• Journal of the Society of Naval Architects of Korea
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• 제32권3호
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• pp.37-43
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• 1995

The procedure and the results of the full scale strain measurement of the long-range high-speed foil catamaran are described. The wave induced stresses at the center struts of the foils were measured during the sea trials in order to evaluate the hydrodynamic force acting on the foils and to verify the structural safety of the foil structures. From the statistical properties of the measured response of the stress, the most probable maximum values of the lift force and the stresses at the foils in service life of the ship are predicted and compared with the design parameters of the foils which were applied in the design of the subject ship. The available prediction processes of the measured stress are studied and the results of the applied processes are compared with each other.

• Ocean and Polar Research
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• 제36권2호
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• pp.135-143
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• 2014

The effect of salinity on the survival, oxygen consumption and blood physiology of Korean rockfish Sebastes schlegelii (body weight $97.4{\pm}1.7g$, $mean{\pm}SD$) was investigated at nine different salinities of 33.4 (control), 33.1, 32.8, 32.2, 31.0, 28.7, 23.9, 14.5 and 3.8 psu, respectively. Survival and blood physiology were measured at each salinity in two separate trials of 96 and 24 hr duration, respectively. Oxygen consumption rate (OCR) was determined at stepwise salinity exposure ($33.4{\rightarrow}33.1{\rightarrow}32.8{\rightarrow}32.2{\rightarrow}31.0{\rightarrow}28.7{\rightarrow}23.9{\rightarrow}14.5{\rightarrow}3.8$ psu) with an interval of 24 hr for each salinity. No death of fishes were observed in the range of 33.4 to 14.5 psu, but the survival rate was reduced to 26.7% at 3.8 psu after 96 hr. The OCRs were not significantly different in the range 33.4 to 28.7 psu (p > 0.05), but significantly increased until 14.5 psu and then drastically decreased at 3.8 psu compared to the control (p < 0.05). The concentrations of plasma $Na^+$ and $Cl^-$ were significantly lower in fish exposed at 3.8 psu compared to the control (p < 0.05). The results of this study provide evidence that S. schlegelii exposed to concentrations below 23.9 psu show significant physiological responses to tolerate salinity changes under the experimental conditions we established.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제52권6호
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• pp.637-643
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• 2019

Three separate feeding trials were performed to evaluate the dietary inclusion of pigments on growth and pigmentation of Semisulcospira coreana. In the first trial (Exp-1), snails (80 mg/snail) were fed diets containing green laver Enteromorpha intestinalis, seaweed fulvescens Capsosiphon fulvescens, chlorella Chlorella vulgaris, green tea, mugwort, kale, broccoli, sea tangle, dried laver Pyropia yezoensis, a synthetic edible dye, and a diet containing no pigment (control) for 12 weeks. Results showed that dietary treatments had no significant effects on growth performance. However, total chlorophyll and chlorophyll a contents of the snail's edible portion were markedly affected and the highest values were found in snails fed green laver. In the second (Exp-2) and third (Exp-3) experiments, the effect of green laver and chlorella were examined in diets for relatively smaller (35 mg/snail) and bigger (139 mg/snail) snails than those examined in the Exp-1, respectively. Feeding the bigger snails with chlorella significantly enhanced their growth rates compared to control group. Total chlorophyll and chlorophyll a contents of the edible portions of snails were significantly increased by dietary chlorella supplementation. These findings suggest that dietary green laver or chlorella could improve the pigmentation of S. coreana without any adverse effects on growth.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제52권4호
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• pp.347-355
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• 2016

In this study, a new designed propeller was applied on 24 ton class squid jigging vessel to reduce of fuel consumption. The selected squid jigging boat was under construction at the shipyard to determine the resistance of the hull through the model experiment. The propeller design was carried out by using the experimental data and ITTC procedures. Sea trials were performed by measuring the speed and the horsepower required by the condition of five power levels of engine load, namely 70%, 80%, 90%, MCR and maximum engine power. The speed and delivered horse power were compared between the conventional propeller and the new design propeller. Delivered horse power by installing the new propeller takes 90% engine load at start-up conducted by decreased 9.06%. The measuring speed is increased up to the 0.6 knots in the low-speed range to high range. This study showed that only the design and installation of a new propeller can improve the propulsion efficiency of the boats; furthermore, reduce fuel costs can be achieved at the same time by improving the increased cruising speed.

