• Korean Journal of Microbiology
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• v.51 no.1
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• pp.86-95
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• 2015

To study the halobacterial diversity at the rhizospheric soil of coastal plant native to Dokdo islands, several host plant were selected and its rhizospheric soil was sampled. Soil sample was diluted serially and pure isolation was done by sub-culture using marine agar media. 26 halophilic strains cultivable at the marine medium containig concentration of 9.0% sodium chloride were selected among total 161 isolates. Their partial 16S rRNA gene sequences extracted from genomic DNA were analyzed and partially identified. Furthermore, to identify their genetic relationship, phylogenetic tree was deduced. Total 26 strains were belongs to Firmicutes (30.8%), Gamma proteobacteria (53.8%), Bacteroidetes (7.7%), Alpha proteobacteria (7.7%), and Actinobacteria (7.7%). These results showed the specific difference from previous researches which has been reported the microbial flora of soil or sea water around the Dokdo islands. Furthermore, 4 among 26 halophilic strains grew at above 12.0% NaCl concentrated marine broth, and 2 strains Idiomarina abyssalis LM4H23 and Halomonas huangheensis AS4H13 grew at 15.0% concentration. These halophilic strains thought to overcoming the severe stress like high salt concentration or variation derived from Dokdo-specific climate and might have unknown, specific relationship with their host coastal plant native to Dokdo islands.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.3
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• pp.151-156
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• 2009

The purpose of this study is to evaluate the affecting factors on Oil-Mineral Aggregates(OMA) for stranded oil on intertidal flat, because the OMA formation enhances the oil dispersion and biodegradation rates. We choose the affecting factors such as spilled oil concentrations(50, 100, 200, 300, 400, 500 mg/L), mineral concentration(100, 200, 500, 1,000, 2,000, 4,000 mg/L), salinity(10, 20, 30, 40 psu), shaking time(1, 2, 4, 8, 12, 24 hr) and applied dispersant volume(0, 5, 10, 15, 20%). Major conclusions derived from this study are as follows. It was observed that the kaolinite interacts three times strongly with crude oil than quartz. OMA formation was enhanced with increasing of spilled oil concentrations, whereas the increase of salinity rarely affected the OMA formation. The shaking time for OMA formation affected positively with kaolinite, but quartz was irrespective the shaking time. The applied dispersant enhanced the OMA formation by 13% in kaolinite and 56% in quartz experimental condition.

• The Korean Journal of Food And Nutrition
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• v.11 no.2
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• pp.237-242
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• 1998

This study was carried out to process canned ark shell with highly quality by management of proper processing conditions for prevention of oxidation and discoloration by heating. Ark shell has hemoglobin as blood pigment in red blood shell which same as other cockles. Hemoglobin is easy to come oxidation and browning reaction, and it has large contents of carotenoid as meat pigment. Proximate compositions in ark shell were 76.9% of moisture, 18.1% of crude protein, 1.8% of crude lipid, 1.3% of carbohydrate and 1.6% of crude ash. And contents of carotenoid and hemoglobin were 0.67~1.02mg% and 0.98~1.64g/dl, respectively. When the living ark shell was soaked in 2% NaCl solutions, about 89% of mud was removed after 10 hours soaking, and over 91% was removed when the pH was adjusted to 7.5. Carotenoid pigment were prepared that extracted from ark shell by using acetone. And determined visible spectrum were two peak at 452nm and 687nm, and λmax were 452nm. During thermal treatment at 95$^{\circ}C$, 111$^{\circ}C$, 116$^{\circ}C$ and 121$^{\circ}C$ for 60 minutes, retention ratio of carotenoid were 71.8%, 66.8%, 64.4% and 36.5%, and after 120 minutes retention ratio were 56.6%, 30.6%, 30.3% and 17.2%, respectively. When heated at 95$^{\circ}C$, 111$^{\circ}C$, 116$^{\circ}C$ and 121$^{\circ}C$, formation of browning material were increased at high temperature and long time treatment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.253-262
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• 1990

