Tuna purse seine fishery (TPF) constitute more than 60% of distant water fishery production in Korea based on a statistic of 2018, and 28 ships from four different companies were under operation at the western and central Pacific Ocean. On this research, common risk factors during TPF were investigated via enumeration of five years Korean fisherman’s insurance payment statement, followed by some counterplans to diminish the accident rate. The accident rate of TPF on the Pacific Ocean peaked by 43.0% in 2014 and constantly decreased to 23.0% until 2018, presenting an average of 33.6%. Meanwhile, the accident rate on the Indian Ocean reached the highest point 55.1% in 2014 and declined to 11.6% in 2016, having an average of 24.7%. The average accident rate of the Indian Ocean scored 8.9% lower than the rate of the Pacific Ocean, but no statistic significance was observed. Depending on the process of operation, ‘casting or hauling of net’ was the most frequent part that people received an injury (40.4%). When the accidents were classified by their types, ‘falling down’ was the most recurrent cause of the injuries (28.5%). At the point of severity, the worst injuries were induced by crush hazard. Considering aforementioned accident frequency and severity, all the factors on the accident type list were divided into three different groups including high risk, moderate risk, and common risk. This study is expected to contribute to the reduction of occupational accidents during the work of fishermen and establishment of a safety management system for distance water fishing vessels.

The research was analyzed the catch data of the five years (2016-2020) for six joint venture company tuna purse seiners in the Atlantic Ocean, with the aim of suggesting improvement measures for responsible and sustainable fishing according to changes of recommendation by International Commission for the Conservation of Atlantic Tuna (ICCAT) on the tropical tunas. In the last five years, the average catch of six tuna purse seiner gradually increased to 7,745 tons, 8,364 tons and 9,053 tons from 2016 to 2018, but decreased to 7,761 tons in 2019 and 6,214 tons in 2020. The reason for the decrease in fishing volume in 2019 and 2020 was the fluctuation of the formation of the cold water zone (22-23℃), and the total ICCAT convention area of FAD closure in January and February due to the expansion of the FAD closure area and poor free school catching during two months period, respectively. The analysis on fishing area showed that the percentage of fishing in the high sea was about 85% although the FAD closure area included the EEZ zone in coastal countries; the rise of the fishing license in coastal countries is also believed to be a factor. In order to overcome such situations and improve catching volume, it will be possible if excellent manpower is secured, school fishing is expanded, and the production of high value-added catch (purse seine special: PS).

Recently, the annual emission rate of CO2 that is the main reason for domestic greenhouse gases is the third highest globally, which means it is an extremely serious issue. It is considered that these greenhouse gases affect climate changes. Especially, the emissions of CO2 in the fishing industry are nearly 4.11 million tons each year, occupying 0.7 percent of domestic total emissions. Therefore, this study clearly analyzed fuel consumption of major fish species over the recent five years focusing on large purse seines. It was revealed that mackerels occupied 55.7 percent of total fish catches of large purse seines and 57.5percent of total fishing earnings. Also, fuel consumption was 236.62 liters per ton caught and 179.51liters per million won earned.

In this study, the risk factors of coastal purse seine fisherman were analyzed through a survey of fishery workers of coastal purse seine fishery and the accident compensation insurance data of the fisheries workers of the National Federation of Fisheries Cooperatives (NFFC). The classified fishing operation accident data was analyzed through 4M (Man, Machine, Media, Management) model of the National Transportation Safety Board (NTSB) and the accident prevention measures were presented using Harvey's 3E (Engineering, Education, Enforcement) model. The rate of accidents on coastal purse seinens each year was 75.8‰, 36.7‰ and 74.8‰ from 2015 to 2017. The accident frequency resulting from slipping was the highest, and the risk of a contact with gear was low. When comparing each insurance data, the average value of the contact with gear accident was the highest. This research result is expected to be important data in identifying and preventing safety hazards of coastal purse seiner fisherman in the future.

In the previous study, a shooting trajectory assuming that the purse seine shooting trajectory is a circle was proposed based on the speed and direction of the movement of the fish school. However, in practice, a trajectory that is closer to an elliptical shape than a circular one is often formed. In this study, the existing circular trajectory and the elliptical trajectory methods were compared under the same conditions to confirm the effectiveness of elliptical shooting trajectory. In addition, changes in the eccentricity of ellipses were derived to assess which type of ellipse was appropriate as a shooting trajectory. When a high-speed fish school moves in a straight line, an elliptical shooting trajectory with the eccentricity of 0.7 to 0.9 will be reasonable, and for middle-low speed fish school, an elliptical shooting trajectory with the eccentricity of 0.4 to 0.6 will be more useful than a circle shooting trajectory.

