• Korean Journal of Plant Resources
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• v.37 no.2
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• pp.130-136
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• 2024

Archidium Brid. (Archidiaceae), comprising a total of 35 species, is known to be widely distributed from subtropical to temperate regions, excluding the polar areas. The distribution of Archidium ohioense Schimp ex Müll. Hal. in Korea has been unclear. This study reports the collection of Archidium ohioense from Mt. Gamak, Yeoncheon-gun, Gyeonggi-do, South Korea. This species is distinguished from similar species by median cell, alar region, capsule. We provide detailed description, illustrations, photographs, and a key to related species.

• Journal of Astronomy and Space Sciences
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• v.19 no.1
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• pp.75-88
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• 2002

The climatological characteristics of the polar ionosphere is examined in terms of the ionospheric conductance and electric field. For this purpose, 109 days of measurements from the Sondrestrom incoherent scatter radar are utilized. By combining these two quantities, it is possible to deduce the overhead ionospheric current distributions. The ionospheric current density thus obtained is compared with the corresponding ground magnetic disturbance. Also examined is the effect of the field-aligned current on the ground magnetic disturbance, particularly on the D component Several interesting climatological characteristics about the ionosphere over the Sonderstrom are apparent from this study. (1) The conductance distribution is mainly due to solar EUV radiation during day-time On the other hand, the conductance distribution during the night-time is very low. (2) The conductance distribution one. the polar cap region during the day-time is controlled mostly by the solar EUV radiation, while it is extremely low during night-time wish the Hall and Pedersen conductances being 1.6 and 1.2 siemen, respectively (3) The region of the maximum N-S electric field tend to locate in the dayside sector. The E-W component of the electric field is stronger than that over Chatanika (4) The E-W auroal inospheric current (J/sub E/) is more important in the sunlit hemisphere than the night hemisphere. And a strong southward current is noted in the prenoon sector (5) There is a significant correlation between the overhead ionospheric current and the simultaneously observed ground magnetic disturbance. However, the assumption for the infinite sheet current approximation is far from realistic, underestimating the current density. And the correlation between ${\Delta}H$ and J/sub E/ is higher than the one between ${\Delta}D$ and J/sub N/ , indicating that field-aligned current affects significantly ${\Delta}D$.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.4
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• pp.52-67
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• 2020

Recently, the Arctic has been exposed to snow-covered land due to melting permafrost every year, and the Korea Geographic Information Institute(NGII) provides polar spatial information service by establishing spatial information of the polar region. However, there is a lack of spatial information on vegetation sensitive to climate change. This research used a multi-temporal Sentinel-2 image to perform land cover classification of the Ny-Ålesund in Arctic Svalbard. In the pre-processing step, 10 bands and 6 vegetation spectral index were generated from multi-temporal Sentinel-2 images. In image-classification step is consisted of extracting the vegetation area through 8-class land cover classification and performing the vegetation species classification. The image classification algorithm used Random Forest to evaluate the accuracy and calculate feature importance through Out-Of-Bag(OOB). To identify the advantages of multi- temporary Sentinel-2 for vegetation classification, the overall accuracy was compared according to the number of images stacked and vegetation spectral index. Overall accuracy was 77% when using single-time Sentinel-2 images, but improved to 81% when using multi-time Sentinel-2 images. In addition, the overall accuracy improved to about 83% in learning when the vegetation index was used additionally. The most important spectral variables to distinguish between vegetation classes are located in the Red, Green, and short wave infrared-1(SWIR1). This research can be used as a basic study that optimizes input characteristics in performing the classification of vegetation in the polar regions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.2 no.2
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• pp.59-66
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• 1990

Various types of ice distribution under low temperature greatly influence the environment of the Arctic and Antarctic Oceans. To understand fundamentals of ice properties such as Polar glaciers, icebergs and sea ice, this study focuses on the material behaviors and failure mechanisms of polycrystalline ice. Utilizing the continuum damage theory, a three-dimensional constitutive model to describe creep deformation characteristics in the glacial flow is developed in consideration of micro-cracking as the major physical process of ice deformation. The numerical model is compared with the published experimental data especially in uniaxial constant stress creep tests. The model can simulate primary and secondary creeps as well as tertiary creep characteristics due to the microcrack accumulation.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.12a
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• pp.63-72
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• 2007