• The Korean Journal of Malacology
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• 제22권2호
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• pp.167-173
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• 2006

The embryos of marine bivalves have been commonly used in bioassays for quality assessments of marine environments. Although several standard protocols for the developmental bioassay of bivalves have been proposed, only a few trials for application of these protocols in environmental assessments or for the development of a new protocol with Korean species have been conducted. As such, there is a strong need to establish standard bioassay protocols with bivalves commonly found in Korean waters. To determine the sensitivity of Mytilus galloprovincialis to establish a standard bioassay, their fertilized eggs were exposed to six metals (Ag, Cd, Cr, Cu, Ni, and Zn). The order of biological impact was Ag > Cu > Ni > Zn > Cr > Cd and their lowest observed effective concentration were 5, 16.4, 25.4, 142, 187 and 1,500${\mu}g/l$, respectively. The proportion of normal larvae appeared to decrease linearly with the logarithm of each toxicant concentration within the tested range. The average values of median effective concentrations $(EC_{50})$ from the triplicate experiments for Ag, Cd, Cr, Cu, Ni, and Zn were 6.8, 1,797, 786, 16.6, 68.1, and 139.2${\mu}g/l$, respectively. There was a more than 100-fold difference in $EC_{50}$ values of Cu and Cd. The value of $EC_{50}$ or median lethal concentration of Cu was within the range observed for other bivalve developmental bioassays. The overall sensitivity of M. galloprovincialis in the present developmental bioassay was also similar to that of other marine organisms commonly used in aquatic bioassays (e.g. sea urchins, oysters). Hence, the bioassay using the embryo of M. galloprovincialis is considered to be a useful tool to monitor and evaluate the quality of marine aquatic environments.

• Journal of Navigation and Port Research
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• 제37권2호
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• pp.137-142
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• 2013

The displacement Deep-V catamaran concept was developed in Newcastle University(UNEW) through development of the systematic Deep-V catamaran series. One of the most important Deep-V catamaran launched to date is Newcastle University's own multi-purpose research vessel, The Princess Royal. The vessel was launched in 2011 and enhanced the Deep-V catamaran concept further with the successful adoption of a novel anti-slamming bulbous bow and tunnel stern for improved efficiency. It was however identified that the vessel has substantial amount of dynamic trim that limited the visibility of the captain. The dynamic trim also increased the wave-making resistance thereby preventing the vessel from attaining its maximum speed in certain sea states. This paper therefore presents the application of devices such as Trim Tabs, Interceptors, Transom Wedges and Integrated Transom Wedges-Tabs to control the dynamic trim and improvement of fuel efficiency of the vessel. All of these energy saving devices were fitted into a model for tests in Newcastle University's Towing Tank. Model test verification confirmed that the optimum appendage was the interceptors, they produced a 5% power saving and 1.2 degree trim reduction at 15 knots, and investigations of full scale trials will be scheduled with and without application of device to compare the improvement of performance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제43권1호
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• pp.62-70
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• 2007

Marine casualties of vessel are serious problems on social and national aspects, because it results in sacrifice of lives, a great lose of properties and marine pollution. According to recent statistics of marine casualties of vessel, fishing boats are more likely to be ended in the casualty, and especially, small fishing boats cause much more accidents than any other big vessels. Most of marine casualties were caused by the human factors such as poor watch keeping, inadequate manoeuvering and negligent action for engine, etc. This study is intended to provide navigator of small fishing boat with a specific information of necessary to assist both the manoeuvering and the avoidance of capsizing. The manoeuvering characteristics of ship can be adequately judged by the results of typical ship trials manoeuvres. For this purpose, the author measured the roll responses of a small fishing boat in waves using the real sea experimental measuring system, and analyzed the experimental data by the statistical and spectral analyzing methods to get the characteristics of the roll motion responses of the small boat through the wave directions and the ship's speed.

