This study quantitatively evaluated size selectivity for three netting shapes (T0; regular, T45, T90) and hanging ratio (35%, 70%) of T0 netting used for trawl codend. The size selectivity experiment was performed in a tank using a cube experimental model with a length of 50 cm on one side and 389 experimental individuals, jack mackerel (Trachurus japonicus). In the selectivity analysis, a selectivity curve was created based on the selection ratio using a logistic function, and the 25%, 50%, and 70% selection length and selection range  were obtained. The T0 netting was 19.54 cm when the 50% selective length, which is a selectivity evaluation index, had a hanging ratio of 35%, a selection range of 0.51 cm, and 22.70 cm and 3.08 cm for the hanging ratio of 70%. The T45 netting was 24.34 cm and 2.13 cm, and the T90 netting was 23.51 cm and 2.84 cm. The results of the T45 netting and the T90 netting are similar, and the 50% selection length and selection range were relatively larger than the T0 netting. There was a significant difference in the correlation between the circumference of the inner circle of the mesh by the shape of the netting and the body girth of the experimental individual (Pearson test,      ). There was no significant difference in the correlation between the selection ratio by the T0 netting, T45 netting, and T90 netting with a 70% hanging ratio (one-way ANOVA,   ). The results of this study showed that selectivity such as T45 netting and T90 netting appeared when the hanging ratio, which maximizes the area of T0 netting, was maintained at 70%.

In this study, a comparative test operation was conducted through the alternate haul method to examine the selectivity of the four mesh sizes (60 mm, 90 mm, 110 mm, and 130 mm) of the trawl codend. The selectivity was analyzed using the SELECT model considering the fishing efficiency (split parameter) of each fishing gear in the comparative test fishing operation in the trawl and the maximum likelihood method for parameter estimation. A selectivity master curve was estimated for several mesh sizes using the extended-SELECT model. As a result of analyzing the selectivity for silver croaker based on the results of three times hauls for each experimental gear, it was found that the size of the fish caught increased as the size of the mesh size increased. When the selectivity for each mesh size analyzed by the SELECT model considering the split ratio was evaluated based on the size of the AIC value, the estimated split model was superior to the equal split model. Based on the master curve, the 50% selection length value was 2.893, which was estimated to be 136 mm based on the mesh size of 60 mm. In some selectivity models, there was a large deviance between observed and theoretical values due to the non-uniformity of the distribution of fished length classes. As a result, it is considered that appropriate sea trials and selectivity evaluation methods with high reliability should be applied to present trawl fishery resource management methods.

Sea anchor for fishery is commonly used in jigging fishery and purse seine. The study of sea anchor was studied for improvement of opening efficiency and drag by changing the type of shape and the diameter of vent. However, standard specification of sea anchor is not set and has not been studied for underwater stability. Therefore, this study aimed to improve underwater stability of sea anchor by changing a vent diameter and weight of sinker. The experiment was conducted in flume water tank. The experiment model of sea anchor was made from actual model of sea anchor which is used in fishery by similarity law. The model of sea anchor was designed to different types of vent diameter and weight of sinker in different current speed. The value of movement of side to side (X-axis), drag of sea anchor (Y-axis) and movement of up and down (Z-axis) was measured for 30 seconds. Each value of X, Y, Z-axis was analyzed through t-test and ANOVA analysis to verify that each value had a significant difference according to the difference compositions. There was correlation between the movement of X-axis and Z-axis. The drag of sea anchor was stronger as the current speed increased. However, the larger the vent diameter, the weaker the drag. From the result of the standard deviation, the movement of X-axis was inversely proportional to the vent diameter. However, movement of Z-axis was larger as the weight of sinker was the heaviest or lightest from the result of the standard deviation. These results suggest that the sea anchor should be combined with proper size of the vent diameter and the weight of sinker to improve the stability.

Fisheries is known as a high-risk industry in Korea, and various efforts have been made to reduce occupational accidents. Trap fisheries represent crustacean production, accounting for 4.7% of total fisheries production and 10.7% of its production value, which is classified as a relatively high-risk industry. With the disaster insurance payment data of the National Federation of Fisheries Cooperatives (NFFC) from 2016 to 2020, the accident rate of the entire fishery, the accident rate of trap fisheries, and the type of disasters in the past five years were analyzed. As a result, the average fishery accident rate for the past five years was 5.31%, but it was high at 6.15% for coastal trap fisheries and 5.59% for offshore trap fisheries. Slips and trips, struck by objects and contact with machinery were the most common types of the accident according to the characteristics of the work, and hand injuries were analyzed the most. Additional efforts, including education for accident prevention, development of personal protective equipment and improvement of the working environment, are needed to prevent accidents caused by repeated types of disasters.

Fishery sea anchor is widely used for many fishing vessels. However, standardization of the dimension and terminology of the fishery sea anchor has not been achieved, reducing the reliability of the performance and safety of the fishery sea anchor. Therefore, this study researches the reality of usage of fishery sea anchor and then attempts to suggest the development direction of the standard draft as basic data. As a result of the survey on the reality of usage show that various terms were used for each part of the fishery sea anchor (including the incorrect form of non-standard words derived from Japanese) and that the production of this product in the fishery sea anchor market was concentrated on one specific manufacturer. In addition, the main specifications of the fishery sea anchor are set and manufactured based on conventional experience without standards. In the field, there was no standardized drawing for fishery sea anchor and users had low awareness of the main specifications of fishery sea anchor. Therefore, this study suggested the following regarding the fishery sea anchor: standard terms for each part including Korean and English names and standard drawing of sea anchor. It is hoped that this study will contribute to research for the standardization of fishery sea anchor, which will increase in reliability and lead to increased interest in standardization in the fishery field.

