• 수산해양교육연구
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• 제22권3호
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• pp.330-340
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• 2010

This study was investigated the species composition of demersal fishes by a bottom trawler GAYA, in order to be used basic data for resources management of fishery in the jointly controlled waters of the East China sea. We caught 52 species, 1,167 individuals and 186.171kg in biomass in summer, and 1,924 individuals and 200.871kg in biomass in winter The first dominant species in individuals in summer was Glossanodon semifasciatus, and in biomass was Dentex tumifrons. But that in winter was Ovalipes punctatus in both individuals and biomass. It was a special phenomenon that crustacea was to be the first dominant species compared with general offshore fishery in Korea. Catch per unit effort (kg/hr) of bottom trawl in winter was higher than that in summer. There was also big difference by station in the diversity index, the evenness index and the dominant index.

• 수산해양교육연구
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• 제23권2호
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• pp.141-152
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• 2011

This study was investigated the species composition of demersal fishes by a bottom trawler GAYA, in order to be used basic data for resources management of fishery in the jointly controlled waters of the West sea. We caught 39 species, 5,532 individuals and 322.518kg in biomass. The number of species was the fewest of the jointly controlled waters of the East china sea and boundary zone between Busan and Tsushima. The first dominant species in individuals in summer was Oregonia gracilis, and in biomass was angler. But angler was the first dominant species in 7 stations of 12 stations. It was a peculiar phenomenon that cod which lives in a cold current was caught in the northern part of the West sea. In this connection it seems to be needs for oceanographic research. Catch per unit effort (kg/hr) of bottom trawl was the higher in northern part and in right line of all surveyed area respectively.

• 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.

• 한국수산과학회지
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• 제54권2호
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• pp.208-217
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• 2021

This study described the fishing characteristics of Pacific herring Clupea pallasii and examined the relationship between its catch and sea temperature in Korean waters from 1970 to 2019. Although the herring catch in Korean waters stayed below 1,000 tons per year from the mid-1970s to mid-1980s, the catch in the winters in the East Sea of Korea started to increase markedly after 1987-1988, when the sea surface temperature (SST) seemed to shift to a warmer regime. Since the mid-2000s, overall, herring was caught throughout the year in the East Sea and eastern South Sea of Korea, and its catch significantly increased by around 30,000 tons per year. The main fishing grounds of herring in the poor fishing years until the mid-1980s were possibly formed in the western offshore of Korea, and subsequently the fishing grounds were distributed in the eastern coast of Korea. While the standardized catch per unit effort (CPUE) for two main fisheries of herring catch was significantly correlated with the herring catch since the 2000s, there was a gradual decline since the 2010s. The herring catch in the East Sea had significant positive correlations with SSTs, but that in the West Sea had a significant negative correlation.

• 한국항해항만학회지
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• 제38권6호
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• pp.637-643
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• 2014

본 연구는 해구별 침적폐기물 추정량을 산정하여 해구별 정화관리 우선순위를 분석하기 위한 전제로서 침적폐기물 정화관리지표를 개발하는 것이 연구목적이다. 이러한 연구목적을 달성하기 위한 연구방법으로 전문가 델파이 조사기법을 활용하였다. 전문가 델파이 기법은 적절한 예측방법을 찾을 수 없을 때, 전문가들의 직관을 동원하여 미래를 예측하는 방법으로써 미래변화 뿐만 아니라, 합의를 도출하여 문제를 추정하거나 구성원의 의견을 수집 수렴하는 연구방법이다. 본 연구에서는 27명의 전문가를 섭외하여 이들을 대상으로 총 3회기에 걸친 델파이 조사를 실시하였다. 전문가 델파이 조사결과 최종적으로 선택된 연근해 침적폐기물 정화관리지표는 수거 후 재침적율, 폐어구 유실구역, 해구별 총 폐기물량, 과거 침적폐기물 수거량, 단위면적당 폐기물량 등의 5개 지표로 도출되었다. 본 연구는 패널의 수가 27명으로 한정되어 있는 문제점이 존재하는데, 본 연구를 선행연구로 하여 향후 패널 수를 더욱 확대하여 정밀한 조사가 이루어지기를 바란다.

