase activity in the presence of 4% alginate even though many known alginate-degrading bacteria degrade in the range of 0.5-1% alginate. The optimum culture conditions for the Y-4 strain were 2% alginate, pH 8.0, and 3% NaCl at $30^{\circ}C$. The highest alginate lyase activity was also observed under the same conditions. To our knowledge, this is the first reported isolation of a marine bacterium degrading high concentrations of alginate.

• 한국표면공학회지
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• 제51권2호
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• pp.87-94
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• 2018

Various sealing techniques were applied to the anodized 5083 aluminum alloy for marine environment to reduce corrosion and cavitation erosion damage. Electrochemical experiments and cavitation erosion tests were conducted to evaluate the corrosion resistance and cavitation resistance of the anodic oxide film treated with sealing in natural seawater solution. Then, damaged surface morphology was analyzed by scanning electron microscope(SEM) and 3D microscope. As the results of the electrochemical experiments, it was observed that the surface damage of all the experimental conditions in the anodic polarization experiment was locally grown by the combination of crack and corrosion damage. In the Tafel analysis, the corrosion resistance of all sealing treatment conditions was improved compared to the anodizing. On the other hand, cavitation erosion tests showed that the anodizing and all the sealing treatment conditions generated local pit damage by cavitation erosion attack and grew to crater damage in the observation of damaged surface by SEM. Also, the weight loss and the surface damage depth measured with the experiment time presented that most of the sealing treatment conditions showed better cavitation erosion resistance than the anodizing, and they had an incubation period at the beginning of the experiment.

• ALGAE
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• 제38권4호
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• pp.283-294
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• 2023

Previous research indicated that free-living sporangial filament keep hollow morph under high-culture density and form bipartite cells under low-culture density, while the following conchospore release was inhibited by high light. Here, we further explored the molecular bases of these affects caused by light and culture density using a transcriptome analysis. Many differentially expressed genes (DEGs) related to carbon dioxide concentration and fixation, photosynthesis, chlorophyll synthesis and nitrogen absorption were upregulated under high-light conditions compared with low-light conditions, indicating the molecular basis of rapid vegetative growth under the former. The stress response- and ion transport-related DEGs, as well as the gene encoding the vacuole formation-brefeldin A-inhibited guanine nucleotide exchange protein (BIG, py05721), were highly expressed under high-density conditions, indicating the molecular basis of the hollow morph of free-living sporangial filaments under high-culture density conditions. Additionally, the brefeldin A treatment indicated that the hollow morph was directly influenced by vacuole formation-related vesicle traffic. Others DEGs related to cell wall components, zinc-finger proteins, ASPO1527, cell cycle and cytoskeleton were highly expressed in the low density with low-light group, which might be related to the formation and release of conchospores. These results provide a deeper understanding of sporangial filaments in Neopyropia yezoensis and related species.

• 소음진동
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• 제6권4호
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• pp.503-511
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• 1996

There is a tendency of using the resilient mounting system to control the structure born noise transimitted from a engine of which weight is comparatively light and of which speed is comparatively high. According to recent reports, the resilient mounting system is applied to control the vibration of a engine running up to 300 - 400 R.P.M.. Furthermore, the resilient system is also used to the ships such as marine exploring ships, fishing boats, and military vessels. It is not desirous to apply the results for the resilient mounting systems of automobile engines to the controls of the vibrations of marine engines. Marine engines are worked under the idle speed in port and are operated up to the maximum contineous revolution at sea(running up condition). And marine engines are usually worked in inevitable conditions such as a misfire and a cut-off cylinder operating condition. Concerning the above running conditions, a resilient mounting system should be designed in the case of marine engines. In this paper, we studied the effect of engine's misfire on the resilient mounting systems. And the influences of design parameters, such as dynamic characteristics and fitting angles of resilient rubber mountings, were also investigated respectively on the single and double resilient mounting systems.

