• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.95-100
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• 2006

A ship collision avoidance system is developed to control the avoidance action of ship actually and properly in wind forces. The 4-DOF maneuvering equations of motion ar derived to catty out the simulation of the motion of a ship, and the wind forces are considered as the external forces in the simulation. This study suggests a new avoidance system that could include the ship's maneuvering characteristics.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.1
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• pp.24-33
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• 2004

Recently, ship acoustics takes more important role in acoustic stealth and classification of underwater targets. In this paper, a theoretical concept is proposed for M＆S-based test and evaluation of ship acoustics. The concept is based on two different approaches: on Top-Down method which emphasizes the survivability of the ship and on Bottom-Up method which considers acoustic characteristics of the ship-equipments. In order to improve the effectiveness of M＆S-based T＆E for ship acoustics, it is recommended in this paper to compromise the two approaches as adequate.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.2
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• pp.59-66
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• 2020

This paper is the result of a study conducted in the ship concept design stage on the concept of system integration of the submarine rescue systems to be mounted and operated on the next submarine rescue ship (ASR-II Batch II) of the Korean Navy. In this paper, the concept of realization of naval ship system integration is considered, the operational concept of the next submarine rescue ship is analyzed, the requirements of the rescue operation system were analyzed, and the conceptual architecture (draft) of the rescue operation system was designed and proposed to meet the naval ship system integration policy.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.164-170
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• 2013

With the introduction of increasingly large-sized ships, the conditions of main domestic port facilities remain the same as in the past. So, there is high probability that marine traffic congestion can occur at the certain ship's routes. The standard ship's length used to assess the marine traffic congestion of domestic trade port is 70 meters. It has been in use for the last 30 years, so, its usefulness is highly recommended for review. This study deeply analyzes the tendency of ship's dimensional changes according to recent enlargement of ship's size by utilizing the particulars of 60,000 ships saved in domestic Port-MIS database and suggests the standard ship's length by figuring out the correlation between length of ship and gross tonnage. In addition, the basis of statistical data on the ship's tonnage in domestic trade over the last five years suggests the standard ship's length by deriving the reference point of cumulative incidences that occupy more than over 50 %, except for small vessels. It is necessary to consider the characteristic of each domestic trade port before the actual application of suggested standard ship's length.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2235-2242
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• 2016

The electric power system based on fuel cell is applied in various forms to the ship and offshore plants. In particular, a research on the hybrid power system of the fuel cell combined with battery in connection topology has been researched actively. Fuel cell-based hybrid ship has not been carried out research, it is not carried out research in the integrated monitoring system. In this paper, we developed an integrated monitoring system to increase the convenience and stability for the hybrid fuel-cell ship operator. Research into integrated monitoring system based on GUI (Graphic User Interface), in consideration of the stability of the user convenience and ship operations, and developed communication and hardwired signal with the main equipment of the ship, to see in realtime state of the ship. The collected ship operation data is stored and it can be seen after the ship operating.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.641-649
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• 2021

Fuel oil consumption (FOC) must be minimized to determine the economic route of a ship; hence, the ship power must be predicted prior to route planning. For this purpose, a numerical method using test results of a model has been widely used. However, predicting ship power using this method is challenging owing to the uncertainty of the model test. An onboard test should be conducted to solve this problem; however, it requires considerable resources and time. Therefore, in this study, a deep feed-forward neural network (DFN) is used to predict ship power using deep learning methods that involve data pattern recognition. To use data in the DFN, the input data and a label (output of prediction) should be configured. In this study, the input data are configured using ocean environmental data (wave height, wave period, wave direction, wind speed, wind direction, and sea surface temperature) and the ship's operational data (draft, speed, and heading). The ship power is selected as the label. In addition, various treatments have been used to improve the prediction accuracy. First, ocean environmental data related to wind and waves are preprocessed using values relative to the ship's velocity. Second, the structure of the DFN is changed based on the characteristics of the input data. Third, the prediction accuracy is analyzed using a combination comprising five hyperparameters (number of hidden layers, number of hidden nodes, learning rate, dropout, and gradient optimizer). Finally, k-means clustering is performed to analyze the effect of the sea state and ship operational status by categorizing it into several models. The performances of various prediction models are compared and analyzed using the DFN in this study.

• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.75-84
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• 2023

Ships need to ensure safety during their navigation, which makes route determination highly important. It must be accompanied by a route following controller that can accurately follow the route. This study proposes a method for automatically generating the ship route based on deep reinforcement learning algorithm and following it using a route following controller. To generate a ship route, under keel clearance was applied to secure the ship's safety and navigation chart information was used to apply ship navigation related regulations. For the experiment, a target ship with a draft of 8.23 m was designated. The target route in this study was to depart from Busan port and arrive at the pilot boarding place of the Ulsan port. As a route following controller, a velocity type fuzzy P ID controller that could compensate for the limitation of a linear controller was applied. As a result of using the deep Q network, a route with a total distance of 62.22 km and 81 waypoints was generated. To simplify the route, the Douglas-Peucker algorithm was introduced to reduce the total distance to 55.67 m and the number of way points to 3. After that, an experiment was conducted to follow the path generated by the target ship. Experiment results revealed that the velocity type fuzzy P ID controller had less overshoot and fast settling time. In addition, it had the advantage of reducing the energy loss of the ship because the change in rudder angle was smooth. This study can be used as a basic study of route automatic generation. It suggests a method of combining ship route generation with the route following control.

• Journal of Navigation and Port Research
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• v.37 no.1
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• pp.63-69
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• 2013

Since most merchant vessels are mainly influenced by the added resistance in an actual sea, they could be navigated more efficiently if this added resistance could be precisely predicted and then effectively reduced. In this paper, we have computed the effective horsepower based on the resistance performance in still water and then calculated the added resistance in regular wave in order to estimate a ship's propulsion performance on a voyage. Firstly, we have performed experiments using a model of KCS in a circulating water channel to estimate the flow characteristics around a container ship and the ship's resistance in still water. Then we have calculated the motion response function in regular wave as well as the values for the increase in resistance, and evaluated the ship's motion performance in waves according to the calculated response function. It was found that the resistance in waves increased because the ship's motion response value became larger as the ship's speed increased in the case of head sea. The effect of the added resistance could be reduced by maneuvering the ship to the encounter angle of $120^{\circ}$ in areas of long wavelengths and to head sea in areas of short wavelengths.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.1
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• pp.55-63
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• 2022

A stranded ship means a ship which is stuck on a rock or a seabed, and cannot move by itself. The lightening plan is required to refloat the stranded ship. For this, we have to understand the forces and moments acting on the ship, which is composed of the gravity, buoyancy, and reaction force due to the touched area below the ship. This study defines those forces and moments, and proposed the calculation method to find the posture based on the static equilibrium. It is divided by two steps. In the first step, the magnitude and position of the reaction force are obtained based on the known information such as initial trim angle and draft of the ship. In the second step, the reaction force and the posture is calculated due to the three cases such as addition, reduction, and movement of the cargo. It is applied to three examples in order to calculate the reaction force, and the trim angle due to changes of the cargo. As a results, we successfully obtain the magnitudes and positions of forces acting on the stranded ship and to check the posture of the stranded ship.

• Journal of the Korean Institute of Navigation
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• v.1 no.1
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• pp.27-44
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• 1977

The Maneuvering Indices of a ship are the values that decide the quantity of her motion in turning when her rudder is turned over to an angle to the starboard or the port. They consist of two kinds of indices, one of which is called index K and the other, index T. Index K decides a ship's turning ability and index T does the length of time delay of a normal turning motion after her rudder has finished the turn of an ordered angle. Generally, the values of the indices are calculated through some mathematic formulas with figures of her heading degrees recorded at a fixed time intervals during her Z test. The values of the same kind index of a ship appear differently according to the ship'sspeed, trim, rudder angle and loaded condition, etc. In this paper, the author analyzed all the amthematic formulas required to calculate the values of the indices in their forming process and examined them from the point of mathematics and dynamics and also actually figured out the values of maneuvering indices of the M.S. "HANBADA", the training ship of Korea Merchant Marine College through her Z test. The author supposed a case in which two same typed ships as the "HANBADA" in size, shape and conditions were approaching each other in meeting end on situation and each ship turned her rudder hard over to the starboard respectively when they approached to the distance of 3 times as long as the ship's length. The author worked out mathematic formulas calculating forward and transverse ship's motions within the above mentioned situation for the quantative analysis of the collision avoding action to certify whether they are in collision status or not. Applying the calculated values of the maneuvering indices of the "HANBADA" to the motion calculating formulas, the author found out the two ships were passing over each other with the clearing distance o 39m between their port quarters. With the above mentioned examinations and explanations, the author demonstrated that a ship's motion in any collision avoiding action can be shown with quantities of time and distance within reliable limit.istance within reliable limit.