Hardened seed oysters which inhabit the Hansan Bay of Korea and Hiroshima Bay of Japan were cultured at the oyster farm of Nino island near Hiroshima from June, 1972. to June, 1973. The present experiment investigated monthly increment of shell height, shell length, meat weight, moisture, fatness and gonad development of the seed oysters. Environmental factors were also checked to know ecology of the oysters. The oyster farm of Nino island near Hiroshima city showed high water temperautre and low salinity com-paring with the oyster farm of Hansan Bay. Korea. Shell height and shell ten求h of the hardened seed oyster of Hansan Bay grew faster than those of Hiroshima Bay, especially in oyster meat weight. Histological observation on gonads showed little difference in developmental process between the two localities from June through December, 1972, whereas the hardened seed oyster from Hansan Bay has grown rapidly in the development of gonad after February, 1973. It can be concluded that in the viewpoint of seed oysters productivity the hardened seed oyster from Hansan Bay is more effective than that of Hiroshima Bay comparing in seed growth, fatness and developmental process of gonad.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.70-76
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• 1986

The purpose of this study is to offer the basic data of the tidal river development program by grasping the diffusion between the high density-sea water and the low density-fresh water in the tidal river. The tidal range of Hyungsan river which flows at Youngil bay in Pohang was selected to analysis the phenomenon of density current. The results obtained are as follows ; The tide of Youngil bay was one time a day, 0.104m in high tide difference and 0.085m in mean tidy difference. The change of sea level by tide was negligible. The volume of reserved water by sea water was $2,700,000m^3$ and available water of irrigation was $1,200,000m^3$ that salt density is below $750{\mu}{\mho}/cm$ out of total volume. Salt intrusion phenomenon by density current was a little water level change, however, it become a salt wedge type by the much salt invasion during the spring tide and it makes a well-mixed type by the retreating salt wedge during the neap tide. As long as there were some density differences between sea water and fresh water, net upstream flow was existed along the bottom of water way from the estuary to the upstream channel.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.4
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• pp.128-134
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• 2022

Nakdong river estuary is being operated with the goal of expanding the period of seawater inflow from this year to 2022 every month and creating a brackish water area within 15 km of the upstream of the river bank. In this study, the deep learning algorithm Long Short-Term Memory (LSTM) was applied to predict the salinity of the Nakdong Bridge (about 5 km upstream of the river bank) for the purpose of rapid decision making for the target brackish water zone and prevention of salt water damage. Input data were constructed to reflect the temporal and spatial characteristics of the Nakdong River estuary, such as the amount of discharge from Changnyeong and Hamanbo, and an optimal model was constructed in consideration of the hydraulic characteristics of the Nakdong River Estuary by changing the degree according to the sequence length. For prediction accuracy, statistical analysis was performed using the coefficient of determination (R-squred) and RMSE (root mean square error). When the sequence length was 12, the R-squred 0.997 and RMSE 0.122 were the highest, and the prior prediction time showed a high degree of R-squred 0.93 or more until the 12-hour interval.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.435-444
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• 2023

Suitable environmental conditions in Saemangeum frequently favor phytoplankton growth. There have been occurrences of sudden phytoplankton blooms, surpassing the algae management standards. A model was designed to prevent such blooms using scientific predictive techniques to forecast and regulate the possibility of phytoplankton blooms. We propose effective and efficient algae control measures concerning every phytoplankton species optimized through the policy control of nutrients (DIN, PO4-P) from rivers and controlling lake salinity using gate operations. The probability of phytoplankton blooms was initially forecast using an artificial neural network algorithm based on observations. The model's Kappa number fluctuated from 0.7889 to 1.0000, indicating good to excellent predictive power. The Garson algorithm was then utilized to assess the significance of explanatory variables for every species. Meanwhile, the probability of phytoplankton blooms was anticipated depending on the DIN and salinity value changes. Therefore, the model predicted the precise DIN and salinity concentrations to inhibit phytoplankton blooms for each species. Hence, the green algae model can create effective proactive measures to avoid future phytoplankton blooms in enormous artificial lakes.

• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.345-354
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• 2020

