• 동력기계공학회지
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• 제21권2호
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• pp.64-69
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• 2017

The purpose of this study is to investigate the performance characteristics of seawater cooling system for a fishing vessel. The circulation amount of refrigerant, condensation capacity, evaporation capacity, compression work and coefficient of performance(COP) were analyzed as the heat source temperature changed. The experimental setup consisted of an open-type compressor, a shell&tube type condenser, an evaporator and an expansion valve. The heat source was controlled by a constant temperature chamber. The main results of this study are summarized as follows. The condensation capacity increased with increasing heat source temperature, and it was confirmed that the effect of circulating amount of refrigerant was dominant. The amount of heat for vaporization was almost constant even though the temperature of the heat source increased. On the other hand, the compression power was increased. This is because the compression ratio increases as the condensation pressure, the enthalpy difference between inlet and outlet, the amount of circulating refrigerant increases. The performance coefficient of this system showed a tendency decreasing with increasing heat source temperature. Therefore, the basic data of the seawater cooling system for the maintenance of the catch line of the shore fishing boats was acquired through this study, and it is considered that it will be sufficient for the actual design.

• 한국수산과학회지
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• 제55권5호
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• pp.721-729
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• 2022

We investigated the ecological characteristics and biomass of white croaker Pennahia argentata population in the South Sea of Korea using catch data from Danish seins fishery and biological data from 2018 to 2020. Survival rate (S), which was estimated using Pauly method (1984) was 0.361 per year, and the instantaneous coefficient of total mortality (Z) was 1.019 per year. The instantaneous coefficient of natural mortality (M) and that of fishing mortality (F) were estimated as 0.351 and 0.668 per year, respectively. At first capture, age was estimated to be 1.19 years and length at this age was 18.7cm. The annual biomass was estimated with a biomass-based cohort analysis using annual catch data between 1997-2020 in Korean water. The biomass of the white croaker declined sharply from 4,000 tons in 1999 to the lowest level of approximately 1,000 tons in 2004. Post 2004, the biomass started to increase gradually and reached approximately 7,000 tons. The amount of resources was 35.7%, 34.8%, and 16.5% at age one, two, and three years, respectively, and 86.9% of all captured white croaker individuals belonged to the age group of 1-3 years.

• 수산해양기술연구
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• 제59권1호
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• pp.28-34
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• 2023

In the anchovy boat seine fishing boat, it is necessary to select other aquatic organisms other than live anchovies, which are the target species of catch. By making a rotating roller sorter using hydraulic pressure, the anchovy sorting amount was compared and the sorting accuracy of the rotary roller sorter, and the discharge speed of butter fish and jerry fish according to the number of roller revolutions were analyzed. The rotating roller sorter increases the weight of the sorted raw anchovy by 54%, 74% and 91.5% compared to the round bar fixed type, so it can reduce the required time by an average of 73.2%. As a result of converting the sorting accuracy to the weight of pure anchovies excluding the catch weight, the round bar fixed type was 89%; however, the average of the rotating roller sorter was 97.7%. Thus, the sorting accuracy of the rotary roller sorter was further improved by about 8.7%. The roller speed moved 7% at 300 rpm, 7.5% at 600 rpm, and 16% at 900 rpm, so butter fish were discharged overboard 10% faster than jelly fish on average. In addition, the average feed speed of butter fish and jelly fish is 1,400 mm/s when the roller rotation speed is 300 rpm, 1,480 mm/s at 600 rpm, and 1,850 mm/s at 900 rpm. A Φ58 mm roller rotates once it moved about 1.23 mm. In the future, a follow-up study of quantitative evaluation is needed targeting more non-target fish species of anchovy boat seine.

• 수산해양기술연구
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• 제44권1호
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• pp.20-30
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• 2008

In order to evaluate the biodegradability of bait used in the pot for swimming crab, water tank experiments were conducted. Mackerel is the most commonly used natural form of bait to catch the swimming crabs, and therefore was used in this experiment for the biodegradability according to the manufacturing process of the bait. From the biodegradability test on chemical oxygen demand(COD), total nitrogen(T - N), total phosphorus(T - P), ammoniac nitrogen, nitrite nitrogen and nitrate nitrogen per unit weight of the bait based on the production rate and the accumulated amount of pollutants, it was concluded that the smaller the size of the mackerel pieces, the higher the production rate and accumulated amount of organic matter and nutrients which was unfavorable to water pollution. The amount of pollutants released from the intestine of the tuna was similar with that from the whole mackerel. For the operation period of 111 days, the accumulated concentrations of tested pollutants from the tuna which were 67.3 mgCOD/g d, 86.4 mgT N/g d, 3.1 mgT - P/g d, were almost half comparing with those from the mackerel which were 65.7 - 94.4 mgCOD/g d, 83.8 - 109.4 mgT - N/g d, 3.1 - 5.2 mgT - P/g d. The amount of pollutants released from the intestine of the tuna was slightly less than that from the mackerel that was cut into 8 pieces. but more than that from the mackerel which was not cut into pieces. Therefore, it can be concluded that the key factor in determining water pollution potential is not the kind of bait, but the processing or preparation method used.

