• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.53 no.4
• /
• pp.413-422
• /
• 2017

The objective of this study was to prove possible effects of a habitable place for fish around semi-submersible drilling rig which measured underwater radiated noise, irradiance distribution of rig's light and conducted experimental fishing in Malaysia territory and observed for distribution of fishes around the rig by ROV during drilling operation in the East Sea of Korea. As a result underwater radiated noise was $130dB/{\mu}Pa$ from 156.25 to 187.50 Hz, irradiance distribution of light was between 21.5 and 43.1 lx. Despite this result, underwater radiated noise was not a threat to fish around rig and low irradiance distribution of light also played a role in the luring influence of the fishes at night. Fish showed up in the beginning of drilling operation and at the end of drilling operation. However, there are few fish in the midst of drilling operation. The main reason for this result was the destruction of the habitable place due to blow out mud and broken pieces of ground formation in drilling hole. The results are expected to contribute to reasonable fishery management around rig.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.55 no.4
• /
• pp.411-418
• /
• 2019

In this study, to investigate the effect of physical and chemical properties of butanol on the engine performance and combustion characteristics, the coefficient of variations of IMEP (indicated mean effective pressure) and fuel conversion efficiency were obtained by measuring the combustion pressure and the fuel consumption quantity according to the engine load and the mixing ratio of diesel oil and butanol. In addition, the combustion pressure was analyzed to obtain the pressure increasing rate and heat release rate, and then the combustion temperature was calculated using a single zone combustion model. The experimental and analysis results of butanol blending oil were compared with the those of diesel oil under the similar operation conditions to determine the performance of the engine and combustion characteristics. As a result, the combustion stabilities of D.O. and butanol blending oil were good in this experimental range, and the indicated fuel conversion efficiency of butanol blending oil was slightly higher at low load but that of D.O. was higher above medium load. The premixed combustion period of D.O. was almost constant regardless of the load. As the load was lower and the butanol blending ratio was higher, the premixed combustion period of butanol blending oil was longer and the premixed combustion period was almost constant at high load regardless of butanol blending ratio. The average heat release rate was higher with increasing loads; especially as butanol blending ratio was increased at high load, the average heat release rate of butanol blending oil was higher than that of D.O. In addition, the calculated maximum. combustion temperature of butanol blending oil was higher than that of D.O. at all loads.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.56 no.2
• /
• pp.138-146
• /
• 2020

Stow net fishery is one of the fishery with high fishing work accidents in southwestern sea of Korea. We conducted to serve as basic data for improving the healthy and safe working environment of fisher using risk assessment process (ISO45001) with fishermen's occupational accidents of the National Federation of Fisheries Cooperative (NFFC) from 2016 to 2018. The average occurrence rate of victim in this fishery was 9.04%, 16.7 times more than such rate in all industries. In addition, the average fatality rate was found to have a very serious level management to 31.06‱, 27.7 times more than such rate in all industries. The safety hazards of stow net fishery was more likely to occur by other general industrial groups, with more severe consequences after the accident. According to 4M analysis, 58.6% of all accidents were caused by human factors, 24.0% by environmental factors, 16.0% by mechanical factors, and 1.5% by managerial factors, respectively. The occurrence frequency by accident type was the highest in 187 cases (32.2%) for struck by object, 158 cases (27.2%) for slipping, and 94 cases (16.2%) for being in contact with machinery. Severity is the highest for others such as diseases etc., in the order of being struck by object, being in contact with machinery, falling from above slipping, collapsing, bumping, and burning. Being struck by object, being in contact with machinery, and slipping are high-risk groups, falling from above others, bumping, and burning are medium-risk groups based on the risk assessment using the occurrence frequency and severity of accident. The obtained results are expected to contribute to the safe operation environment subsidy for fishing crews on the stow net fishing vessel.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.56 no.2
• /
• pp.155-162
• /
• 2020

The adjudication of Korean Maritime Safety Tribunal (KMST) was analyzed to collect basic data to identify the cause of the risk that did not appear in the current data provided by the fishermen's occupational accidents of the National Federation of Fisheries Cooperative (NFFC) in stow net fishing vessel from 2015 to 2019. The personnel's carelessness was the most common in 29 out of 33 accidents (87.9%), followed by 25 cases (75.8%) of inadequacy of instructions, 24 cases (72.7%) of inadequacy of education on hazard factor, 20 cases (60.6%) of no personal protection equipment, 18 cases (54.5%) of poor guard, 17 cases (51.5%) of inadequacy of work method, 16 cases (48.5%) of absence of emergency stop button, 14 cases (42.4%) of work practice of poor safety precautions that affected more than 40% of all accidents as accident causes. These causes had a strong influence on each other, and the ratio of accident causes is high. With this relationship, accidents can be prevented or the severity of human injury can be reduced if types of accident process can be estimated with a scenario, and the key points before the accident in the scenario are switched to safe points.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.56 no.2
• /
• pp.147-154
• /
• 2020

