• Ocean and Polar Research
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• 제37권1호
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• pp.73-80
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• 2015

In order to determine the appropriate volume of the a pressure compensator of deep seabed mining robots, this paper reports on an experimental test for oil volume change in an oil-filled box. At the design stage of underwater robots, it is crucial to determine the capacity of the hydraulic compensator which is replenished as much as the contracted oil volume of the robots. A pilot mining robot, MienRo was designed to work under 6,000 m in the deep sea. The hydraulic actuating oil and pressure compensating oil of MineRo may be exposed at a hydrostatic pressure environment of 600 bar. Although the oil can be assumed to be incompressible, its volume is actually changed under high pressure conditions due to air contained in the oil and oil contraction. To determine the capacity of the pressure compensator, the oil contraction rate should be verified through an experimental test using a hyperbaric chamber.

• Ocean and Polar Research
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• 제37권3호
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• pp.211-223
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• 2015

Korean society has been recently promoting the restoration of coastal wetlands. These efforts might become the basis of a policy framework that compensates for the limitations of a regulation-oriented policy such as the designation of Marine Protected Areas (MPAs). The shift in government policy could contribute to strengthening the socioeconomic infrastructure of coastal development through the accumulation of ecological capital. Although our scientific efforts and social demands in regard to the ecological restoration of the coastal wetlands have increased during the past years, the bases for restoration in Korea requires that scientific, technological, financial, social and legal aspects be enhanced. The present study re-examined the concept and attitudes behind coastal wetland restoration in the light of changing circumstances in Korea. Herein, we first defined coastal wetland restoration as "An act of recovering the functions of the ecosystem of coastal wetlands to a state that resembles conditions prior to being damaged." Next, this study discussed the limitations and future directions of such restoration efforts based on the descriptive analyses of recent restoration practices from social, economic, and technological aspects. Finally, we suggest future policy directions regarding coastal wetland restoration on the basis of a PFST (Policy, Financial, Social, and Technological) analysis; 1) re-arranging legal mechanisms, 2) setting multi-dimensional restoration goals, 3) establishing a multi-discipline- and convergence based R&D system, 4) linking spatial management and local development to the restoration, 5) building restoration governance at the local level, 6) implementing an ecosystem service payment system, and 7) applying test-bed projects in accordance with proper directions.

• Ocean and Polar Research
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• 제30권3호
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• pp.325-334
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• 2008

A biogeochemical model was used to estimate air-sea $CO_2$ exchange over the East China Sea. Since fresh water discharge from the Changjiang River and relevant chemistry were not considered in the employed model, we were not able to produce accurate results around the Changjiang River mouth. This factor aside, the model showed that the East China Sea, away from the Changjiang River mouth, takes approximately $1.5{\sim}2\;mole\;m^{-2}yr^{-1}$ of $CO_2$ from the atmosphere. The model also showed that biological factors modify the air-sea $CO_2$ flux by only a few percent when we assumed that biological activity increased two-fold. Therefore, we can argue that the biological effect is not strong enough over this area within the framework of the current phosphate-based biological model. Compared to the preindustrial era, in 1995 the East China Sea absorbed $0.4{\sim}0.8\;mole\;m^{-2}yr^{-1}$ more $CO_2$. If warming of the sea surface is considered, in addition to the increase in atmospheric $CO_2$ concentration, by 2045 the East China Sea would absorb $0.2{\sim}0.4\;mole\;m^{-2}yr^{-1}$ less $CO_2$ compared to the non-warming case.

• Ocean and Polar Research
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• 제36권4호
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• pp.423-435
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• 2014

Verifying the similarity of environmental characteristics between an artificial impact site and a preserved or reference site is necessary to quantitatively and qualitatively evaluate the environmental impact of mining activity. Although an impact site (BIS station) and a preserved site (called KOMO station) that have been selected in the Korea manganese nodule contract area may share similar environmental characteristics, similarities in terms of the water column environment between both sites has not been investigated. In this study, we compared the chemical properties of the water columns and sinking particle fluxes between BIS and KOMO stations through two observations (August 2011 and September 2012). Additionally, we observed particle fluxes at the KOMO station for five years (July 2003~July 2008) to understand long-term natural variability. Vertical distributions of water column properties such as dissolved oxygen, inorganic nutrients (N, P, Si), total organic carbon below surface layer (within the depth range of 200 m) were not considerably different between the two sites. Especially, values of water column parameters in the abyssopelagic zone from 4000 m to bottom layer (~5000 m) were very similar between the BIS and KOMO sites. Sinking particle fluxes from the two sites also showed similar seasonality. However, natural variation of particle flux at the KOMO site varied from 3.5 to $129.9mg\;m^{-2}day^{-1}$, with a distinct temporal variation originating from ENSO events (almost forty times higher than a minimum value). These results could provide valuable information to more exactly evaluate the environmental impact of mining activity on water columns.