• 수산해양기술연구
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• 제57권2호
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• pp.173-184
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• 2021

In this study, internationally widely utilized bioeconomic models were used to make a comparison and analyze the effectiveness of red snow crab fisheries management measures. As a specific effect analysis, biological and economic effects of both total allowable catch (TAC) and effort reduction management measures were analyzed simultaneously. Model results showed that the red snow crab biomass would be decreased from 106,000 tons to 73,076 tons after ten years when the TAC is set to and maintained at the current level of 26,000 tons. The amount of biomass would be increased to 125,316 tons when the level of TAC is set to 22,000 tons. In cases of reduced fishing efforts, a 30% decrease from the current level would result in greater biomass and NPV would be also estimated at the highest level. In addition, a sensitivity analysis by market price was conducted to analyze the minimum TAC level of the red snow crab offshore pot fishery. Results showed that the minimum TAC level would be 8,210 tons when the market price increased by 30% and it would be also 15,247 tons when the market price decreased by 30%. Furthermore, results of the sensitivity analysis by fishing cost showed that the minimum TAC level was analyzed to be 13,857 tons when the fishing cost increased by 30% from the current level.

• 수산해양기술연구
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• 제54권3호
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• pp.224-230
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• 2018

Squid is one of the important fisheries resources in Korea. Therefore, squid has been designated and managed as a target species of total allowable catch (TAC) since 2007, but the catch amount is gradually decreasing. The analysis was conducted to identify the change of relative fishing power index to develop the vessel and gear technology that may have improved the fishing efficiency of the offshore squid jigging fishery from 1960s to 2010s. Gross tonnage per fishing vessel increased with the increase in size until 1990, but then gradually decreased to 41.0 tons in 2000 and 37.1 tons in 2010. The illuminating power (energy consumption) by fishing lamps increased to 180 kW in 2005 and stabilized to 120 kW in 2015. Jigging machine started to be supplied to fishing vessels from the early 1970s, and fish finders began to be supplied in the early 1980s and gradually increased. Therefore, the relative fishing power index in the offshore squid jigging fishery increased from 1.0 in 1980 to 1.1 in 1990, to 3.5 in 2000 and to 2.5 in 2010, but the increment rate slowed down gradually. The results are expected to contribute to reasonable fisheries stock management.

• 한국수산과학회지
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• 제54권6호
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• pp.1030-1035
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• 2021

Diving fishermen are demanding permission to use an inspirator that can efficiently catch Manila clam; however, coastal fishermenargue that the use of inspirator devastates the seabed and depletes fishery resources. Therefore, the aim of this study was to evaluate the fishing power of diving gears and its effect on coastal fishing grounds. The average time taken to fish in the seabed (4 m²) with a rake, water gun, and an inspirator was 11.17 min, 13.33 min and 7.81 min, respectivelyThe values of catch per unit time with a rake, water gun, and an inspirator were 3.35 kg/min, 2.26 kg/min, and 3.83 kg/min, respectively. Suspended sediments were observed the most in the water gun fishing area, and were observed more in April when fishing was not carried out than in February when fishing was carried out. However, the difference in the amount of sediment deposited in the fishing area using the three-fishing gears was very small. For an accurate analysis of the impact of the fishing gears on the seabed, supplementary tests such as grain size analysis and changes in benthic organisms need to be conducted.

• 수산해양기술연구
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• 제47권1호
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• pp.10-17
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• 2011

Biodegradable octopus pot was developed to reduce plastic pollution problem in the sea and fishing trouble between fishermen. It can be expect to recycle other wasted biodegrade fishing gear. Experimental fishing was carried out to understand the difference in fishing efficiency between Polyethylene (PE) octopus pots and biodegradable (Polybutylene Succinate and Polybutylene adipate-co-terephthalate) octopus pots which was tried to make in this study in the sea. There were caught by 237 numbers of fishing during the experimental period. Among the 237 numbers of fishing, 160 or 67.5% were PE pots which were more than the biodegradable pots. A comparison of the monthly catches between the PE pots and biodegradable pots shows that the catches were overall higher in the PE pots than in the other pots. The result is very similar with the comparison of total catches by each type of the pots. In terms of bycatch, the number of species, amount of catches and the number of fishing with bycatch were more significant in the biodegradable pots than in the PE pots.

• 한국물환경학회지
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• 제20권5호
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• pp.525-533
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• 2004

The object ofthis study was to test for STORMSYS process that composed Catch Basin and Stormsys(three units: vortex solids separator, filter media bed and vegetated filter strips). It could be applied to treat the first-flush non-point pollution materials on the road(especially, motorway). This study investigated that the runoff characteristics of non-point pollutions containing the heavy metal(Fe, Zn and Cu) by rainfall showed relatively high pollution concentration in the early-stage storm runoff on the road, which seems to be caused by the vehicular traffic, and showed the rapid reduction of pollution concentration on the basis of about 5mm rainfall volume. As the number of the non-rainy days were increased, the pollution concentration by storm runoff was increased, also. As a test result of this process, the average removal efficiency of BOD, $COD_{mn}$, SS, T-N and T-P over the testing period were 92.7%,88.6%,97.4%,93.0% and 93.3%, respectively. Also, the average removal efficiency of n-Hexane, Fe, Zn and Cu were 86.7%, 96.1%, 84.4% and 78.4%, respectively. As shown in the characteristics of storm runoff, the non-point pollution materials have high pollution concentration in the early-stage storm runoff on the road, the installation of STORMSYS process is expected to reduce considerable amount of non-point pollutions.

• Communications for Statistical Applications and Methods
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• 제19권1호
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• pp.117-128
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• 2012

In Baccarat, the gambler can bet on either the Player or Banker. The only gambler's strategy is to consider the previous winning history on the round. The winning probabilities of Player or Banker are calculated by simulation using R. Conditional winning probabilities given that Player or Banker has won i consecutive times are also calculated by simulation. Conditional winning probability implies that the sequence of Baccarat results is an almost independent sequence of events. It has been shown that the total amount of returns in each round of games is almost identical to a random walk. Thus, one possible strategy is to catch the trend(the Player or the Banker) of the random walk and to bet on that side of the trend.