• 수산해양기술연구
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• 제34권3호
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• pp.259-273
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• 1998

The hydroacoustic surveys to provide the essential information for the assessment, management and utilization of fishery resources in the southern waters of Korea were carried out during five research cruises between October 1996 and October 1997 by the training ship KAYA of Pukyong National University. These hydroacoustic investigations were designed to obtain more precise estimates of the geographic distribution, absolute abundance and biological characteristics of the fishery resources, and the vertically integrated densities of fish in terms of volume backscattering strength(SV) by survey region and depth bins, such as the entire water column and the 0~ 10 m from bottom fraction, were measured separately. Hydroacoustic data were collected by using a Simrad EK 500 Scientific echo sounder operating at two frequencies of 38kHz and 120kHz and the data stored in field were later processed on a HP PC using a Simrad EP 500 echo integration and target strength analysis system. The biological compositions of echo signal were identified and sampled using a demersal trawl during daylight hours. The mean target strength to scale the echo integration data for hydroacoustic surveys was derived from the relationship between the SV and the weight of trawl catch per unit volume of the water column sampled by demersal trawls. The results obtained can be summarized as follow : 1. The mean volume backscattering strength for the entire water column in the southern waters of Korea between 1996 and 1997 were -67.2 dB and -70.9 dB at two frequencies of 38 kHz and 120 kHz , respectively, and for the bottom layer of the 0-10 m from bottom friction were -68.8 dB, -70.2 dB, respectively. That is, the volume backscattering strength for the entire water column at low frequency was higher than that at high frequency. 2. The relationship between the mean backscattering strength (〈SV〉, dB) for the depth strata of trawl hauls and the weight (C, kg/m3) per cubic meter of the catch sampled by bottom trawling in the southern waters of Korea in January and July 1997 were expressed by the following equations: 38 kHz : 〈SV〉= -28.2 + 10 log(C), 120 kHz : 〈SV〉= -32.4 + 10 log(C). The mean weight -normalized target strengths derived from these equitions were -28.2 dB/ kg, -32.4 dB/ kg at 38 kHz and 120 kHz , respectively. That is, the mean weight -normalized target strength at 38 kHz was 4.2 dB higher than that at 120 kHz. 3. The distribution density of fish in terms of biomass per unit volume in the southern waters of Korea were estimated to be 125.9 $\times$ 10-6 kg/m3 and 141.3 $\times$ 10-6 kg/m3 at 38 kHz and 120 kHz , respectively.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2003년도 한국해안해양공학발표논문집
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• pp.363-368
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• 2003

Quantification of sediment losses into the ambient waters associated with various works of coastal developments is highly required for predicting their possible detrimental impacts on the aquatic environments. Although there have been some studies especially related to dredging (e.g., Nakai, 1978; Kirby and Land, 1991; Collins, 1995; Pennekamp et al., 1996; Lorenz, 1999; Jin et al.,2003), none can be regarded as a general guidance up to date, which results from the facts that the amount of sediments released into the ambient waters is influenced by several site/case-specific conditions, and that the existing studies have been carried out using different methods. (omitted)

• ALGAE
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• 제39권1호
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• pp.1-16
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• 2024

Many dinoflagellates produce bioluminescence. To estimate the intensity of bioluminescence produced by populations of the heterotrophic dinoflagellates Noctiluca scintillans and Polykrikos kofoidii and autotrophic dinoflagellate Alexandrium mediterraneum in Korean waters, we measured cellular bioluminescence intensity as a function of water temperature and calculated population bioluminescence intensity with cell abundances and water temperature. The mean 200-second-integrated bioluminescence intensity per cell (BL_cell) of N. scintillans satiated with the chlorophyte Dunaliella salina decreased continuously with increasing water temperature from 5 to 25℃. However, the BL_cell of P. kofoidii satiated with the mixotrophic dinoflagellate Alexandrium minutum continuously increased from 5 to 15℃ but decreased at temperatures exceeding this (to 30℃). Similarly, the BL_cell of A. mediterraneum continuously increased from 10 to 20℃ but decreased between 20 and 30℃. The difference between highest and lowest BL_cell of N. scintillans, P. kofoidii, and A. mediterraneum at the tested water temperatures was 3.5, 11.8, and 21.0 times, respectively, indicating that water temperature clearly affected BL_cell. The highest estimated population bioluminescence intensity (BL_popul) of N. scintillans in Korean waters in 1998-2022 was 4.22 × 10¹³ relative light unit per liter (RLU L^-1), which was 1,850 and 554,000 times greater than that of P. kofoidii and A. mediterraneum, respectively. This indicates that N. scintillans populations produced much brighter bioluminescence in Korean waters than the populations of P. kofoidii or A. mediterraneum.