The International Labor Organization (ILO) selected fishing as the most dangerous group of jobs in the world, and it is well known in Korea as a 4D industry. Offshore large purse seine accounts for the largest portion of the fishing industry in the coastal region with high death rate and the accident rate. The repeated disaster rate survey by the Korea Maritime Institute (KMI) shows offshore large purse seiner is the highest at 22.3 percent and coastal gill nets and offshore stow net are following at 12.4 percent and 11.9 percent in order. Therefore, risk factors occurring in offshore large purse seiners were analyzed based on data from the National Federation of Fisheries Cooperatives (NFFC) for three years from 2015 to 2017 and 4M (Man, Machine, Media, Management) 3E (Engineering, Education, Enforcement) techniques were used to provide a safe fishing environment. The number of accidents on offshore large purse seiners each year was more than 150, and the number of accidents on every fishing boats was as high as 17 percent in 2015. If the accident rate and the risk level were divided by insurance, the accident resulting from contact with machinery was the highest, and the risk of a contact with gear was low but frequently occurring. This was caused by collisions and contact with gear in situations where death and disappearance risk are not high, and accident types in situations where death and loss risk are considered to be contact with machinery, falls or other accidents. Through these analysis techniques, the frequency and risk of each type of accident on a offshore large purse seiners can be demonstrated, and it is expected to raise awareness of a safer fishing environment and contribute to the reduction of accidents.

우리나라에서 다랑어 선망어업은 국내 원양산업 중 업종별 생산량 1위의 업종으로, 1980년대 중 후반부터 연구가 지속적으로 수행되어왔으며, 기술의 현대화 연구가 활발히 진행되어왔다. 하지만, 어선에 탑재되는 보조작업선들은 원양어업에서 중요한 역할을 맡고 있음에도 관련 연구가 미흡한 실정이다. 이에 본 연구에서는 보조작업선들 중 네트보트의 추진기를 프로펠러에서 워터제트 형태로 변경하고, 그에 따른 선형 변환을 통한 선체 부가저항 감소 및 운항성능을 향상하고자 하였다. 이를 위해 전산수치해석을 통해서 선박의 유체 성능 변화를 계산하였으며, 또한 기존 선형 및 추진기 변화 선형에 대해 모형선 수조시험을 수행하여 속도별 저항성능 비교를 수행하였다. 수치해석 및 1/7의 축소모형의 수조시험 결과, 기존의 네트보트 대비 45~58% 저항성능이 크게 향상되었으며, 이는 철망 제거에 의한 단순 침수표면적 및 선형개선에 의한 저항성능 향상을 확인하였다.

우리나라에서는 다랑어 선망어업의 기술 경쟁력을 높이기 위한 많은 연구개발이 이루어지고 있으며, 이러한 노력으로 인하여 다랑어 선망어선의 선형개선과 어군 탐지를 위한 레이다, 소나 및 위성정보시스템의 개발로 인해 조업 효율이 향상되었다. 그러나 다랑어 선망어선에 탑재되는 보조 작업선인 스키프보트, 네트보트 및 스피드보트의 경우에는 본선의 기술 현대화에 비해 기술력이 낙후되어 있 는 실정이다. 이에 본 논문에서는 그물을 끌기 위한 양망의 기능과 프로펠러로부터 다랑어를 보호하기 위하여 설치된 철망을 가진 기존 의 네트보트의 선체를 워터제트 추진기 탑재가 가능한 선체로 변경하여 다랑어 보호, 선체저항 감소 및 운항성능 향상하고자 하였다. 결 과적으로 워터제트 형태에 적합한 선형에 대해 해양수산부 고시에 의거한 알루미늄 구조강도 기준을 적용한 시제선 제작하였으며 낙하 시험을 수행하여 안전성을 확인하였다. 또한 해상시운전을 통하여 기존의 네트보트는 2,500 RPM에서 속도는 12.0 knot, 예인력은 2,545 kgf 이며, 워터제트가 탑재된 네트보트는 3,200 RPM에서 속도는 26.7 knot, 예인력은 2,011 kgf로 워터제트가 탑재된 네트보트 또한 다랑어 선망 어선의 보조 작업선으로 예인용량 기준에 충분히 만족함을 알 수 있었다.

