• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.667-679
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• 2022

Fatigue damage analysis of ships includes parameters considering operational factors. Due to these operational variables, there is a difference between the fatigue damage estimated during the design stage and the actual accumulated fatigue damage. Likewise, there are various loading conditions for the real container ships, but at design stage the fatigue damage is calculated by applying the representative loading conditions. Moreover, although the difference in fatigue damages is expected when the actual and design loading conditions are applied, there are few studies on the contributions of the fatigue damage based on the loading conditions of container ships. In this paper, fatigue contributions were investigated from various cargo weight distributions. The hull girder loads calculated through seakeeping analysis and fatigue damages obtained by performing spectral fatigue analysis were identified under new loading conditions. As a result, it was found that the variation of cargo weight distribution in the container ship brought about changes in the hull girder loads and fatigue damage by affecting the hull girder stress.

• Journal of Navigation and Port Research
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• v.46 no.3
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• pp.203-208
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• 2022

Recently, various digital technology issues such as e-Navigation, Maritime Autonomous Surface Ship (MASS) and Smart ships have constantly emerged in the maritime industry, based on the fourth industrial revolution. The International Maritime Organization is gradually tightening regulations for marine safety and marine environmental protection, and these strengthened regulations are leading to new maritime industries. Thus, the purpose of this study was to design a suitable model to analyze the industrial competitiveness of domestic autonomous operation technology industry, based on the Porter's diamond model. Based on a total of five evaluation factors and 13 detailed factors, the industrial competitiveness of the domestic autonomous operation technology industry was evaluated qualitatively and quantitatively. This industry, which is in the early stage of industrial development, was evaluated as 16.9 points relative to indexing industrial competitiveness. Currently, it is characterized by the simultaneous development of related regulations and core technologies, from the establishment of the scope of the industry. The industrial competitiveness evaluation considering these industrial characteristics is expected to serve as the basis for strategic support and new industrial policy, and impact a wide range of related industries such as shipping, logistics, ports, and shipbuilding and equipment industries.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.567-576
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• 2022

Seafarers are exposed to various unpredictable maritime risks due to the spatial specificity of the working environment of the sea; thus, sufficient compensation for injured crewmembers is needed. However, Korea does not provide such compensation. Therefore, this study attempted to examine the Maritime Labor Act and the Industrial Accident Insurance Act of Germany, an advanced European social insurance country, and derive implications compared to Korea. First, we investigated how compensations are managed by a public institution in Germany and by shipowners in Korea. Second, regarding the contents of accident compensation, Germany does not only provide continuous treatment and care through various support systems, but also operates various programs to enable a return to ship work. In contrast, Korea has a temporary compensation system that allows shipowners to avoid liability for accident compensation, which is disadvantageous to shipwrecked seafarers. Finally, in Germany, workers' compensation insurance is public, judged considering the origin of work, whereas in Korea, it is determined by shipowners or insurance companies. Therefore, it is necessary to establish a public institution in charge of crew accident compensation to ensure proper compensation for crewmembers in Korea and to improve the Seafarers Act or system to provide compensation for additional medical care, disability pension, and rehabilitation benefits.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1038-1043
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• 2021

Guaranteed seafarer wage payment is essential to ensure a stable supply of seafarers. However, disputes over non-payment of wages to seafarers often occur. In this study, an automatic wage payment system was designed using a blockchain-based smart contract to resolve the problem of seafarers' wage arrears. The designed system consists of an information register, a matching processing unit, a review rating management unit, and wage remittance before deploying smart contracts. The matching process was designed to send an automatic notification to seafarers and shipowners if the sum of the weight of the four variables, namely wages, ship type/fishery, position, and license, exceeded a pre-defined threshold. In addition, a review rating management system, based on a combination of mean and median, was presented to serve as a medium to mutually fulfill the normal working conditions. The smart contract automatically fulfills the labor contract between the parties without an intermediary. This system will naturally resolve problems such as fraudulent advance payment to seafarers, embezzlement by unregistered employment agencies, overdue wages, and forgery of seafarers' books. If this system design is commercialized and institutionally activated, it is expected that stable wages will be guaranteed to seafarers, and in turn, the difficulties in human resources supply will be solved. We plan to test it in a local environment for further developing this system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.773-779
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• 2022

Deep-sea fisheries in Korea play an essential role in supplying popular seafood and providing food security. Countries, as well as the IMO (International Maritime Organization), have attempted to establish an internationally harmonized safety standard for fishing vessels. However, starting with the adoption of 'The Torremolinos International Convention for the Safety of Fishing Vessel 1977', the '2012 Cape Town Agreement' was adopted, but the requirements for enforcement were not met. However, with the 2019 Torremolinos Declaration, the effect of the agreement became visible. Korea is also about to ratify the agreement, and deep-sea fishing vessels are subject to the agreement. The length of the hull or the gross tonnage can be selected as the criteria for applying the 2012 Cape Town Agreement, and this is also partially applied to the existing vessels. Analyzing 188 deep-sea fishing vessels registered as members of the Korea Overseas Fisheries Association to confirm the effect on the existing vessels showed that the application of gross tonnage had little impact on the ratification of the agreement. In addition, laws must be revised for the compulsorization of GMDSS facilities such as two-way VHF and radar transponders and for the safety familiarization of fishermen. In the industry, the facilities required by the agreement must be provided, and the fishermen must be familiarized with safety.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1267-1273
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• 2022

