• Journal of Microbiology and Biotechnology
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• v.28 no.3
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• pp.432-438
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• 2018

Microalgae hold promise as a renewable energy source for the production of biofuel, as they can convert light energy into chemical energy through photosynthesis. However, cost-efficient harvest of microalgae remains a major challenge to commercial-scale algal biofuel production. We first investigated the potential of electrolytic water as a flocculant for harvesting Tetraselmis sp. Alkaline electrolyzed water (AEW) is produced at the cathode through water electrolysis. It contains mineral ions such as $Na^+$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$ that can act as flocculants. The flocculation activity with AEW was evaluated via culture density, AEW concentration, medium pH, settling time, and ionic strength analyses. The flocculation efficiency was 88.7% at 20% AEW (pH 8, 10 min) with a biomass concentration of 2 g/l. The initial biomass concentration and medium pH had significant influences on the flocculation activity of AEW. A viability test of flocculated microalgal cells was conducted using Evans blue stain, and the cells appeared intact. Furthermore, the growth rate of Tetraselmis sp. in recycled flocculation medium was similar to the growth rate in fresh F/2 medium. Our results suggested that AEW flocculation could be a very useful and affordable methodology for fresh biomass harvesting with environmentally friendly easy operation in part of the algal biofuel production process.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.1040-1048
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• 2010

An infiltration storage can be installed as a method of reducing runoff from catchment and increasing stream flow during the dry period by recharging groundwater. However, there is no proper model and method that can be used to design storage capacity of an infiltration storage in Korea. The purpose of the study is to evaluate capacities of infiltration storages planned on Jeju-do in Korea by modifying Storm Water Management Model (SWMM). The basic equations for the infiltration storage are same as those of the infiltration trench used in MIDUSS. Infiltration rates of the infiltration storages were first measured by double ring infiltrometers, and then the modified model was applied to evaluate adequacy for the capacities of three infiltration storages planned on Jeju-do in Korea. The application results show that the two infiltration storages with higher infiltration rates have adequate capacities to infiltrate the total water inflow to the storages. However, the other infiltration storage with lower infiltration rates has not sufficient capacity to infiltrate the total water inflow to the storage and release occurs to the downstream region. The simulation model and method applied can be used for capacity evaluation of future infiltration storages on highly pervious areas in Jeju-do.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.1
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• pp.19-40
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• 2023

To investigate the role of water masses in the Jeju Strait in summer on the shallow coastal region and the characteristics of water properties in the strait, temperature and salinity were observed across the Jeju Strait in June, July, and August 2019. The cold water pool, whose temperature is lower than 15℃, was observed in the mid-depths of the central Jeju Strait and on the northern bottom slope of the strait. The cold water pools have the lowest temperature in the strait. To identify water masses comprising the cold water pool in the Jeju Strait, mixing ratios of water masses were calculated. The mid-depth cold water pool of the Jeju Strait consists of 54% of the Kuroshio Subsurface Water (KSSW) and 33% of the Yellow Sea Bottom Cold Water (YSBCW). Although the cold water pool is dominantly affected by the KSSW, the YSBCW plays a major role to make the cold water pool maintain the lowest temperature in the Jeju Strait. To find origin of the cold water pool, temperature and salinity data from the Yellow Sea, East China Sea, and Korea Strait in the summer of 2019 were analyzed. The cold water pool was generated along the thermohaline frontal zone between the KSSW and YSBCW in the East China Sea where intrusion and mixing of water masses are active below the seasonal thermocline. The cold water in the thermohaline frontal zone had similar mixing ratio to the cold water pool in the Jeju Strait and it advected toward the Korea Strait and shallow coastal region off the south coast of Korea. Intrusion of the mid-depth cold water pool made temperature inversion in the Jeju Strait and affected sea surface temperature variations at the coastal region off the south coast of Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.3
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• pp.379-385
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• 2022

This study was conducted to evaluate the dietary supplementation of citrus byproduct (CBP) on the growth performance, feed utilization, and innate immune responses of juvenile olive flounder Paralichthys olivaceus under low water temperatures (11-15℃). Dietary L-ascorbyl-2-polyphosphate was replaced with graded CBP levels at 0 (Con), 25 (CBP25), 50 (CBP50), 75 (CBP75), and 100% (CBP100). Triplicate groups of juvenile olive flounder were handfed with one of the diets twice a day for 42 days. The growth performance and feed utilization of fish fed with diet containing levels of CBP75 or CBP100 increased significantly compared to those of fish with fed Con. Dietary CBP supplementation increased the protein efficiency ratio in fish. There was no significant differences in innate immune responses between groups, even though CBP supplementation tended to increase. These findings indicate that CBP could be used as a vitamin C source and improve the growth performance of juvenile olive flounder under low water temperatures.

