• Journal of Aquaculture
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• v.15 no.1
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• pp.69-75
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• 2002

Two different sizes of olive founder were abruptly (within 30 min) exposed to hyposalinities from 35 to 0 $\textperthousand$ and to 15 $\textperthousand$ in a flow through seawater culture systems with 8 tanks (300 l/tank). Analysis of blood samples showed the following significant increase at 0 $\textperthousand$ S: hematocrit from 16.1 to 23.4% after 3 hr exposure and to 24.6% after 24 hours; plasma cortisol from 1.6 to 22.8 and 9.5 ng/$ml$ at 1 and 24 hi after exposure. At this salinity, survival decreased to 92 and 20 % after 72 and 144 hours of exposure, respectively. Levels of glucose, $Na^{+}and Cl$^{-}$, total protein and AST showed that the fish was under considerable stress. However, the fish showed no significant stress on exposure to 15 $\textperthousand$S.

• Journal of Aquaculture
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• v.15 no.1
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• pp.61-68
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• 2002

A comparative study on the effect of rearing depths at 2 (surface) and 5 (bottom) m on growth of the scallop was undertaken in Nam-myeon coastal area during June to December, 1997. There were very little difference in the levels of temperature (12.2 ~24.5$^{\circ}C$), salinity (27.3 ~33.1$\textperthousand) and dissolved oxygen (>7.05 mg/l) at a given month. But the chlorophyll level fluctuated between 1.2 and 11.0 $\mu g/l$ at the surface but below 2 $\mu g/l$ at the bosom. Highest phytoplankton density occurred in August and Ceratium dominated it during the period from June to October. Mean growth of the bay scallop at surface and bottom for the six months rearing period was as follows; 0.19 and 0.16 mm/day for shell height, and 0.16 and 0.12 g/day for total weight. Maximum predicted values of shell height calculated by von Bertalanffy growth model were 52.62 mm for the surface and 46.73 mm for the bottom reared scallop. Survival of the scallop was higher (80 %) for the surface group than that at the bottom (60%).

• Journal of Aquaculture
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• v.15 no.1
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• pp.31-37
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• 2002

Effect of 2,4-Dichlorophenoxy acetic acid (2,4-D) on vitellogenin (VTG) production and estrogen ($E_2$)-estrogen receptor (ER) binding affinity were examined in primary hepatocyte cultures of rainbow trout, Oncorhynchus mykiss. Hepatocytes were pre-cultured for 2 days; subsequently, $E_2$( 2$\times$$10^{-6}$/ M) and 2,4-D ($10^{-9}~10^{-6}/M$) were simultaneously added to the incubation medium. They were cultured for more than 5 days. VTG and $E_2$-ER binding affinities were analyzed by SDS-PAGE and ELISA, respectively. 2,4-D concentration used had no appreciable effect on the morphology, viability, and DNA content of hepatocytes in culture. It had also no effect on VTG production. However, it interfered with $E_2$-ER binding affinity, which was reduced with increasing concentration of 2,4-D. The affinity was inhibited by 25 and 30% at $10^{-7}$ M and $10^{-6}$ M of 2,4-D, respectively. This result suggested that although 2,4-D had no effect on VTG production, it acted as reno-estrogenic contaminant in ER.

• Journal of Aquaculture
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• v.15 no.1
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• pp.15-21
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• 2002

Two groups of juvenile flounders (90 g/each) were fed on moist pellet feed thrice a day for a period of 8 weeks; the first group, reared in 4 circular (6m $\times$ 0.8 m) tanks (1200 flounders/tank), was fed daily (ED) and the second one on alternate days (EO). There was no significant difference in growth and feed conversion ratio (FCR) between these groups. There was also no difference in chemical composition, except in lipid, which was significantly higher (4.1%) in the ED group than the EO group (3.4%). Food intake and gain in the whole body nitrogen (N) were higher in the ED group but there was no significant difference between these groups in N retention; they excreted almost equal amount (114 vs 112 g) of N. Although phosphorus intake was significantly different between these groups, the flounders retained equal amount (0.5 g) of P in their body and excreted also equal amount (27.6 vs 26.0 g/kg weight gain) of p. Energy intake (2528 kJ) of the ED group was higher than that (2116 kJ) of the EO group. However, there was no significant difference in their energy retention efficiency. Clearly, alternate day feeding regimen led to more efficient utilization of food by the juvenile flounder.

• Ocean and Polar Research
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• v.28 no.2
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• pp.95-105
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• 2006

To clarify the seasonal changes of the phytoplankton community in seagrass beds, the abundance and distribution of phytoplankton, and environmental factors were measured in seagrass beds: in the Dongdae Bay and Aenggang Bay on the southern coast of Korea, and off Seungbong Island on the western coast of Korea, in October 2002, January, March, and June 2003. Water temperature, salinity, SPM, chlorophyll a, aboveground biomass of seagrass, DIN and DIP concentrations significantly changed within the sampling time. The taxa of phytoplankton observed in seagrass beds were classified as 3 divisions, 3 classes,4 orders,16 families, 27 genera, 65 species. 50 species of diatoms were recognized with 14 species of dinoflagellates, and 1 species of silicoflagellate. The species of genera Coscinodiscus and Thalassiosira were dominant all around the study areas but Peridinium granii, Eucampia zodiacus and Pleurosigma elongatum were seasonally dominant. Phytoplankton standing crops varied from minimum of $0.6{\times}10^3\;cells\;l^{-1}$ (June, Dongdae Bay) to maximum$21.1{\times}10^3\;cells\;l^{-1}$(March, Aenggang Bay). The standing crops and species composition of phytoplankton were relatively lower and simpler than those of other southern and western coastal areas. Seasonal variations of diatom standing crops in seagrass beds were attributed to seasonal changes in DIN and in DIP of water column.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.193-198
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• 2015

