• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.237-247
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• 1991

To characterize the community structure and spatial distribution of phytoplankton, observations on seawater temperature, salinity, nutrients, primary productivity and abundance and species composition of phytoplankton were made in the polar front region and its neighborhood off the east coast of Korea in summer 1990. Among the 96 taxa identified, Rhizosolenia setigera and Thalassionema nitzschioides were the most dominant species. The assemblage at the surface and 50 m depth was quite different in the northern inshore part of the study area but similar in the southern and offshore part. Principal component analysis by the species abundance showed that the phytoplankton consisted of the communities representing the surface of the northern inshore part with the neritic-warm dinoflagellates, the Northern Korean Cold Water with the cold water diatoms and the southern and offshore part, which seems to represent the Eastern Korean Warm Water, with the warm water diatoms. At the frontal region, diatoms were mixed with warm and cold water species. Primary productivity and phytoplankton standing crops were higher at the front than the neighboring waters. Nutrients were markedly high at the Northern Korean Cold Water. Horizontal advection of the Northern Korean Cold Water accompanied by nutrient supply seems to contribute to the high phytoplankton biomass at the front.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.1 s.28
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• pp.1-7
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• 2007

In order to develop the deep ocean water, the characteristics of vertical distribution of dissolved trace metals(Cd, Co, Cu, Ni, Pb, Zn) were investigated from Apr. to Oct., 2005 in the East Sea. Total six sampling sites were selected in Gangwon-Do and Gyeongsangbuk-Do. Accuracy of the analytical procedures was assessed by the SRM(CASS-4) for dissolved metals in seawater. The mean recoveries cf CASS-4 ranged from 89.4% for Co to 99.8% for Cd. In this study, the dissolved metal concentrations varied with space, time and element. The metal concentrations showed wide range in the surface. Cd, Ni and Zn showed a nutrient-type profile with surface depletion and enrichment at depths. However, Co, Cu and Pb were irregular in the vertical distribution. All metal concentrations studied in this study are lower than the criteria cf Korean drinking water.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.40-48
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• 2016

This study mainly focused on isolation of marine algicidal bacteria associated with phytoplankton blooms and characterization of algicidal activity against harmful algae. Harmful algal blooms (HABs) found naturally in surface waters have caused many environmental problems worldwide. In this study, forty bacterial strains that have capability of inhibiting harmful algal growth were isolated from Masan Bay, Jinhae Bay, Dol Island, Jangmok Bay, and the Tongyeong Sea, Republic of Korea. The bacteria were screened furthermore for the characteristics on algicidal activities against Cochlodinium polykrikoides, Chattonella marina, Skeletonema costatum, Heterosigma akashiwo, Heterocapsa triquetra, Prorocentrum minimum, and Scrippsiella trochoidea. As a result, the algicidal bacteria that were screened from double over layer agar and microscopic counts tests belonged to genera Pseudomonas, Vibrio, Bacillus, Pseudoalteromonas, Ruegeria, Joostella, Marinomonas, Stakelama, Porphyrobacter, and Albirhodobacter. One of the most important HAB species is Co. polykrikoides and the strongest algicidal activity against the dinoflagellate was 94.00% after 6 h treatment with 10% bacterial culture filtrate. In this study, Marinomonas sp. M Jin 1-8, Stakelama sp. ZB Yeonmyeong 1-11 & 1-13, Porphyrobacter sp. M Yeonmyeong 2-22, and Albirhodobacter sp. 6-R Jin 6-1 were found to be as new genera of bacteria having anti-algal activity. These results suggest that these bacteria might play an important role in controlling phytoplankton blooms.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.270-275
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• 2006

The cultivated pearls collected for the study were pretreated through the removal of contaminants and the surface bleaching for easy dyeing. Coloring of pearls are necessary after selecting dyes adsorbable to the Conchiolin layer, a kind of hard protein formed in the seawater, covering the surface of the pretreated pearls. Dyes adsorbable to the Conchiolin layers are mostly basic dyes such as Rhodamine 6G(R6G), Rhodamine B(RB), Methylene Blue(MB) etc. and the binary and ternary competitive adsorption were performed by mixing two or three dyes together. The multi-dye adsorption data were compared with the predictions from the ideal adsorbed solution theory(IASI) combined with the single-dye adsorption model, the Langmuir or the Redlich-Peterson(RP) model. The quality of prediction was compared by using determination coefficient($R^2$) and standard deviation(SSE) values. Predictions from the IAST were found to be in good agreement with the data for the R6G/RB binary adsorption to the pearl layers not fractionated with their size, except for the adsorption data for RB at high concentrations. Among the three binary adsorption systems, R6G/RB, R6G/MB, and MB/RB, only the RB sorption data in the R6G/RB binary system was in poor agreement with the IAST prediction. Competitive adsorption data in ternay systems were in good agreement with the predictions from the IAST except for the RB data.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.164-164
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• 2016

