• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.3
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• pp.185-200
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• 2021

The Marine Environment QA/QC management system has been operated since 2010 to secure the reliability of data and improve the analysis capabilities of measurement and analysis institutions. From 2010 to 2020, the cumulative number of measurement and analysis institutions participated in the QA/QC management system was 266. And the number of certificates issued by the ministry of oceans and fisheries is 182. A total of 32 reference materials for proficiency testing and interlaboratory comparisons have been developed. They were first developed focusing on items (Nutrients, COD) commonly analyzed in marine environmental measuring network, marine pollution impact surveys, sea area utilization impact assessment, deepsea water surveys, and information network on fishing ground environments. In addition, it is time to expand the filed of the QA/QC management system, such as seawater temperature, salinity, PCBs and PAHs in sediments, which are mainly analyzed in most monitoring programs. On-site assessment has been conducted for 162 laboratories according to ISO/IEC 17025 to evaluate their conformity of the quality management system and deficiency. In terms of management and technology requirements, about 4.2% of organizations showed insufficient division of duties among employees 8.7% of them revealed the lack of employee training. By test item, about 6.3% of organizations showed the lack of standard substance management and the state of the cleaning glassware was pointed out in about 5.4% of them. The QA/QC management system should be continuously supplemented by identifying the causes of nonconformities and area for improvement.

• Journal of Navigation and Port Research
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• v.46 no.3
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• pp.209-215
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• 2022

On the Jeju coast, international cruise ships, passenger ships, and other ships pass frequently, as well as many fishing boats. Thus, there is a high risk of marine accidents and frequent ship collisions. Accordingly, it is urgent to establish a coastal VTS for systematic safety management of ships passing through the coastal waters of Jeju. The purpose of this study was to set the area of the VTS to be newly established. In this study, to calculate the workload of the VTS operators, a formula was proposed that reflects the monitoring workload considering the monitoring frequency and required time for target as well as non-target ships and the workload for ship collision situations. The proposed formula was applied to the newly established VTS area in Jeju. Three control sectors were set up in each VTS center. The average number of workstations per hour was approximately 1, so the division between sectors was appropriate. Thus, it was deduced that there would be no workload for the VTS operators. It is expected that the method proposed in this study can be used as primary data for calculating the appropriate number of workstations for the current VTS, and setting the VTS area for a new coastal VTS in the future.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.2
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• pp.49-70
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• 2022

Sea Surface Temperature (SST), one of the ocean features, has a significant impact on climate, marine ecosystem and human activities. Therefore, SST prediction has been always an important issue. Recently, deep learning has drawn much attentions, since it can predict SST by training past SST patterns. Compared to the numerical simulations, deep learning model is highly efficient, since it can estimate nonlinear relationships between input data. With the recent development of Graphics Processing Unit (GPU) in computer, large amounts of data can be calculated repeatedly and rapidly. In this study, Short-term SST will be predicted through Convolutional Neural Network (CNN)-based U-Net that can handle spatiotemporal data concurrently and overcome the drawbacks of previously existing deep learning-based models. The SST prediction performance depends on the seasonal and interannual SST variabilities around the southern coast of Korea. The predicted SST has a wide range of variance during spring and summer, while it has small range of variance during fall and winter. A wide range of variance also has a significant correlation with the change of the Pacific Decadal Oscillation (PDO) index. These results are found to be affected by the intensity of the seasonal and PDO-related interannual SST fronts and their intensity variations along the southern Korean seas. This study implies that the SST prediction performance using the developed deep learning model can be significantly varied by seasonal and interannual variabilities in SST.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.244-253
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• 2022

Recently, installation projects of structures such as offshore wind farms have been increasing, and the installation of such marine obstacles could affect ships that pass nearby. Therefore, the purpose of this study was to quantitatively evaluate the risk posed to passing ships due to obstacles in their passage. Hence, parameters that affected the risk were selected, and scenarios were set based on the parameters. The scenarios were evaluated through the ES model, which is a risk assessment model, and we confirmed that the risk ratio increased as the size of the obstacle increased, the safe distance from the obstacle increased, the speed of ship decreased, and the traffic volume increased. Additionally, we found that when the traffic flow direction was designated, the risk ratio was lower than that of general traffic flow. In this study, we proposed a generalization model based on the results of the performed scenarios, applied it to the Dadaepo offshore wind farm, and demonstrated that the estimation of the approximate risk ratio was possible through the generalization model. Finally, we judged that the generalization model proposed in this study could be used as a preliminary reference for the installation of marine obstacles.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.254-261
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• 2022

Every vessel shall proceed at a safe speed to avoid collision. Additionally, every vessel shall comply with the speed limit rules in the territorial water and internal waters of Korea. The VTS operator shall properly control the compliance of the vessel with the safe speed and speed limit rules. Safe speed under the COLREG 1972 is not explicitly stipulated in knots. However, under the Domestic law for traffic safety-specific sea areas, etc., the speed limit is specified in knots and complied with. This speed limit rule is mainly based on the 'speed made good over the ground'; however, in some places, it is based on the 'speed making way through the water'. In this paper, I analyzed marine accidents that occurred in the past 5 years and the rate of violation of speed limits. Furthermore, I reviewed safe speed under the COLREG 1972, speed limit rules under domestic and foreign laws, and cases of non-compliance with safe speed in the judgment of the Korea Maritime Safety Tribunal. Resultantly, I suggested in this paper that the speed limit rules in the domestic law must be observed by vessels to prevent marine accidents, and the rules which are stipulated in terms of 'speed making way through the water' must be revised as 'speed made good over the ground' such that the vessels can easily comply with them and the VTS operator can control the vessel properly.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.1
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• pp.39-48
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• 2022

