• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.2
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• pp.99-107
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• 2011

The relationships among long-term variation in catches of Spanish mackerel (Scomberomorus niphonius) and main food organism such as common mackerel (Scomber japonicus), anchovy (Engraulis japonicus), and oceanic condition in Korean waters were analyzed using 40 years of time-series data from 1971－2010. In the 1990s, oceanic conditions around the Korean peninsula shifted to a warmer regime with higher SST (sea surface temperature). The total catch of Spanish mackerel in Korean waters increased dramatically since the early 2000s, and main fishing ground form into South Sea in winter season from December to January. From the results of correlation analysis, we found a significant relationship between the Spanish mackerel catch and environmental factor such as SST, common mackerel and anchovy catch in Korean waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.2
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• pp.186-194
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• 2013

We compiled and analyzed long-term time-series data collected in Korea to evaluate changes in oceanographic conditions and marine ecosystems near Jeju Island ($33^{\circ}00^{\prime}-34^{\circ}00^{\prime}\;N$, $125^{\circ}30^{\prime}-127^{\circ}30^{\prime}\;E$) from 1981 to 2010. Environmental data included depth-specific time series of temperature and salinity that have been measured bimonthly since 1961 in water columns at 175 fixed stations along 22 oceanographic lines in Korean waters by the National Fisheries Research & Development Institute, and time series of estimated volume transport of the Tsushima Warm Current (TWC) and Korea Strait Bottom Cold Water (KSBCW) for the period from 1961 to 2008. We analyzed the species composition in terms of biomass of fish species caught by Korean fishing vessels in the waters near Jeju Island (1981-2010). Data were summarized and related to environmental changes using canonical correspondence analysis (CCA). The CCA detected major shifts in fish community structure between 1982 and 1983 and between 1990 and 1992; the dominant species were a filefish during 1981-1992 and chub mackerel from 1992 to 2007. CCA suggested that water temperature and salinity in the mixed layer and the volume transport of the TWC and the KSBCW were significantly related to the long-term changes in the fish community in the waters off Jeju Island. Fish community shifts seemed to be related to the well-established 1989 regime shift in the North Pacific. Further studies are required to elucidate the mechanisms driving climate change effects on the thermal windows and habitat ranges of commercial species to develop fisheries management plans based on reliable projections of long-term changes in the oceanographic conditions in waters off Jeju Island.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.394-410
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• 2007

Anchovy spawn from the end of May to mid-October, when the water temperature is $14.8-27.2\;^{\circ}C$ and the salinity is 26.0-33.6 psu. The main spawning season is between July to August, when the water temperature is $21.7-27.2\;^{\circ}C$ and the salinity is between 26.0-32.2 psu. The main spawning grounds of anchovy are coastal areas shallower than 50 m around the islands located in the Jeju Strait. Anchovy larvae are distributed near the fronts between Chuja-do, Jangsu-do, Yeoseo-do, and the open sea rather than in the spawning grounds. Anchovy eggs and larvae density increased in accordance with the high level of $Chlorophyll-{\alpha}$ during the summer season (July-August). In terms of the suspended sediment (SS) levels along the northern coast of the Jeju Strait, high densities of anchovy eggs (12.0-18.0 mg/L) were observed, mainly in the area affected by the coastal waters of the southern sea with high SS levels, while larvae (10.0-19.0 mg/L) tended to be distributed over a wide area with high SS levels, including the open sea. In terms of the dissolved oxygen (DO) content, eggs (5.4-6.8 mg/L) were observed in coastal areas with a high DO content, while larvae (4.2-6.4 mg/L) were distributed widely in areas with a relatively low DO content, from the southern coast to the open sea.

