• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.2
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• pp.149-159
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• 2007

Marine casualties of fishing vessels were analyzed to reduce the sacrifice of human life using data of the Korean Maritime Safety Tribunal from 1995 to 2004 in Korea. The occurred number of fishing vessel casualties were likely to be higher portion than non-fishing vessels, but the occurring ratio of fishing vessel casualties were marked 2.96 times lower than that of non-fishing vessel casualties. The occurring ratios of bigger fishing vessel casualties were higher than smaller ones. Most marine casualties were resulted from the human factors such as poor watchkeeping, negligent action for engine and etc. The trend of marine casualties showed that the machinery damage hold the first and collision accidents took the second, but on a point of cause of them, operating errors took first and poor handling or inspection of machinery held the second place. Because those two casualties took major portion, and very important problems for safety of fishing vessels, so we ought to try to reduce the factors before everything else. In addition, since collision, sinking and capsizing in marine casualties have led to death, missing and injury of lives, it is necessary for navigation operators to take more educations and training intended to reduce the marine casualties systematically and continuously.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.1-9
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• 2016

Oysters are rich in nutrients with good flavor, and disease prevention is required in both the East and the West for high-quality seafood. The best way to store and transport mass-produced oysters is using dry techniques. Using both hot and frozen drying technologies to obtain a perfectly dried oyster often destroys much of the flavor and nutrients found with the oyster meat. This study uses a low temperature vacuum drying technology to investigate the final weight ratio of wild and farmed dried oysters. Additionally, the heat transfer characteristics of steamed oysters are discussed in this paper.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.1
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• pp.1-10
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• 2006

Present study was conducted to improve the spring frame net trap for conger eel, Conger myriaster which prevents by-catch and protects immature fish. A series of comparative fishing experiment was carried out in water off the south-east coast of Korea from Nov. 2004 to Jul. 2005. And analyzed the amount of catch, by-catch rate, and CPUE, etc. of experimental traps which were the spring frame net traps, sorted four types of flappers. And the compared gear was a plastic conger eel pot. The conclusions were as follows. By-catch rates of spring frame net trap with the compressed flapper bound by nylon mono-filament was about 0-3%. CPUE of spring frame net trap with the compressed flapper was about 50-60% lower than that of traditional and plastic pot. And in case of conger eel that the total length is over 350mm, CPUE was little different on each type of flapper of every mesh size.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.1-14
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• 1992

With 16 years' oceanographic data(1973-1988) of the National Fisheries Research and Development Agency and the CTD data collected by a training ship of Korea Maritime University during Nov. 6-11, 1989, the inflow path of the bottom cold water in the western channel of the Korea Strait were investigated. Temperature of the bottom water in the western channel shows the lowest in summer and large annual variation. According to the temperature distributions in the years when the bottom cold water exists in the western channel in summer, the cold water in the southwestern region of the East Sea seems to intrude into the western channel through the sea southeast 10- 15 miles off Ulsan with its properties showing slight change during advection.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.887-894
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• 2016

In the underwater acoustic communication channels, a multipath reflection becomes the cause of obstacle. To solve this problem, a rake receiver has been required for which one could take the time diversity. However, there is a concern about using incorrect path to recover signals with a high weighting value as underwater acoustic communication channels have severe time-variant property. In order to prevent these problem, a rake receiver is proposed which is based on BER(bit error rate) train sequence duration. The performance is evaluated through lake trials; there are three methods that are a proposed rake receiver, a conventional rake receiver, and a non-rake receiver. As a result, the number of bit errors in the proposed rake receiver, that of bit errors in the conventional rake receiver, and that of bit errors in the non-rake receiver is 8, 45, and 72, respectively.

• Journal of Navigation and Port Research
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• v.32 no.5
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• pp.379-385
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• 2008

In this paper, we presents a scheme for the parameter estimation and optimal control scheme for apparatus of container crane system. For parameter estimation, first, we construct the open loop of the container crane system and estimate its parameters based on input-output data, a real-coded genetic algorithm(RCGA) and the model adjustment technique. The RCGA plays an important role in parameter estimation as an adaptive mechanism. For controller design, state feedback gain matrix is searched by another RCGA and the estimated model. The performance of the proposed methods are demonstrated through a set of simulation and experiments of the experimental apparatus.

• Journal of Navigation and Port Research
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• v.32 no.5
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• pp.333-339
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• 2008

When a vessel is underway in a heavy weather, passengers and crew suffer from seasickness caused by ship motions such as pitch, heave or roll, or all combined Sickness induces drowsiness, dizziness, headache, stomachache etc, in extreme conditions, they are met with a serious trouble which is physiologically unrecoverable. It results in weakening of spiritual activities or making errors from decrease of motivation, dropping off skills, poor recognition and poor judgement. In this paper, it was examined the international standards concerning the occurrence of sickness and the execution of works, also evaluated the boarding comfort by conducting several times of questionnaire on cadets boarding on the training ship HANBADA As a result, it was confirmed that the main factor of occurring the sickness was the vertical acceleration and the level was more than 0.2g. Also, it was presented the way how to reduce the sickness by changing the speed and/or course in relation to the encounter period.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.16-23
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• 2018

Chaos is one of the most significant topics in nonlinear science, and has been intensively studied since the Lorenz system was introduced. One characteristic of a chaotic system is that the signals produced by it do not synchronize with any other system. It therefore seems impossible for two chaotic systems to synchronize with each other, but if the two systems exchange information in just the right way, they can synchronize. This paper addresses the problem of synchronization in a modified Lorenz chaotic system based on active control, sliding mode control, and the Lyapunov stability theory. The considered synchronization scheme consists of identical drive and response generalized systems coupled with linear state error variables. For this, a brief overview of the modified Lorenz chaotic system is given. Then, control rules are derived for chaos synchronization via active control and slide mode control theory, with a strategy for solving the chattering problem. The asymptotic stability of the overall feedback system is established using the Lyapunov stability theory. A set of computer simulation works is presented graphically to confirm the validity of the proposed method.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.849-854
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• 2013

Many researches on green ship with increasing on economics, efficiency and convenience have been carried out consistently. One of them is development of diesel engines with electronic control. While small duty one for automobiles had been adopted mainly already, disseminating heavy duty one for ships has trouble due to safety and reliability. In order to solve these problem in this study, performance of electronic control and cam type engine installed in parallel on training ship HANBADA of korea maritime university was analyzed and compared. It is certain that specific fuel oil consumption of the electronic control type is lower than cam type and excellent at lower engine load, especially. And the electronic control type shows more effective characteristic at sea trial on specific fuel oil consumption.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.43-49
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• 2004

Defects inspection of commodities are very important with those design and manufacturing process and essential to strengthen the competitiveness of those. If on-line automatic defects detection is performed without damaging to products, the production cost shall be curtailed through the reducing man-power, economical management of Q.C(Quality Control). In this paper, it is suggested three spatial filtering methods which can extract the necessary information in case of defects being on the surface of object like iron plate. In addition, the dependence of filtering characteristics on parameters such as the pitch and width of slits is analyzed and the surface defect detection system is constructed. Several experiments were carried out for determining the adequate spatial filtering method through comparing and analyzing effects of parameters like defect's size and shape, intensity of light, noise of coherent source and slit number.