• Journal of the Korean earth science society
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• v.24 no.3
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• pp.216-233
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• 2003

This study delineates the phenomena related with global environmental changes such as global warming, ozone depletion, and El Ni${\tilde{n}}$o/Southern Oscillation (ENSO) noted in the Antarctic. Retreat of ice cliffs, glaciers, and calving of ice shelves indicate the effects of recently aggravated global warming. The ice cliff located at Marian Cove, King George Island, South Shetland Islands off the Antarctic Peninsula has been observed to be retreating faster in the last 7 years than in the previous 38 years since 1956. There are some indications of temperature and precipitation changes associated with ENSO around King Sejong Station. The regression analyses indicate significant trends such as a decrease in the total amount of ozone and an increase in ultraviolet radiation which was seen by a satellite (TOMS-EUV) in September and October which correspond to ozone-hole season over King Sejong Station. Increase of UV radiation due to the ozone depletion in the Antarctic has changed the growth rate of marine organisms. It may also result in changes to the productivity, biomass, and species composition of marine organisms which can affect the whole marine ecosystem. The recent ice-core drilling over Lake Vostok has been reviewed with emphasis on the four cycles of glacial stages over the past 420,000 years. It is time to show more interest in mainland Antarctica through investigations of the coring and vast ice sheet, terrestrial geology, and upper atmospheric sciences in order to understand the past environmental changes and to predict possible changes to the environment in the future.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.1
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• pp.9-16
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• 2013

Coastal sand dune area is an important ecosystem as an ecotone which is located between coastal area and terrestrial area. In order to understand the sand dune ecosystem in terms of its habitat characteristics, micrometeorological analysis was carried out in a coastal sand dune in Hakampo, Taeanhaean National Park, Korea. Micrometeorological measurements were made to monitor air and soil temperatures, relative humidity, soil water content, rainfall, solar radiation, wind speed, and wind direction. In contrary to a forest ecosystem, the coastal sand dune grassland ecosystem was relatively hotter and very humid with heavy rainfalls concentrated between June and July. The seasonal change of daily mean soil temperature was greater than that of air temperature by $2{\sim}3^{\circ}C$. Daily mean soil water content was less than 10% throughout the year. Also, the maximum wind speed of 156.7 m $s^{-1}$ was recorded on 7 October 2011. The observed seasonal wind direction was different from those observed at Seosan by KMA (Korea Meteorological Administration). To better understand the habitat characteristics in a costal sand dune grassland ecosystem, long-term multi-year measurements are needed.

• Journal of Astronomy and Space Sciences
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• v.28 no.1
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• pp.17-26
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• 2011

Bow shock, formed by the interaction between the solar wind and a planet, is generated in different patterns depending on the conditions of the planet. In the case of the earth, its own strong magnetic field plays a critical role in determining the position of the bow shock. However, in the case of Mars of which has very a small intrinsic magnetic field, the bow shock is formed by the direct interaction between the solar wind and the Martian ionosphere. It is known that the position of the Martian bow shock is affected by the mass loading-effect by which the supersonic solar wind velocity becomes subsonic as the heavy ions originating from the planet are loaded on the solar wind. We simulated the Martian magnetosphere depending on the changes of the density and velocity of the solar wind by using the three-dimensional magnetohydrodynamic model built by modifying the comet code that includes the mass loading effect. The Martian exosphere model of was employed as the Martian atmosphere model, and only the photoionization by the solar radiation was considered in the ionization process of the neutral atmosphere. In the simulation result under the normal solar wind conditions, the Martian bow shock position in the subsolar point direction was consistent with the result of the previous studies. The three-dimensional simulation results produced by varying the solar wind density and velocity were all included in the range of the Martian bow shock position observed by Mariner 4, Mars 2, 3, 5, and Phobos 2. Additionally, the simulation result also showed that the change of the solar wind density had a greater effect on the Martian bow shock position than the change of the solar wind velocity. Our result may be useful in analyzing the future observation data by Martian probes.

