• Development and Reproduction
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• v.18 no.4
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• pp.321-327
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• 2014

Ultrastructural studies of oocyte degeneration in the oocyte, and the functions of follicle cells during oocyte degeneration are described to clarify the reproductive mechanism on oocyte degeneration of Mactra chinensis using cytological methods. Commonly, the follicle cells are attached to the oocyte. Follicle cells play an important role in oocyte degeneration. In particular, the functions of follicle cells during oocyte degeneration are associated with phagocytosis and the intracellular digestion of products. In this study, morphologically similar degenerated phagosomes (various lysosomes), which were observed in the degenerated oocytes, appeared in the follicle cells. After the spawning of the oocytes, the follicle cells were involved in oocyte degeneration through phagocytosis by phagolysosomes. Therefore, it can be assumed that follicle cells reabsorb phagosomes from degenerated oocytes. In this study, the presence of lipid granules, which occurred from degenerating yolk granules, gradually increased in degenerating oocytes. The function of follicle cells can accumulate reserves of lipid granules and glycogen in the cytoplasm, which can be employed by the vitellogenic oocyte. Based on observations of follicle cells attached to degenerating oocytes after spawning, the follicle cells of this species are involved in the lysosomal induction of oocyte degeneration for the reabsorption of phagosomes (phagolysosomes) in the cytoplasm for nutrient storage, as seen in other bivalves.

• Korean Journal of Environmental Biology
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• v.17 no.3
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• pp.217-232
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• 1999

The author made a special review on/red-tides from the following points: definition, terms, yearly progress of researches, causative organisms, searching the causes, toxins, a loss of lives, damages of aquatic products, reducing aquacultural damages and removal efficiency. Red-tides in Korea were caused by diatoms in the early 1960’s, in the end of 1970’s it was caused by non-toxic dinoflagellates when marine pollutions were growing more and more serious. In the end of 1980’s, red-tides were caused by toxic dinoflagellates. Red-tide was only found in selected areas at first, but recently large-scaled red-tides are frequently found in the southern coastal waters of Korea, causing huge losses of marine life. A plan is greatly needed to reduce the damaging red-tides, and removal systems need to be developed.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.533-536
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• 2009

Withdrawal time of erythromycin in the cultured black rockfish (Sebastes schlegeli) was investigated to provide regulatory authority and fishery industry with full information needed to secure food safety of the fish treated with erythromycin. Medication was carried out using the experimental diet containing erythromycin of which concentration was 200 mg/kg diet and its daily dose was about 40 mg/kg body weight. The withdrawal time needed to reduce antibiotic contents around 10.0 mg/kg accumulated during 9 days medication below 0.2 mg/kg was identified about 10 days. The antibiotic with 13.7 mg/kg of fish on the $9^{th}$ days of medication was completely depleted after 30 days from stop of medication.

• Animal cells and systems
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• v.16 no.6
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• pp.498-505
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• 2012

This study uses the mitochondrial DNA control region to identify the genetic diversity and population structure of the marbled soles (Pleuronectes yokohamae) that inhabit Jinhae Bay and Yokji Island in the nearby sea and the adjacent waters of Namhae, Hansan Island, and Jaran Bay. Direct sequencing of the PCR products revealed 379 bp sequences with 83 variable nucleotide sites, defining a total of 91 haplotypes. The haplotype diversity was high, ranging from $0.917{\pm}0.031$ to $0.983{\pm}0.008$, and nucleotide diversity ranged from $0.015{\pm}0.008$ to $0.024{\pm}0.012$. In addition, 48 haplotypes (52.7%) were unique. Pairwise $F_{ST}$ values were very low, with the maximum value occurring between PYH (Hansan Island) and PJI (Jinhae Bay) ($F_{ST}$ = 0.011). Therefore, no significant genetic differentiation was evident between any pair of sampling localities.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.647-656
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• 2007

Simulation model of outdoor block movement of shipyard is implemented in this paper. The load of the outdoor workshops in a shipyard influences a mid-term planning and scheduling of the shipyard. Since the load analysis is expected in advance before confirming the planning and scheduling, a discrete event simulation (DES) may be a good solution. The accuracy of DES is up to the accurate modeling of Products, Processes, and Resources (PPR) included in a system. PPR in the outdoor system are clearly defined and the simulation model for the outdoor logistics is implemented by modeling the selective PPR with the help of a DES tool which is programmable by users. The simulation model is verified by comparing the results with the real shipyard data. The outputs through the simulation are discussed.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.3
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• pp.212-216
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• 2004