The purpose of this study was to investigate the effects of soil amendment treatments, such as hydroball, and active carbon, and planting Pennisetum alopecuroides for reducing calcium chloride (CaCl₂) of soil leachate and the growth of Pennisetum alopecuroides. The experiment planted Pennisetum alopecuroides in a plastic pot with a diameter of 10 cm and a height of 9 cm in a greenhouse April-October 2018. The experimental group comprised six treatments, including Non-treatment (Cont.), Hydroball (H), Active carbon (AC), planting Pennisetum alopecuroides (P), hydroball + planting Pennisetum alopecuroides (H + P), and active carbon + planting Pennisetum alopecuroides (AC + P). The dissolution of the CaCl₂ concentration 200ml of 10g/L was irrigated once every two weeks. We measured the growth (plant height, leaf length, leaf width, number of leaves), EC, pH, and exchangeable cations (K⁺, Ca²⁺, Na⁺, and Mg²⁺) according to the high concentration of CaCl₂ in the plant and soil leachate. In a treatment with the 'hydroball' amendment, the soil leachate electrical conductivity (EC), and the cation exchangeable were decreased more than those of the control, while the growth of Pennisetum alopecuroides relative growth rate(RGR) increased. Overall, application with the hydroball amendment added the planting of Pennisetum alopecuroides improved the salt reduction effect more than the control group. These results indicate that the application of the soil amendment agent hydroball was suitable soil amendments in accordance with the high concentration of calcium chloride (CaCl₂). Also, Planting Pennisetum alopecuroides is expected to be appropriate for salt-tolerant plant for soil affected by deicing salt agents.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.2
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• pp.101-114
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• 2012

The physico-chemical characteristics including water temperature, salinity, dissolved oxygen(DO), chemical oxygen demand (COD), chlorophyll-a(Chl. a), suspended particulate matter(SPM) and dissolved inorganic nutrients were investigated in the Garolim Bay, Yellow Sea, Korea in 2010 carried out six times per year at 11 fixed stations by Korea Fisheries Research & Development Institute. The water temperature, salinity, COD, dissolved inorganic nutrients, Chl. a and SPM showed significant difference between surface and bottom water but the other parameters didn't. There were not significant difference between stations. The water temperature showed typical change patterns of the temperate seawater. The annual average of salinity showed more than 31 so that there could not have occurred low saline water. The average of DO from June to August showed over than 3mg/L which showed higher than the below standard value of the hypoxic (oxygen-deficient) water. The average of Chl. a varied $1.68{\mu}g/L$ at surface, $2.38{\mu}g/L$ at bottom layer in June and $1.68{\mu}g/L$ at surface, $1.57{\mu}g/L$ at bottom layer at August. The dissolved inorganic nutrients showed high concentration in February and low concentration in August due to the limitation of the freshwater input in summer and phytoplankton used to the dissolved inorganic nutrients. The ratio of DIN/DIP showed 30.52 at surface and 37.89 at bottom layer in June which was higher than other month. The SPM was 44.15mg/L at bottom layer in February which was the highest value in this study due to the northwest monsoon. Because of the actively water change in the open sea without inflow of freshwater from land in Garolom Bay, there were not occurred low saline water and hypoxic water. thus, this Bay showed good water quality and required to be conserved continuously as important costal area for fisheries.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.303-312
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• 2007

In order to investigate the dynamics of phytoplankton standing crops affecting by environmental factors, biological and environmental factors, this study was examined in the marine ranching ground of Tongyeong coastal waters from 2000 to 2007. During the study, mean water temperature and salinity were 16.7$^{\circ}C$ and 32.9 psu, respectively. pH, DO and SS varied from 7.81$\sim$8.09, 3.02$\sim$8.97 mg $L^{-1}$ and 2.7$\sim$32.2 mg $L^{-1}$, respectively. Mean concentrations of dissolved inorganic nitrogen, phosphate and silicate were 21.75 ${\mu}M$, 0.90 ${\mu}M$ and 14.38 ${\mu}M$, respectively. Chlorophyll a concentrations varied from 0.02 ${\mu}g$ $L^{-1}$ to 25.29 ${\mu}g$ $L^{-1}$ with mean a value of 2.0 ${\mu}g$ $L^{-1}$. These factors did show significant differences on each layer and season, while did not show on the sampling stations. Phytoplankton standing crops varied from $4.21\times10^3$ cells $L^{-1}$ to $1.44\times10^6$ cells $L^{-1}$ with a mean value of $1.92\times10^5$ cells $L^{-1}$. Especially, variations of phytoplankton standing crops had an unimodal pattern as only bloomed in autumn rather than a bimodal pattern as generally bloomed in spring and autumn. In results of stepwise multiple regression analysis, the coefficient of determination $(R^2)$ for total standing crops was 0.35 and the standing crops were affected by water temperature, salinity, phosphate and silicate. The factors affected were different seasonally; water temperature in spring, salinity in summer, water temperature, salinity and silicate in autumn and water temperature, salinity and suspended solids in winter. Therefore, the results from the statistical analysis showed that the environmental factors influencing on the variations of the phytoplankton standing crops were predominantly water temperature and salinity.