• Ocean and Polar Research
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• v.44 no.3
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• pp.191-207
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• 2022

Using the results of CTD casts made in Spring from 2017 to 2021, in this study we investigated the water mass distribution and occurrence of temperature inversion in the western seas of Jeju Island in spring. The distribution of water masses was characterized by cold and fresh water in the northwest and warm and saline water in the southeast, forming a strong thermohaline front running in the southwest-to-northeast direction. Strong temperature inversion mainly occurred in the frontal boundary when the cold water intrudes beneath the warm water at depths of 30-50 m. Analysis of the mixing ratio demonstrated that Jeju Warm Water is dominantly distributed in the western seas of Jeju Island, but its ratio can be modified depending on the southward extension of Yellow Sea Cold Water (YSCW). Results of in situ measurement showed that in 2020, the YSCW largely expanded to the western seas of Jeju Island, occupying approximately 40 % of the mixing ratio. Due to the expansion of YSCW, a strong thermohaline front was formed in the study area, thereby causing thick and strong temperature inversion. On the other hand, in 2018 the mixing ratio of YSCW was minimum (~18%) during the study period of 2017-2021, and thus a relatively weak frontal boundary was formed, without the occurrence of temperature inversion. The observational results also suggest that the interannual changes of water mass distribution and the associated temperature inversion in the western seas of Jeju Island are closely related with wind-driven Yellow Sea circulation in spring, which is the summer monsoon transition period.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.2
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• pp.106-112
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• 2022

As a series of basic research to draw the pilot design measures for developing the habitat apparatus of Sulculus diversicolor supertexta inhabiting the coastal area of Jeju island, this study conducted a water tank experiment to understand the habitat marine environment of Sulculus diversicolor supertexta and the preference of habitat space focusing on the research fisheries performing the discharge of marine products. In the composition degree of marine algae in both fisheries, Donggwi-ri showed the highest gulfweed (79.3%) as brown algae and there were some coralline algae (17.2%) as red algae. Hansu-ri yielded the highest gulfweed (48.1%) as brown algae, which was followed by sea lettuce (10.4%) as green algae. In the preference of habitat space, the shelter angles 40° showed the highest adhesion as number of 82.9, which was followed by 60° and 70° as 69.2 and 68.2 respectively (P<0.05) by reviewing the environmental characteristics of habit of Salculus diversicolor supertexta in the coastal fishery of Jeju Island, when considering the adhesion rate in each of five shelters with different angles. In the future, there should be continuous research and monitoring for designing the fish shelters suitable for the coastal fisheries of Jeju island, and it would be also necessary to add the field-centered sustainable concrete research.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.255-262
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• 1982

The data of 37 oceanographic stations in the coastal sea of Jeju island are compiled in terms of temperature, salinity, dissolved oxygen, silicate, nitrate and phosphate to analyge the chelnical characteristics in this region. This work was carried out during June, 1951. The concentrations of nutrients in the layer more than 50 m are generally 0.5-3 times larger than the surface layer. Each constituents in this layer are as follows: temperature ranged 11.8 to $15.4^{\circ}C$ and salinity, 33.8 to $34.8\%_{\circ}$; and also dissolved oxygen and slicate are 5.2 to 5.6ml/l and 5.6 to $9.0{\mu}g-at/l$, respectively. And nitrate and phosphate ranged 1.0 to $6.0{\mu}g-at/l$ and 0.1 to $0.5{\mu}g-at/l$, respectively. The coastal sea of Jeju island is divided into two parts in chemical view point : one is the southeastern sea of Jeju island under the influence of the Tsushima Current, md the other is the northeastern sea of Jejo island under the influence of the Yellow Sea Bottom Cold Water and the south coastal water of Korea. The north-western sea of Jeju island had relatively a cold (about $13^{\circ}C$) and low saline water (about $34\%_{\circ}$), and dissolved oxygen was higher than in the neibouring waters. It seems that in the southern area between Moseulpo and Seogwipo of Jeju island, two different Ivater masses are complicately intermixed and a tidal front is formed.

• Journal of the Korean association of regional geographers
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• v.16 no.6
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• pp.623-634
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• 2010

The elevated water storage tanks highly crowded in the western region in Jeju island is an important landmark of Jeju island. This study examines the reasons that the elevated water storage tanks appeared in a high density. After examination, this study found that the elevated water storage tanks formed under the influences of climate, hydrogeologic structure, soil, topography and land use. In particular, the elevated water storage tanks in Jeju are closely related to the crapping system with which water has to be supplied using sprinkler due to well drained soil and hydrogeological characteristics. The results of this study show that elevated water storage tank landscape in the western region of Jeju island is an agricultural landscape particularly made in the course of farmers' adaptation to the natural environment of Jeju island.

• ALGAE
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• v.33 no.4
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• pp.341-349
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• 2018

Sargassum horneri is edible brown seaweed abundant along the coasts of Jeju Island, South Korea. In addition to the native S. horneri population, a large amount of S. horneri has been found to invade Jeju Island from the east coast of China. Thus, S. horneri of both Korea (SK) and China (SC) strains now inhabits along with the shore of Jeju Island and have become a threat to the coastal biodiversity. However, they could be used in obtaining functional ingredients for industrial level applications provided an optimized cost effective strategy. In the present study, we compared SK and SC strains for the extraction efficiency, components, antioxidant, and anti-inflammatory properties of 80% methanolic extracts and their partially purified fractions. According to the results, two strains indicated similar bioactive properties such as DPPH and alkyl radical scavenging activity as well as anti-inflammatory activities on lipopolysaccharide-stimulated RAW 264.7 cells. The yield of 80% methanol extract from SC was higher than SK. However, the yields of the ethyl acetate and chloroform fractions from SK were higher than those of SC strain. The major peaks in the high-performance liquid chromatography chromatograms, which was identified as Apo-9 fucoxanthinone, indicated that both methanolic extracts of SK and SC contains major target peaks but with different amounts. This study might be useful for developing functional materials from SC and SK in future.

