• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1997.10a
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• pp.185-202
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• 1997

Hull forms of ancient ships in Korea and China have been changed according to their voyages and routes. Therefore it is necessary for shipbuilding engineers to reestablish the ancient shipbuilding history, and to presume, restore and revive the lost cultural inheritances. We, however, do not have many historical documents or credible materials that can our ancestors' great shipbuilding techniques : at the same time we do not have paid much attention to the research on such documents and materials. This paper aims not only to study and compare shifting process of ancient ship's hull forms in Korea and China by making use of verifiable materials obtained in the process of excavating and restoring Shinan ancient ship. The results of comparing structural characteristics and hull forms of ancient ships in Korea and China and as follwing : (1) Korean ancient ships have transverse beam instead of frame . Judged from the bottomform, Korean ancient ships are grooved clinker type ships of flat bottom type, in which bottom planking is fixed by wooden bar. (2) Chinese ancient ships have transverse bulkhead structure instead of frame, Judged from the bottom form , Chinese ancient ships are rabetted clinker type ships of V-bottom type with a bar keel. The form , the position, and the size of a sail are closely related with the wind force. It is not only quite difficult to presume forms and sizes of ancient ships' sails precisely, but also impossible to come to an accurate conclusion wihtout much experience. Current 10-year-statistics of the wind force are used to obtain presumed routes of ancient ships in Korea and China. Conclusions obtained from the hull form , sail form and size , and mast height of Shinan ancient ship will provide credible data for sea trade routes and transformation capability, and wil be used for effective materials on the study of the shifting process of ancient ships in Korea and China.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.41-46
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• 2006

This paper describes a marine watch system on a ship, which is aided by an image processing method. The system detects other ships through a navigational image sequence to prevent oversights, and it measures their bearings to maintain their movements. The proposed method is described, the detection techniques and measurement of bearings techniques are derived, and the results have been reported. The image is divided into small regions on the basis of the brightness value and then labeled. Each region is considered as a template. A template is assumed to be a ship. Then, the template is compared with frames in the original image after a selected time. A moving vector of the regions is calculated using an Excel table. Ships are detected using the characteristics of the moving vector. The video camera captures 30 frames per second. We segmented one frame into approximately 5000 regions; from these, approximately 100 regions are presumed to be ships and considered to be templates. Each template was compared with frames captured at 0.33 s or 0.66 s. In order to improve the accuracy, this interval was changed on the basis of the magnification of the video camera. Ships’ bearings also need to be determined. The proposed method can measure the ships’ bearings on the basis of three parameters: (1) the course of the own ship, (2) arrangement between the camera and hull, and (3) coordinates of the ships detected from the image. The course of the own ship can be obtained by using a gyrocompass. The camera axis is calibrated along a particular direction using a stable position on a bridge. The field of view of the video camera is measured from the size of a known structure on the hull in the image. Thus, ships’ bearings can be calculated using these parameters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2189-2196
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• 2015

According to increase environmental pollutions and fuel costs, The study of energy saving in the ship is proceeding actively. PCS is pump control system for cooling system in the ship to improve the energy efficiency by controling rotation speed of sea water pump, fresh water pump and position of 3way valve. In this paper, we develop the PCS simulator that has an environment similar to the cooling system of the actual vessel to ensure reliability of the PCS. Also, PC-based control and data storage system for PCS simulator is developed. To develop this system, National Instrument's cDAQ and LabVIEW are used. Finally, confirm the behavior of the simulator by analyzing the saving data.

• Journal of Navigation and Port Research
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• v.26 no.3
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• pp.261-268
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• 2002

At recently, Oil spill accident of large size oiler that happen domestic and outside the country is occured to social impact us as well as economical damage in sea environment. Also, because spread extent of pollution accident is reaching harbor, bay and close water areas, as necessity that traffic control ships are sea place. VTS is changing to concept that control space is magnified gradually. Our country is operated to 14 harbors which is control center. But abroad is operating coastal VTS that do main waterway and coastals to authority dimension. Therefore, necessity that traffic density of ship manages high coastals and ship traffic of waterway to our country is risen. This paper is execute sea traffic survey at Mokop sea areas and sea casualty occurs. It proposal that coastal VTS center field of most suitable and position of radar site.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2489-2496
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• 2014

The existing ship repair tool management system based on hand writing has many problems such as frequent loss of tool and overdue. To solve this problem, same systems have adopted the bar-code system. However, the systems can't cope with a problem to substitute spurious tool for genuine one on bar-code damage. Therefore, additional validation steps are necessary in order to manage expensive ship repair tool. In this paper, we propose an image comparison method for ship repair tool management. To be more concrete, we propose a normalization method and determination conditions for image comparison to use characteristics of mobile device. The normalization method makes use of the characteristics of mobile device that provides functions of real time recording, overlapping and cropping images. The proposed method applies three conditions(sum of inner angles, size of angle, position of corner coordinates) into the comparison module. The implemented system shows good performance on change direction, lighting, size and etc. The accuracy is more than 95%.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.22-26
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• 2013

