• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.201-207
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• 2010

Recently, about 600 cases of marine accidents occur annually in Korea. According to many studies and analyses on occurrence of marine accidents, 70~80% of marine accidents were caused by human factors. Among the human factors, navigation officers' fatigue is very important factor. Although navigation officers' fatigue serves as an important role in marine accidents, there is no method to exactly examine the degree of officers' fatigue. Accordingly, this study analyzed human factors according to types of marine accidents and extracted important five factors affecting navigation officers' fatigue through the questionnaire survey by means of literatures and 5-point scale. In addition, evaluation factors of marine accident risks caused by fatigue factors were divided and structured by using ISM. Lastly, it found out the importance of each fatigue factor drawn by AHP and decided marine accidents that were most highly caused by navigation officers' fatigue in order. At the result, weights were high as sleep time 0.385, stress 0.302, health condition 0.139, rest time 0.099, alcohol and drug 0.074 in fatigue factors, and death and injury 0.328, collision 0.308, grounding 0.195, sinking 0.094, fire accident 0.075 in evaluation factors of marine accident risks. Therefore, the control plan to lower marine accident risks should be prepared on the basis of high weight factors.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.3
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• pp.35-47
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• 1996

A surface panel method treating a boundary-value problem of the Dirichlet type is presented to design a three dimensional body with free surface corresponding to a prescribed pressure distribution. An integral equation is derived from Green's theorem, giving a relation between total potential of known strength and the unknown local flux. Upon discretization, a system of linear simultaneous equations is formed including free surface boundary condition and is solved for an assumed geometry. The pseudo local flux, present due to the incorrect positioning of the assumed geometry, plays a role f the geometry corrector, with which the new geometry is computed for the next iteration. Sample designs for submerged spheroids and Wigley hull and carried out to demonstrate the stable convergence, the effectiveness and the robustness of the method. For the calculation of the wave resistance, normal dipoles and Rankine sources are distributed on the body surface and Rankine sources on the free surface. The free surface boundary condition is linearized with respect to the oncoming flow. Four-points upwind finite difference scheme is used to compute the free surface boundary condition. A hyperboloidal panel is adopted to represent the hull surface, which can compensate the defects of the low-order panel method. The design of a 5500TEU container carrier is performed with respect to reduction of the wave resistance. To reduce the wave resistance, calculated pressure on the hull surface is modified to have the lower fluctuation, and is applied as a Dirichlet type dynamic boundary condition on the hull surface. The designed hull form is verified to have the lower wave resistance than the initial one not only by computation but by experiment.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.2
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• pp.76-85
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• 1993

In order to predict the free surface signature of turbulent ship wakes two things are essential; a basic understanding of the mechanism of turbulent vortical flow/free surface interactions and a mathematical model to accurately predict the signature. The goal of the study described here is both to supplement experimental work to obtain basic understanding, as well as to condense this understanding in a model(or models) that captures the essential phenomena and thus allows predictions. To do so we followed two main paths guided by experimental observations. One is full simulations of the flow using the clavier-Stokes equations. The other is a vortex modeling, where the vortical structures of the flows are approximated by idealized structures, an the interaction assumed to be essentially inviscid. These approaches complement each other. Full simulations are only applicable to small scale phenomena, where the system is simple, and the Reynolds number is low. The vortex modeling, on the other hand, cannot represent essentially viscous aspects of the problem such as the effect of contamination gradient. Obviously, the modeling is what may eventually lead to a prediction method; the full simulations-too limited to mimic all but the simplest circumstances-are to aid and support the construction of realistic models. We address two-dimensional aspects of the vortex/free surface interaction first. Secondly we obtain some basic understanding of the interaction process through an experiment and then talk about several three-dimensional problems hoping to develop a successful prediction model.

