• 수산해양기술연구
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• 제51권4호
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• pp.527-534
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• 2015

The twenty six specimens of leptocephali (15.8-32.6 mm TL) of the family Congridae, collected from southeastern waters offshore of Jeju Island during August 2014, and were identified by means of morphology and genetics. Those specimens were identified as belonging to the family Congridae based on various combinations of morphological characters. An analysis of the partial 12S rRNA sequences (886 base pairs) of mitochondrial DNA showed that our specimens must be Gnathophis nystromi, because their sequences were concordant with those of G. nystromi adult (genetic distance= 0.001), furthermore their total myomeres being consistent with those of G. nystromi adult. Catch rates of G. nystromi leptocephali were higher in the offshore regions than coastal regions of Jeju Island. The smallest leptocephali (< 20 mm TL) were collected offshore from Jeju Island. We hypothesize that one of the spawning grounds of G. nystromi is located offshore in the Jeju Island. In conclusion, the hatched preleptocephali of G. nystromi might have been transported from offshore near Jeju Island to the Korea Strait by the Kuroshio Current and Tsushima Warm Current.

• 한국음향학회지
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• 제40권6호
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• pp.537-545
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• 2021

인간에 의한 연안 지역 개발 및 변형의 가속화로 인해 해양포유류에 대한 피해가 우려되고 있다. 연안 개발이 해양포유류에 어떤 영향을 미칠 수 있는지 이해하려면 이들의 분포를 파악하는 것이 중요하다. 본 연구에서는 서남해 해상풍력 실증단지에서 수동 음향 관측을 통해 상괭이의 출현을 확인하였다. 실험지역에서의 상괭이에 대한 목시관측 결과가 없으므로, 풍력단지에서 탐지된 클릭은 상괭이 발견율이 높은 지역에서 측정한 클릭과 음향특성을 비교하여 검증하였다. 음향 측정 결과에 의하면 상괭이는 매일 출몰하였으며, 평균 클릭수는 40.7회, 상괭이의 출현 비율은 9.7 %, 출현 시간은 18.2 min이며, 대기 시간은 94.9 min으로 나타났다. 이 연구를 통해 서남해 해상풍력 실증단지에서 알려지지 않은 상괭이 출현에 대한 정보를 제공하였으며, 이러한 결과는 풍력단지 운영으로 인한 해양포유류의 영향을 모니터링하는데 도움을 줄 수 있다.

• 수산해양기술연구
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• 제31권1호
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• pp.15-23
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• 1995

여수 연안 정치망 어장의 주변 해역을 중심으로 1990년 4월부터 11월까지 매월 채집해서 분석한 식물플랑크톤의 분포량과 여수수협 위판장으로부터 구한 어획량 자료등을 이용하여 여수 연안 정치망 어장의 환경요인인 식물플랑크톤의 분포량과 어획량 변동과의 관계를 분석 정리한 결과를 요약하면 다음과 같다. 1) 식물성 플랑크톤의 출현량은 춘계와 추계보다 하계에 최대가 되고, 특히 육수의 유입이 많은 여수만 중 돌산연안 수역 분포량이 많고, 소리도와 세존도부근의 식물성 플랑크톤 분포량은 내만수의 확장 경향을 추정하는데 유익하게 이용될 수 있다. 2) 여수 연안 정치망에 어획되는 주요 어종의 어획량은 삼치, 갈치, 고등어, 정어리, 멸치, 전갱이 및 방어의 순이고, 어획되는 시기는 정어리와 멸치가 4~6월, 전갱이, 갈치 및 고등어는 6~10월이 였으며, 삼치는 전 어기에 걸쳐 어획되었다. 3) 여수 연안 정치망 어장의 어획량은 식물성 플랑크톤 출현량과 상관 관계가 있고, 이들 식물성 플랑크톤량은 하계 육수의 영향을 많이 받는 내만수에 최대의 출현량을 보인다. 또, 이 어장의 어획량은 하계에 많으므로 여수 연안 정치망 어장은 육수의 유입에 의해 풍부한 영양염류를 공급받는 내만수내의 이료생물의 생산력이 어획량을 좌우하는 어장의 중요한 환경요인이 될 수 있다

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.553-556
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• 2004

