• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.132-138
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• 2019

Among several marine-derived microorganisms isolated from the coast of Jeju Island that had antimicrobial activity against fish disease pathogens, Bacillus subtilis MD-02 was tested for its dietary effect on the innate immune response and disease resistance of olive flounder. Strain MD-02 was fed to the olive flounder at a concentration of $1.2{\times}10^4$, $1.2{\times}10^6$, or $1.2{\times}10^8CFU/100g$, respectively. Consequently, the hematocrit was higher in these three groups than that in the control group at 4 weeks, and the aspartate aminotransferase and alanine aminotransferase levels were decreased in the $1.2{\times}10^8$ and $1.2{\times}10^4CFU/100$ groups compared with the control group levels. The amylase activity and total protein were significantly increased in the $1.2{\times}10^4CFU/100g$ group at 3 weeks. The innate immune response, determined from the lysozyme and macrophage activities, was higher in the $1.2{\times}10^8CFU/100g$ group than in the control group. In addition, treatment of the olive flounders with Streptococcus parauberis at $1.2{\times}10^6CFU/ml$ confirmed the mortality rate, which was 100% in the control group and 40-60% in the groups fed B. subtilis MD-02, indicating that the fish had resistance to fish disease pathogens. Therefore, it was confirmed that when fed MD-02, olive flounder builds an innate immune response and acquires resistance to fish disease pathogens, indicating that B. subtilis MD-02 can be developed as a beneficial feed additive.

• The Korean Journal of Malacology
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• v.31 no.4
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• pp.267-272
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• 2015

This study was conducted in order to elucidate the dissemination mechanism of P. olseni using field and laboratory experiments. For this purpose, we quantified the level of P. olseni infection in buried (healthy) and surfaced (gapped) R. philippinarum from a clam bed on Wi-do Island on the west coast of Korea. In addition, the levels of internal and released P. olseni cells from artificially infected (and later dead) R. philippinarum were monitored for 8 days using the RFTM-2 M NaOH lysis method. Our results indicate that P. olseni cells in buried R. philippinarum was $2,655,625{\pm}1,536,936cells/clam$; the level in gapped R. philippinarum was considerably lower, $28,203{\pm}24,889cells/clam$ (p < 0.05). In the laboratory experiment, the P. olseni cells remained in the host tissue 2 days after death was approximately 50% lower than the level of infection measured in living clams. The level dropped to 20% 4 days after death and to 1.5% 6 days after death; eight days after death, P. olseni cells were undetectable since the R. philippinarum flesh had completely decomposed. The level of released cells on the day of death was only 0.05% of the internal level in live R. philippinarum; however, the level increased to 2.3% 5 days after death then gradually decreased and no released cells were detected 8 days after death. Therefore, our laboratory experiment suggest that the low level of P. olseni infection observed in gapped R. philippinarum at Wi-do Island could be caused by lysis of the most of P. olseni cells during the decomposition of dead R. philippinarum tissues. Until the end of decomposition of R. philippinarum, 6.68% of the total amount of P. olseni was released within 8 days. Our study showed that the amount of P. olseni cells from dead host is a considerably higher level than naturally released from healthy R. philippinarum, suggesting that death of the host plays an important role in the dissemination of P. olseni.

• Korean Journal of Environmental Biology
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• v.20 no.2
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• pp.109-117
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• 2002

Detection of protozoan parasites Perkinsus sp. and P. atlanticus was developed in this study using a specific polymerase chain reaction (PCR) to diagnose the presence of those organisms that causes extensive mortalities of marine shellfishes. The PCR was conducted together with fluid thioglycollate medium (FTM) method and 2 M NaOH lysis method. For the test, Manila clams, Ruditapes philippinarum, were collected from four coastal locations in Korea including Wando Island, Gimnyeong, Sungsan and Sogwipo in Jeju. In addition, trophozites of Perkinsus sp. cultivated in vitro and the granular ark clam, Tegillarca granosa, taken from Gangjin on the south coast of Korea, were used as positive and negative controls, respectively. Expected DNA bands were detected in the samples from Wando Island, Sungsan and the in vitro cultured Perkinsus sp. when the probes specific for the genus Perkinsus and P. atlanticus were used. The samples were also positively diagnosed by the FTM and 2 M NaOH methods. In contrast, the Manila clams from Gimnyeong and Sogwipo, and the granular arks clams from Gangjin showed no detectable signs of infection with the PCR, the FTM method and the 2 M NaOH lysis method. On the other hand, being amplified by p. atlanticus specific primer, it is suggested that the protozoan parasite Perkinsus sp. found in the Korean Manila clam is P. atlanticus. Finally the PCR- based assay developed in the present study can be used in detection of Perkinsus infection and discrimination of Peykinsus species in quarantine stations or laboratories due to the high sensitivity and specificity as well as its rapid detection.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.587-593
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• 2020

