• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.420-426
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• 2020

The purpose and main points of the ROK-US Navy were analyzed from various angles using the big data technology Word Cloud for efficient sea trials. First, a comparison of words extracted through keyword cleansing in the ROK-US Navy sea trial showed that the ROK Navy conducted a single equipment test, and the US Navy conducted an integrated test run focusing on the system. Second, an analysis of the ROK-US Navy sea trials showed that approximately 66.6% were analyzed as similar items, of which more than two items were 112 items Approximately 44% of the 252 items of the ROK Navy sea trials overlapped, and that 89 items (35% of the total) could be reduced when integrated into the US Navy sea trials. A ship is a complex system in which multiple equipment operates simultaneously. The focus on checking the functions and performance of individual equipment, such as the ROK Navy's sea trials, will increase the sea trial period because of the excessive number of sea trial targets. In addition, the budget required will inevitably increase due to an increase in schedule and evaluation costs. In the future, further research will be needed to achieve more efficient and accurate sea trials through integrated system evaluations, such as the U.S. Navy sea trials.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.396-404
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• 2021

It is important to verify that the contracted speed-power performance of a ship is satisfied in sea trials. International Organization for Standardization (ISO) has published the procedure for measuring and assessing ship speed during sea trials. The results obtained from actual sea conditions inevitably include various uncertainty factors. In this study, double run tests were performed on one container ship to analyze the uncertainty of sea trial on three maximum continuous rating conditions. The uncertainty factors and scale of uncertainty were examined based on the measured raw data during sea trial. The results indicate that the expanded uncertainty for ideal power performance is approximately ±1.4% at 95% confidence level (coverage factor k = 2) and most of the uncertainty factors were because of the shaft power measurement system.

• Journal of Ocean Engineering and Technology
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• v.12 no.1
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• pp.135-142
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• 1998

In this study, the frequency transfer function of motions are predicted from the result of a full-scale seakeeping trials. Because the real sea has the characteristics of multi-directional waves,we compare the results in the one directional waves with ones in the directional waves. For calculation of the frequency transfer function in the directional waves, Takezawa's inverse estimation method was introduced and the frequency ranges were divided into three parts in order to consider following seas. The full-scale seakeeping trials was executed in the south sea of Korea using the stern trawler. Those results show that analysis method of the multi-directional waves is more reliable than that of one directional waves, and confirm the possibility of applying this method to the full-scale seakeeping trials.

• Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.211-220
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• 2013

A shaking motion could be used to improve fish escapement from a cod-end net by creating a sieving effect over the swept volume or by disturbing the optomotor response of the fish. In this study, a perpendicular shaking motion was generated in a towed cod-end net by a circular canvas attached to the end of the codend, which formed a biased cap-like shape. This concept was tested by using a model in a flow tank and by towing a prototype cod-end during sea trials. For the model tests, the amplitude of the shaking motion was $0.6{\pm}0.1$ times the rear diameter of the cod-end, and the period of the shaking motion was $2.6{\pm}0.1$ s at a flow velocity of 0.6 or 0.8 m/s. In the sea trials, the amplitude was $0.5{\pm}0.2$ times the rear diameter of the cod-end, and the period of the shaking motion was $7{\pm}4$ s at towing speeds of 1.2 or 1.7 m/s. Thus, the shaking amplitude during the sea trials was equal to or less than that observed in the tank tests, and the shaking period was twice as long. The shaking motion described by the amplitude and period could be an effective means to stimulate fish escapement from cod-end during fishing operations considering the response of the fish.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.6
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• pp.603-610
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• 2009

Ice load is one of the important design parameters for the construction of icebreaking vessels. In this paper, the design ice load prediction for the icebreaking vessels under normal operating condition in ice-covered sea is discussed. The ice loads under normal operating condition are expected from sea trials in moderate ice conditions. In this sense the extreme ice loads during heavy ramming or accidental collision are not considered. Current study describes the global ice load on the hull of the icebreaking vessels. Available ice load data from full-scale sea trials are collected and analyzed according to various ship-ice interaction parameters including displacement, stem angle, speed of a ship and flexural strength and thickness of sea ice. The ice load prediction formula is compared with the collected full-scale sea trials data and it shows a good agreement.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.3
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• pp.254-258
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• 2014

Field trial in ice-covered sea is one of the most important tasks in the design of icebreaking ships. To correctly estimate ice load and ice resistance on ship's hull, It is essential to understand the material properties of sea ice during ice field trials and to perform the proper experimental procedure by gathering sea ice data. A measurement of sea ice properties was conducted during February and March of 2012 with the Korean Icebreaking research vessel "ARAON" in the Amundsen Sea, Antarctica. This paper describes a test procedure to obtain sea ice data which provide basic information to estimate ice loads and icebreaking performance of the ship. The data gathered from sea ice field trials during the 2012 Antarctic voyage of the ARAON includes ice temperature/salinity/density and the compressive/flexural strength of sea ice. This paper analyses the gathered Antarctic sea ice material properties comparing with the previous data obtained during ARAON's Arctic and Antarctic voyages in 2010.