• Korean Journal of Remote Sensing
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• v.36 no.1
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• pp.41-53
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• 2020

The production of near- and off-shore fisheries in South Korea is decreasing due to rapid changes in the fishing environment, particularly including higher sea temperature in recent years. To improve the competitiveness of the fisheries, it is necessary to provide fish catch information that changes spatiotemporally according to the sea state. In this study, artificial intelligence models that predict the CPUE (catch per unit effort) of mackerel, anchovies, and squid (Todarodes pacificus), which are three major fish species in the near- and off-shore areas of South Korea, on a 15-km grid and daily basis were developed. The models were trained and validated using the sea surface temperature, rainfall, relative humidity, pressure,sea surface wind velocity, significant wave height, and salinity as input data, and the fish catch statistics of Suhyup (National Federation of Fisheries Cooperatives) as observed data. The 10-fold blind test results showed that the developed artificial intelligence models exhibited accuracy with a corresponding correlation coefficient of 0.86. It is expected that the fish catch models can be actually operated with high accuracy under various sea conditions if high-quality large-volume data are available.

• Journal of Adhesion and Interface
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• v.17 no.1
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• pp.21-28
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• 2016

Foam-type biodegradable polyurethane adhesives were developed as a non-lethal weapon against illegal fishing boats. The adhesives were prepared from a hardener of polymeric methylene diphenyl diisocyanate (MDI) and a base composed of polyester and/or polyether polyols. In order to accelerate biodegradability, starch, dextrin, and amylase were added into the base, and which present about 34% degradability within 4 weeks confirmed by OECD 301C method. For proper mixing and corresponding prompt foam reaction, viscosities of hardener and base compositions were investigated in the temperature ranges from 0 to $50^{\circ}C$. For fast completion of the foam forming and corresponding adhesion, rising time was recorded in the same temperature range, and the rising time of the adhesive was varied within around 1 minute. T-peel adhesion tests with cotton fabrics were performed which showed 20.78 N/cm and 11.95 N/cm as the maximum and the average values, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.197-201
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• 2017

Most fishing vessels use an ice cooling system to manage and store captured fish. However, it is difficult to maintain an adequate temperature and salt concentration as well as operating time limitations in ice cooling systems. The purpose of this study is to investigate the heat transfer characteristics of flooded-type evaporators for a seawater cooling system to maintain proper seawater temperature in a fish tank. Experiments were conducted to investigate the heat transfer characteristics by changing the seawater temperature, flow rate, and saturation temperature of the refrigerant. It was confirmed that the heat transfer coefficient of an aluminum-brass tube was approximately 10% higher than that of a copper-nickel tube at the same heat flux. Furthermore, it was confirmed that applying the aluminum-brass tube to the heat transfer tube of a seawater heat exchanger was effective in terms of heat transfer. A comparison of the overall heat transfer coefficient of a single-tube heat exchanger and the flooded-type multi-tube heat exchanger for an 18-kW cooling system showed that the heat transfer coefficient of the single-tube heat exchanger was 25% higher under the same conditions. These results are considered to be important data for designing a flooded-type multi-tube heat exchanger.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.603-614
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• 2021

Recently, the surface temperature in the seas around Korea has been continuously rising. This temperature rise causes changes in fishery resources and affects leisure activities such as fishing. In particular, high temperatures lead to the occurrence of red tides, causing severe damage to ocean industries such as aquaculture. Meanwhile, changes in sea temperature are closely related to military operation to detect submarines. This is because the degree of diffraction, refraction, or reflection of sound waves used to detect submarines varies depending on the ocean mixed layer. Currently, research on the prediction of changes in sea water temperature is being actively conducted. However, existing research is focused on predicting only the surface temperature of the ocean, so it is difficult to identify fishery resources according to depth and apply them to military operations such as submarine detection. Therefore, in this study, we predicted the temperature of the ocean mixed layer at a depth of 38m by using temperature data for each water depth in the upper mixed layer and meteorological data such as temperature, atmospheric pressure, and sunlight that are related to the surface temperature. The data used are meteorological data and sea temperature data by water depth observed from 2016 to 2020 at the IEODO Ocean Research Station. In order to increase the accuracy and efficiency of prediction, LSTM (Long Short-Term Memory), which is known to be suitable for time series data among deep learning techniques, was used. As a result of the experiment, in the daily prediction, the RMSE (Root Mean Square Error) of the model using temperature, atmospheric pressure, and sunlight data together was 0.473. On the other hand, the RMSE of the model using only the surface temperature was 0.631. These results confirm that the model using meteorological data together shows better performance in predicting the temperature of the upper ocean mixed layer.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.3
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• pp.97-102
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• 2014