The securing safety of ferry ships on the domestic coast is evaluated by comparing the external force applied and the securing device based on the cargo weight and hull acceleration that can exist at the loaded position. The hull acceleration based on the domestic standard, which is the basis for securing safety evaluation, is applied without reflecting the characteristics of the ship and the sailing conditions. In this study, a total of 12 acceleration measurements were performed at four points of the hull of a ship with a DWT 6,800 ton class 15.5 knots passing through Busan-Jeju to analyze the hull acceleration of the domestic coastal ferry ship. Data were collected for the buoy. For a theoretical comparative analysis of the limited measurement results, the response amplitude operator (RAO) was analyzed through frequency-response analysis by numerical simulation, and acceleration analysis for the four points was performed using the RAO results. Based on the acceleration comparison, differences in the degree of each position were observed, but in the case of the Y-axis acceleration, the analysis was 1.81 m/s², and the measurement was 1.47 m/s². The analyzed simulation result was as high as 0.34 m/s². Moreover, analysis was performed at 22 % level, and measurement at 18 % level.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.135-146
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• 2015

To provide the data necessary to determine the design wind speed for calculating the wind load acting on a greenhouse, we measured the wind speed below 10m height and analyzed the power law exponents at Buan and Gunwi. A wind speed greater than $5m{\cdot}s^{-1}$ is appropriate for calculating the power law exponent necessary to determine the wind speed distribution function according to height. We observed that the wind speed increased according to a power law function with increased height at Buan, showing a similar trend to the RDC and JGHA standards. Therefore, this result should be applied when determining the power law function for calculating the design wind speed of the greenhouse structure. The ordinary trend is that if terrain roughness increases the value of power law exponent also increases, but in the case of Gunwi the value of power law exponent was 0.06, which shows contrary value than that of the ordinary trend. This contrary trend was due to the elevations difference of 2m between tower installed and surrounding area, which cause contraction in streamline. The power law exponent started to decrease at 7 am, stopped decreasing and started to increase at 3 pm, and stopped increasing and remained constant at 12 pm at Buan. These changes correspond to the general change trends of the power law exponent. The calculated value of the shape parameter for Buan was 1.51, confirming that the wind characteristics at Buan, a reclaimed area near the coast, were similar to those of coastal areas in Jeju.

• Ocean Science Journal
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• v.41 no.1
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• pp.11-29
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• 2006

We investigated species composition and spatial distribution of the euphausiid community in the Yellow Sea and identified the relationship with environmental factors (temperature, salinity, chlorophyll $\alpha$, nitrate, phosphate, and silicate) using bimonthly data from June, 1997 to April, 1998. The environment varied during the sampling period. In warm seasons, thermocline was well developed rendering lower temperature and higher salinity and nutrient concentrations in the bottom layer. During cold seasons the water column was well mixed and no such vertical stratification was noted. Horizontal distribution of temperature, however, differed slightly between near-coast and offshore areas because of the shallow depth of the Yellow Sea, and between southern and northern areas because of the intrusion of water masses such as Yellow Sea Warm Current and Changjiang River Diluted Water. Four euphausiid species were identified: Euphausia pacifica, E. sanzoi, Pseudeuphausia sp. and Stylocheron affine. E. sanzoi and S. affine were collected, just one juvenile each, from the southern area in June and December, respectively. Pseudeuphausia sp. were collected in the eastern area all the year round except June. E. pacifica occurred at the whole study area and were the predominant species, representing at least 97.6% of the euphausiid abundance. Further, the distribution pattern of the species was varied in regards to developmental stages (adult, furcilia, calyptopis, egg). From spring to fall, E. pacifica adults were abundant in the central area where the Yellow Sea Bottom Cold Water prevailed. Furcilia and calyptopis extended their distribution into nearly all the study area during the same period. From late fall to winter, adults were found at the near-coastal are a with similar pattern for furcilia and calyptopis. The distribution pattern of E. pacifica was consistent regarding temperature, salinity, and three nutrients during the sampling period, whereas chlorophyll $\alpha$ showed a different pattern according to the developmental stages. The nutrients should indirectly affect via chlorophyll $\alpha$ and phytoplankton concentration. With respect to these results, we presented a scenario about how the environmental factors along with the water current affect the distribution of E. pacifica in the Yellow Sea.

• Korean Journal of Environmental Biology
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• v.25 no.1
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• pp.34-41
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• 2007