Peroxynitrite formation in vivo is implicated in numerous human diseases and there is considerable interest in the use of antioxidants and natural products for their treatment. The three components (1-3) isolated from Sargassum thunbergii as well as the organic solvent-soluble fractions and the aqueous layer of S. thunbergii were evaluated for their potential to scavenge authentic ONOO$\^$-/ and ONOO$\^$-/ derived from 3-morpholinosydnonimine (SIN-1). The antioxidant activity of the individual fractions was in the order of 85% aqueous (aq.) MeOH＞n$\^$-/ BuOH＞n-hexane＞H$_2$O. The three known compounds, sargahydroquinoic acid (1), sargaquinoic acid (2) and sargachromenol (3) showed peroxynitrite-scavenging activities comparable to those of L-ascorbic acid and penicillamine. These results showed a possible antioxidant activity in major constituents of S. thunbergii.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.427-434
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• 2000

In tradition, there have been two kinds of drying methods, which are sun drying and artificial drying. The sun drying method which has been adopted traditionally has been replaced by the hot-air drying method which is one of the most general methods of artificial drying, with its simple drying system, low initial cost of drying plant, and easy operating method. But the hot-air drying method has some defects; (1) much energy loss happens due to the discharge of hot air during the drying process, (2) control of drying rate is not easy on account of changing relative humidity of inlet air for uniform hot air temperature, (3) high temperature of foods in drying process brings about the production of low-grade drying products. Vacuum drying takes advantage of energy saving and mass production because it reduces the drying time by increasing the drying rate under low temperature condition. The aim of this paper is to develop the low temperature vacum dryer, with low initial investments and operating costs, easy operating method and trouble-free operation.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.912-923
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• 2015

In the results of analyzing Korean corrective action for what are required to be improved according to EU listing Korea as yellow-card non-cooperating third countries against IUU fishing, in order to establish advanced fishery order, it is thought that the following additional improvements are required. (1) The introduction of integrated management system of fishing vessel sailing route, fishing activity, fish catch, and inshore fishing vessel must be considered. (2) It is necessary to establish a system to cross check catch transaction, catch landing, and fish catch report submitted by fishing vessel. (3) Catch transshipment approval system shall be introduced. And a system of reporting and checking catch transshipment at sea shall be reinforced. (4) Punishment shall be strengthened to the extent of making people to perceive that loss due to punishment is larger than profit made from illegal fishing. (5) It shall be so improved that more than a certain percentage of all vessels with fish and fish products caught in waters outside Korea's judicial waters shall be arbitrarily chosen and searched besides a case of being suspected to be IUU fishing. In conclusion, on being listed by EU as yellow-card non-cooperating third countries against IUU fishing, Korean fishery management system shall be generally reexamined, and it shall serve as an occasion to exterminate IUU fishing and to advance fishery management system.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.1118-1128
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• 2015

In the midst of the advancement of global economic trade restrictions, the internationalization of domestic agriculture, which has occurred at a time of crisis in the industry, has presented an opportunity for Korea's agricultural products to be exported overseas. In particular, from 2015, after favorable outlooks for Korean rice, it is expected that the domestic agricultural industry is in a strong position to play a major role in export markets. Due to this, among existing measures targeting the import of rice, increasing domestic measures to boost rice exports and establish an effective operating plan are being pursued. However, until now, appropriate measures targeting domestic rice markets have not been found. In addition, domestic grain piers, which are currently used exclusively for the import of grain, do not have sufficient capacity to handle export operations. Therefore this paper will examine the current status of domestic grain piers, and will suggest a operating plan in grain terminal for the export of grain in order to successfully bring domestically produced rice to foreign markets. The conclusions drawn from this paper are designed to be used as a basic application for the operational plan of grain piers for the purpose of increasing domestic rice exports.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1792-1800
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• 2016

This study is aimed to analyze the profitability of flatfish fry production farms in the Republic of Korea. The continuous and stable production of flatfish fries is one of important factors that increases the possibility of flatfish aquaculture's success. It is also the basis of aquaculture industry that estimates the quantity and quality of fishery products from aquaculture. Based on the surveyed data, production values and costs of flatfish fry production are estimated and compared to determine the profitability of flatfish fry production by farm. Results show that average return on sales of farms is 21.2%(12.4~26.3%), indicating that flatfish fry production would be profitable under the current production and market conditions. Sensitivity analyses of main variables (survival rate and selling price) indicate that the profitability of flatfish fry production farms can be significantly decreased when the survival rate and selling price would be slightly decreased.