• Journal of the Korean Society of Marine Environment & Safety
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• 제24권6호
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• pp.810-817
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• 2018

In Korea, tuna purse seine fishery is the industry with the highest production volume in domestic deep-sea fishery. Research has been continuously carried out since the late 1980s, and research on modernization of technology has been actively conducted. However, while auxiliary works boats on the fishing vessels play an important role in the purse seine fishing, related research is not sufficient. In this study, we tried to rebuild the propulsion system of the Net-boat from the propeller to the waterjet type and to perform the hull form conversion to improve the resistance performance of the hull part and improve the motion performance. For this, we calculated the change of the fluid performance of the ship through computational numerical analysis. In addition, towing tank tests were carried out to verify the performance of the existing ship and the ship which changed the propulsion system. As a result, resistance performance of the waterjet type compared to the propeller type was improved by approximately 45 %. It was confirmed that this was due to reduction of the wetted surface area by removing net and improvements in hull form.

• Journal of the Korean Society of Marine Environment & Safety
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• 제20권4호
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• pp.412-418
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• 2014

In this paper, for better boarding performance and pleasant boarding sensitivity of the ship, comparison and analysis was performed of motion sickness questionnaire with MSI(Motion Sickness Incidence) calculation based on ship motion theory(Strip Method) due to sea condition, incident angle in main sail way, economic speed, and calculation position of the training ship Kaya of Pukyong National University. On theses works, the rougher sea conditions became, the higher total motion sickness rate was occurred. The weights of vertical acceleration and the rates of MSI were higher at the bridge and the accommodation, which were located farther from the center of gravity of the ship. And effects of the vertical acceleration of the ship were increased in rolling then in head sea. In comparison between motion sickness questionnaire with MSI calculation, when the vertical acceleration increased, the motion sickness rate increased. The location to increase vertical acceleration and the location to cause motion sickness were agreed.

• Journal of the Korean Society of Marine Environment & Safety
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• 제20권5호
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• pp.543-551
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• 2014

This study has searched to find a program in order to manage simply and practically use the expelled AtoN database from the AtoN Simulator and to support the idea decision for the AtoN placement. It examines a program that manages AtoN database through the hierarchy structure, history card and endowment with condition same as a scenario. And accomplishes this study's goal owing to realizing AtoN operational software that helps for visual, hearing sense, fixed amount verification upon AtoN placement project. The AtoN operational software contributes not only flexible control like a newly establishment, relocation etc, but also supports idea decision for AtoN placement plan through many functions such as condition search, virtual sailing and fixed amount appraisal result exhibition, etc. Through utilization of this, it is to help upon the presupposition of the impact to ship or sailor about many designs and in addition, upon the judgment of whether or not for the efficiency and appropriation of the design. It is expected to reduce possible failure costs and management costs due to AtoN design and placement plans, because to compare more various designs thru the easier verification method.

• Journal of the Korean Society of Marine Environment & Safety
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• 제29권2호
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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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• 제30권5호
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• pp.506-515
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• 2024

Owing to the interaction between a ship and the river bed, several phenomena resulting in increased resistance may have occurred. This increase in resistance is primarily due to the wave-making performance. Thus, this study aims to reduce the wave-making resistance by optimizing the performance of an electric canal cruise through changing the longitudinal center of gravity (LCG). Numerical simulations are performed to obtain the lowest resistance by optimizing the LCG position; subsequently, the ef ect of water depth is included as the next variable. Results show that LCG variations of 37.5%-52.5% Lpp can result in a wide range of total resistance. In deep water, a 72.67% resistance gap is achieved by comparing the highest and lowest resistances, whereas a slightly lower gap of up to 62.97% is achieved in shallow water. Additionally, smaller water depths correspond to higher resistance. The resistance increased by a maximum of 67.68% in shallow water measuring 1.5 m, as compared with the case of deep water. This increase in resistance is primarily due to wave-making resistance, which constitutes 84.99% of the total resistance.

• Journal of Navigation and Port Research
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• 제48권4호
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• pp.267-273
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• 2024

Bridge lanterns are installed on bridges or piers to signal the presence of these structures on navigational routes and navigable waters, and they fall under the category of light wave signals in Aids to Navigation. In Korea, medium to large bridges installed over major rivers and seas are equipped with bridge lanterns, which are necessary for routes frequented by ships and require periodic inspections on a monthly or multi-month basis. However, most bridge lanterns are mounted externally on bridge railings as fixed or manual rotary supports, posing a high risk of fatal falls during inspections. Furthermore, high -traffic bridges demand quick maintenance works due to complaints about traffic disruption, thus increasing work hazards. Consequently, this study introduced a tailored automatic bridge lantern support concept based on different types of bridge lantern installations, aiming for safe and rapid inspections. Additionally, the study sought to achieve full automation of the bridge lighting system by integrating it with a management program for monitoring and controlling bridge lanterns, utilizing both wired and wireless communication technologies. These findings provide foundational design data for new and refurbished bridges that will be installed in the future.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제39C권7호
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• pp.582-588
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• 2014

IMO and IALA have undertaken projects that GMDSS Modernization and E-navigation, which refer to "Future digital communications systems" for a more efficient transmission of voice and data communications in the VHF maritime mobile service. ITU has also resolved in WRC-07 Resolution 357 to study the use of spectrum-efficient technologies in order to provide for the operation of ship and port security and maritime safety systems. IALA and ITU WP5B have coordinated for the technical developments and the spectrum issues. Recommendation ITU-R M.1842-1 has approved by WP5B meeting. This revision provides a wideband data service both 50kHz and 100kHz in the VHF maritime mobile service. This paper has studied E-navigation, its needs for data exchange that includes explanations of the current methods for transmitting data by VHF that based in land mobile radio service. A further technologies trend is estimated for Recommendation ITU-R M.1842-1, that is based on the land mobile radio standards with some tailored to fit the needs of the maritime mobile service.

• Journal of the Korean Society for Marine Environment & Energy
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• 제4권2호
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• pp.43-51
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• 2001

Now our ocean environment pollution is very serious. Its harm hinders in marine breeding and the safe navigation of ships at the coast. We have used an assembly system for a measure taken against environment pollution like this. But, here are some problems awaiting solution. First, most of combustible materials among ocean waste are high polymer, so it is necessary some special equipment to incinerate them. In the process we can't overlook air pollution by exhaust gas. Also, when we reclaim these wastes, we remember that they can't be decomposed naturally and leaking water may pollute soil. Thus now a days new treatment method has been developed, it recycles and doesn't product secondary pollution materials by recovering oil from pyrolysis. For it, this study investigated chemicalㆍphysical properties of wastes. And it found condition of recovering the most oil. Also it probed that the variation of temperature raising speed affects the weight reduction characteristics of wastes. Also, while studying recovered oil by waste pyrolysis and the rate of non-condensing gas in accordance with the variation of temperature raising speed. Finally we had confidence the development of pyrolysis oil recovery would succeed because we carried out evaluation at an economic point of view about it.