A study on the distribution of V. parahaemolyticus among sea water, sea mud, and marine products in Hwabuk, Samyang, Daepo, Jungmun, Pyoson, Anduk, Aewol, and Gwakji on the coastal area of Jeju island was conducted from January to December in 2002. The 2,880 total specimens of 960 sea waters, 960 sea mud, 960 marine products were collected and studied for the rate of isolation of V. parahaemolyticus, and biochemical, serological and antibiotic sensitivity tests were performed. A total of 417 strains of V. parahaemolyticus were isolated and identified from 2,880 total specimens. In the test of biochemical properties, 100 of V. parahaemolyticus isolates in the presence of 0.85% NaCl were positive in the utilization of lysine, ornithine, indole, glucose, and mannitol, and negative in the utilization of ONPG, arginine, sodium citrate, urea, tryptophane, inositol, sorbitol, rhamnose, sucrose, and melibiose, $H_2S$ production and VP reaction, while positive or negative in gelatin liquefaction and utilization of amygdalin or arabinose. The isolation rates to the specimen were 161 strains (16.8%) from 960 of sea waters, 137 strains (14.3%) from 960 of sea mud, and 119 strains (12.4%) from 960 of marine products. The isolation rates of V. parahaemolyticus from 8 coastal areas were 14.4% (52/360) in Hwabuk area, 15.3% (55/360) in Samyang area, 13.6% (49/360) in Daepo area, 18.3% (66/360) Jungmun area, 13.1% (47/360) in Pyosun area, 16.4% (59/360) in Anduk area, 12.5% (45/360) in Aewol area and 12.2% (44/360) in Gwakji area, respectively. The distribution of 417 V. parahaemolyticus, isolates was high at Jungmun with 18.3% (66/360), and from sea water with 16.8% (161/960).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.4
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• pp.179-195
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• 2004

The trophic state of the coastal waters of the southern part of Korea was assessed using biogeochemical data obtained from the National Marine Environmental Monitoring Program conducted by the National Fisheries Research and Development Institute for six years. The trophic state of different areas, analyzed by non-metric multi-dimensional scaling (MDS) analysis, could divide the areas into three groups. Masan Bay, with suboxic water masses and/or the highest concentrations of dissolved inorganic nitrogen and phosphorus occurred, was assessed as being in a hypertrophic state. Ulsan Bay, Onsan Bay, Busan and Jinhae Bay, located near strong point sources, were in a eutrophic state. Other areas, including Tongyong, Yosu, Mokpo and Jeju island, were evaluated as being in a mesotrophic state. During 1997 to 2002, the average values of excess nitrogen, which is the difference between the measured dissolved inorganic nitrogen (DIN) and the corrected DIN using the Redfield ratio, were positive at Ulsan, Onsan, and Busan, where there were inflows from polluted rivers. In contrast, those were negative values in Haengam Bay, Gwangyang Bay and nearby Yosu. This suggests that the limiting element for phytoplankton growth differed among sites. The time series data of excess nitrogen showed gradual decrease over time in the hypertrophic waters, but the opposite trend in the mesotrophic waters. This indicated that the ratio of nitrogen to phosphate varied according to the trophic state of the coastal waters. The enrichment of organic matter in sediment in eutrophic waters would disturb the normal pattern of biogeochemical cycling of nitrogen and phosphate. In order to assess the condition of the coastal environment, the benthic boundary layer should be considered.

• Progress in Medical Physics
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• v.18 no.2
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• pp.73-80
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• 2007

Fruitful findings have been produced from five out of sixty cells which were obtained from each 63 individual Aplisia caught at the Jeju coast. Spiking patterns of three out of five cells, such as relaxation oscillator, bursting within a short time of the inter-burst interval, chaotic bursting, period doubling sequences, bursting with long trains of action potentials separated by short silent periods, regular repeated beating or elliptic bursting, and silent states had been changed in order as the temperature was lowered to $10^{\circ}C\;from\;32^{\circ}C$. In the intervals of every about 40 minutes repeated ups and downs of temperature produced similar firing patterns at the allowable temperature ranges. The other two cells showed difference from these. The amplitudes of the action potentials of the two cells will not be highly decreased in 24 hours. Average spike frequencies, the inter-burst interval, peak to peak spike amplitude of action potentials, minimum potential values are compared and analyzed by using the computer programme. The spike frequencies according to temperature show the distribution of bell type, with maximal spike frequencies at intermediate temperatures and minimal ones at either end. The most common pattern consist of high spike frequency during failing and low one during rising temperatures.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.937-941
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• 2010

This study investigated the effect of global warming on full bloom date (FBD) of 'Niitaka' pear ($Pyrus$ $pyrifolia$ Nakai) tree by calculating the development stage index by hourly temperatures recorded at Pear Research Station, estimating the distribution of average FBD and the change of FBD according to temperature rising by integrating development rate at 67 locations in Korea Meteorological Administration site. Development stage index of 'Niitaka' pear tree was 0.9593 at Naju location. Differences between full bloom dates observed at Cheonan region and predictions by development stage index were 0-7 days, and matched year was 35.3%. FBDs of 67 locations were distributed from April 4 to May 28. When yearly temperature was raised 1, 2, 3, 4, and $5^{\circ}C$ at 67 locations, predicted FBD was accelerated at most of the locations. However, FBD decelerated at south coast locations from $3^{\circ}C$ rise and did not bloom at 'Gosan', 'Seogwipo', and 'Jeju' locations from $4^{\circ}C$ rise. When monthly temperature was raised 1, 3, and $5^{\circ}C$ at 67 locations, predicted FBD was the most accelerated at March temperature rise, and followed by April, February, January and December. Therefore, global warming will cause acceleration of the full bloom date at pear production areas in Korea.