• Journal of the Korean earth science society
• /
• v.27 no.1
• /
• pp.61-72
• /
• 2006

Numerical studies on the influence of interaction between atmosphere and ocean on the variation of Karman vortex at the lee side of Jeju Island were carried out. Karman vortex tends to be occurred at limited height associated with Hanla mountain. And we can find clear Karman vortex at 900 hPa height in this study. One big vortex cell occurred at lee side of Jeju Island in the begging stage of its development and the cell was divided into three small cells as time goes by. And the strength and lifetime of small vortexes depend on the distribution of SST (Sea Surface Temperature). Weak gradient of SST makes long-lasting Karman vortex but produces weak potential vorticity at lee side of Jeju-do in comparison with the vortex under strong SST gradient. Strong SST gradient also increases not only the mixing depth but also the mixing ratio at lower level of troposphere. And the increased atmospheric mixing decreases the mechanical forcing due to isolated topography. Then the strength of Karman vortex at the lee side of Jeju Island becomes weak under strong gradient of SST. Thus the evolution of Karman vortex is closely related to distribution of SST around the isolated island.

• Korean Journal of Ecology and Environment
• /
• v.48 no.3
• /
• pp.188-194
• /
• 2015

River channel dredging and riparian development have been influenced morphology and quantity of natural river habitat. We compared distribution of riverside land and alluvial island in the Nakdong River with field survey and remote sensing analysis after the 4 Large River Project in South Korea. We digitized geomorphological elements, includes main channel, riverside land, and alluvial island by using georeferenced aerial photos taken in pre-dredging (2008) and post-dredging (2012) periods. Field survey was followed in 2012 for a ground truth of digitized boundaries and identification of newly constructed wetland types such as pond, channel, branch, and riverine type. We found that during the dredging period, riverside land and alluvial island were lost by 20.2% and 72.7%, respectively. Modification rate of riverside land was higher in the section of river kilometer 50~90, 140~180, and 210~270. Alluvial island had higher change rate in the section of river kilometer 50~70, 190~210, and 270~310. Average change rate for the riverside land and alluvial island was $-1.02{\pm}0.14km^2{\cdot}10km^{-1}$ and $-0.05{\pm}0.05km^2{\cdot}10km^{-1}$, respectively. Channel shaped wetlands (72.5%) constituted large portion of newly constructed wetlands.

• Journal of Soil and Groundwater Environment
• /
• v.26 no.4
• /
• pp.8-19
• /
• 2021

In this study, the evaluation standard for nitrate nitrogen contamination degree (WELCUP) was established using six factors that influence the groundwater quality in Jeju Island. To do this, weightings, ranges, and ratings were assigned for each factor and the relative possibility of nitrate nitrogen contamination degree was evaluated using WELCUP index for each well. As a result of calculating the WELCUP index using groundwater quality data of 5,112 wells in Jeju Island for 27 years (1993-2019), all 61 wells with the WELCUP index value higher than 100 are distributed in Daejung and Hangyung watershed with relatively large area of farmland in Jeju Island. In particular, as the ratio of private wells is more than 64%, it is necessary that systematic management is needed for private wells in terms of nitrate nitrogen contamination. Consequently, based on the results of applying the WELCUP evaluation standard, it is necessary to select the prioritization of nitrate nitrogen contamination pathways project for groundwater wells in Jeju Island.

• The Journal of Engineering Geology
• /
• v.17 no.4
• /
• pp.665-671
• /
• 2007

In this study, the soil characteristics and the landslide probability are investigated in East Island of Dok-do. The distribution and depth of soil layer were investigated and the soil samples were taken from the soil layer in East Island. As the results of field investigation, the soil layer was partly distributed in specific location and the soil depth was ranged from 1cm to 50cm. Also, the soil depth was mainly ranged about 10cm in the large part of soil layer. The soils were classed as the weathered residual soils and involved many organic contents such as rotten roots and leaves. The average of water contents is 23.2%, and the average of liquid limits is 42.2%. Also, the soils is non-plastic condition. Also, the soils were mainly classed as the poor graded sand including loam contents. Meanwhile, the landslide probability was investigated through a survey of the soil layer distribution in East Island. The soil depth was very shallow in the large part of the soil layer, and the distribution area of soil layer was small. Therefore, it may predict that the landslide probability is very low due to the dissatisfaction of landslide occurrence condition.

• Korean Journal of Plant Taxonomy
• /
• v.45 no.2
• /
• pp.192-212
• /
• 2015

This study was carried out to survey the flora of the vascular plants of Ulleungdo Island. Fieldwork related to the study was carried out 55 times from 2007 to 2011. The results of the study showed that the flora of Ulleungdo Island consisted of a total of 494 taxa, with 93 families, 313 genera, 462 species, 6 subspecies, 52 varieties and 4 formas. Among the collected plants, there were 9 taxa of critically endangered species (CR), 6 taxa of endangered species (EN) and 12 taxa of vulnerable species (VU). Furthermore, protected species and those of floristic regional plants above degree III according to the Korean Ministry of Environment included 4 taxa and 72 taxa, respectively. In addition, 33 taxa were endemic to Ulleungdo Island and 66 taxa were naturalized plants.