항만 및 해양 구조물은 육상과는 비교할 수 없을 정도로 가혹한 해수 환경에서 사용되며 계속적으로 부식 손상을 받는다. 따라서 강구조물이 장기적으로 안전하게 사용되기 위해서는 적절한 방식은 물론 철저한 유지관리가 필수적이다. 한편, 현재 해양환경 중 항만, 조선, 해양산업 등에 많이 이용되는 강구조물은 이에 대응하기 위하여 일반적으로 도장방식이나 음극방식이 사용되고 있다. 음극방식은 피방식체를 일정전위로 음극 분극하는 원리로써 외부전원을 인가하거나 비전위의 금속을 희생양극으로 연결하여 방식하는 방법이다. 이와같이 해수 중 음극방식을 실시할 경우 해수 중 용존하는 많은 이온들 중에서 특히 $Ca^{2+}$ 이나 $Mg^{2+}$ 이온이 탄산칼슘, 수산화마그네슘을 주성분으로하는 화합물로 형성된다. 이렇게 생성된 전착막은 산소 확산을 방지하는 물리적 장벽을 형성하고 부식율을 감소시키는 것으로 보고되고 있다. 그러나 전착막은 소지 금속과의 결합력이 불균일 함은 물론 막을 형성하는데 있어서 장시간이 소요된다는 단점이 있다. 따라서 본 연구에서는 해수 중 음극방식 응용 원리에 의해 전착막을 형성하고, 석출속도, 밀착성 및 내식특성을 향상시키기 위해 해수 중 기체를 용해시켜 제작한 막의 특성을 분석-평가하였다. 본 연구에 사용된 기판(substrate)은 일반구조용 강(SS400)을 사용하였으며, 면적은 $70mm{\times}30mm$, 두께는 1 mm로 제작하여 실험을 진행하였다. 외부전원은 정류기(Rectifier, xantrex, XDL 35-5T)를 사용하여 3 및 $5A/m^2$ 의 조건으로 인가하였고, 양극은 Carbon Rod를 사용하였다. 이때 해수에 주입한 이산화탄소의 양은 0.5 NL/min 였다. 각 조건별로 제작된 전착막에 대해 외관관찰, 석출량, 모폴로지, 조성원소 및 결정구조 분석을 실시하였고, 밀착성 및 내식특성을 평가하기 위해 테이핑 테스트(Taping Test, JIS K 5600-5-6)와 3.5 % NaCl 용액에서 전기화학적 양극 분극 시험을 진행하였다. 시간에 따른 전착막의 외관관찰 결과 전류밀도의 증가와 함께 상대적으로 많은 피막이 형성되었고, 용해시킨 기체에 의해 더 치밀하고 두터운 피막이 형성됨을 확인할 수 있었다. 성분 및 결정구조 분석 결과 $Mg(OH)_2$ 성분의 Brucite 및 $CaCO_3$ 성분의 Calcite 구조 및 Aragonite 구조를 확인하였으며, 용해시킨 기체의 영향으로 $CaCO_3$ 성분의 Aragonite 구조가 상대적으로 많이 검출되었다. 이는 해수 중 용해된 이산화탄소의 영향으로 인해 풍부한 ${CO_3}^{2-}$ 이온이 형성되고 용액 pH를 낮게 유지시켜 Ca 화합물 형성이 용이한 환경이 조성되는 것으로 판단된다. 밀착성 및 내식성 평가를 실시한 결과 해수중 용해시킨 기체에 의해 제작한 시편의 경우 견고하고 화학적 친화력이 높은 Aragonite 결정이 표면을 치밀하게 덮어 전해질로부터 산소와 물의 침입을 차단하는 역할을 하여 기체를 용해시키지 않은 $3A/m^2$ 및 $5A/m^2$ 보다 비교적 우수한 밀착성 및 내식 특성을 보이는 것으로 사료된다.

• Korean Journal of Ichthyology
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• v.27 no.4
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• pp.284-292
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• 2015

Monthly variation of species composition and abundance of fish eggs were examined to know the spawning time and location of the fishes inhabiting the coastal region of Jejudo Island. Samplings had been performed at the four locations (Jeju port, Seongsanpo, Seogwipo port and Chagwido) with a bongo net which was towed monthly at the sea surface from August 2006 to July 2007. The fish eggs were identified based on phylogenetic analyses with the DNA sequences generated through PCR-amplification and sequencing of the mitochondrial cytochrome b gene. Among a total of 43 taxa classified during the study period, 34 were identified to species, 4 to families, and the remaining 5 were unidentified. Of them, 23 taxa were occurred at Jeju port, 21 at Seongsanpo, 19 at Seogwipo port and 18 at Chagwido, whereas 15 taxa were found in September 2006, 12 in June 2007, 6 to 8 in August 2006 and January~May 2007, 5 in each October and November 2006, 3 in each December 2006 and July 2007. Among 34 species of fish eggs, Engraulis japonicus and Callanthias japonicus most frequently appeared at 16 times out of 48 observations in total. When those eggs were collected, the surface seawater temperature ranged $14.0{\sim}28.6^{\circ}C$ for E. japonicus and $14.9{\sim}20.5^{\circ}C$ for C. japonicus. The success rates of PCR-amplification and species identification in this study were 68.3% and 79.1%, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.474-485
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• 2014