The questionnaire survey was carried out to collect basic data to identify the cause of the risk that did not appear in the current data provided by the fishermen's occupational accidents of the National Federation of Fisheries Cooperative (NFFC) to the onsite specialist, such as a fishing master, chief engineer and fisher in stow net fishing vessel from June to July 2018. The results are as follows. A total of 134 cases were surveyed, including 53 cases in Yeosu, 44 cases in Mokpo, 30 cases in Boryeong and 7 cases in Gunsan. Approximately 60% of the respondents on board the stow net fishing vessel were more than 20 years old, and the boarding experience was seasoned and suitable for the respondents. In the 4M analysis by safety accident factor during fishing work, the mechanical factors included 51 cases (25.0%) of decrepit equipment or poor maintenance and 49 cases (24.0%) of systemic error of fishing equipment. The environmental factors exhibited 71 cases (33.5%) of poor communication by mixed manning of foreign fishermen and 63 cases (29.7%) of poor environment such as heavy weather etc. The human factors showed 78 cases (37.3%) of personnel's carelessness and 45 cases (21.5%) of unskillfulness of operating net and haulers. The management factors exhibited 59 cases (32.1%) of work practice of poor safety precautions and 56 cases (30.4%) of inadequacy of education on hazard factor. The results are expected to contribute to the creation of a safe operating environment for stow net fishery, such as a fisher boarding a stow net fishing vessel, enabling the analysis of major causes of working safety accidents by cause.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.6
• /
• pp.743-748
• /
• 2003

An oil boom was set up in order to contain diffused oil from spills and for the retrenchment of damage caused by oil Pollution. Therefore, the oil boom anchor needed proper holding power to endure high resistance from flowing streams and to secure the oil boom around the spill, and must dredge directly into the seabed when it is dropped and block oil outflow immediately. This study investigated the holding power of the danforth anchor and the coastal fishing vessel anchor used for oil booms in the KMPRC (Korea Marine Pollution Response Corporation). For each type, a 30 kg and 20 kg anchor were used. The holding power of the danforth anchors were measured by dropping both weights 10 times. However the coastal fishing vessel anchors were dropped only 5 times each, because no substantial differences were found between drops. In the results of the danforth anchors, an anchor awoke occurred in 2 drops of the 30 kg anchor and in 4 drops of the 20 kg anchor, wherein there was no holding power to be measured. With exception to the anchor awoke cases, the maximum holding power of the danforth 30 kg and 20 kg anchors was 250-520 kg and 123-233 kg, respectively. In the case of the coastal fishing vessel anchors of 30 kg and 20 kg, throughout the experiment, there was no occurrence of an anchor awoke. For the 30 kg and 20 kg anchors, the maximum holding power was measured to be 209-230 kg and 155-170 kg, respectively. Therefore, the holding power of the coastal fishing vessel anchor was shown to be much poorer than that of the danforth anchor. However, the holding power of the danforth anchor was very unstable. Due to the occurrences of anchor awoke, there was no holding power and the measurement value of maximum holding power showed too much variation among the drop tests. Also, after the maximum holding power was achieved, anchor awoke occurred easily. In the case of the coastal fishing vessel anchor was much more stabile, because there was no anchor awoke and no instance where holding power failed. Also the maximum holding power was reached quickly and almost no variation occurred among the drop tests.

• Ocean and Polar Research
• /
• v.45 no.2
• /
• pp.43-55
• /
• 2023

This study was conducted to understand the seasonal patterns and variation of the copepod community in the Anma Islands of Yeonggwang, Yellow Sea, with a focus on seasonal surveys to assess the factors affecting their occurrence. Throughout the survey period, Acartia hongi, Paracalanus parvus s. l., and Ditrichocorycaeus affinis were dominant species, while Acartia ohtsukai, Acartia pacifica, Bestiolina coreana, Centropages abdominalis, Labidocera rotunda, Paracalanus sp., Tortanus derjugini, Tortanus forcipatus occurred differently by season and station. As a results of cluster analysis, the copepod communities were distinguished into three distinct groups: spring-winter, summer, and autumn. The results of this study showed that the occurrence patterns of copepod species can vary depending on environmental conditions (topographic, distance from the inshore, etc.), and their spatial occurrence patterns between seasons were controlled by water temperature and prey conditions. One of the physical mechanisms that can affect the distribution of zooplankton in the Yellow Sea is the behavior of the Yellow Sea Bottom Cold Water (YSBCW), which shows remarkable seasonal fluctuations. More detailed further studies are needed for clear grounds for mainly why to many Calanus sinicus in the central region of the Yellow Sea are seasonally moving to the inshore, what strategies to seasonally maintain the population, and support the possibilities of complex factors.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.7
• /
• pp.1209-1215
• /
• 2022

