• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.1
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• pp.26-29
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• 2016

This study investigated the effects of dietary inclusion of sea mud on growth and body composition of juvenile sea cucumber Apostichopus japonicus. In experiment 1, three experimental diets containing sea mud at the level of 0, 30 and 60% were prepared. After feeding trial for 7 weeks, survival was not significantly different among groups. Final mean weight of sea cucumber fed the experimental diet without sea mud supplementation was significantly higher than that of sea cucumber fed the diet containing 30 and 60% sea mud. In experiment 2, three experimental diets containing sea mud at the levels of 0, 15 and 30% were prepared. After feeding trial for 19 weeks, survival was not significantly different among groups. Final mean weight of sea cucumber fed the diet without sea mud supplementation was not significantly different from that of 15%, but was significantly higher than that of sea cucumber fed the diet containing 30% sea mud. It was concluded that dietary inclusion of sea mud may inhibit growth of sea cucumber.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.3
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• pp.135-141
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• 1994

In order to investigate remotely the behavior and distribution of fishes, the telesounder system which was composed of two parts with a buoy station at sea and a base station on land was manufactured trial. The buoy station at sea consists of fishfinder, transmission interface and transceiver. On the other hand, the base station on land consist of transceiver, receiving interface, trigger/signal separator and color display monitor. The system simulation for the performance of telesounder was carried out by use of echo simulator which could input echo signal into fishfinder. The received power (dBm) of transceiver at 29.4MHz decreased almost in proportion to distance between transmitter and receiver, and the electric field intensity was 12.12mV/m at 100 meters distance from transmitter. The image of color display monitor at the base station on land was very well coincident with the records of fishfinder from the buoy station located at sea. Therefore, it is concluded that the telesounder system is very useful in the analysis of the information on the behavior and the distribution of fishes detected from sea.

• Journal of Ocean Engineering and Technology
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• v.31 no.5
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• pp.335-339
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• 2017

This study investigated the sea trial performance of a wave piercing high speed planing hull (WPH). The bow shape of the boat is sharp, and it has no chine or spray strip like a normal planing boat. The skeg is attached to the bottom of the boat in the longitudinal direction from the bow to the stern. The speed performance was analyzed as the speed dropped in a wave, and the seakeeping performance was compared with that of a planing boat with a similar velocity coefficient by measuring the vertical acceleration of the bow in the wave. The turning circle was compared with Lewandowski's estimation for a planing boat. As a result of this study, it was confirmed that the velocity drop of the developed WPH was not large in a wave, and the vertical acceleration was greatly reduced compared with that of a normal planing boat. The turning circle was somewhat larger than the estimated results for a planing boat, but the overall tendency was the same.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.572-578
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• 2007

A Rigid Inflatable Boat (RIB) is now widely used for commercial and military purpose. In this paper, it is supposed that seven-meter-class RIB be used as an unmanned target ship for naval training. In order to develop many tactical maneuvering patterns of a target ship, a simple horizontal maneuvering model of a RIB is needed. Therefore, models of speed and yaw rate are constructed as the first-order differential equations based on Lewandowski#s empirical formula for steady turning circle diameter of a conventional planning hull. Some parameters in the models are determined using the results of sea trial tests. Finally, proposed models are validated through the comparison of the simulation result with the sea trial result for a specific scenario. Even though a simple model does not represent the horizontal motion of a RIB precisely, however, it can be used enough to develop tactical trajectory patterns.

• The Journal of Fisheries Business Administration
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• v.46 no.1
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• pp.109-119
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• 2015

This paper is to estimate the economic effect of benefits of the R&D and recreational fishing as well as input-output analysis in the Tae-an Trial Sea Farm Project(TTSFP). We use B/C model to indicate the effects of economic valuation. B/C analyses model consists of Benefit Cost Ratio(BCR), Net Present Value(NPV) and Internal Ration of Return(IRR). Using 5.5% discounting rates and the survey data, the sub-models show economically feasible in the all of analysis and analyzed the results as follows. NPV is 42,147 million won, BCR is 3.29 and IRR is 34.30%. This study attempts to apply input-output(I-O) analysis in connecting the economic effect of TTSFP. I-O model was constructed, focusing on three effects; the production-inducing effect, the value-added-inducing effect and employment-inducing effect. There are positive effects on economic value and job creation in Tae-an and Nation.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.2 s.140
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• pp.105-112
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• 2005