• Journal of Digital Convergence
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• v.18 no.9
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• pp.413-421
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• 2020

Because of space constraints of the ship, accessibility to supporting system for nonsmoking is poor in seafarers' group. This study was performed to find the smoking status, second-hand smoking status and factors related to smoking habit of Korean seafarers. So, we examined the rate of smoking and secondhand smoking, and knowledge about smoking, attitude for smoking behavior, smoking cessation intention and working environment related to smoking of 155 seafarers. Their smoking rate was 32.3% and secondhand smoke rate was very high by 86.5%. Their working place equipped a separate smoking room, but most of them had been smoked in where they were stayed. and we found the inadequate ventilation facility in 42.6%. Only 21.9% had a experience of education for smoking cessation. From the study Attitude for smoking behavior was negative and smoking knowledge was high. 90% of them tried to stop to smoke, but intention of smoking cessation was low. We need to motivate seafarers and increase their smoking cessation intention by regular education in available ways. From the study, we purpose that government will realign regulations related to ventilation facility and appointed smoking area on the board to prevent seondhand smoke, and the policy need to possess the regular survey of smoking status and customized smoking cessation education for seafarers.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.3
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• pp.116-125
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• 1995

In ship and of offshore structures, there exist many local panels of various shapes having many kinds of attachments reducible to damped spring-mass systems. For the vibration analysis of panels, analytical methods such as Rayleight-Ritz method or the assumed mode method can be efficiently applied. There have been many studies on the vibration analysis of rectangular panels using the analytical methods but relatively few for arbitrary shape panels. An efficient formulation based on the assumed mode method is presented for the vibration analysis of an arbitrary quadrangular plate having concentrated masses, supporting springs such as pillars and spring-mass systems. In the formulation, the natural coordinate system is used for the efficient treatment of an arbitrary quadrangular shape. Through some numerical calculations, accuracy and efficiency of the presented method are shown.

• Journal of Navigation and Port Research
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• v.36 no.3
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• pp.205-213
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• 2012

This study focused on the supply-demand and training system of the crew for domestic coastal shipping. First of all, it forecasted the prospect and effect in the future of the crew supply-demand through the analysis to the current situation of crew employment and the internal and external environment changes. Next, it suggested the specific role and alternatives of government, industry and educational institutions after the comparison and examination of the sailor policies among Korea and major shipping countries. In regard to the demand of crew manpower in coastal shipping, it figured out the bottoms and the current circumstances of sailors, and it could anticipate the future demand by the gradational approach. According to the findings, firstly the result of this simulation by the changes of the ship numbers demonstrated that the demand over the next 10 years will be 7,890~8,025 in the case of the growth 0.4%, and 7,894~8,063 in 0.5%. Secondly, assuming the growth 0.1~1%, the result illustrated that the demand will come to 7,879~8,258. This means the fact that the additional manpower has to be input to 20~430 annually from now on. To conclude, this study showed the more rational numbers about the supply-demand than the past researches and displayed the systematic approach to supply and train the crew in domestic coastal shipping.

• Strategy21
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• s.44
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• pp.213-253
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• 2018