The selective catalytic reduction (SCR) is known as a very efficient method to reduce nitrogen oxides (NOx) and the catalyst performs reduction from nitrogen oxides (NOx) to nitrogen (N₂) and water vapor (H2O). The catalyst, which is one of the factors determining the performance of the nitrogen oxide (NOx) ruduction method, is known to increase catalyst efficiency as cell density increases. In this study, the reduction characteristics of nitrogen oxides (NOx) under various engine loads investigated. A 100CPSI(60Cell) catalysts was studied through a laboratory-sized simulating device that can simulate the exhaust gas conditions from the power generation engine installed in the training ship SEGERO. The effect of 100CPSI(60Cell) cell density was compared with that of 25.8CPSI(30Cell) cell density that already had NOx reduction data from the SCR manufacturing. The experimental catalysts were honeycomb type and its compositions and materials of V₂O₅-WO₃-TiO₂ were retained, with only change on cell density. As a result, the NOx concentration reduction rate from 100CPSI(60Cell) catalyst was 88.5%, and IMO specific NOx emission was 0.99g/kwh satisfying the IMO Tier III NOx emission requirement. The NOx concentration reduction rate from 25.8CPSI(30Cell) was 78%, and IMO specific NOx emission was 2.00g/kwh. Comparing the NOx concentration reduction rate and emission of 100CPSI(60Cell) and 25.8CPSI(30Cell) catalysts, notably, the NOx concentration reduction rate of 100CPSI(60Cell) catalyst was 10.5% higher and its IMO specific NOx emission was about twice less than that of the 25.8CPSI(30Cell) catalysts. Therefore, an efficient NOx reduction effect can be expected by increasing the cell density of catalysts. In other words, effects to production cost reduction, efficient arrangement of engine room and cargo space can be estimated from the reduced catalyst volume.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.6
• /
• pp.697-703
• /
• 2023

As a part of the global industrial efforts to reduce environmental pollution owing to air pollution, regulations have been established by the International Maritime Organization (IMO). The IMO has implemented various regulations such as EEXI, EEDI, and CII to reduce air pollution emissions from ships. They are also promoting measures to decrease the power consumption in ships, aiming to conserve energy. Most of the power used in ships is consumed by electric motors. Among the motors installed on ships, the engine room blower that takes up a significant load, operates at a constant irrespective of demand. Therefore, energy savings can be expected through frequency control. In this study, we demonstrated the efficacy of energy savings by controlling the frequency of the electric motor of the generator blower that supplies combustion air to the generator's turbocharger. The system was modeled based on the output data of the turboharger outlet temperature in response to the blower frequency inpu. A PI control system was established to control the frequency with the target being the turbocharger outlet temperature. By maintaining the turbocharger design standard outlet temperature and controlling the blower frequency, we achieved an annual energy saving of 15,552kW in power consumption. The effectiveness of energy savings through frequency control of blower fans was verified during the summer (April to September) and winter (March to October) periods. Based on this, we achieved annual fuel cost savings of 6,091 thousand won and reduction of 8.5 tons of carbon dioxide, 2.4 kg of SOx, and 7.8 kg of NOx air pollutants on the training ship.

• Korean Journal of Remote Sensing
• /
• v.38 no.6_1
• /
• pp.1463-1478
• /
• 2022

Maritime transport accounts for 99.7% of the exports and imports of the Republic of Korea; therefore, developing a vessel monitoring system for efficient operation is of significant interest. Several studies have focused on tracking and monitoring vessel movements based on automatic identification system (AIS) data; however, ships without AIS have limited monitoring and tracking ability. High-resolution optical satellite images can provide the missing layer of information in AIS-based monitoring systems because they can identify non-AIS vessels and small ships over a wide range. Therefore, it is necessary to investigate vessel monitoring and small vessel classification systems using high-resolution optical satellite images. This study examined the possibility of developing ship monitoring systems using Compact Advanced Satellite 500-1 (CAS500-1) satellite images by first training a deep learning model using satellite image data and then performing detection in other images. To determine the effectiveness of the proposed method, the learning data was acquired from ships in the Yellow Sea and its major ports, and the detection model was established using the You Only Look Once (YOLO) algorithm. The ship detection performance was evaluated for a domestic and an international port. The results obtained using the detection model in ships in the anchorage and berth areas were compared with the ship classification information obtained using AIS, and an accuracy of 85.5% and 70% was achieved using domestic and international classification models, respectively. The results indicate that high-resolution satellite images can be used in mooring ships for vessel monitoring. The developed approach can potentially be used in vessel tracking and monitoring systems at major ports around the world if the accuracy of the detection model is improved through continuous learning data construction.