Current estimates of the ice-mass balance over the Greenland and the Antarctica using retrievals of time-varying gravity from GRACE are presented. Two different GRACE gravity data, UTCSR RL01 and UTCSR RL04, are used for the estimates to examine the impact of the relative accuracy of background models in the GRACE data processing for inter-annual variations of GRACE gravity data. In addition, the ice-mass balance is appraised from the conventional GRACE data, which represents global gravity, and the filtered GRACE data, which isolates the terrestrial gravity effect from GRACE gravity data. The former estimate shows that there exists similar negative trends of ice-mass balance over the Greenland from UTCSR RL01 and UTCSR RL04 while the time series from the both GRACE data over the Antarctica differ significantly from each other, and no apparent trends are observed. The result for the Greenland from the latter calculation is similar to the former estimate. However, the latter calculation presents positive trends of ice-mass balance for the Antarctica from both GRACE data. These results imply that residual oceanic geophysical signals, particularly for ocean tides, significantly corrupt the ice-mass estimate over the Antarctica as leakage error. In addition, the spatial alias of GRACE is likely to affect the ice-mass balance because the spatial spectrum of ocean tides is not conserved via GRACE sampling, and thus ocean tides contaminate terrestrial gravity signal. To minimize the alias effect, I suggest to use the combined gravity models from GRACE, SLR and polar motion.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.3
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• pp.401-411
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• 1999

IMT-2000 will provide worldwide mobile telecommunication services with the extended coverage areas such as polar regions and mountainous district. GMPCS also provides global telephony and paging services via satellite network at the altitude of 500~12,000 km. "Big LEO" which is one of the GMPCS systems using frequency above 1 GHz and IMT-2000 will share the frequency range of 1 to 3 GHz. Therefore, there exists possible interference between the two systems which can cause the performance degradation of both systems. In this paper, the radio-propagation modeling and interference analysis methods are presented and these methods are used to analyse the effect of the interference between IMT-2000 and GMPCS on system performance.rformance.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.337-339
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• 2017

Here we report the draft genome sequence of the Caballeronia sordidicola strain PAMC 26633, isolated from Psoroma species, a lichen material from Barton Peninsula, King George Island in Antarctica. As we have observed in previous genomic studies in the genus Caballeronia from polar lichen, draft genomic sequences of PAMC 26633 had an assortment of genes of ecological importance and of biotechnical potentials, which include diverse metabolic genes for carbohydrates, amino acids, and genes for nitrogen/sulfur metabolisms, stress responses, membrane transporters, antibiotic resistance, and heavy metal resistance. CRISPR genes and sequences were not found and there were some phage remnants and transposons.

• Journal of the Korean GEO-environmental Society
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• v.23 no.10
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• pp.21-31
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• 2022

Prospecting ice on Moon requires drilling systems to obtain subsurface samples and measure composition of ice deposits. Landers and rovers need to be equipped with drilling equipment in order to analyze the ice and subsurface resources located at the poles of Moon. These devices must be small, lightweight, low-power, highly efficient and high-performance units in order to function properly under the extreme conditions of the lunar environment. Researchers have developed a prototype drilling apparatus that is able to operate in atmospheric and cold environments. Newly developed drilling system in Korea, which is capable of performing not only sampling but also subsurface investigation, is introduced.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.324-331
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• 2018

The thermal environment on lunar surface is more severe than that of earth's surface or low earth orbit because of the long daytime and nighttime due to 28 days of rotation cycle of moon. Thus, analyzing heat flux on lunar lander at potential landing sites is important to determine the landing site in its initial design phase. In this study, thermal model of lunar regolith that can simulate lunar surface temperature was constructed for analyzing thermal characteristics according to the potential landing sites of lunar lander. The heat flux analyses were performed various latitudes of equator, mid-latitude, polar regions, lunar mare and highland. In addition, we also investigated the heat flux of lunar lander when it is landed on adjacent area to hill.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.302-307
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• 2017

Draft ice in polar regions is formed due to sea level changes and various environmental factors cause damage due to collision with offshore plants and ships for resource development. Drift ice in polar regions is a potential source of accidents for offshore plants that perform long-term operations in one place, as well as on the ship. To prevent accidents with drift ice, offshore plants and ships in polar regions use satellite image information and detection radar to detect drift ice. However, the inability to use visible satellite images at night significantly lowers the detection probability by radar for small drift ice. In this study, we used a thermal imaging system which can be operated day and night for the detection of drift ice, and carried out an experimental study on the detection characteristics of drift ice. To examine the night operation of the thermal imaging system, the experimental condition was set and the thermal image was measured according to the measurement angle change. Under this condition, the correlation was analyzed by theoretical calculating the radiant energy of the drift ice and the sea water.