• Ocean and Polar Research
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• v.42 no.3
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• pp.263-270
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• 2020

The distribution and genotypes of the sea nettle Chrysaora pacifica have been reported in the South Sea of Korea; however, little research work has been attempted in the East Sea. Here, we collected similar jellyfishes from the East Sea coasts (Goseong, Yangyang and Sokcho), and identified them to the sea nettle morphologically. In addition, the genotypes of these sea nettle were compared with those from the South Sea (Tongyeong and Geoje). Phylogenetic analysis by using the mitochondrial COI sequences showed that the genus Chrysaora was clearly separated from other taxa to be formed a monophyletic group, with each species distinctly separated. C. pacifica in the East and South Seas was separated geographically by the COI phylogeography, representing potentially different populations. The COI gene of the Korean C. pacifica had approximately 7 times more genetic variation than the nuclear ITS rDNA, and thus it might be considered as a useful marker for genetic analysis of the jellyfish population.

• Ocean and Polar Research
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• v.42 no.3
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• pp.225-231
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• 2020

The aim of this study was to examine optimal induction method for carpospore release from Agarophyton vermiculophyllum cystocarps for seedling production. We tested the effects of environmental factors on carpospore release by using five different induction methods; spontaneous, desiccation, low temperature, desiccation+low temperature, and osmotic shock. Also, carpospores release was estimated at three temperatures (20, 25, and 30℃), and then under combinations of three day lengths (8, 12, and 16h) and two irradiances (30 and 60 μmol photons m^-2 s^-1), after pretreatment at desiccation+low temperature for 2 hr. The number of carpospores released was between 113 ~ 682 spores /cystocarp/day and it was maximal in the desiccation+low temperature treatment. Optimal environmental conditions for carpospore release of A. vermiculophyllum were 25℃, 16 h, and 60 μmol photons m^-2 s^-1. The present results suggest that massive carpospores for seedling production of A. vermiculophyllum could be obtained under a combination of 25℃, 16 h, and 60 μmol photons m^-2 s^-1 after pretreatment in the desiccation+low temperature.

• Ocean and Polar Research
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• v.42 no.2
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• pp.157-169
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• 2020

This study aimed to analyze the effect of total allowable catches (TACs) on the target species. First to effects analyse of TACs, the 8 TAC target species and 75 non-target species were selected for which catch data were available before and after the introduction of the TACs. The 8 target species were simply compared to catch changes before and after TACs. Through the comparison, it was confirmed how the catches of target fishes have changed after the implementation of the TACs. Secondly, the Difference In Differences(DID) analysis was conducted to confirm the effects of the TACs on the catches of the target fishes using the catch data of 8 TAC target species and 75 non-TAC species. Finally, to overcome the limitations of the DID analysis, the random effects model was estimated to confirm the effects of the TACs on the catch of the TAC target species. Overall, this study confirmed that the TACs affects catches of target species, not only through simple comparisons of catches before and after the introduction of the TACs but also through econometric analysis.

• Ocean and Polar Research
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• v.42 no.2
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• pp.97-113
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• 2020

In-situ observations were carried out in April 2015 to investigate the occurrence of water temperature inversion in a region west of Jeju Island. Analysis of in-situ in the western part of Jeju island showed that cold water moved to the southeast from the surface to the middle layer and warm water moved from the middle to the lower layer of the northwest direction. The water temperature inversion occurred at 84 stations (63.1%) out of 133 stations. At the boundary of the water temperature inversion layer, it was formed in the middle layer and disappeared. In the strongly appearing, it started from the middle layer to the lower layer. The shape of the water temperature inversion layer was different. As a result of horizontal water temperature slope analysis of the water temperature inversion zone, maximum 0.23℃/km was obtained and the mean was 0.06℃/km. The role of water temperature inversion as an indicator to determine the formation of water front. As a result of the water mass analysis, Jeju Warm Current Water and Tsushima Warm Current Water of high temperature and high salt intruded from the middle to the bottom. In the middle layer occurred as the Yellow Sea Cold Water of low water temperature and low salinity expanded.

• Nuclear industry
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• v.36 no.11
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• pp.29-44
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• 2016

1980~1990년대 OPR1000 기술 자립을 추진할 때도 그랬지만 한국은 원자력 기술 자립에 대한 도전이 선진국에 비해 늦었지만 과학기술자의 열정과 정부의 적극적인 지원으로 오늘날 원자력 선진국이 될 수 있었고, 원자력산업을 해외 수출 산업으로서 다양한 노력을 시도하고 있다. 특히 국내 가동 중인 원전은 외국과 차별되게 1기당 고장 정지율이 0.1건으로 외국 평균의 5.5건과 크게 대별된다. 또한 운전 신뢰성을 나타내는 발전소 가동률도 10% 이상 차로 월등히 높다. 한마디로 한국은 가장 원전의 기술 개발과 운영을 잘하고 있는 원전 선진국임을 자타가 인정하고 있다. 그러나 현재의 기술 수준에 머물면 미래 원전 기술에서는 다른 선진국 내지 중국, 인도 등 신흥국에 그 자리를 양보할 수밖에 없을 것이다. 미래 원자력이란 시대적 요건인 고유 안전성과 지속 가능성을 확보하고 경제성과 함께 핵확산 저항성이 전제되는 원자력 신기술로서 세계와의 경쟁 대상이다. 여기에 핵연료 자원의 유한성에 지속 가능성을 확보하기 위해서 우라늄 효율을 극대화하는 제4세대의 고속로 개발까지 우리나라는 선도적 위치로 가야 한다. 이 기술 개발 역시 출발은 늦었지만 적극적인 개발을 추진하고 있어 소듐고속로의 시현 원자로인 PGSFR을 2028년까지 완성하는 목표를 달성하면, 이를 근간으로 세계 선진국의 경쟁 대열에 나설 수 있다. 정부의 적극적인 지원이 선도적 위치에 갈 수 있는 지름길이다. 고속로 기술 개발과 관련하여 사용후핵연료(SF)의 국가 정책이 아직 확정되지 않아 재활용주기를 전제하고 있는 고속로 개발에 어려움을 주고 있다. 따라서 SF 부지를 2028년까지 확정하는 일정과 함께 국가 SF 정책이 조속히 확정되어야 한다.

