• 한국해양학회지
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• v.11 no.2
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• pp.43-50
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• 1976

The annual nariation of surface heat exchange at ten selected station in the Korean coastal seas was studied using data of monthly mean surface temperature and meteorological parameters averaged for many years. Through heat exchange between the sea and the atmosphere, the surfaces in the Korean coastal seas are warmed by accepting heat from the atmosphere during march to September in the west coast sea, during Aprill to August in the south coast sea which includes the Ulleung-do coast sea and during April to September in the east coast sea. The periods which are cooled by losing heat to the atmosphere correspond to residual months excepting the above warming periods. Maximum total heat exchange during the warming period at each station shows the distribution of 320-720cal/ $\textrm{cm}^2$ day in June to July and during the cooling period shows the distribution of -260∼-940 cal/$\textrm{cm}^2$ day in November to January. The annual average total heat exchange shows warming of 100-240 Cal/$\textrm{cm}^2$ day in the west coast sea, cooling of -90∼-150 Cal/$\textrm{cm}^2$ day in the south coast sea and the Ulleung-do coast sea, and slight warming or cooling of -15∼65 Cal/$\textrm{cm}^2$ day in the east coast sea. Maxima or minima of the surface temperature in the Korean coastal seas appear in the month that the warming or cooling period is ended. The evaporation rate is highest during October to next January with the distribution of 5∼12mm/day.

• Journal of the Korean earth science society
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• v.23 no.3
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• pp.259-269
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• 2002

Based on sedimentary structures, degree of bioturbation, and internal erosional layers, the deep-sea core sediments in the East Sea (Ulleung and Yamato basins) and the Northwestern Pacific Ocean (Shikoku Basin) can be divided into two parts (upper and lower) with the boundary of around 10,000 years B.P. in age. The upper part of core KT94-10 from Shikoku Basin is characterized by low sedimentation rate, internal erosion layer, high degree of bioturbation and cross-lamination structures. It can be interpreted as the bottom-current deposits which show some different characteristics from turbidite or hemipelagic sediment. However, its lower part consists of highly bioturbated, massive mud, suggesting that it be not related to the influence of bottom current. On the other hand, the cores in Ulleung and Yamato basins do not show any evidence of bottom-current deposits: their upper parts consist of bioturbated mud, and lower parts are characterized by laminated mud with pyrite filaments, indicating anaerobic condition. Consequently, these sedimentological characteristics suggest that deep-sea circulation would be changed from slow-moving to fast-moving one at this bounding time commonly in the Northwestern Pacific Ocean and the East Sea. Also, even in the same time, the deep-sea circulation in the Northwestern Pacific area would be relatively faster than that in the East Sea.

• Geophysics and Geophysical Exploration
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• v.19 no.3
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• pp.121-130
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• 2016

Several factors are discussed that should be considered in measuring thermal conductivity of rock cores with a PEDB (potable electronic divided bar) system, which is relatively accurate and easy to operate, and can measure the thermal conductivity of rock cores for various diameters. Then the system is applied to measure thermal conductivity of 70 rock cores from Ulleung Island. Air temperature affects most on the thermal conductivity measurements, so that it is very important to minimize the temperature change during the measurement. Other factors such as the temperature of heat source, averaging time window on the thermal conductivity measurements do not affect much compared to air temperature. Slightly higher thermal conductivity is measured when using the thermal contact paste between the sample and heat source or heat sink. Especially, rock cores with irregular surface showed bigger difference. Repeatability showed less than ${\pm}0.3%$ for standard samples and less than ${\pm}4%$ for rock samples, respectively, when the room temperature changes within $1^{\circ}C$ during the measurements. Thermal conductivity of the rock cores from Ulleung Island roughly increases as depth increases but does not show any dependency on the rock types.

• Journal of Life Science
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• v.22 no.10
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• pp.1384-1391
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• 2012