Temporal and spatial variations of temperature and salinity around Ganjeol Point during January, April, August and November 2011 were studied using the data from CTD observations and temperature monitoring buoys deployed at 20 stations in the southeast coast of Korea. Temperature and salinity were nearly homogeneous through the whole depth by mixing of the seawater in spring and winter related to the sea surface cooling. Stratification induced by the river runoff and the bottom cold water was clear in summer. In autumn, sea water had vertical mixing initiated from surface layer and weak stratification at the middle and bottom layers. Low temperature and high salinity emerged throughout the year near Ganjeol Point, which inferred from turbulent mixing and upwelling by its topographical effect. Major periods of 1/4~1.4 day temperature fluctuations were recorded for the most part of the stations. According to the cross spectral density analysis, high coherence and small time lag for temperature fluctuation between layers were shown at Ganjeol Point. However, those features at the northen area of Hoeya river were opposed to Ganjeol Point. From analyses, thermohaline structure and its fluctuation around Ganjeol Point were characterized into those three parts, the south of Ganjeol Point, Ganjeol Point and the north of Ganjeol Point.

• Journal of Life Science
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• v.26 no.2
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• pp.164-173
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• 2016

Isotocin (IT), a nonapeptide homolog of oxytocin in mammals, has been suggested to be involved in physiological processes including social behaviors, stress responses, and osmoregulation in teleost fish. To study its structure and function, the gene encoding the IT precursor was cloned from the genomic DNA and brain cDNA of the cinnamon clownfish, Amphiprion melanopus. The IT precursor gene consists of three exons separated by two introns, and encodes an open reading frame of 156 amino acid (aa) residues, comprising a putative signal peptide of 19 aa, a mature IT protein of 9 aa, a proteolytic processing site of 3 aa, and 125 aa of neurophysin. Tissue-specific analysis of the IT precursor transcript indicated its expression in the brain and gonads of A. melanopus. To examine its osmoregulatory effects, the salinity of the seawater (34 ppt) used for rearing A. melanopus was lowered to 15 ppt. Histological analysis of the gills indicated the apparent disappearance of an apical crypt on the surface of the gill lamella of A. melanopus, as pavement cells covered the surface upon acclimation to the lower salinity. The level of Na⁺/K^+-ATPase activity in the gills was increased during the initial stage of acclimation, followed by a decrease to its normal level, suggesting its involvement in osmoregulation and homeostasis. The only slight increase in the level of IT precursor transcript in the A. melanopus brain upon low-salinity acclimation suggested that IT played a minor role, if any, in the process of osmoregulation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.177-186
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• 2003

The influences of horizontal and vertical flow components including the stratification of water column and the wind field on the formation of oxygen-deficient water in summer in Jindong Bay, northern part of Chinhae Bay, were examined. Temperature, salinity and dissolved oxygen in seawater, and direction and velocity of wind were observed in Jindong Bay from March 1998 to February 1999. Low concentration of 5 mg/L in dissolved oxygen (DO) appeared at the bottom layer from May to September. Extremely low DO concentration less than 3 mg/L was investigated in summer (July to August) when stratification was strongest due to abrupt vertical gradients of temperature and salinity in water column. Bottom waters with the extremely low DO concentration were observed even in spring (May to June) at the inner part of the bay. In summer (August to September), the bottom waters with the low DO concentration (less than 5 mg/L) existed at the water depth from 4 to 6 m, being moved upward to the surface layer compared to other seasons. Vertical components of residual flow, calculated by the direction and velocity of wind, in Jindong Bay in summer showed that locally prevailed northerly and westerly wind resulted in downwelling flow at the outer part of the bay and conversely, upwelling at the inner part of the bay. In addition, bottom current at the outer part corresponding to the downwelling area directed to the inner part, probably resulting in a transport of the particulate organic matter settled at the bottom waters to the inner part of the bay. The oxygen-deficient watermass, which was formed at the bottom layer of the inner part, was likely to transported to the surface layer by the upwelling flow.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1201-1208
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• 2020

A mass of seawater with similar properties in the ocean is called a water mass, and the front is a sea area where two masses of different properties meet. The gradient algorithm is a method of extracting where the sea water temperature pixel changes rapidly assuming that the slope is large, and the place with the large slope is assumed to be a front. This method is able to process large amounts of satellite data at once. Therefore, in this study, we tried to find the front lines in the sea area around the Korean Peninsula by using a gradient algorithm. The study data used gridded sea surface temperature satellite data. The resolution was 1/4°, and the monthly average data from January 1993 to December 2018 were used. There were major five fronts representatively, China Coastal Front, South Sea Coastal Front, Kuroshio Front/ Kuroshio Extension Front, Subpolar Front and the Subarctic Front. As a result of comparing the distribution of front by season, more types of front were distributed in winter and spring than in summer and autumn, and the distribution range was wider.