• Korean Journal of Ichthyology
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• v.20 no.3
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• pp.173-178
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• 2008

The substrate preferences of juvenile black sea bass Centropristis striata (Linnaeus) was tested in a circular tank (1.5 m diameter${\times}$0.4 m deep) divided into two equal areas of oyster-related (oyster reef and whole oyster shell) and sand substrates. All trials were video taped for 20 min. Tapes were viewed on a monitor and locations of all fish recorded and timed with respect to substrate. $Mean{\pm}SE$ times on oyster shell were $18.1{\pm}2.0min$ (1-fish trial-1) and $17.5{\pm}1.7min$ (5-fish trial-1). $Mean{\pm}SE$ times on sand were $2.0{\pm}1.0min$ (1-fish trial-1) and $2.5{\pm}1.7min$ (5-fish trial-1). Black sea bass juveniles showed a significant preference for oyster reef and shell over sand substrate in single-fish trials (paired t-test, P<0.05) and also in five-fish trials (paired t-test, P<0.05). $Mean{\pm}SE$ times under oyster reefs were $16.6{\pm}2.0min$ in single-fish trials and $10.7{\pm}2.3min$ in five-fish trials. Mean numbers of movements among oyster reefs were $1.1{\pm}1.0$ in single-fish trials and $11.5{\pm}3.1$ in fivefish trials. Fish spent significantly less time under oyster reefs in five-fish trials, compared to single-fish trials (paired t-test, P<0.05) and they moved more frequently in five-fish trials than in single-fish trials (paired t-test, P<0.05). Significantly higher competition for a refuge in five-fish trials may induce less time under oyster reefs as well as frequent movement of black sea bass juveniles on shell substrate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.3
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• pp.269-276
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• 2020

Sea trial tests are necessary to verify speed-power performance, and are an import contract between ship owners and shipyards. The International Organization for Standardization (ISO) published ISO 15016:2015, which specifies the correlation method between model and full-scale ships. The results of sea trials have been questioned because of the uncertainty of speed and power measurements, especially when sea conditions differ from ideal calm water conditions. In this paper, such uncertainties were investigated by utilizing the standard speed-power trial analysis procedure defined in ISO 15016:2015 through Monte Carlo simulations. It was found that the expanded uncertainty of the delivered power (P_Did) at 95 % confidence interval (k = 2) was ±1.5 % under 75 % MCR conditions.

• Journal of Ocean Engineering and Technology
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• v.26 no.1
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• pp.1-8
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• 2012

To correctly estimate ice load and ice resistance for a ship's hull, it is essential to understand the material properties of sea ice during ice field trials and to use the proper experimental procedure for gathering ice strength data. The first Korean-made icebreaking research vessel (IBRV), ARAON, had her second sea ice trial in the Arctic Ocean during July and August of 2010. This paper describes the test procedures used to properly obtain sea ice strength data, which provides the basic information on the ship's performance in an ice-covered sea and can be used to estimate the correct ice load and ice resistance on the IBRV ARAON. The data gathered from three sea ice field trials during the Arctic voyage of the ARAON includes the ice compressive strength, flexural strength, and failure strain of sea ice. This paper analyzes the gathered sea ice data in comparison with data from the first voyage of the ARAON during her Antarctic Sea ice trial in January 2010.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.458-465
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• 2005

Sensitivity Analysis(SA) is used to predict how the model response varies according to changes in the model parameters. With SA, confidences in models which are developed to approximate certain processes and their predictions can be increased. The influences of hydrodynamic coefficients on the prediction of manoeuvrability are examined by SA of direct method. The equations of motion used are the standard equations of motion for submarine(Gertler 1967), and submerged bodies with three different appendages are considered. Through numerical simulations of three kinds of sea trials, the sensitivities of motions to hydrodynamic coefficients are found. Changes of sensitivities during trials are found to be highly dependent on the actuator scenarios and geometry of submerged body.