Five coastal plant species, Artemisia fukudo, Aster sphathulifolius, Plantago camtschatica, Sedum oryzifolium, and Setaria viridis, were collected from the coastal region of Ulleung Island (Ulleung-Do, South Korea). Thirty-six endophytic fungi were isolated from the roots of these plants, and all were identified by using PCR with the following specifications: internal transcribed spacer 1 (ITS1), 5.8S rRNA, and ITS2 regions. Phylogenetic analysis indicated that all fungal strains belong to the phylum Ascomycota and comprise four orders (Capnodiales, Eurotiales, Hypocreales, and Pleosporales). Among all the identified species, the Eurotiales species were more abundant than species in the other orders. Nine different genera (Alternaria, Aspergillus, Cladosporium, Exserohilum, Fusarium, Neosartorya, Penicillium, Phoma, and Pyrenochaeta) in the four orders were confirmed. Penicillium and Aspergillus species were the most dominant species among the endophytic fungi isolated from the coastal plants. Shannon's diversity index (H') ranged from 0.684 to 1.609, and the endophytic fungi in S. oryzifolium was more diverse compared to the endophytic fungi in the other plants.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.565-582
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• 2018

We investigated the hydrochemical properties of ChusanYongchulso Spring located in Buk-myeon, Ulleung Island, focusing on the formation and characteristics of aquifers in and around the Nari caldera. Abundant pumice with high permeability and numerous fractures (including faults and joints) that formed as a result of caldera subsidence are widely distributed in the subsurface, favoring the formation of aquifers. Because of the presence of porous pyroclastic rocks with a high internal surface area, the water type of the springs is characterized by $NaHCO_3$, with upper stream waters and the upper spring being characterized by $NaHCO_3$ and NaCl, respectively. Components with a high coefficient of determination with EC are $HCO_3$, Na, F, Ca, Mg, Cl, $SiO_2$, and $SO_4$. The high concentrations of Na and Cl might be attributable to the main lithologies in the area, given that alkaline volcanic rocks are distributed extensively across Ulleung Island. Eh and pH, which are considered to be important indicators of water-rock interaction, are unrelated to most components. According to the results obtained from factor analysis, the variance explained by factor 1 is 54% and by factor 2 is 25.8%. Components with a high loading on factor 1 are F, Na, EC, Cl, $HCO_3$, $SO_4$, $SiO_2$, Ca, $NO_3$, and Mg, whereas components with a high loading on factor 2 are Mg and Ca, along with K, $NO_3$, and DO with negative loadings. It is suggested that the high concentrations of Na, Cl, F, and $SO_4$ are closely related to the presence of fine-grained alkaline pyroclastic rocks with high permeability and porosity, which favorintensewater-rock interaction. However, a wide-ranging investigation that encompasses methods such as geophysical prospecting and geochemical analysis (including isotope, trace-element, and tracer techniques) will be necessary to gain a better understanding of the groundwater chemistry, aquifer distribution, and water cycling of Ulleung Island.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.2
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• pp.351-373
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• 2019

The cold eddies around the Ulleung Basin in the East Sea were identified from satellite altimeter sea level data using the Winding-Angle method from 1993 to 2015. Among the cold eddies, the Dokdo Cold Eddies (DCEs), which were formed at the first meandering trough of the East Korea Warm Current (EKWC) and were pinched off to the southwest from the eastward flow, were classified and their migration patterns were analyzed. The vertical structures of water temperature, salinity, and flow velocity near the DCE center were also examined using numerical simulation and observation data provided by the Hybrid Coordinate Ocean Model and the National Institute of Fisheries Science, respectively. A total of 112 DCEs were generated for 23 years. Of these, 39 DCEs migrated westward and arrived off the east coast of Korea. The average travel distance was 250.9 km, the average lifespan was 93 days, and the average travel speed was 3.5 cm/s. The other 73 DCEs had moved to the east or had hovered around the generated location until they disappeared. At 50-100 m depth under the DCE, water temperature and salinity (T < $5^{\circ}C$, S < 34.1) were lower than those of ambient water and isotherms made a dome shape. Current faster than 10 cm/s circulates counterclockwise from the surface to 300 m depth at 38 km away from the center of DCE. After the EKWC separates from the coast, it flows eastward and starts to meander near Ulleungdo. The first trough of the meander in the east of Ulleungdo is pushed deep into the southwest and forms a cold eddy (DCE), which is shed from the meander in the south of Ulleungdo. While a DCE moves westward, it circumvents the Ulleung Warm Eddy (UWE) clockwise and follows U shape path toward the east coast of Korea. When the DCE arrives near the coast, the EKWC separates from the coast at the south of DCE and circumvents the DCE. As the DCE near the coast weakens and extinguishes about 30 days later after the arrival, the EKWC flows northward along the coast recovering its original path. The DCE steadily transports heat and salt from the north to the south, which helps to form a cold water region in the southwest of the Ulleung Basin and brings positive vorticity to change the separation latitude and path of the EKWC. Some of the DCEs moving to the west were merged into a coastal cold eddy to form a wide cold water region in the west of Ulleung Basin and to create a elongated anticlockwise circulation, which separated the UWE in the north from the EKWC in the south.