• Ocean and Polar Research
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• 제27권1호
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• pp.109-113
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• 2005

To facilitate estimation of the barbel size of a striped sea catfish, Plotosus lineatus Thumberg total length (TL) and head length (HL) against body weight (BW), HL against TL, and 1st maxillary barbel $(MxBL_1)$, 2nd maxillary barbel $(MxBL_2)$, 1st mandibular barbel $(MnBL_1)$ and 2nd mandibular barbel $(MnBL_2)$ against HL were regressed. The relationship of TL and HL for BW were described by the equation $TL=50.9373BW^{0.3072}\;(r^2=0.9898)$ and $HL=11.2938BW^{0.3144}(r^2=0.9572)$, respectively. The relationship of HL for TL was described by the linear equation $HL=0.1982TL+2.1996(r^2=0.9568)$. The relationship of each barbel for HL described by the equation of $HxBL_1=0.04420HL+0.3105(r^2=0.9615),\;MxBL_2=0.4592HL+0.5321(r^2=0.9519), MnBL_l=0.4057HL+1.9824 (r^2=0.9465)\;and\;MnBL_2=0.4355HL+1.8010(r^2=0.9429)$. Knowledge of the relative growth patterns about each barbel of this species is important for the propagation of seed as stock for large-scale striped sea catfish culture.

• Ocean and Polar Research
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• 제27권1호
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• pp.59-65
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• 2005

To assess the effect of anaesthetic on stress response in cultured sweetfish (Plecoglossus altivelis) during transportation, the levels of plasma cortisol, glucose, lactic acid, $Na^+,\;K^+,\;Cl^-$, osmolality and survival were determined. The transportation was performed in square boxes where liquefied oxygen was saturated in polyethylene bags. Fish transportation was carried by car for 2 hours after anaesthesis with lidocaine-HCl/1,000 ppm $NaHCO_3$ in experiment. Mean plasma cortisol concentration before transportation was 170.7ng/ml. After transportation, the levels of plasma cortisol increased to 518.5ng/ml (Control), 461.9ng/ml (Sham control), 369.4ng/ml (20ppm anaesthetic), 304.0ng/ml (40 ppm anaesthetic), 405.7ng/ml (80 ppm anaesthetic) and 499.1ng/ml (160ppm anaesthetic) in each experimental groups, respectively (p<0.05). However levels of glucose, lactic acid, $Na^+,\;Cl^-$ and osmolality in 40ppm anaesthetic group did not show significant differences in this before and after transportation (P>0.05). These result reveal an anaesthetic lidocaine HCl/1,000ppm $NaHCO_3$ is effective as sedative for transportation mixture in this species. This research provides baseline data on cortisol, glucose, lactic acid, $Na^+,\;K^+,\;Cl^-$, osmolality and survival for anaesthetic transportation.

• Ocean and Polar Research
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• 제35권4호
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• pp.427-439
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• 2013

Carbon cycling and productivity within Weno Island of Micronesia enclosed by the coral reef may be likely self-maintained and insignificantly affected by the open ocean. Therefore, it is important to understand the role of the mangrove known as providing the organic matter and habitats for many organisms in this enclosed area. In order to trace the nutritional source of fauna (mostly invertebrates) in the mangrove forest of Weno island, we analyzed the fatty acid (FA) and carbon and nitrogen stable isotopes of potential nutritional sources (mangrove leaf & pneumatophore, seagrass leaf & root, surface sediment, and particulate organic matter (POM) in water) and consumers (4 gastropods and anomura). The mangrove and seagrass contained the abundance of 18:2${\omega}$6, and 18:3${\omega}$3, whereas FAs associated with phytoplankton and bacteria were accounted for a high proportion in the surface sediment and POM. FA composition of consumers was found to be similar to those of the surface sediment, mangrove, and seagrass. These were also confirmed through the mixing model of stable isotope for contribution of nutritional sources to consumers. Overall results with the feeding types of investigated mangrove fauna indicate that investigated mangrove fauna obtained their nutrition from the various sources, i.e. the mangrove for Littorina cf. scabra, the microalgae for Strombus sp., and omnivorous Pagurus sp. and Terebralia cf. palustris. However, it is obvious that the nutrition of most species living in the mangrove ecosystem is highly dependent on the mangrove, either directly or indirectly. More detail food-web structure and function of the mangrove ecosystem would be established with the analysis of additional fauna and flora.

