• Journal of Navigation and Port Research
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• v.33 no.10
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• pp.723-734
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• 2009

Container Vessel is becoming larger and faster thanks to the rapid growth of global trade and development of technology. Therefore, 15,000TEU vessel is expected to be ordered in near future. Every nations in north-east Asia are facing strong competition to be logistics hub to get the initiatives of logistics in response to the rapid change of logistics environment. According to the globalization of economy and major ports in this region also are trying to catch big shipping line for their survival. Considering above circumstances of the advent of ultra-large container vessel and spoke-and-hub strategy, it is inevitably necessary to make a fast and accurate vessel job in the terminal in order to be a leading port To meet this objective, current vessel planning system has to be improved innovatively. Therefore, this thesis propose multi distributed vessel planning system which enables multi loading/discharging planning with several planner simultaneously for faster and more accurate than existing planning and enhances quality of planning through information sharing among planners. Also this thesis uses simulation through Arena to verify the efficiency of this multi-distributed vessel planning system.

• Fire Science and Engineering
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• v.20 no.2 s.62
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• pp.44-53
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• 2006

We have conducted a numerical simulation under two-dimensional unsteady conditions in order to analyze the effect according to the injection angle and velocity of the $CO_2$ agent nozzle which is one of the elements for the fixed type $CO_2$ fire extinguishing system installed in a ship on the characteristics of flow and $CO_2$ concentration distribution. The flow fields and concentration fields were measured and analyzed. We can found that the difference of flow patterns according to the conditions of $CO_2$ agent injection nozzle, and in all the conditions of $CO_2$ agent injection nozzle, the iso-concentration line was expanded from the region at which vortex was generated to the surroundings. We can expected that the intensity of the wall jet on the bottom floor was generated differently and the iso-concentration lines were expanded or shrunk according to the angle of $CO_2$ agent injection nozzle. In case of increasing $CO_2$ agent injection velocity maintaining the flow quantity of the $CO_2$ agent injection equally, the iso-concentration line of $CO_2$ agent on bottom floor can be formed more higher than in case of decreasing $CO_2$ agent injection velocity.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.2
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• pp.323-335
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• 2016

The main reason of marine casualties is the human error in respect of ship's operation. The human error of officers in charge of a navigational watch is related to their abilities to handle of navigational equipment. Navigational devices play a key role to help officers decide what to do for safe navigation. Thus, the abilities to handle of navigational equipment mean not only operation of devices but also entire understanding of the system such as interpretation of information obtained from devices, appropriate use of information considering navigational circumstance. Qualification of seafarers is in accordance with STCW and detailed training courses for their qualification are provided by IMO model course series. Recently, ships engaged on international voyages shall be fitted with an ECDIS not later than the first survey on or after 1 July 2018. As increasing use of ECDIS on ships, marine casualties related to ECDIS are on the rise. The primary causes of the accidents are lacking understanding of ECDIS system, wrong presentation of information on display, wrong safety setting by seafarers who use ECDIS, using small-scale chart and missing charts update. As a result of these primary causes, some problems like wrong route planning and use of limited or omitted information occur. It could be happening by inappropriate seafarers' training which is not sufficient to support improving abilities of officers to handle navigational equipment. For efficient training, it is need to develop training courses. Applying full mission simulation system to seafarers' training courses with case studies and best practices which are well-constructed scenarios based on true marine casualties can increase the effect of training. To use the simulation system, it is possible that seafarers are trained under condition that closely resemble real situation. It should be considered that IMO model course be revised depending on the level of seafarers also. It could be helpful for increasing seafarers' abilities of equipment operation in place of accumulation of experience spending much time. In the short term, effort of training courses improvement for seafarers is needed and long term, it should be tried to provide stable system and services relate to ECDIS.