This research was conducted to provide an improvement plan concerning medical treatment on board and medical health care conditions for seafarers. 139 persons from government agencies and seafarer related organizations, who could influence the government's seafarers healthcare policy-making, were asked to fill in the questionnaire prepared for this research about their perceptive views on actual condition of health and disease management for seafarers. The results of the survey on seafarer's health care management conditions(p<0.01), health care manage ability(p<0.01), current radio emergency medical service policy(p<0.01), usefulness of on board medicine chest and medical equipment(p<0.05), and the system of the onboard medical care persons show the difference of perception level among the seafarer related organizations. But generally, the rate of negative responses was high. And this research suggests that there is an urgent need to provide portable health measurement equipment on board, reenforce regular medical examination and establish the seafarer's health promotion center for telemedicine and healthcare management(p<0.01) in order to improve the onboard medical treatment support system for healthcare of seafarers.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.149-156
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• 2015

The Dynamic Positioning System consists of 7 elements which are namely Power system, Human machine interface, DP Computer, Position Reference System(PRS), Sensors, Thruster system and DP Operator. Incidents like loss of position(LOP) on DP vessel usually occur due to errors in these 7 elements. The purpose of this study is to find out safety operation method of DP vessel through qualitative and quantitative analyze of DP LOP incidents which are submitted to IMCA every year. The 612 DP LOP incidents submitted from 2001 to 2010 were analyzed to find out the main cause of the incidents and its rate among other causes. Consequently, the highest rate of incidents involving DP elements are PRS errors. DP computer, Power system, Human error and thruster system came next. The PRS has been analyzed and a flowchart was drawn through expert brainstorming. Also, the conditional probability has been analyzed through Bayesian Networks based on this flowchart. Consequentially, the main causes of drive off incidents were DGPS, microwave radar and HPR. Also, this study identified the main causes of DGPS errors through Bayesian Networks. These causes are signal blocked, electric components failure, relative mode error, signal weak or fail.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.375-384
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• 2016

This study aimed to specify Vessel Traffic System(VTS) operators' situational awareness(SA) tasks and examine differences in subjective ratings for three levels of SA. Data for relative frequencies of SA tasks were collected by using direct in field observation. Subjective rating scores were obtained using a questionnaire method and compared in terms of VTS operator's gender and length of service career. The results are as follows. First, it was found that the VTS operators perform information perception task elements more frequently than those for information integration and prediction. Second, VTS operators tended to show subjectively lower evaluation scores for prediction than information perception or integration. Third, male VTS operators rated their SA ability higher than females. Fourth, the male VTS operators more than 15 years of career service showed higher subjective rating scores than those with under 5 years of service. Female VTS operators with different levels of career service showed a similar level of subjective rating scores. These results suggest that the frequency of SA related tasks and subjective SA evaluation can differ in terms of SA levels and individual differences.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.401-412
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• 2016

The sustainable operation and development of ports is a key industry for Korea's national economy. It is increasingly more important to resolve conflicts with local communities due to port environmental problems such as air pollution, water pollution, noise and ecosystem destruction while securing port competitiveness through infrastructure expansion. In case of the Busan New Port development project in Korea, construction has been temporally suspended due to conflict with local fishermen over marine sand mining for construction. A primary reason for this is the absence and limitation of qualitative port environmental impact assessment methodologies in Korea. This includes the current investigation of fisheries damaged by ports. Therefore, the main purpose of this study is to propose economic valuation methods for assessing environmental impacts that are essential for efficient port environmental management and for sustainable port operation and development in Korea. To do this, this study examines the overall port environmental problems and their effects (damages) through the analysis of environmental policies and case studies of domestic and overseas ports. Then economic valuation methods are suggested for total economic values (TEV) of damaged environmental goods and services. Among the proposed methods, Habitat Equivalency Analysis (HEA), as a more scientific data based method, was applied to estimate marine ecosystem service damages from the designation of Busan New Port Anchorages. Finally, based on the study results, more efficient port environmental management will be achieved through the institutional adoption of the proposed economic impact assessment methods for port environmental damages.

• Journal of Bio-Environment Control
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• v.29 no.1
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• pp.28-35
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• 2020

This study is to compare irrigation efficiency between sap flow sensor automated system (SF) and conventional irrigation system based on integrated solar radiation automated system (ISR) in tomato rockwool hydroponics. Total irrigated volumes was higher in the ISR system by 5.0L per plant, a lower drainage rate was found in the SF system, compared to the ISR system. There was no difference in shoot and fruit fresh weights, water use efficiency (WUE) and water amount consumed for producing 200g of tomato fruit. The daily average sap flow density (SFD) was closer to the change of solar irradiance (SI) in the plant grown under the SF system, compared to the ISR system. The correlation coefficient (r²) between the fruit diameter and the volumetric water content during the 56 and 82 days after transplant showed the SF treatment was higher than the ISR at night and daytime, and the correlation was higher at night time. The sap flow density and humidity deficit (HD) of SF treatment was related as closely as the solar irradiance. Further studies should demonstrate that SF irrigation system is a convenient method for hydroponic farmers with advantages, such as growth, higher yield, WUE, and accuracy.