IMO standards for ship manoeuvrability were applied from January 1, 2004. Though model test or sea trial in full load condition is needed, it is not always possible to get such data for every ships. Therefore it is required to study the effect of loading conditions on ship manoeuvrability. Approximate formulae to estimate the hydrodynamic forces acting on a ship and the 2nd overshoot angle of $10^{\circ}$/$10^{\circ}$ zig-zag test in certain loading condition are proposed in this study These were derived from the results of model test and sea trial data. Captive model tests for 7 ships with 15 different loading conditions and sea trial data including free running test of 6 cases were used. Compared with experiment data and prediction formulae already proposed by others, the approximate formulae in this study show good agreement with model test results.

• Journal of Ship and Ocean Technology
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• v.10 no.4
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• pp.34-48
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• 2006

The visual observation of wave condition depends on the observer's skill and experience. Also, the environmental conditions such as light and cloud heavily influence the visual measurement. In the speed test of sea trial, the wave measurement should be objective and accurate. In this paper, the problems of visual measurement and their effects on speed test are described. To overcome those problems, we developed the wave measurement system using commercial marine X-band radar, WaveFinder. The system installed at inland base was calibrated by waverider buoy and then the system's operability was defined. Onboard tests had also been performed three times for formal wave measurement to correct the ship speed. The results illustrated very good agreement with visual observation by experts. It can be concluded that the system would be useful to measure wave and swell information for the sea trial, irrespective of day and night.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.318-320
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• 2018

When a ship sails on sea, it may be influenced by the environmental disturbance such as wind, wave, sea surface temperature, etc. These affect on the ship's speed, fuel consumption, safety and operating performance. It is necessary to find the optimal weather route of a ship to avoid adverse weather conditions which can put the crews in serious danger or cause structural damage to the vessel, machinery, and equipment. This study introduced how to apply A* algorithm based on sea trial test data for determining the optimal ship routes. The path cost function was modelled as a function of minimum arrival time or minimum energy depending on the time of various environment conditions. The specially modelled path-cost function and the safety constraints were applied to the A* algorithm in order to find the optimal path of the ship. The comparison of ship performances estimated by real sea trial's path and estimated optimal route during the voyage of the ship was investigated. The result of this study can be used to create a schedule to ensure safe operation of the ship with short passage time or minimum energy. In addition, the result of this study can be integrated into an on-board decision supporting expert system and displayed in Electronic Chart Display and Information System (ECDIS) to provide all the useful information to ship master.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.304-313
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• 2021

This paper presents the results of a sea trial for long range underwater acoustic communication conducted in the East Sea in November 2020. Signals were collected through a moving transmitter and 16 vertically arranged receivers, and the range between the transmitter and receiver was about 20 km. The signal in the experiment is a conventional Direct Sequence Spread Spectrum (DSSS) method and a superimposed DSSS method that increases data rate by superimposing of multiple circulated Pseudo Noise (PN) sequences for each symbol. The results show that the uncoded bit error rate averaged over 16 channels to which the channel coding technique was not applied was 0.0005 for the conventional direct sequence spreading method, and was 0.00124 for the superimposed direct sequence spreading method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.98-107
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• 2021

During the sea trial test for the aerovane in AOE-II, a malfunction occurred in the wind detector movement around 40 to 90° on the starboard side and around 270 to 320° on the port side. The purpose of this study was to analyze and improve the cause of the above phenomenon. The wind detector was covered with a mast structure and was not affected directly by the blowing wind, and a vortex air current was formed behind the mast structure, causing the motion malfunction. The above problem was solved by moving and installing the wind detector on the newly installed mast yard. After conducting vibration analysis and reviewing the effects of vibration, the wind detector was installed in the new mast yard and verified by a sea trial test. Since the improvement plan was slightly effective, the position of the wind detector moved away from the mast on the new mast yard and was re-verified through a sea trial test. The movement malfunction of the wind detector did not occur, confirming that it is an appropriate improvement plan.