• 대한원격탐사학회지
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• 제29권2호
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• pp.173-182
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• 2013

천리안 위성 해양탑재체(Geostationary Ocean Color Imager, GOCI) 대기보정의 근간이 되는 Sea-viewing Wide Field-of-view Sensor(SeaWiFS) 초기 대기보정 기법은 근적외선 파장대의 해수 반사도를 0으로 가정한다. 이러한 가정에 근거하여 근적외선 파장에서 탐지되는 모든 신호는 에어로졸 산란에 의한 반사도로 간주된다. 그러나 이러한 가정은 탁한 해역에서 해수 반사도를 과소 추정하는 문제점을 야기시킨다. 이를 해결하기 위하여 Management Unit of the North Sea Mathematical Models(MUMM) 대기보정 알고리즘이 개발되었다. 이 알고리즘은 근적외선 파장에서 탐지되는 해수 반사도 비율인 ${\alpha}$를 도입하였다. ${\alpha}$는 통계적 방법에 의하여 결정되며 영상 내의 모든 픽셀에 고정적인 값으로 사용된다. 이 알고리즘은 근적외선 해수 반사도가 0.01보다 작은 중간 탁도의 해역에서는 잘 맞는 반면 매우 탁한 해역에서는 ${\alpha}$가 탁도에 따라 변하기 때문에 오차율이 다시 증가한다. 본 연구에서는 매우 탁한 해역 해수 반사도의 정확도를 향상시키고자 ${\alpha}$를 고정하지 않고, 반복계산을 통해 탁도에 적합한 ${\alpha}$를 계산하도록 MUMM 알고리즘을 수정 보완하였다. 그 결과 MUMM 알고리즘의 모든 밴드의 평균 Root Mean Square Error(RMSE)는 0.0048인 반면 수정된 MUMM 알고리즘은 0.002로 개선된 결과를 얻었다.

• 해양환경안전학회지
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• 제27권1호
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• pp.81-87
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• 2021

제주해역은 많은 상선 및 어선들이 항해를 하고, 자망, 트롤 등 다양한 어구를 활용하여 어로활동을 하고 있다. 그 동안 해양폐기물 수집은 주로 제주도 해안 및 연안해역에서 시행되고 있으나, 연근해 해역에서 발생되는 해양폐기물 발생에 대한 수집 및 연구가 미미하였다. 이에 본 연구는 제주대학교 실습선을 이용하여 제주도 북서해역에 침전한 해양폐기물을 수거하고 각 폐기물별로 관련 선박의 항적을 분석하였다. 또한 일정 구역 및 선박 체류시간별로 얼마나 많은 해양폐기물을 투기하고 있는지 분석하기 위해 선박자동식별장치 항적데이터를 활용하여 대상해역에 선박이 체류한 시간을 추출하여, 어선업종별로 1 ㎢ 단위구역에서 시간당 해양폐기물 발생양을 분석하였다. 분석 결과 연근해 해역은 어선기인 폐어구가 대다수였으며, 그중 자망 및 통발 어구가 많은 비율을 차지하고 있었다. 본 연구에서 단위구역에서 시간당 해양폐기물 발생량은 자망어업이 평균 0.94 kg, 통발어업이 3.49 kg, 저인망어업이 0.10 kg, 연승어업이 0.11 kg, 기타어업이 0.02 kg으로 산출되었다. 이 결과를 활용하여 향후 연근해 수중환경 정화시 해양폐기물 발생이 높은 해역위주로 해양폐기물 수거가 가능할 것이다.