• Korean Journal of Plant Taxonomy
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• v.40 no.4
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• pp.267-273
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• 2010

The distribution of three typical warm-temperate evergreen trees, Quercus acuta Thunb., Neolitsea sericea (Blume) Koidz., and Machilus thunbergii Siebold & Zucc., were surveyed on the Korean Peninsula based on field and specimen investigations and the distribution maps of the three species were prepared. The distribution patterns of the species correspond to the south coast floristic region in Korea, which includes the distributional areas of Jeju-do, Isl. Ulleung, the southern coastal areas, and the areas up to the islands around Incheon in the Yellow Sea. The northernmost limit of the distribution of Quercus acuta is Isl. Nap of Incheon in the west, and a new distribution was found at Isl. Ulleung in the East Sea; additionally, the limit of Neolitsea sericea is the Deojoek archipelago of Incheon. The northernmost limit of Machilus thunbergii is Isl. Daecheong of Incheon, which is the highest latitude among those of the three species. This distribution survey of evergreen broad-leaved trees in Korea can be used as basic data for the delimitation of floristic regions and as a bio-indicator of climatic change.

• 한국해양학회지
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• v.26 no.2
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• pp.117-132
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• 1991

Marine total magnetic intensity over the southern part of the Ulleung Basin and geomagnetic data measured at a land base station are analyzed. Fourteen days observation of geomagnetic field at a fixed on-land base station showed how the geomagnetic field around the study area behaves. geomagnetic data at the base station can also be used as correction data for a diurnal variation. Magnetic anomalies in the study area do not reflect an effect of sea bottom topography but mainly subsurface basement. The southern part of the Ulleung Basin can be devided into two zones according to a different anomaly pattern; along the coastal shelves the isolated anomalies with a short wave and a strong amplitude are dominant, and toward the open sea the anomalies become much more subdued. The high anomaly zone adjoined to land is interpreted to be caused by granitic intrusives or volcanic rocks, and the weak anomaly zone to the outer sea to be arisen from an existence of deep basement. A spectrum analysis is applied to estimate magnetic basement depths from three anomaly profiles with a long period and a weak amplitude toward the outer sea. The calculated depths are 7.0km, 5.0km, and 2.6km respectively from outer profile. The basement might be correlated with the mixed layer of tuff, basalt, and sediment, which had been defined as L-2 layer in the Yamato basin and the Japan Basin.

• Journal of Korean Society of Forest Science
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• v.100 no.1
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• pp.34-41
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• 2011

Vegetation structure, composition and diversity were quantified for 10 samples ($10m{\times}10m$) representing woody vegetation and for 30 samples ($1m {\times}3m$) representing understory vegetation in Pinus parviflora and Tsuga sieboldii forest of Taeharyeong, Ulleung-gun (Gyeongsangbuk-do). P. parviflora was limitedly advanced to sapling layer from seedling stage, and based on Mantel tests, composition of canopy layer was not established in ground woody vegetation. Non-metric multidimensional scaling revealed influence of biotic and abiotic factors in species composition of woody and understory vegetation. In the result of multiple regression model, abundance of P. parviflora (density and breast height area) and percent cover of woody debris were significant predict variables for understory diversity. These results suggest that relatively large disturbance is required for regeneration of P. parviflora and T. sieboldii forest, and control of expansion of monocultural understory species that monopolize resources such as Carex blepharicarpa and Maianthemum dilatatum, is necessary for maintenance of diversity.

• Animal Systematics, Evolution and Diversity
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• v.36 no.3
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• pp.236-239
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• 2020

Pelagic tunicate, Thetys vagina Tilesius, 1802, is newly reported from Korean waters. The genus Thetys Tilesius, 1802 is also first recorded as Korean fauna. Thetys vagina is the only valid species in the genus Thetys. It is distinct from other genera by having at least 16 body muscles widely interrupted, no anterior proboscis, bent alimentary canal in the solitary oozooid, and five narrow body muscles, no ventral peduncle, an almost compact loop alimentary canal in the aggregate blastozooids. The specimens of T. vagina examined in this study were collected at the subtidal zone of Ulleung-do Island by scuba diving. In this paper, the detailed descriptions and photographs of both the solitary and aggregate living forms of T. vagina are provided.