• Journal of Ocean Engineering and Technology
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• 제30권4호
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• pp.243-252
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• 2016

Conventionally, the static angle of attack and static elevator tests are carried out separately to estimate hydrodynamic stability derivatives of underwater vehicles. However, it is difficult to verify the interaction between the angle of attack and elevator angle in such cases. In this study, we perform a static elevator with angle of attack test where both the angle of attack and elevator angle are varied simultaneously. The experimental results show that the angle of attack has an influence on the elevator control force and that this tendency is dependent on the sense in which the angle of attack and elevator angle are varied. We predict level flight performance using hydrodynamic derivatives estimated through this experiment. The predictions considering the effect of angle of attack show good agreement with trials conducted in the open sea.

• Fisheries and Aquatic Sciences
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• 제24권11호
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• pp.375-382
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• 2021

In this study, the reproductive behavior and embryonic and larval development of the short ninespine stickleback Pungitius kaibarae was described and illustrated based on observations during spawning, hatching, and larval rearing trials. Adult P. kaibarae were collected downstream in Jinhae during the reproductive season (April-May). Males had nuptial coloration on their entire black bodies, with blue dorsal spines and yellow eyes, whereas females had a brown spotted pattern on their bodies. Males built nests on the stems of water weeds and attracted females. Fertilization occurred in the nest immediately after spawning, and males guarded the eggs until hatching. The fertilized eggs of P. kaibarae were spherical, demersal, adhesive, and transparent, and each egg measured 1.43 ± 0.07 mm in diameter. The morula, blastula, and gastrula stages, as well as hatching began at 5, 18.5, 21.5, and 96 post fertilization (HPF), respectively, at 20.0 ± 0.5℃. The newly hatched larvae had a total length (TL) of 5.67 ± 0.50 mm, with a yolk volume of 0.583 ± 0.059 mm³. Their mouths and anuses had not yet opened. At 2 days posthatching (days post hatching, DPH), the yolk was completely absorbed and the larvae began to feed exogenously. Pigmentation was observed in freshly hatched larvae 4 h after hatching, with the presence of eight areas with a dotted pattern on the dorsal surface of the larvae and dispersed spots on the head and yolk sac. At 30 DPH, the TL of the juveniles was 21.34 ± 1.70 mm. The nest area and number of eggs were 259.56 ± 101.39 mm² (75.18-506.04) and 155.33 ± 114.12 (0-437), respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제59권2호
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• pp.99-109
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• 2023

In this study, a comparative test operation was conducted through the alternate haul method to examine the selectivity of the four mesh sizes (60 mm, 90 mm, 110 mm, and 130 mm) of the trawl codend. The selectivity was analyzed using the SELECT model considering the fishing efficiency (split parameter) of each fishing gear in the comparative test fishing operation in the trawl and the maximum likelihood method for parameter estimation. A selectivity master curve was estimated for several mesh sizes using the extended-SELECT model. As a result of analyzing the selectivity for silver croaker based on the results of three times hauls for each experimental gear, it was found that the size of the fish caught increased as the size of the mesh size increased. When the selectivity for each mesh size analyzed by the SELECT model considering the split ratio was evaluated based on the size of the AIC value, the estimated split model was superior to the equal split model. Based on the master curve, the 50% selection length value was 2.893, which was estimated to be 136 mm based on the mesh size of 60 mm. In some selectivity models, there was a large deviance between observed and theoretical values due to the non-uniformity of the distribution of fished length classes. As a result, it is considered that appropriate sea trials and selectivity evaluation methods with high reliability should be applied to present trawl fishery resource management methods.