Using environmental DNA (eDNA) in the fisheries and oceanography fields, research on the diversity of biological species, the presence or absence of specific species and quantitative evaluation of species has considerably been performed. Up to date, no study on eDNA has been tried in the area of fisheries acoustics in Korea. In this study, the biomass of a dominant species in the northwestern waters of Jeju Island was examined using 1) the catch ratio of the species from trawl survey results and 2) the ranking ratio of the species from the eDNA results. The dominant species was Zoarces gillii, and its trawl catch ratio was 68.2% and its eDNA ratio was 81.3%. The Zoarces gillii biomass from the two methods was 7199.4 tons (trawl) and 8584.6 tons (eDNA), respectively. The mean and standard deviation of the acoustic backscattering strength values (120 kHz) from the entire survey area were 135.5 and 157.7 m²/nm², respectively. The strongest echo signal occurred at latitude 34° and longitude 126°15' (northwest of Jeju Island). High echo signals were observed in a specific oceanographic feature (salinity range of 32-33 psu and the water temperature range of 19-20℃). This study was a pilot study on evaluating quantitatively aquatic resources by applying the eDNA technique into acoustic-trawl survey method. Points to be considered for high-quality quantitative estimation using the eDNA to fisheries acosutics were discussed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1004-1010
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• 2021

Ship-floating object accidents can lead not only to a delay in ship's operations, but also to large scale casualties. Hence, preventive measures are required to avoid them. This study analyzed the spatiotemporal aspects of such collisions based on the data on ship-floating object accidents in sea areas in the last five years, including the collisions in South Korea's territorial seas and exclusive economic zones. We also provide basic data for related research fields. To understand the distribution of the relative density of accidents involving floating objects, the sea area under analysis was visualized as a grid and a two-dimensional histogram was generated. A multinomial logistic regression model was used to analyze the effect of variables such as time of day and season on the collisions. The spatial analysis revealed that the collision density was highest for the areas extending from Geoje Island to Tongyeong, including Jinhae Bay, and that it was high near Jeongok Port in the West Sea and the northern part of Jeju Island. The temporal analysis revealed that the collisions occurred most frequently during the day (71.4%) and in autumn. Furthermore, the likelihood of collision with floating objects was much higher for professional fishing vessels, leisure vessels, and recreational fishing vessels than for cargo vessels during the day and in autumn. The results of this analysis can be used as primary data for the arrangement of Coast Guard vessels, rigid enforcement of regulations, removal of floating objects, and preparation of countermeasures involving preliminary removal of floating objects to prevent accidents by time and season.

• Journal of Navigation and Port Research
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• v.46 no.4
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• pp.321-330
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• 2022

Busan New Port manages the largest volume of traffic among Korean ports, and accounts for 68.5% of the total volume of the Busan port. Due to this increase in volume, ultra large container ships call at Busan New Port. When the additional south container terminal as well as ongoing construction project of the west container terminal are completed, various encounters may occur at the Busan New Port entrance, which may cause collision risk.s Thus, the purpose of this study was to provide a plan to improve the safety of vessel traffic, in the in/out bound fairway of Busan New Port. For this purpose, the status of arrivals and departures of vessels in Busan New Port, was examined through maritime traffic flow analysis. Additionally, risk factors and safety measures were identified, by AHP analysis with ship operators of the study area. Also, based on the derived safety measures, scenarios were set using the Environmental Stress model (ES model), and the traffic risk level of each safety measure was identified through simulation. As a result, it is expected that setting the no entry area for one-way traffic would have a significant effect on mitigating risks at the Busan New Port entrance. This study can serve as a basis for preparing safety measures, to improve the navigation of vessels using Busan New Port. If safety measures are prepared in the future, it is necessary to verify the safety by using the traffic volume and flow changes according to the newly-opened berths.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.753-763
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• 2022

In coastal and inland bays, where most of Korea's aquaculture is located, massive aquaculture damage occurs every year due to frequent anomalous high water temperatures. The interannual fluctuations of water temperature in July over the past four years (2018-2021) were the second largest since 1990 (after the period of 1994-1997) due to anomalous high temperatures, rainy seasons, and typhoons. Through analysis of heat flux and heat balance in areas of concern for high water temperatures (i.e., Cheonsu Bay, Gamak Bay, Guryongpo), the occurrence of high water temperatures in Cheonsu Bay and Gamak Bay in the summer seasons was confirmed to derive mainly from heat inflow through the sea surface from the air. Based on estimations of the average ocean heat transport rate in July for the four-year period of 2018-2021, Cheonsu Bay and Gamak Bay accounted for 13.5% and 62.3% outflow of the net heat flux, respectively. However, the ocean heat transport rate in Guryongpo Hajeong differed significantly from -174.5% to 132.5% of the net heat flux by year depending on the occurrence of cold water mass.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.427-434
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• 2023

Oysters are an important organism, accounting for an average of 76% of shellfish aquaculture production. In this study, optimal habitat was searched for by calculating the Habitat Suitability Index (HSI) using water temperature, salinity, hydrodynamics, DO, SS and Chl.a in Jaran Bay. As a result, the inside of Jaran Bay was found to be a more suitable habitat than the outside with a wide entrance and rapid hydrodynamics. Oyster production and HSI showed a significant correlation (0.710, p<0.05). Hydrodynamics helps the growth of aquaculture organisms, such as food supply through seawater exchange in the bay, which showed a high correlation (0.709, p<0.05) with oyster production. It was found to have a greater effect on habitat suitability than Chl.a. The results of this study are expected to be helpful for the efficient conservation, use and management of coastal fisheries.