The Russo-Japanese War(1904-1905) in the early 20th century greatly influenced the international politics in Northeast Asia and the destiny of both countries. There are many studies on the cause of the outbreak and its effect on the Korean peninsula. The victory and defeat of the battle of Tsushima also the subject of research by renowned scholars and navy officers. Many previous studies have analyzed the process of engagement. However, There was a lack of research that analyzed at the tactical level of naval commanders. Therefore, this study tries to review the battle of Tsushima in terms of tactical level, that is formation, maneuvering, damage control. Naval operations at sea with many variables are not always done as planned. The intuitive judgement and readiness have had a decisive impact on victory and defeat. The analysis of the naval warfare on the basis of formation, maneuvering, and damage control makes the cause of the win more clearly. The conclusion of the this study can be summarized in five ways. First, victory would be achieved through the suppression of the beginning. The destiny of the Tsushima battle was determined by an 1 hour after first firing. The Japanese fleet caught fire by paralyzing the command and control capabilities of the Russian fleet. Second, the Japanese fleet's power was superior to the Russian fleet. In general, Japan and Russia had similar powers, and Admiral Togo's "T crossing tactics" decisively contributed the victory. However, when compared to the weapon system level, formation and maneuvering, Japan was much more dominant. Third, people realized that one side to be annihilated in the battle between similar powers after the Tsushima battle. The common perception before the Battle of Tsushima was that the battle ship would not sunken, and that the result of wiping out was difficult. However, there is s time for one sided victory and defeat depending on the early suppression nad the destruction of the command and control ability. Fourth, it is the importance of damage control ability. The main cause of the Russian fleet's loss of command and control ability was thick smoke from fire, and maneuverability was greatly deteriorated due to coal overload. In this way, importance is still valid after more than 100 tears. Fifth, the area of uncertainty. In the navy battles, one or two shots of clear firing in the beginning and small misconception and minor mistakes decide win or loss. Ultimately, this area of fortune can be linked to mindset of the commander. I hope this research will be help to naval researchers and naval commanders at the sea.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.299-305
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• 2015

Modbus is a serial communications protocol, it has since become a practically standard communication protocol, and it is now a commonly available means of connecting industrial electronic devices. Therefore, it can be connected with all devices using Modbus protocol to the measurement and remote control on the ships, buildings, trains, airplanes and etc.. In this paper, we add the Modbus communication protocol to the existing lighting controller sensitivity to enable verification and remote control by external environmental factors, and also introduces a fuzzy inference system was configured by external environmental factors to control LED lighting. External environmental factors of temperature, humidity, illuminance value represented by the LED through a fuzzy control algorithm, the values accepted by the controller through the sensor. Modbus is using the RS485 Serial communication with other devices connected to the temperature, humidity, illumination and LED output status check is possible. In addition, the remote user is changed to enable it is possible to change the RGB values in the desired color change. Produced was confirmed that the LED controller output is based on the temperature, humidity and illumination.

• Journal of Navigation and Port Research
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• v.33 no.3
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• pp.199-206
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• 2009

Since Emma Maersk, which is a container vessel capable of holding a freight capacity of 11,000 TEU, was launched early last year, the appearance of the ULCS (Ultra Large Container Ship) will be expected in 5 years. That requires the high productivity, the high technology, the automation, and the high efficiency in port operations. GTO (Global Terminal Operator) and port equipment companies are striving for the prior occupation of the port market and the development of the port technology. Within the country, however, there has been few systematic, analytic, and detailed technology road map, and the effective execution of the development policy for the port technology and the activation of port industries has not been achieved. In this study, we deduces the development subject of the domestic port technology and analyzes the priority of them. In conclusion, we establishes the macro technology road map and the product-related road map for container ports in Korea.

• Journal of Navigation and Port Research
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• v.42 no.1
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• pp.25-30
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• 2018

This study was carried out to analyze the risk attitude based on situation awareness of the Vessel Traffic Service Operator (VTSO) on the risk of collision between vessels during the monitoring of vessel traffic through the use of the VTS system. In general, when two vessels are in the close quarters situation, we analyzed the degree of risk of collision from the subjective viewpoint of the VTSOs through an administered survey. Chiefly, we analyzed the risk attitudes of each VTSO in the close quarters situation, by comparing it with the calculated value by the CoRi, which is the ship collision risk model from the VTSO's viewpoint. As a result, it was confirmed that more than 40% of the total VTSO was noted as being in a weak risk aversion type of category. Through a review of the results of analyzing the risk attitude of VTSO according to gender, age, VTS career, VTS center position, accident experience, and boarded career, it was found that there was a significant difference in the VTS career, VTS center position and accident experience. In addition, a regression model that is able to further explain the risk attitude of VTSO was derived as a factor that confirmed the significant difference and applied to CoRi to predict the collision risk according to the individual VTSO to be used as a fundamental information gathering tool for providing more accurate and safe VTS service at sea.