• Journal of Navigation and Port Research
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• v.43 no.3
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• pp.143-152
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• 2019

In this paper, the towing stability of the LNG bunker barge was estimated. Currently, LNG bunkering barge is being developed for the bunkering of LNG (Liquefied Natural Gas), an eco-friendly energy source. Since the LNG bunkering barge assumes the form of a towed ship connected to the tow line, the towing stability of the LNG bunker barge is crucial f not only for the safety of the LNG bunker barge but also the neighboring sailing vessels. In the initial stages, a numerical code for towing simulation was developed to estimate the towing stability of the LNG bunkering barge. The MMG (Maneuvering Mathematical modeling Group) model was applied to the equations of motion while the empirical formula was applied to the maneuvering coefficients for use in the initial design stage. To validate the developed numerical code, it was compared with published calculation and model test results. Towing simulations were done based on the changing skeg area and the towing position of the LNG bunkering barge using the developed numerical codes. As a result, the suitability of the designed stern skeg area was confirmed.

• Explosives and Blasting
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• v.37 no.3
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• pp.13-24
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• 2019

This paper was prepared to investigate the behavior of fragments in underwater torpedo explosion beneath a frigate or surface ship by using an explicit finite element analysis. In this study, a fluid-structure interaction (FSI) methodology, called the multi-material arbitrary Lagrangian-Eulerian (MM-ALE) approach in LS-DYNA, was employed to obtain the responses of the torpedo fragments and frigate hull to the explosion. The Euler models for the analysis were comprised of air, water, and explosive, while the Lagrange models consisted of the fragment and the hull. The focus of this modeling was to examine whether a worst-case fragment could penetrate the frigate hull located close (4.5 m) to the exploding torpedo. The simulation was performed in two separate steps. At first, with the assumption that the expanding skin of the torpedo had been torn apart by consuming 30% of the explosive energy, the initial velocity of the worst-case fragment was sought based on a well-known experimental result concerning the fragment velocity in underwater bomb explosion. Then, the terminal velocity of the worst-case fragment that is expected to occur before the fragment hit the frigate hull was sought in the second step. Under the given conditions, the possible initial velocities of the worst-case fragment were found to be very fast (400 and 1000 m/s). But, the velocity difference between the fragment and the hull was merely 4 m/s at the instant of collision. This result was likely to be due to both the tremendous drag force exerted by the water and the non-failure condition given to the frigate hull. Anyway, at least under the given conditions, it is thought that the worst-case fragment seldom penetrate the frigate hull because there is no significant velocity difference between them.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.22-28
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• 2021

This is a basic study on the development of deep learning-based algorithms to detect smoke before the smoke detector operates in the event of a ship fire, analyze and utilize the detected data, and support fire suppression and evacuation activities by predicting the spread of smoke before it spreads to remote areas. Proposed algorithms were reviewed in accordance with the following procedures. As a first step, smoke images obtained through fire simulation were applied to the YOLO (You Only Look Once) model, which is a deep learning-based object detection algorithm. The mean average precision (mAP) of the trained YOLO model was measured to be 98.71%, and smoke was detected at a processing speed of 9 frames per second (FPS). The second step was to estimate the spread of smoke using the coordinates of the boundary box, from which was utilized to extract the smoke geometry from YOLO. This smoke geometry was then applied to the time series prediction algorithm, long short-term memory (LSTM). As a result, smoke spread data obtained from the coordinates of the boundary box between the estimated fire occurrence and 30 s were entered into the LSTM learning model to predict smoke spread data from 31 s to 90 s in the smoke image of a fast fire obtained from fire simulation. The average square root error between the estimated spread of smoke and its predicted value was 2.74.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.137-148
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• 2022

In this study, ship movement simulation was performed based on a marine physics model for the ancient port presumed under the past environmental conditions in the coastal area of Hwaseong, which played an important role as a center of trade in the Three Kingdoms and Unified Silla periods. The paleo topographical surface was reconstructed through the analysis of borehole sediments, and the paleo coastline was extracted through the geomorphological maps published during before independence. Based on the established paleo environmental conditions of the Hwaseong coast, the marine physics model (FVCOM) was used to simulate the flow of surface currents and the route of floating materials assumed to be ancient ships. As a result, the processes of moving ships from the port to the open sea in the Eunsupo area, which is estimated location of the ancient port related to Dangseong, was well simulated, and thus the reliability of the location of the ancient port estimated by the scientific method was secured. This study is significant as a result of convergence research that encompasses archeology, history, geomorpology, geology, and oceanography.

