• Title/Summary/Keyword: Ulleung

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Validation of Ocean Color Algorithms in the Ulleung Basin, East/Japan Sea

  • Yoo, Sin-Jae;Park, Ji-Soo;Kim, Hyun-Cheol
    • Korean Journal of Remote Sensing
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    • v.16 no.4
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    • pp.315-325
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    • 2000
  • Observations were made to validate ocean color algorithms in the Ulleung Basin, East Sea in May 2000. Small scale and meso-scale surveys were conducted for the validation of ocean color products (nLw: normalized water-leaving radiance and chlorophyll concentration). There were discrepancies between SeaWiFS and in situ nLw showing the current aerosol models of standard SeaWiFS processing software are less than adequate (Gordon and Wang, 1994). Applying the standard SeaWiFS in-water algorithm resulted in an overestimation of chlorophyll concentration. This is because that CDOM absorption was higher than the estimated chlorophyll absorption. TSS concentration was also high. Therefore, the study region deviated from Case 1 waters. The source of these materials seems to be the entrainment of coastal water by the Tsushima Warm Current. Study of the bio-optical properties in other season is desirable.

A New Species of the Genus Euseius (Acari: Phytoseiidae) from Ulleungdo Island in Korea (울릉도산 순모이리응애속(Acari: Phytoseiidae) 1신종 보고)

  • Kim, A Young;Seo, Hong Yul;Ryu, Myon Ok
    • Korean journal of applied entomology
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    • v.58 no.1
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    • pp.85-87
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    • 2019
  • A new species, Euseius ulleungensis sp. nov. is described from Korea. The new species was collected on Aster glehni Fr. Schm. at Jeodong, Ulleung-up, Ulleung-gun, Gyeongsangbuk-do.

Use of big data for estimation of impacts of meteorological variables on environmental radiation dose on Ulleung Island, Republic of Korea

  • Joo, Han Young;Kim, Jae Wook;Jeong, So Yun;Kim, Young Seo;Moon, Joo Hyun
    • 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.

Gas Hydrate Occurrence in the Southwestern Slope of the Ulleung Basin, East Sea, Inferred from Seismic Evidence (동해 울릉분지 남서 사면지역에서 탄성파 특징으로부터 유추한 가스 수화물의 존재 가능성)

  • Hong, Jong-Kuk;Yoo, Hai-Soo;Jou, Hyeong-Tae;Han, Sang-Joon;Choi, Dong-Lim
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.6 no.4
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    • pp.242-248
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    • 2001
  • A high resolution Chirp seismic profile and a multichannel seismic reflection profile were analysed to study the possibility of gas hydrate presence in the southwestern upper slope of the Ulleung Basin. The Chirp profile shows acoustic turbidity, acoustic void, and pockmarks, suggesting the presence of shallow gas in the sediments .Slope failures appear to have occurred in association with decomposition of gas hydrated sediments. A bottom-simulating reflector (BSR) is seen in subbottom depths of 60 to 110 m below the seafloor at water depths of 750 to 1130 m. The sediments above BSR are characterized by acoustic blanking probably due to amplitude reduction caused by a mixture of gas hydrate with sediments. The interval velocity above the BSR is 1,650 m/sec and it drops abruptly to 1,080 m/sec below the BSR. The sediment column between seafloor and the BSR thins with increasing water depth, which is very closely related to increasing geothermal gradient with increasing water depth in the Ulleung Basin.

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The Establishment of Conservation Area and Conservation Strategy in Ulleung Island (I) -Flora- (울릉도의 보전지역 설정 및 보전전략(I) - 울릉도 지역의 식물상 -)

  • 신현탁;김용식
    • Korean Journal of Environment and Ecology
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    • v.16 no.2
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    • pp.195-216
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    • 2002
  • The flora of Ulleung island was summarized as 975 taxa with 122 families, 465 genus, 762 species, 5 sub-species, 178 varieties, 21 forms, and 9 hybrids. This extent of plant diversity of the island ecosystem was modified from the field surveys by the authors adding the number of 627 taxa; 109 families, 355 genus, 526 species, 2 sub-species, 89 varieties and 10 forms, and Considering the aspects of geographical distribution of the island, the flora showed much closer to the Korean penninsula than that of the Japanese Archipelago. An action plan including intensive conservation and management both for habitat and plant to conserve the island ecosystem should be prepared. The naturalized plants is expanding gradually due to the increase of the tourist. The Ulleung island ecosystem should be conserved as the Protected Area, which is enlarged habitat compared with the present legal conservation actions.

Numerical Analysis on Flow Behavior of Gas Hydrate Bearing Sediments in the Ulleung Basin, East Sea of Korea (동해 울릉분지 가스하이드레이트 퇴적층의 해리 유동 전산 분석 연구)

  • Kim, Ji-Su;Lee, Rok-Sang;Lim, Jong-Se;Kim, Se-Joon
    • Journal of Energy Engineering
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    • v.23 no.3
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    • pp.102-115
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    • 2014
  • In the Ulleung basin in the East Sea of Korea, it is assumed that huge amounts of gas hydrate(GH) are buried. In 2010, drilling operation was performed at the 2nd Ulleung Basin Gas Hydrate Drilling Expedition(UBGH2) to designate a site for field production test. In this study, based on the field production test site model reflecting geological properties, GH dissociation flow interpretation is analyzed and sensitivity analysis is performed to gain understanding of production behavior properties following bottomhole pressure(BHP) variation by using the numerical simulation. The results of this study provide a basis for the preliminary analysis of field production test site.