• Safety and Health at Work
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• 제8권2호
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• pp.151-155
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• 2017

Background: At the entrance of a tunnel, reflection of sunlight from the surrounding environment and a lack of adequate lighting usually cause some vision problems. The purpose of this study was to perform a safety evaluation of lighting on a very long road in Ilam, Iran. Methods: The average luminance was measured using a luminance meter (model S3; Hagner, Solna, Sweden). A camera (model 108, 35-mm single-lens reflex; Yashica, Nagano, Japan) was used to take photographs of the safe stopping distance from the tunnel entrance. Equivalent luminance was determined according to the Holliday polar diagram. Results: Considering the average luminance at the tunnel entrance ($116.7cd/m^2$) and using Adrian's equation, the safe level of lighting at the entrance of the tunnel was determined to be 0.7. Conclusion: A comparison between the results of the safe levels of lighting at the entrance of the tunnel and the De Boer scale showed that the phenomenon of black holes is created at the tunnel entrance. This may lead to a misadaptation of the drivers' eyes to the change in luminance level at the entrance of the tunnel, thereby increasing the risk of road accidents in this zone.

• Ocean and Polar Research
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• 제25권4호
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• pp.607-615
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• 2003

Many organisms are known to survive in icy environments. These include both over wintering terrestrial insects and plants as well the marine fish inhabiting high latitudes. The adaptation of these organisms is both a fascinating and important topic in biology. Marine teleosts in particular, can encounter ice-laden seawater that is approximately $1^{\circ}C$ colder than the colligative freezing point of their body fluids. These animals produce a unique group of proteins, the antifreeze proteins (AFPs) or antifreeze glycoproteins (AFGPs) that absorb the ice nuclei and prevent ice crystal growth. Presently, there are at least four different AFP types and one AFGP type that are isolated from a wide variety of fish. Despite their functional similarity, there is no apparent common protein homology or ice-binding motifs among these proteins, except that the surface-surface complementarity between the protein and ice are important for binding. The remarkable diversity of these proteins and their odd phylogenetic distribution would suggest that these proteins might have evolved recently in response to sea level glaciations just 1-2 million years ago in the northern hemisphere and 10-30 million years ago around Antarctica. Winter flounder, Pleuronectes americanus, has been used as a popular model to study the regulation of AFP gene expression. It has a built-in annual cycle of AFP expression controlled negatively by the growth hormone. The signal transduction pathways, transcription factors and promoter elements involved in this process have been studied in our laboratory and these studies will be presented.

• Ocean and Polar Research
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• 제25권4호
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• pp.653-662
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• 2003

Changes in the area of geo-ecosystem $(62^{\circ}09'S,\;58^{\circ}31'w)$ reflect climatic changes in the South Shetland Islands. Air temperature and deglaciation will increase. The ice-free space area at the SSSS 8- (ASPA 121) site has enlarged threefold during the last 21 years, thus creating conditions for inhabitation and succession. Wind, water and snow play important roles in transportation of geochemical components. They distribute nutrients, mineral substances, seeds, fragments of plants and animals, etc. Plant and animal colonization is patchy and it happens at random in an 'island' - like manner. The colonization pattern is dependant, to a high degree on physical factors. The newly uncovered ice-free areas are at first inhabited by a vascular plant known as the Deschampsia antarctica. The border of the land-oasis with Admiralty Bay is the place where the processes related to animal feeding at the sea and reproduction on the land take place. Bird colonies and pinniped lairs form centers of fertilization surrounded by high chemical gradients dependent on the direction of the flow of nutrients $(e.g.\;NH_4)$. During the last 25 years, the numbers of penguins in this region have decreased, and thus the amount of materials excreted on land has diminished. The numbers of fur seals change in multi-annual cycles, and their migration into this area is related to the E1 $Ni\~{n}o$ phenomenon. The numbers of elephant seals in the area did not change. Organic matter deposited by the sea onto the shore are a source of nutrients and deficient chemical elements on land. Mineral matter is washed out into the waters of Admiralty Bay. These processes change seasonally, and multi annually. Negative effects on the environment at Arctowski Station induced by man are slight, but noticeable nevertheless. Physical processes have the largest influence on the living conditions and distribution of plants and animals, and as a consequence, on the functioning of the geo-ecosystem in the coastal-shore zone of the Maritime Antarctic.