• Journal of Environmental Science International
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• v.24 no.12
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• pp.1649-1656
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• 2015

Jeju Island is the highest rain-prone area in Korea that possesses affluent water resources, but future climate changes are predicted to further increase vulnerabilities as resultant of increasing of extreme events and creating spatial-temporal imbalance in water resources. Therefore, this study aimed to provide basic information to establish a proper water resources management plan by evaluating the effects of climate change on water resources using climate change scenario. Direct runoff ratio for 15 years (2000~2014) was analyzed to be 11~32% (average of 23%), and average direct runoff ratio for the next 86 years (2015~2100) was found as 28%, showing an increase of about 22% compared to the present average direct runoff ratio (23%). To assess the effects of climate change on long-term runoff, monthly runoff variation of future Gangjeong watershed was analyzed by dividing three time periods as follows: Present (2000~2030), Future 1 (2031~2070) and Future 2 (2071~2100). The estimated results showed that average monthly runoff increases in the future and the highest runoff is shown by Future 2. Extreme values has been expected to occur more frequently in the future as compared to the present.

• Journal of Environmental Science International
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• v.21 no.9
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• pp.1031-1041
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• 2012

This study was carried out to investigate the characteristics of disinfection by-products (DBPs-trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) formation in chlorination of principal raw waters used for drinking water on Jeju Island, Korea. The domestic water supply of other area and humic acid solution (HA) were used as a reference point. The effects of chlorine contact time, solution temperature and pH on DBPs formation potential (DBPFP) were investigated for raw waters. In addition, the effect of $Br^-$ was studied for HA. The DBPFP (THMFP, HAAFP and HANFP) were increased with increasing chlorine contact time. Comparing the individual DBPFPs for raw waters, they decreased in the order of HAAFP > THMFP ${\geq}$ HANFP. As the solution temperature was increased, the THMFP, HAAFP and HANFP increased. With increasing the solution pH, the THMFP was increased, but HAAFP and HANFP were decreased. With the addition of 0.3 mg/L $Br^-$ for HA, the DBPFP was increased and the major chemical species changed: from trichloromethane to dibromochloromethane and tribromomethane for THMs; from dichloroacetic acid and trichloroacetic acid to tribromoacetic acid for HAAs; and from dichloroacetonitrile to dibromoacetonitrile for HANs.

• Journal of Soil and Groundwater Environment
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• v.17 no.2
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• pp.62-70
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• 2012

Rainfall, on Jeju Island varies regionally in relation to Mt. Halla with higher rainfall within southern area and lower in western area, and its variability is expected to expand according to the climate change scenario. Non-parametric trend analysis for rainfall, using both historic (1971-2010) and simulated (2011-2100) data assuming the A1B emissions scenario, shows regionally increasing trends with time. In perspective of agricultural land use, area for market garden including various crop types with high water demand is increasing over the Island, especially in the western area with lower rainfall compared to southern area. On the other hand, area for fruit including mandarin and kiwi with low water demand is widely distributed over southern and northern part having higher rainfall. These regional disparity of water demand/supply may be more affected by extreme events such as drought and heavy rainfall that has not yet been considered. Therefore, it is necessary to make policies for water resource management considering both demand and supply in different regions with climate change impacts over Jeju Island.

• Journal of Applied Biological Chemistry
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• v.58 no.1
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• pp.75-79
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• 2015

Extracted mushroom water showed an ability to suppress the accumulation of body fat in female mice after feeding 5 weeks with high fat diet. Particularly, in parametrial and mesenteric adipose, it significantly reduced 44 and 47% of weight, respectively. In non-obese mice, maturated NK cell ($CD11b^{hi}CD27^{lo}$) population were increased ($70.9{\pm}3.8%$) in mushroom water fed mice compared to control ($61.4{\pm}4.3%$) and NK cell population were augmented in mushroom fed mice compared to control.

• Journal of Marine Bioscience and Biotechnology
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• v.13 no.1
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• pp.48-57
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• 2021

Vibrio species are Gram-negative basophils that are ubiquitous in seawater, increasing in number as the water temperature increases. Humans are usually infected by the consumption of contaminated seawater or seafood. V. alginolyticus infection in humans is mainly associated with infections of the skin and ears, such as acute otitis media and cellulitis. In this study, the distribution of V. alginolyticus along the coast of Jeju Island, and its relationship with water temperature, salinity, DO, and pH was investigated. The antibiotic susceptibility of the bacteria isolated was also tested. In seawater, the Daejeong area had the highest detection rate, with 13 cases (21.7%), and the Hallim area showed the lowest detection rate, with eight cases (13.3%) in. In shellfish, the Daejeong area had the highest rate, with seven cases (23.3%), and the Seongsan and Hallim areas had the lowest detection rate, with four cases (13.3%). The overall detection rate was the highest in Daejeong area, with 20 cases (22.2%), and the lowest in the Hallim area, with 12 cases (13.3%). The detection rate was highest when the water temperature was highest.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1945-1949
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• 2006

A storm-induced coastal inundation model (SICIM) is presented to simulate the flood event during typhoon passage that often results in significant rise in sea-level heights especially in the upstream region of the basin. The SICIM is a GIS-based distributed hydrodynamic model, both storm surge and storm water inundations are taken into account. The spatial and temporal distribution of the storm water level and flux are calculated. The model was applied to Jeju Island since it has an isolated watershed that is easy to handle as a first step of model application. Another reason is that it is surrounded by coastal area exposed to storm surge inundation. The model is still advancing and will be the framework of a predictive early inundation warning system.