Spatial and temporal aspects of toxic dinoflagellate Cochlodinium.p blooms and consequences of physical features in complex coastal ecosystems, off the southern Korean coast, have been investigated using data obtained from SeaWiFS and AVHRR as well as in-situ observations. Hydrographic parameters measured using CTD sensors were used to elucidate physical factors affecting the spatial distribution and abundance of Cochlodinium.p blooms. The results show spatial and temporal variations of chlorophyll-a (Chl-a) and sea surface temperature (SST) and reveal significant information about Cochlodinium.p blooms and process underlying their evolution. Satellitederived Chl-a estimates appear to be potential in explicating the evolution, movement and distribution of Cochlodinium.p blooms in the enclosed bays of the South Sea. The existence of thromohaline waters offshore provide favorable conditions for the rapid growth and subsequent southward initiation of Cochlodinium.p blooms that are influenced to flow on the offshore branch (OB) during September. It was observed that there was a significant variation in the sun-induced chlorophyll-a fluorescence signal in the remote sensing fluorescence spectra and its high-intensity was recognized during the period of exponential growth and physical transport. Satellite-derived Chl-a concentration during September 1999 ranged between $3­60mg/m^3$ inside the Jin-hae and adjacent Bays and $1-6mg/m^3$ in offshore waters, with varying Cochlodinium.p abundances 1500 to 26000 cells $ml^{-1}.$ The closely spaced CTD surveys and satellite-derived SST give a complete overview on the initiation of Cochlodinium.p blooms in hydrodynamically active regions of the offshore southern East Sea by the influence of Tsushima Warm Current (TWC).

• 한국연안방재학회지
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• 제4권spc호
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• pp.245-253
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• 2017

In this study, surface currents measured by small lagrangian GPS drifters (Aquadrifter) in Anmok coastal waters were analysed to account for the variability of nearshore surface current and wave-induced current to understand sediment transport mechanism near the crescentic bars in the surf-zone and near Kangneung breakwater and submerged breakwater in Anmok. The 8 times lagrangian drifter experiments were conducted mostly during in 2nd, 3rd, 4th intensive measurements in winter, summer, and spring seasons with long-term wave observation at the station W1. The analysed surface currents near the breakwaters in Anmok show that wave-induced currents at the middle of the submerged breakwater were separated and flowed toward the shoreline but offshore currents were dominant through the channels between the breakwaters. The longshore currents near the shoreline were flowed to the northwest (southeast) depending on the incoming waves from ENE (NNE). The surface nearshore offshore currents were generated mostly by waves and winds in case of high and low wave energy environments. Using the small-size lagrangian surface drifter experiments, we successfully measured longshore and offshore wave-induced currents in the surf-zone and near submerged breakwater close to Kangneung breakwater. The drifter experiment results show the availability of direct observation of nearshore surface currents to understand the mechanism of sediment transport analysing observed wave-induced current and ebb-current in the surf-zone generated by incoming waves and local winds.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 춘계학술발표회
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• pp.43-50
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• 2007

In order to calculate the strength and to. see the variation af the stratification in the Southern Waters af Korea, the stratification parameter defined as potential energy anomaly (PEA, $V(J/m^3)$) introduced by Simpson and Hunter (1974) was used The data used in this paper were observed in August 1999 and February 2000 by National Fisheries Research and Development Institute (NFRDI). Also to know the effects af the temperature and the salinity an the stratification respectively, averaged temperature and salinity were used in the process af calculation the parameter. V is generally high in the offshore. However, in February, V in the onshore is higher than that of the offshore due to the vertical temperature gradient caused by the expansion of South Korean Coastal Waters (SKCW). In the summer, the increase af the atmospheric heating, the temperature inversion phenomenon act an the stratification as the buoyancy forcing. In most cases, the effects of the temperature on the stratification is stronger than that of the salinity. The temperature effect is predominantly due to the extent af the intrusion of Tsushima Warm Current into the study area. However, at stations where V is high the effect af the salinity is also significant. In the winter, V is very low due to the decrease of the buoyancy forcing, but same stations show the relatively high V due to the expansion of SKCW and Tsushima Warm Current.

