• Journal of Environmental Science International
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• v.15 no.1
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• pp.59-66
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• 2006

High concentration of chlorophyll a occurred around the Ulleung Warm Eddy off Ulleung Island in the East Sea of Korea in spring season. The abnormal distributions of chlorophyll a were captured by satellite remote sensing and measured field data. The temporal and spatial scale of the abnormal distributions were around 20days and 50km diameter off Ullung Island. The anomalies were quantified b)'estimated chlorophyll a derived from OCM and SeaWiFS ocean color data from 2000 to 2004. The origin of abnormal hish concentrations was estimated by this study. It was that suspended material discharged from the Nakdong River and the coastal water located in the southeastern part of Korean Peninsula moved to northeastern coast, and then moved to off Ullung island, The high chlorophyll a concentrations including inorganic materials were accumulated by anticyclonic eddy such as the Ullung Warm Eddy around Ullung island in the East Sea of Korea in spring season.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.378-384
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• 2004

We investigated the variations of epilithic diatom community and assessed water quality of the water system of Ulleung Island by DAIpo in April, May, July, August, October, and November of 2003, and January and February of 2004. Samples were collected from four sampling stations. Total 95 taxa were identified from this study and dominant species were Nitzschia inconspicua, Achnanthes minutissima, Gomphonema angustum and Cocconeis placentuja var. lineata. The variation of DAIpo values was ranged from 51.14 to 77.77 and the water quality by DAIpo was estimated between ${\alpha}-oligosaprobic$ and ${\beta}- oligosaprobic$ states.

• Journal of Soil and Groundwater Environment
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• v.23 no.6
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• pp.37-45
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• 2018

The source of Chusan Spring water in the Ulleungdo is the precipitation in the Nari caldera basin, which permeates in the Trachitic pumice and tuff area and moves downward, outflowing at the lithologic boundary between the trachyte and Nari tuff. It is known that the discharge rate of the Chusan Spring is large enough to be used for the small hydroelectric power generation, but the exact discharge rate and hydrogeologic characteristics have not been known. The discharge rates of the Spring were measured 11 times, which ranged from $15,220m^3/d$ to $36,278m^3/d$. The discharge rates, measured by the automatic level recorder, for two-year period, were $20,000{\sim}38,000m^3/d$. The variation of discharge rates did not coincide with rainfall event, but showed daily increases of $3,000{\sim}5,000m^3/d$. The annual discharge rate excluding the evapotranspiration and the surrounding stream discharge corresponded to 70.6% of the annual precipitation of the recharge area. Therefore, meteorological observations at the Nari basin, rather than the Ulleung-do meteorological station, are more appropriate to properly interpret the discharge characteristics of the Chusam Spring and the recharge rate of the basin.

• Journal of Species Research
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• v.6 no.spc
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• pp.94-109
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• 2017

Eleven new species of two genera, Psammocinia and Ircinia (Demospongiae: Dictyoceratida: Irciniidae) are described from Gageo Island, Ulleung Island and Jeju Island, South Korea. The separation of these two genera was made on basis of morphological evidence, especially skeletal structure with foreign debris. Six new species of Psammocinia and five new species of Ircinia were added to known fauna. All skeletal fibres are very irregular.

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

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4189-4200
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• 2021

In this study, the relationship between the environmental radiation dose rate and meteorological variables was investigated with multiple regression analysis and big data of those variables. The environmental radiation dose rate and 36 different meteorological variables were measured on Ulleung Island, Republic of Korea, from 2011 to 2015. Not all meteorological variables were used in the regression analysis because the different meteorological variables significantly affect the environmental radiation dose rate during different periods, and the degree of influence changes with time. By applying the Pearson correlation analysis and stepwise selection methods to the big dataset, the major meteorological variables influencing the environmental radiation dose rate were identified, which were then used as the independent variables for the regression model. Subsequently, multiple regression models for the monthly datasets and dataset of the entire period were developed.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2010.04a
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• pp.55-58
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• 2010

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2010.04a
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• pp.52-54
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• 2010

• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.124.3-124
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• 2003

No Abstract, See Full Text

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.468-474
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• 2009

Thyme leaves of aerial part in 5 domestic species was extracted by several solvens, and chemical composition of extracts was analyzed by GC-MS to determine the effective solvent for phenol compound extracts. Total phenol contents containing thymol and carvacrol according to methanol extracts of Ulleung island, Jeju middle mountain, Kyeonggido, Jeju alpine species, and Gangwondo were 92.21, 84.92, 77.43, 74.16, and 73.51%, while them of ethanol extracts of Gangwondo, Jeju middle mountain, Kyeonggido, Ulleung island, and Jeju alpine species were in the order of and their contents were 93.64, 93.62, 90.74, 89.52, and 72.65%, separately. Hexane extracts of Gangwondo and Ulleung island thyme were almost composed by phenol contents containing thymol for 100 and 95.71%.