To suggest more efficient fishing operation, it was analyzed using five years (2011~2015) catch data of six Korean-flagged tuna purse seiners (with 1000 mt of haul capacity) operating in the western and central Pacific Ocean. In terms of annual total catch, it presented a two-year cycle of variation on catch, showing that catches of 2012, 2014 and 2015 were high, whereas those of 2011 and 2013 were low. The proportions on fishing effort of associated set were around 21.9~30.8% having 21.5~45.0% of total catch. In this study, there was no significant difference between catches of unassociated set and associated set. When considered having good fishing conditions, fishing activities were concentrated in the areas of Papua New Guinea (PNG) and Kiribati, while it showed that fishing ground spreaded out to the areas of not only PNG and Kiribati but also Federated States of Micronesia (FSM), Tuvalu and Solomon islands. The average number of fishing days was 271 with a range of 246~285. As restriction on fishing operation such as reduction of fishing days and higher fishing fee are expected to strengthen, the result of this study will be helpful to select more efficient fishing methods for purse seine fishery based on fishing conditions.

The powered purse seine fishery is an important fishery accounting for 19.4% of adjacent water fishery production in Korea, and the commercial fishing is associated with high rate of fatal and non-fatal occupational injury. The hazard analysis for the fishermen’s safety of offshore large powered purse seiner was conducted to serve as a basic data for improving the healthy and safe working environment of fishermen using fishermen’s occupational accidents of the national federation of fisheries cooperatives (NFFC) in 2013 (n=583). As a result, the occupational accident occurrence rate of this fishery was 182.6‰ in all industries 30.9 times the rate of that. In addition, death and missing rate was found to have a very serious level management to 25.1‱ in all industries of death of 17.5 times. The accident occurred in 72.3 to 85.8% was happened at sea. The others, slipping and struck by object etc occurred more frequently in order in the frequency of accident occurrence pattern. However, the occurrence rate of death and missing did not match the frequency of accident pattern. In other words, slipping occurred frequently higher while death and missing risk was not high. And the contact with fishing gear and fall in the waters was low while death and missing risk was high. The results are expected to contribute for identification and assessment of safety hazard occurred in offshore large powered purse seiners.

The inherent efficiency of a ship would be prior to any other quality factors in ship's safety, because lack of it may give rise to a serious sea casuality even if it were a light mistake in operation. And the representative casualty comes from a deficiency of stability and an operating error combined would be capsizing. The Korean offshore large purseiner looks to have a structural weak point with small range of stability in spite of her big initial metacentric height, and have various type of roll reduction devices in order to cover up the defect. The aim of this study is to grasp for the roll reduction characteristics of the purseiner with bilge keel only and a stern keel additionally attached. The results are summarized as follows; The rolling angle of the model ship was increased in accordance with increase of the wave period and height, especially at close to the natural wave period of her, and the trends were more distinguished in the situation of bilge keel only installation than in the stern keel additionally installed. And stern keel has not noticeable effect on the reduction of the roll in the light ship condition, but has a little effect in full load condition.

Marine casualties of vessel are said to be in most case caused by human error, but it would be valid for the assumption that the ship is built with high quality and then should be acceptable to the safety standards. It means that the inherent characteristics of a ship should be the first consideration on the safety of ship. Therefore it is basically necessary for navigator to grasp the inherent stability of his ship and ensure that the ship complies with the minimum statutory standards of stability. This study is to realize the stability of the Korean offshore large purseiner varying with loading conditions by the inclining data and some calculations. The author compared the stability of the ship with IMO criteria and domestic rule, and proposed some improvement for the safety of the ship. The results are summarized as follows ; The values of GM of the ship according to the loading condition in navigation satisfy both of the IMO criteria and the domestic rule, but in case of the area under the GZ curves between the heel angles of 30˚ and 40˚, and the heel angle occuring the maximum righting lever not satisfy the IMO rule at the fishing ground departure and arrival conditions in the haul in net situation. The initial metacentric height of the ship is very large, but the range of stability and the occurring angle of the maximum GZ are very small, so even small inclining can bring about the beam end. The best method of improvement for that is to increase the freeboard of the model among the variables.

The purpose of present research is to develop and efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. Havelock was considered the wave resistance of a post extending vertically downwards through the water from the surface, its section by a horizontal plane being the same at all depths and having its breadth small compared with its length. This enables us to elucidate certain points of interest in ship resistance. However, the ship has not infinite draft. So, the problem which is investigated ind detail in this paper is the wave resistance of a mathematical quadratic model in a uniform stream. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. The numerical results using the panel shift method and finite difference method are compared with the experimental results for wigley mono hull. There are no differences in the wave resistance. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. Some numerical results for series 60, C sub(b) =0.6, hull are presented in this paper. The wave pattern and wave resistance are computed at two Froude numbers, 0.267 and 0.304. These results are better than those of Michell's thin ship theory in comparison with measured results. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.