• 한국수산과학회지
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• 제48권5호
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• pp.776-782
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• 2015

We examined the community structure of fish off the coast of Jindo Island in response to a cold water appearance in the southwestern sea of Korea each August between 2013–2015. Using a gape net with wings, we collected 31 taxa during the study period, wherein the most dominant species was Engraulis japonicus. Collichthys lucidus and Neosalanx andersoni, which are mainly distributed in the western sea of Korea, increased in abundance and were dominant in August 2013, possibly due to the apparent intrusion of cold water (< 19°C) from offshore into the coastal waters of Jindo Island. Meanwhile, Scomberomorus niphonius and Sardinella zunasi, which are known as warmwater migratory species, increased in abundance and were dominant in August 2015, likely influenced by the warmer water (> 20°C) at the coast, which resulted in a noticeable lessening of the cold water in the study area. However, no significant differences were observed in fish community structure in the month of August between 2013–1015. This implies that the small-scale spatial and temporal variations in the cold water had limited effects on the fish community structure, even though the abundances of several dominant species varied in the coastal waters.

• 한국해양공학회지
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• 제38권1호
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• pp.18-29
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• 2024

Waves are a complex phenomenon in marine and coastal areas, and accurate wave prediction is essential for the safety and resource management of ships at sea. In this study, three types of machine learning techniques specialized in nonlinear data processing were used to predict the waves of Korea waters. An optimized algorithm for each area is presented for performance evaluation and comparison. The optimal parameters were determined by varying the window size, and the performance was evaluated by comparing the mean absolute error (MAE). All the models showed good results when the window size was 4 or 7 d, with the gated recurrent unit (GRU) performing well in all waters. The MAE results were within 0.161 m to 0.051 m for significant wave heights and 0.491 s to 0.272 s for periods. In addition, the GRU showed higher prediction accuracy for certain data with waves greater than 3 m or 8 s, which is likely due to the number of training parameters. When conducting marine and offshore research at new locations, the results presented in this study can help ensure safety and improve work efficiency. If additional wave-related data are obtained, more accurate wave predictions will be possible.

• 해양환경안전학회지
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• 제15권3호
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• pp.165-171
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• 2009

1999년 10월, 12월의 국립수산과학원 정선관측 자료를 이용하여 수온역전 현상이 성층변동에 미치는 영향을 분석하였다. 10월, 12월 모두 수심 25-75m 사이에서 수온역전현상이 빈번하게 발생하며, 12월에는 표층 부근에도 수온역전현상이 나타났다. 고온, 고염분수인 쓰시마난류의 수평 이류가 10월, 12월에 나타나는 수온역전현상의 주원인으로 작용하며, 12월에는 연안역에서 외양역으로 수송되는 차가운 표층수의 영향이 함께 작용한다. 10월에는 북풍이 지속적으로 불지만 남해연안수가 외해역으로 확장하는 현상이 뚜렷하지 않는 반면, 북서풍계열의 풍속이 강해지고 쓰시마난류의 세력이 약해지는 12월에는 남해연안수가 상층부를 통해 외해역으로 확장하면서 수온역전현상을 나타나게 한다. 10월과 12월 모두 수온역전현상이 발생하는 해역을 따라 성층의 변동폭이 크게 나타난다.

• 대한원격탐사학회지
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• 제38권4호
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• pp.355-364
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• 2022

In this study a tendency of abnormal sea surface temperature (SST) occurrence in the seas around South Korea is analyzed from daily SST data from satellite and 14 buoys from August 2020 to July 2021. As thresholds 28℃ and 4℃ are used to determine marine heatwaves(MHWs) and abnormal low water temperature (ALWT), respectively, because those values are adopted by the National Institute of Fisheries Science for the breaking news of abnormal temperature. In order to calculate frequency of abnormal SST occurrence spatially by using satellite SST, research area was divided into six areas of coast and three open seas. ALWT dominantly appeared over a wide area (7,745 km²) in Gyeonggi Bay for total 94 days and it was also confirmed from buoy temperature showing an occurrence number of 47 days. MHWs tended to be high in frequency in the coastal areas of Chungcheongdo and Jeollabukdo and the south coastal areas while in case of buoy temperature Jupo was the place of high frequency (32 days). This difference was supposed to be due to the low accuracy of satellite SST at the coasts. MHWs are also dominant in offshore waters around Korean Peninsula. Although detecting abnormal SST by using satellite SST has advantage of understanding occurrence from a spatial point of view, we also need to perform detection using buoys to increase detection accuracy along the coast.