The purpose of this study was to improve the design of a mooring line by attaching a lumped mass to it on the seabed. A numerical analysis of the redesigned mooring system is performed to analyze the effect of the weight of the attached lumped mass using the commercial software Orcaflex. The ultimate tension of the mooring system with the lumped mass is compared with that of a bare mooring line in the original design. An appropriately designed weight for the lumped mass is found to induce a critical lifted point in the mooring line by floater motion in the ultimate condition to move toward the floater position from the anchor point, while maintaining a similar safety factor for the mooring line. On the other hand, it is shown that excess weight for the lumped mass induces snapping in a mooring line, resulting in low safety factor for the mooring system. The distance between lumped weights is shown to be a minor parameter affecting the safety of a mooring line, although a shorter line has an advantage from an economic point of view. Using the optimal weight for the lumped mass attached to the mooring line on a seabed reduces the mooring line length and installation area occupied by a mooring system under real sea conditions.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.47-53
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• 2001

When a ship advancing in waves is subjected to impact forces or irregular forces, the motion analyses for ship are convenient for being calculated in the time domain. The added mass, wave damping coefficients, wave exciting forces and mean drift forces are calculated by 3-Dimensional panel method used the translating pulsating Green function in the frequency domain and the motion equations which are considered by the memory effect due to waves are numerically solved by using the Newmark-$\beta$ method in the time domain. The motion analyses are carried out for a Series 60($C_B=0.7$) moving in irregular waves. The items of calculation are 6-degree motions, accelerations at the fore and after position, numbers of deck wetness and numbers of exposure at ship-bottom, etc. Moreover, the thrust addition in waves is examined by considering the time mean drift forces in the motion equations of time domain.

• Journal of Ocean Engineering and Technology
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• v.33 no.3
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• pp.222-228
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• 2019

An extreme value analysis (EVA) is essential to obtain a design value for highly nonlinear variables such as long-term environmental data for wind and waves, and slamming or sloshing impact pressures. According to the extreme value theory (EVT), the extreme value distribution is derived by multiplying the initial cumulative distribution functions for independent and identically distributed (IID) random variables. However, in the position mooring of DNVGL, the sampled global maxima of the mooring line tension are assumed to be IID stochastic variables without checking their independence. The ITTC Recommended Procedures and Guidelines for Sloshing Model Tests never deal with the independence of the sampling data. Hence, a design value estimated without the IID check would be under- or over-estimated because of considering observations far away from a Weibull or generalized Pareto distribution (GPD) as outliers. In this study, the IID sampling data are first checked in an EVA. With no IID random variables, an automatic resampling scheme is recommended using the block maxima approach for a generalized extreme value (GEV) distribution and peaks-over-threshold (POT) approach for a GPD. A partial autocorrelation function (PACF) is used to check the IID variables. In this study, only one 5 h sample of sloshing test results was used for a feasibility study of the resampling IID variables approach. Based on this study, the resampling IID variables may reduce the number of outliers, and the statistically more appropriate design value could be achieved with independent samples.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.3
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• pp.155-164
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• 2023

About 75% of vessel collision accidents are caused by human error, which causes enormous economic loss, environmental pollution, and human casualties, thus research on automatic collision avoidance of vessels is being actively conducted. In addition, vessels must comply with the COLREGs rules stipulated by IMO when performing collision avoidance with other vessels in motion. In this study, the collision risk was calculated by estimating the position and velocity of other vessels through the Probabilistic Data Association Filter (PDAF) algorithm based on RADAR sensor data. When a collision risk is detected, we propose an event-triggered Nonlinear Model Predict Control (NMPC) algorithm that geometrically creates waypoints that satisfy COLREGs and follows them. To verify the proposed algorithm, simulations through MATLAB are performed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.18-20
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• 2021

In order to prevent collision accidents of ships, which has been increasing recently, research on artificial intelligence-based autonomously operated ships (Maritime Autonomous Surface Ship, MASS) is underway. However, most of the studies related to autonomous ships mainly target medium-to-large ships due to the size and cost of the autonomous navigation system, and the sensors used here have a problem in that it is difficult to mount them on small ships. Therefore, this paper provides a path tracking system equipped with GPS and IMU sensors for autonomous operation of small ships. GPS and IMU sensors are utilized to determine the exact position of the vessel, which allows the proposed system to manually control the small vessel model to create a path and then when the small vessel travels the same path. Use the Pure Pursuit algorithm to follow the path. As a result, In this research, it is expected that a lightweight and low-cost sensor can be used to develop an autonomous operation system for small ships at low cost.