It was mathematically analyzed at which steps to activate TTI in the cold chain for Alaska pollack, assuming that the performance of a commercial TTI product, and Fresh-check, could not always be optimized for the pollack. Three places were selected for the TTI activation, such as on fishing ship, Busan cooperative fish market, and mart. First, the kinetic and Arrhenius temperature dependent models were experimentally built under isothermal conditions. The color index of TTI and the level of Pseudomonas spp. of pollack were measured at time intervals. Second, the resultant models were used in the mathematical calculations for dynamic temperature conditions included in the cold chain. As a result, the TTI activated at the mart place showed the best agreement between the spoilage time of the pollack and the time for the TTI color to reach its end-point. It was therefore found that it is practically important to optimally select the TTI activation place or time when using a commercial TTI product.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.520-524
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• 2023

Regalecus russellii, which spends most of its life in the deep sea, occasionally appears in coastal waters. However, the reasons for its appearance remain unclear. In Korea, R. russellii mainly appears along the eastern coastal waters, and most of them are caught in fishing gear, such as gill nets, or are stranded on the shore; nevertheless, the frequency of appearance is extremely low. Even if found, this species is often identified to be morphologically similar to Trachipterus ishikawae, and comprehensive analysis to identify the species through sample collection is limited. Consequently, information on the biological characteristics of R. russellii appearing in the coastal waters of Korea is scarce. Herein, the anatomical characteristics of R. russellii caught in a gill net off the Gangwon-do coast on March 14, 2023, were analyzed, and coastal water temperature was measured using an ocean buoy. Our results showed that the individual was male, its total length was 320 cm, body weight was 27.52 kg, body length was 26.62 cm, gonad weight was 619.45 g, and liver weight was 218.71 g. The stomach was full of euphausiids. The water temperature changed drastically at 15-30 m roughly a week before the R. russellii individual was caught, and the subsurface water temperature was lower than 10 ℃. Our findings provide baseline data to understand the ecological characteristics of R. russellii appearing along the eastern coast of the Korea.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.292-303
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• 2016

This study described the spatial distributions of marine environmental factors such as water temperature, salinity, chlorophyll a concentration and turbidity, and characteristics of phytoplankton community such as species composition, standing crops and dominant species at 19 fishing ports around Jeju Island during the early summer of 2016. I analyzed bio-oceanographical characteristics using principal component analysis (PCA) of the environmental factors and biological parameters. Water temperature, salinity, chlorophyll a and turbidity ranged from 17.6 to $20.7^{\circ}C$, from 26.19 to 32.33 psu, from 0.76 to $7.13{\mu}g\;L^{-1}$, and from 0.51 to 14.49 FTU, respectively. A total of 51 species of phytoplankton belonging to 35 genera were identified. In particular, diatoms and dinoflagellates accounted for more than 56.8% and 27.4% of all the species, respectively. Moreover, the number of phytoplankton species was controlled by salinity. Phytoplankton cell density ranged from $2.9cells\;mL^{-1}$ to $185.9cells\;mL^{-1}$. The dominant species were Navicula spp. Stephanopyxis turris, Eutreptiella gymnastica and Mesodinium rubrum. Environmental factors and the phytoplankton community varied greatly between sampling sites. According to PCA, the biological oceanographic characteristics of the around Jeju Island were characterized by meteorological factors such as air temperature, precipitation and discharge of ground water during early summer.