• Ocean and Polar Research
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• v.33 no.2
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• pp.185-191
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• 2011

Crude extracts of Limonium tetragonum and their solvent-partitioned fractions were evaluated for their potential to scavenge authentic $ONOO^-$, and $ONOO^-$ derived from 3-morpholinosydnonimine (SIN-1). Four flavonol glycosides (1-4) were isolated by activity-guided separation. Their chemical structures were elucidated by extensive 2 D NMR experiments and by comparison with published spectral data. These compounds were also estimated for their peroxynitrite scavenging effects. The scavenging ratios of compounds 1-4 on authentic $ONOO^-$ were 56, 37, 56, and 54%, respectively, at a concentration of 1 ${\mu}M$. On the other hand, the inbihition ratios of compounds 1-4 against $ONOO^-$ generation from SIN-1 were 59, 39, 44, and 54% at the same concentration, respectively.

• Ocean and Polar Research
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• v.33 no.2
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• pp.127-133
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• 2011

The comet assay, also called single-cell electrophoresis (SCGE) assay, is a potential sensitive monitoring tool for DNA damage in cells. The primary objective of this study was to use comet assay to ascertain if the blood cells of flounder (Pleuronichthys olivaceus) and muscle cells of clam (Saxidomus purpurata) are suitable for genotoxicity screening. This was achieved by initially exposing blood and muscle cells under in vitro conditions to the reference genotoxin hydrogen peroxide ($H_2O_2$); strong correlation between $H_2O_2$ concentration and comet values were found. Subsequently, the identification of DNA damage in isolated cells from flounder and clam was performed under in vivo exposure to benzo(a)pyrene (BaP) and tributyltin (TBT). Flounder and clam were exposed to different concentrations (1, 10, 50, 100 ${\mu}g/L$) of BaP or TBT for 4 days. Regardless of treated chemicals, blood cells of flounder were more prone to DNA breakage compared to muscle cells of clam. In conclusion, in vivo genotoxicity of BaP and TBT can be biomonitored using the comet assay. This study suggests that flounder and clam do show potential as mediums for monitoring genotoxic damage by comet assay.

• Ocean and Polar Research
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• v.27 no.3
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• pp.323-333
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• 2005

The paper is to serve as a guide for deciding on a desirable direction for the vessel buyback program, reviewing their performance and economic effects from fish harvest reduction due to not reaching MSY. Compared with maximum willingness to pay for vessel buyback programs designed to avoid economic losses occurring as a result of overfishing, the portions of investment costs for buyback program are so small comparatively to the range of 0.32% to 12.19% at the annual base. The economic loss effects occurred in terms of the reduction of fishing harvest are comprehensively estimated at the present value of 30,877 billion won since 1971, and exceeded the revenues for fish harvests from 1999. In order to resole fish stocks through a vessel buyback program, this paper recommends that the yield should be reduced to less than the intrinsic growth rate. Otherwise, the buyback program policy eventually fails regardless of the temporal effect of benefits. This paper further argues that technical policy tools such as fishing grounds, fishing seasons, size of fish and minimum size of meshes should be effectively utilized.

• Ocean and Polar Research
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• v.27 no.3
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• pp.311-322
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• 2005

Fisheries buyback programs in Korea have been implemented since 1994, and their scales are estimated to be the present value of 930 billion won for the last 9 yens since 1994. The paper attempts to identify the patterns of each fish species, of which their yields can be steadily increased or significant]y decreased, and to evaluate its effective level and the optimal level for buyback programs by means of fishing capacity analysis. The paper distinguishes fish species, that there is no need to reduce the fishing efforts, such as anchovies, mackerels, squids, Spanish mackerels, and herrings, because MSY exceeds yields, from fish species to control overfishing such as file fish, yellow corvenias, young pollack, hair tail, snow crab, and pollack. The paper also suggests that 65% of the fishing efforts (total tonnages) should be cut back at the national aggregate level in order to restore fish stocks.

• Ocean and Polar Research
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• v.27 no.3
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• pp.289-297
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• 2005

The change in global climate and Asian monsoon patterns during the mid-Holocene, 6000 years before present (6 ka), is simulated by a climate model at spectral truncations of T170 with 18 vertical layers, corresponding to grid-cell sizes of roughly 75km. The present simulation is forced with the observed monthly data of sea surface temperatures, and the specified concentration of atmospheric carbon dioxide, while in the mid-Holocene experiment, orbital parameters such as obliquity, precession, and eccentricity are changed to the 6ka conditions. Under such conditions, the precipitation associated with the summer monsoon is enhanced over a wider zonal band from the Middle East to Southeast Asia, while no significant alteration takes Place in winter. The monsoonal wind also increases over the Arabian Sea, showing the enhanced southwesterly wind during summer and northeasterly wind during winter. Overall, the showing of the Asian monsoon is enhanced during the mid-Holocene, especially in summer, which is consistent with the proxy estimates and other previous model simulations.