• Journal of Navigation and Port Research
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• v.47 no.4
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• pp.256-270
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• 2023

In this study, a sliding mode (SM) controller for dynamic positioning (DP) was specifically designed for a turret connection operation of a ship or an offshore structure in which an arbitrary point on the structure could be controlled as the motion center instead of the center of mass. The SM controller allows control of the arbitrary point and provides capability to manage uncertainties in the dynamics of ships and offshore structures, external forces caused by unknown changing marine environments, and transient performance of DP systems. The Jacobian matrix included in kinematic equations of the controlled object was modified to design the SM controller to control based on an arbitrary point of ships or offshore structures. To ensure robustness of the controller, the Lyapunov stability theory was applied in the design of the SM controller. In general, for robustness in DP control, gain scheduling based on a proportional-derivative (PD) control algorithm is employed. However, finding appropriate gains for gain scheduling complicates the application of DP systems. Therefore, in this study, the SM control algorithm was considered to mitigate the complexity of the DP controller for ships and offshore structures. To validate the proposed SM control algorithm, time-domain simulations were conducted and utilized to evaluate the performance of the control algorithm. The effectiveness of the proposed SM controller was assessed by comparing simulation results with results of a conventional PD control algorithm applied in DP control.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.704-711
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• 2023

This paper discusses the control method of BLDC(Brushless Direct Current) motor that has similar electrical characteristics with DC motor but has improved its lifespan and reliability. The BLDC motor can improve durability and speed stability by using rotor position information to eliminate commutators that require mechanical contact with DC motors. In this study, a controller for a DC motor was designed based on the fact that the current in the windings of a BLDC motor is a square-wave current like the current flowing in the armature of a DC motor. Next, the designed controller was applied to a 3-phase BLDC motor to confirm the effectiveness of the controller. In detail, a single-phase DC motor with electrical parameter values of a three-phase BLDC motor was modeled and a PI controller for motor speed control was designed by applying the root locus method to the derived system. The speed control simulation of the DC motor was performed to confirm the validity of the controller, and the same controller was applied to the speed control of the 3-phase BLDC motor implemented in MATLAB. From the simulation, similar results of the DC motor were obtained in the 3 phase BLDC motor and confirmed the usefulness of the proposed control scheme.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.175-185
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• 2000

This paper described on a basic study to organize fishing vessel control system in order to control efficiently fishing vessel in Korean offshore. It was digitalized ARPA image on the fishing processing of a fleet of purse seiner in conducting fishing operation at Cheju offshore in Korea as a digital camera and then simulated by used VTMS. Futhermore, it was investigated on the application of FVTMS which can control efficiently fishing vessels in fishing ground. The results obtained were as follows ; (1) It was taken 16 minutes and 35 minutes to casting and hauling net in fishing processing respectively. The length of rope pulled by scout boat was 200m, tactical diameter in casting net was 340.8m, turning speed was 6kts as well. (2) The processing of casting and hauling net was moved to SW, NE as results of simulation when the current direction and speed set into NE, 2kts and SW, 2kts respectively. Such as these results suggest that can predict to control the fishing vessel previously with information of fishing ground, fishery and ship's maneuvering, etc. (3) The control range of VTMS radar used in simulation was about 16 miles. Although converting from a radar of the control vessel to another one, it was continuously acquired for the vector and the target data. The optimum control position could be determined by measuring and analyzing to distance and direction between the control vessel and the fleet of fishing vessel. (4) The FVTMS(fishing vessel traffic management services) model was suggested that fishing vessels received fishing conditions and safety navigation information can operate safely and efficiently.