Although the Korea shipbuilding industry has recently been receiving most of the orders for ships in the world, production processes are being disrupted due to a shortage of manpower at the production site. This is because the workers quit the shipyard as both work and wages were reduced due to the long slump in the shipbuilding industry. The main reason for the increase in orders was the large-scale orders for Qatar LNG carriers, and the situation in which the technical specifications required for ships are becoming more complex is also working to an advantage. Because the contract delivery time is of utmost importance for ships, the dock launch plan is the most important management item among the shipyard's major processes. The structure to be built in the dock may be a hull that has left the design work or a finished vessel, and in some cases, it is often at the level of some blocks of the hull. When launching, the hull is affected by the hogging or sagging moment due to the fluid force, and securing the safety of the structural strength of the block connection is of utmost importance. In a normal process, the connecting member launches after welding has been completed, but in actual shipbuilders, quick decision-making is needed on the conditions for securing structural safety to comply with the docking schedule. In this study, a detailed analysis method and applicability using a bending stress evaluation method and finite element analysis modelling were analyzed to rationally judge the above-mentioned problems from an engineering point of view. The main contents mentioned in the thesis can be used as good examples when conducting similar structural strength evaluations in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1259-1266
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• 2022

Recently, due to the specialization of structural design standards and evaluation methods, the classification rules are being integrated. A good example is the common international rules (CSR). However, detailed regulations are presented only for the cargo hold area where the longitudinal load is greatly applied, and no specific evaluation guidelines exist for the bow and stern structures. Structural design of the mentioned area is carried out depending on the design experience of the shipbuilder, and because no clear standard exists even in the classification, determining the root cause is difficult even if a structural damage problem occurs. In this study, an engineering-based solution was presented to identify the root cause of representative cases of buckling damage that occurs mainly in the stern. Buckling may occur at the panel wall owing to hull girder bending moment acting on the stern structure, and the plate thickness must be increased or vertical stiffeners must be added to increase the buckling rigidity. For structural strength verification based on finite element analysis modeling, reasonable solutions for load conditions, boundary conditions, modeling methods, and evaluation criteria were presented. This result is expected to be helpful in examining the structural strength of the stern part of similar carriers in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.230-237
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• 2023

Due to the COVID-19 pandemic and climate change, shortages of essential commodities and resources continue to occur globally. To address this problem, trade volume demand suddenly increased, driving up the freight rate of container ships sharply. The size of container vessels progressively increased from 1,500 TEU (twenty-foot equivalent unit) in the 1960s to 24,400 TEU in 2021. As the improvement of container loading capacity is closely related to the enlargement of the lashing bridge structure, it is necessary to design a structure effective for good container securing and safe under the various external loads that occur during voyage. Major classification societies have recently issued structural-analysis-based guidelines to evaluate the structural safety of lashing bridges, but their acceptance criteria and evaluation methods are different, causing confusion among engineers during design. In this study, the strength change characteristics are summarized by variations in the main variables (modeling range, opening consideration, mesh size) likely to affect the results. Based on this result, the authors propose a reasonable structural-analysis-based evaluation that is expected to serve as a reference in the next revision of classification standards.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.139-146
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• 2023

Maritime object detection systems, which detects small maritime obstacles such as fish farm buoys and visualizes distance and direction, is equipped with a 3-axis gimbal to compensate for errors caused by hull motion, but there is a limit to distance error corrections necessitated by the vertical movement of the camera and the maritime object due to wave motions. Therefore, in this study, the distance error of maritime object detection systems caused by the movement of the water surface according to the external environment is analyzed and corrected using average filter and moving average filter. Random numbers following a Gaussian standard normal distribution were added to or subtracted from the image coordinates to reproduce the rise or fall of the buoy under irregular waves. The distance calculated according to the change of image coordinates, the predicted distance through the average filter and the moving average filter, and the actual distance measured by laser distance meter were compared. In phases 1 and 2, the error rate increased to a maximum of 98.5% due to the changes of image coordinates due to irregular waves, but the error rate decreased to 16.3% with the moving average filter. This error correction capability was better than with the average filter, but there was a limit due to failure to respond to the distance change. Therefore, it is considered that use of the moving average filter to correct the distance error of the maritime object detection system will enhance responses to the real-time distance change and greatly improve the error rate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.338-347
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• 2023

Jinhae Bay, characterized by frequent runaway ships and strong winds during typhoon attacks, poses a high risk of maritime accidents such as ship collisions and groundings. This study aims to determine a safe separation distance between ships in the Jinhae Bay anchorage, considering the unique environmental characteristics of the Korean sea area. Analysis revealed that an average of 100-200 ships anchor in the typhoon avoidance area in Jinhae Bay during typhoon attacks, with approximately 70% of ships experiencing anchor dragging owing to strong external forces exceeding 25 m/s wind speeds. In this study, we analyzed and presented the separation distances between ships during anchoring operations based on domestic and international design standards, separation distances between ships used as actual typhoon shelters in Jinhae Bay, and appropriate safe distances for ships drifting under strong external forces. The analysis indicated that considering the minimum criteria based on the design standards and emergency response time, a minimum safe distance of approximately 400-900 m was required. In cases where ample space was available, the separation distance was recommended to be set between 700 to 900 m. The findings of this study are anticipated to contribute to the development of guidelines for establishing safe separation distances between ships seeking refuge from typhoons in Jinhae Bay in the future.