This study was performed as a part of serial experiments of applying convolutional neural network(CNN) in determining osteoporosis on panoramic radiograph. The purpose of this study was to investigate how sensitively CNN determine osteoporosis on cropped panoramic radiograph. Panoramic radiographs from 1268 female patients(mean age 45.2 ± 21.1 yrs) were selected for this study. For the osteoporosis group, 633(mean age 72.2 ± 8.5 yrs) were selected, while for the normal group 635(mean age 28.3 ± 7.0 yrs). AlexNet was utilized as CNN in this study. A multiple-column CNN was designed with two rectangular regions of interest on the mandible inferior area. An occluding method was used to analyze the sensitive area in determining osteoporosis on AlexNet. Testing of AlexNet showed accuracy of 99% in determining osteoporosis on panoramic radiographs. AlexNet was sensitive at the area of cortical and cancellous bone of the mandible inferior area including adjacent soft tissue.

Deep convolutional network is a deep learning approach to optimize image recognition. This study aimed to apply DCNN to the reading of mandibular cortical thinning in digital panoramic radiographs. Digital panoramic radiographs of 1,268 female dental patients (age 45.2 ± 21.1yrs) were used in the reading of the mandibular cortical bone by two maxillofacial radiologists. Among the subjects, 535 normal subject’s panoramic radiographs (age 28.6 ±7.4 yrs) and 533 those of osteoporosis pationts (age 72.1 ± 8.7 yrs) with mandibular cortical thinning were used for training DCNN. In the testing of mandibular cortical thinning, 100 panoramic radiographs of normal subjects (age 26.6 ± 4.5 yrs) and 100 mandibular cortical thinning (age 72.5 ± 7.2 yrs) were used. The sensitive area of DCNN to mandibular cortical thinning was investigated by occluding analysis. The readings of DCNN were compared by two maxillofacial radiologists. DCNN showed 97.5% accuracy, 96% sensitivity, and 99% specificity in reading mandibular cortical thinning. DCNN was sensitively responded on the cancellous and cortical bone of the mandibular inferior area. DCNN was effective in diagnosing mandibular cortical thinning.

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).

The breakdown of the Korea-Japan fishing negotiations since 2016 has made it impossible for many domestic fishing vessels to operate in the Japanese EEZ water, and large purse seine fishing vessels are one of them. Mackerel is a highly migratory fish species, circulating in the East China Sea, South Sea, West Sea and East Coast throughout the year, and goes through a period of wintering, spawning, growth and feeding migration. In this study, in order to find out the dependence of large purse seine fishing vessels on mackerel fishing in the Japanese EEZ waters, we analyzed the characteristics of mackerel by large purse seine fisheries in the Japanese EEZ waters from 2010 to 2016. The catch and fishing details were investigated. The total catch of mackerel by large purse seine fishery, the average catch rate of mackerel in Japanese EEZ is 4 percent per year. The amount is estimated at 10.2 billion won per year. Although there was an effect, it was not judged to be a significant factor, and it was found that the amount of catch and fish price in the domestic waters had a greater influence on the total catch than the Japanese EEZ waters.

Artificial intelligence, has been applied in interpreting osteoporosis on dental panoramic radiograph with high accuracy. The purpose of this study was to investigate the sensitive area of convolutional neural network(CNN), one of artificial intelligence, in interpreting osteoporosis on dental panoramic radiograph. Dental panoramic radiographs taken from 1,170 female (49.19 ±21.91 average age, 21 minimum age, and 84 maximum age) were selected for this study. Two oral maxillofacial radiologists agreed upon interpreting osteoporosis by interpreting mandibular inferior cortical changes. The region of interest included upper and lower jaws for training and testing CNN in interpreting osteoporosis. A filter which was set to look for image characteristics moved through the entire panoramic radiography to identify sensitive areas that distinguish normal groups and osteoporosis patients. In interpreting osteoporosis on panoramic radiograph, CNN responded sensitively at the cancellous bone of the upper and lower jaws while oral maxillofacial radiologists interpreted mandibular inferior cortical change.

According to the statistics of KMST (2010~2019), 68.5% of marine casualties have been occurred in fishing boats in the last 10 years. Although the incidence rate of annual average per ship is 10.4% for merchant ships and 2.3% for fishing boats, it is necessary to first reduce the marine casualties of fishing boats in order to reduce the occurrence of the whole marine casualty, considering that the number of registered fishing boats are 86.5% of the total. In this study, the top 10 fishing types with high occurring marine casualties in the past 10 years were selected using the statistics of KMST. Then, the causes of the marine casualties, focusing on the collision, were analyzed and counterplan were suggested. The biggest marine casualty that the top 10 fishing types have caused in the past 10 years was a collision, accounting for 71.7% of the total, and the rest were less than 10.0% each. Also, it was found that the biggest environment and cause of the collision were due to human factors such as poor look out or negligence of duty. Eventually, it was concluded that a reduction in the human factors for the causes basically, could lower the incidence of the marine casualties. Therefore, if the continuous and systematic correcting education of the attitude toward the ship operating of seafarers could conducted with the focus on the main human factors, the whole marine casualties will be expected to decrease gradually.

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.