• 한국해양바이오학회지
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• 제12권2호
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• pp.115-122
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• 2020

Eisenia bicyclis, a perennial macroalga is a primary producer of in the ocean, It has been identified as a key species that plays a vital role in maintaining the ecosystem stability. Also, it is an important target in marine afforestation projects and useful marine organisms. In addition, E. bicyclis is used as a health food for humans. This study investigated the effect of water temperature, light (photon irradiance), and duration of light (photoperiod) on the growth of gametophytes and young sporophytes of E. bicyclis. The germination and growth of the zoospores of E. bicyclis were examined at five temperatures (5℃, 10℃, 15℃, 20℃ and 25℃), four intensities of photon irradiance (10, 20, 40, and 80 μmol m-2s-1), and photoperiods (14:10 and 10:14 light/dark cycles). The zoospores released from mature plant germinated into the gametophytes under all experimental conditions. The gametophytes were able to grow at water temperature 5℃-25℃ and mature at 10℃-20℃. The optimal range of water temperature for the maturation of the gametophyte was 15℃-20℃. At 25℃, E. bicyclis gametophytes grew rapidly but did not mature. The optimal culture conditions for the growth of young sporophytes grew slowly in low temperature and photon irradiances.

• 동력기계공학회지
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• 제22권1호
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• pp.25-33
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• 2018

The safety of structure was evaluated by taking into consideration the complex marine environmental conditions of the Lattice boom crane, which is widely used in offshore plants due to less influence by wind. CFX analysis was carried out to take into account the influence of wind speed, and the result was applied as a boundary condition to perform static analysis according to the luffing angles of $28^{\circ}$, $61^{\circ}$, and $80^{\circ}$ in the on board and off board, respectively. In addition, the Lattice Boom Crane is large slender structure, and the possibility of buckling is interpreted under three conditions where the biggest stress occurs. All conditions satisfied the safety requirements of the Classification Regulations. Also, as a result of the buckling analysis, the load less than the critical load was applied so buckling does not occur.

• Journal of Species Research
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• 제9권4호
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• pp.339-345
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• 2020

The Earth contains billions of microbial species, although the vast majority cannot be cultured in laboratories and are thus considered unidentified and uncharacterized. Extremophiles are microorganisms that thrive in extreme conditions, including temperature, salinity, and pH. Extremophilic microorganisms have provided important insights for biological, metabolic, and evolutionary studies. Between 2017 and 2019, as part of a comprehensive investigation to identify bacterial species in Korea, eight bacterial strains were isolated from marine and non-marine environments in Jeju Island. These strains were cultured under extreme salinity or pH conditions. Phylogenetic analysis using 16S ribosomal RNA(rRNA) gene sequencing indicated that all eight strains belonged to the phyla Gammaproteobacteria, Bacilli, and Alphaproteobacteria. Based on their high 16S rRNA gene sequence similarities(>98.7%) and the formation of strong monophyletic clades with their closest related species, all isolated strains were considered as an unrecorded strain, previously unidentified species. Gram stain reaction, culture conditions, colony and cell morphology, biochemical characteristics, isolation source, and National Institute of Biological Resources(NIBR) IDs are described in this article. The characterization of these unrecorded strains provides information on microorganisms living in Korea.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.267-273
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• 2018

Hydrothermal liquefaction of Chlorella vulgaris feedstock containing 80% (w/w) water was conducted in a batch reactor as a function of temperature (300, 325 and $350^{\circ}C$) and reaction times (5, 10 and 30 min). The biocrude yield, elemental composition and higher heating value obtained for various reaction conditions helped to predict the optimum conditions for maximizing energy recovery. To optimize the recovery of inorganic nutrients, we further investigated the effect of reaction conditions on the ammonium ($NH_4{^+}$), phosphate ($PO_4{^{3-}}$), nitrate ($NO_3{^-}$) and nitrite ($NO_2{^-}$) concentrations in the aqueous phase. A maximum energy recovery of 78% was obtained at $350^{\circ}C$ and 5 min, with a high energy density of 34.3 MJ/kg and lower contents of oxygen. For the recovery of inorganic nutrients, shorter reaction times achieved higher phosphorus recovery, with maximum recovery being 53% at $350^{\circ}C$ and 5 min. Our results indicate that the reaction condition of $350^{\circ}C$ for 5 min was optimal for maximizing energy recovery with improved quality, at the same time achieving a high phosphorus recovery.