• Journal of Korean Society of Forest Science
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• v.35 no.1
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• pp.9-14
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• 1977

The productive structure and the productivity of ${\times}$Populus albaglandulosa plantations, where are middle parts of the Korean peninsula, were studied by means of stratifying clip technique and of allometry. The densities of stands in the sample areas were 693 trees/ha in 6 year-old plantation and 527 or 625 trees/ha in 9 year-old one. The photosynthetic part of the productive structure was not shown normal conical form but layering. So this was efficient to transmit solar radiation into the stand floor. The standing crop of the terrestrial parts of 6 year-old plantation was 18.11 ton/ha and that of 9 year-old one 38.8 to 47.3 ton/ha. The wood volume to trunk to 6 year-old was $31.3m^3/ha$ and that of 9 year-old was 68.8 to $83.9m^3/ha$. The annual net production of 6 year-old plantation was 4.8 ton/ha/year and that of 9 year-old one was 10.0 to 11.7 ton/ha/year and its wood volume of trunks was 17.9 to $21.1m^3/ha/year$. In the 9 year-old plantation the standing crop or the annual net production was different between two sample areas. This seemed that the cause was not due to chemical character but to physical character of soil.

• Journal of Life Science
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• v.33 no.7
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• pp.593-604
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• 2023

The ocean accounts for over 70% of the Earth's surface and is a space of largely unexplored unknowns and opportunities. Korea is a peninsula surrounded by the sea on three sides, emphasizing the importance of marine research. The ocean has an extremely complex environment with immense biological diversity. In terms of microbiology, the marine environment has varying factors like extreme temperature, pressure, solar radiation, salt concentration, and pH, providing ecologically unique habitats. Due to this variety, marine organisms have very different phylogenetic classifications compared with terrestrial organisms. Although various microorganisms inhabit the ocean, studies on the diversity, isolation, and cultivation of marine microorganisms and the secondary metabolites they produce are still insufficient. Research on bioactive substances from marine microorganisms, which were rarely studied until the 1990s, has accelerated in terms of natural products from marine Actinomycetes since the 2000s. Since then, industries for bioplastic and biofuel production, carbon dioxide capture, probiotics, and pharmaceutical discovery and development of antibacterial, anticancer, antioxidant, and anti-inflammatory drugs using bacteria, archaea, and algae have significantly grown. In this review, we introduce current research findings and the latest trends in life science and biotechnology using marine microorganisms. Through this article, we hope to create consumer awareness of the importance of basic and applied research in various natural product-related discovery fields other than conventional pharmaceutical drug discovery. The article aims to suggest pathways that may boost research on the optimization and application of future marine-derived materials.

• Korean Journal of Remote Sensing
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• v.27 no.4
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• pp.481-494
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• 2011

Investigation of the $CO_2$ exchange between biosphere and atmosphere at regional, continental, and global scales can be directed to combining remote sensing with carbon cycle process to estimate vegetation productivity. NASA Earth Observing System (EOS) currently produces a regular global estimate of gross primary productivity (GPP) and annual net primary productivity (NPP) of the entire terrestrial earth surface at 1 km spatial resolution. While the MODIS GPP algorithm uses meteorological data provided by the NASA Data Assimilation Office (DAO), the sub-pixel heterogeneity or complex terrain are generally reflected due to coarse spatial resolutions of the DAO data (a resolution of $1{\circ}\;{\times}\;1.25{\circ}$). In this study, we estimated inputs retrieved from MODIS products of the AQUA and TERRA satellites with 5 km spatial resolution for the purpose of finer GPP and/or NPP determinations. The derivatives included temperature, VPD, and solar radiation. Seven AmeriFlux data located in the Corn Belt region were obtained to use for evaluation of the input data from MODIS. MODIS-derived air temperature values showed a good agreement with ground-based observations. The mean error (ME) and coefficient of correlation (R) ranged from $-0.9^{\circ}C$ to $+5.2^{\circ}C$ and from 0.83 to 0.98, respectively. VPD somewhat coarsely agreed with tower observations (ME = -183.8 Pa ~ +382.1 Pa; R = 0.51 ~ 0.92). While MODIS-derived shortwave radiation showed a good correlation with observations, it was slightly overestimated (ME = -0.4 MJ $day^{-1}$ ~ +7.9 MJ $day^{-1}$; R = 0.67 ~ 0.97). Our results indicate that the use of inputs derived MODIS atmosphere and land products can provide a useful tool for estimating crop GPP.