• Journal of Environmental Science International
• /
• v.22 no.8
• /
• pp.979-997
• /
• 2013

This study aims at classifying and interpreting on the vegetation structure, the correlation between a vegetation and an environment, a species diversity and a life-form of Evergreen Broad-Leaved Forest(EBLF) located in Gageo-do Island. It is also the objective that the estimation of vegetation change founded on the species composition and characteristics. The vegetation of EBLF was classified into three forests or four community units as Machilus thunbergii forest (Polystichum polyblepharon-M. thunbergii community and Phaenosperma globosum-M. thunbergii community), Ilex integra-Castanopsis sieboldii community, Quercus acuta community and Neolitsea sericea stand. The ordination analysis by DCA is analogous with the vegetation structure analysis. As a result of the correlation (Pearson's correlation coefficient) with environmental conditions, the Altitude has the significance with the distribution of communities. The total vegetation change by progress of succession will not be wandered away from the present vegetation structure practically, and the vegetation on the underlayers will be a little changed.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.12
• /
• pp.2190-2194
• /
• 2010

Wind power generation system (WPGS) of Ulleung Island causes frequency and voltage fluctuation due to wind speed variation during night time. Superconducting magnetic energy storage (SMES) system can overcome the fluctuations through the fast response time of energy charging and discharging. The SMES system should be connected to the terminal of the WPGS for frequency stabilization. To demonstrated the effectiveness of SMES system for power quality improvement, Ulleung Island power network was modeled in a real time digital simulator (RTDS). The RTDS-based simulation results of power quality improvement with SMES are investigated and discussed in detail.

• Korean Journal of Plant Taxonomy
• /
• v.52 no.4
• /
• pp.251-254
• /
• 2022

Saxifraga cortusifolia Siebold & Zucc. (Saxifragaceae, sect. Irregulares, ser. Rufescentes), a species considered endemic along mountain streams throughout Honshu, Shikoku, and Kyushu in Japan, was discovered as a wild population in the Cheona Valley in Haean-dong, Jeju-si on Jeju-do Island of Korea. The population consisted of three subpopulations occupying narrow areas 10 × 10 m², 5 × 5 m², and 10 × 5 m² in size. The number of individuals in the three subpopulations was confirmed to exceed 100. Most of the individuals were on or below rocks at the edge of the valley. A morphological description, detailed photos, and a key to related taxa in Korea are presented.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.5
• /
• pp.733-741
• /
• 2021

Jeju island is the largest island of South Korea, and has a relatively warm climate due to its geographical characteristics. These features have fostered development of various fermented foods distinct to Jeju island. Therefore, the functional activity of the lactic acid bacteria (LAB) isolated from the Jeju region's traditional fermented foods, including Kimchi and Jeotgal was characterized in this study. Fifteen strains were isolated from 6 types of fermented food. These strains include Enterococcus spp., Lactoplantibacillus spp., and Weisella spp. Several experiments were carried out to assess functional characteristics including acid resistance, bile resistance, hemolysis, DPPH and ABTS radical scavenging activity, and cholesterol-lowering activity. Three isolated strains (J-4, J-6 and J-10) exhibited high acid resistance, while the other 3 isolates (J-1, J-4 and J-6) showed high bile salt resistance. The strains displayed varied DPPH and ABTS radical scavenging activity: 71.14-86.42% among the first 3 strains, and 50.11-75.11% among the remaining 3 strains. Cholesterol-lowering activities were in the range 15.74-82.90% for all isolated strains. In conclusion, these studies suggest that isolated LAB strains from Jeju island traditional fermented foods possess the potential for broader application in the food industry.

• Journal of Environmental Impact Assessment
• /
• v.26 no.5
• /
• pp.315-330
• /
• 2017

The aim of this study is to examine the damage of plants in the islands due to the habitat and feeding of European rabbit (Oryctolagus cuniculus) and to suggest future management plan. The survey area Beomseom Island is found to be a vegetation distribution type that was formed secondary by the exposure of artificial interference except for evergreen vegetation distribution and European rabbit showed high habitat track density mainly in the lumbering area. Kkamakseom Island was identified as a severe vegetation distribution area due to interference, and European rabbit showed high habitat track density around deciduous broad leaved forests. Feeding plants of European rabbit was identified as a total of 12 families 17 breeds. Total 9 families 11 breeds were found in Beomseom Island while 5 families 6 breeds were found in Kkamakseom where most available food resources were loss to European rabbit. As for vegetation index of Beomseom Island, about 6.6% of total island area was declined and the vegetation index of Kkamakseom Island was reduced at most area of the island. In Kkamakseom Island, the area where EVI decreased to less than -0.008 unit/yr was reduced to 5.2%, and the area where it was reduced to -0.008 to -0.006 unit/yr in total was 13.32% of the total area. Thus, it was estimated to be seriously damaged by vegetation. Therefore, immediate management is required.