• Land and Housing Review
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• v.9 no.4
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• pp.10-18
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• 2018

As the volatility increasement of the number of tourist, there was been controversy over supply-demand imbalance in hotel market. The purpose of this study is to analysis on determinants of hotel occupancy rate in Jeju Island. The quantitative method is based on cointegrating regression, using an empirical dataset with hotel from 2000 to 2017. The primary results of research is briefly summarized as follows; First, there are high relationship between total hotel occupancy rate and hotel occupancy of foreign tourist. The volatility of hotel occupancy is caused by foreigner user than local tourists though local tourist high propotion of hotel occupancy in Jeju Island. Second, hotel occupancy of local tourist has not relationship with demand and supply variables. Because some hotel users are not local tourists but local resident, and effects to other variables of hotel consumer trend, accommodation such as Guest house, Airbnb. Third, there are high relationship between foreign hotel occupancy rate and demand-supply variables. These research imply that total management of supply-demand is very important to seek stability of hotel occupancy rate in Jeju Island. Also it can provide a useful solution regarding mismatch problem between supply-demand as well as development the systematic forecasting model for hotel market participants.

• Journal of Environmental Science International
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• v.18 no.9
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• pp.1045-1055
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• 2009

The discharge within the basin in Jeju Island was calculated by using SWAT model, which a Semi-distributed rainfall-runoff model to the important rivers. The basin of Chunmi river of the eastern region of Jeju Island, as the result of correcting as utilizing direct runoff data of 2 surveys, appeared the similar value to the existing basin average runoff rate as 22% of average direct runoff rate for the applied period. The basin of Oaedo river of the northern region showed $R^2$ of 0.93, RMSE of 14.92 and ME of 0.70 as the result of correcting as utilizing runoff data in the occurrence of 7 rainfalls. The basin of Ongpo river of the western region showed $R^2$ of 0.86, RMSE of 0.62 and ME of 0.56 as the result of correcting as utilizing runoff data except for the period of flood in $2002{\sim}2003$. Yeonoae river of the southern region showed $R^2$ of 0.85, RMSE of 0.99 and ME of 0.83 as the result of correcting as utilizing runoff data of 2003. As the result of calculating runoff for the long term about 4 basins of Jeju Island from the above results, SWAT model wholly appears the excellent results about the long-term daily runoff simulation.

• Ocean and Polar Research
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• v.34 no.1
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• pp.65-71
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• 2012

Gambierdiscus toxicus, Adachi et. Fukuyo, is a benthic ciguatoxin-producing armored dinoflagellate, often attached to macroalgae. This organism is the primary causative agent of ciguatera fish poisoning which occurs in tropical and subtropical regions. However, regardless of the fact that the population of Gambierdiscus spp. has expanded to such temperate areas from sub-trophic and trophic areas, monitoring of G. toxicus has been lacking in the Korean coastal waters of temperate areas. This study was performed at the uninhabited Baekdo Islands off the southern coast of Korea and at Seopsom Island in the vicinity of Seogwipo, Jeju Province during April and May, 2011. Cell densities of Gambierdiscus spp. on macroalgae at Baekdo and Jeju Island ranged from zero to 56.4 cells $g^{-1}$. Maximum density was recorded on the brown alga Cladophora japonica at St. 3 of Jeju Island. In particular, the cell densities of Gambierdiscus spp. were influenced by the substrate characteristics of macroalgae. In the future, the continuous monitoring of toxic benthic dinoflagellate is necessary to predict and prevent ciguatera poisoning in Korean coastal waters.

• Journal of Korean Society of Rural Planning
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• v.26 no.2
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• pp.95-106
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• 2020

The Onishi model is an objective indicator which can be used to evaluate the relevance of city environmental management in regard to the capacities and processing status of existing urban infrastructure. This study is to analyze the facility carrying capacity and processing status of Jeju Island, a famous tourist site in South Korea. General variables covered by the Onishi model are considered, including water supply, wastewater treatment, waste disposal, and air pollution. Furthermore, the facility carrying capacities for transportation, such as airports and ports, as well as accommodations are assessed as variables pertinent to the characteristics of Jeju island. With the annual number of tourists exceeding that of residents on the island, more facilities for sewage treatment and waste disposal are required. Furthermore, transportation and accommodations used by tourists have already exceeded their capacity. For the future sustainability of Jeju Island, a plan will be needed for adjusting the volume of tourists based on the capacity of each relevant facility.

• Animal cells and systems
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• v.14 no.3
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• pp.213-219
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• 2010

Bottlenose dolphins (Tursiops sp.) commonly inhabit Korean waters, including the coastal waters of Jeju Island. However, their taxonomic position was unclear because of the validity of this genus. The genus Tursiops has recently been determined to comprise two species: the common bottlenose dolphin (Tursiops truncatus) and the Indo-Pacific bottlenose dolphin (Tursiops aduncus). To confirm the taxonomic position of bottlenose dolphins frequenting the coastal waters of Jeju Island, the external morphology and osteology of specimens from Jeju Island were examined. Photographs of free-swimming individuals were also used for determining external morphological characters. The cranial and meristic measurements fell within the ranges of T. aduncus. Osteological ratios were also consistent with those of T. aduncus. The presence of a prominent ventral spot was observed among some individuals. As a result, the dolphins mainly distributed in the coastal waters of Jeju Island were identified as Indo-Pacific bottlenose dolphins (T. aduncus) in terms of their cranial characters and ventral spotting. We propose a new Korean name, 'Nambang-keun-dol-go-rae'.