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Hong, Seungbum,Jang, Inyoung,Jeong, Heon-Mo National Institute of Ecology 2020 국립생태원회보(PNIE) Vol.1 No.1
Terrestrial ecosystems influence climate change via their climate regulation function, which is manifested within the carbon, water, and energy circulation between the atmosphere and surface. However, it has been challenging to quantify the climate regulation of terrestrial ecosystems and identify its regional distribution, which provides useful information for establishing regional climate-mitigation plans as well as facilitates better understanding of the interactions between the climate and land processes. In this study, a land surface model (LSM) that represents the land-atmosphere interactions and plant phenological variations was introduced to assess the contributions of terrestrial ecosystems to atmospheric warming or cooling effects over East Asia over the last half century. Three main climate-regulating components were simulated: net radiation flux, carbon exchange, and moisture flux at the surface. Then, the contribution of each component to the atmospheric warming or cooling (negative or positive feedback to the atmosphere, respectively) was investigated. The results showed that the terrestrial ecosystem over the Siberian region has shown a relatively large increase in positive feedback due to the enhancement of biogeochemical processes, indicating an offset effect to delay global warming. Meanwhile, the Gobi Desert shows different regional variations: increase in positive feedback in its southern part but increase in negative one in its eastern part, which implies the eastward movements of desert areas. As such, even though the LSM has limitations, this model approach to quantify the climate regulation is useful to extract the relevant characteristics in its spatio-temporal variations.
Hong, SeungBum,Na, Hyungho,Ahn, Jaemyung Professional Engineering Publishing Ltd 2014 Proceedings of the Institution of Mechanical Engin Vol. No.
<P>This paper introduces a concept, a baseline design, and a trade study for a new space-based global continuous disaster monitoring system composed of a dual-mode satellite constellation and on-orbit propellant depots. The proposed constellation operates in two different modes: a normal mode and a disaster mode, which are responsible for atmospheric/oceanic imaging and disaster monitoring, respectively. The dual-mode concept enables the system to manage the uncertainties associated with the unknown time and location of a disaster and to enhance its operational efficiency by improving its utilization. The mode-change requires orbit transfers accompanying large amounts of fuel consumption, and this challenge is addressed by an on-orbit refueling system to support the constellation. A reference design for the proposed satellite constellation and the orbiting depot is presented. Orbital parameters and the options for mode-change transfers are explored considering the trade-off relationships among the propellant consumption (to minimize), the response time (to minimize), and the access area in normal mode (to maximize). Options for the number of on-orbit propellant depots and the drift rate for the refueling operation are also explored considering the time to complete the preparation and associated probability to get ready for the next disaster outbreak.</P>
Nanoscale piezoresponse studies of ferroelectric domains in epitaxial BiFeO3 nanostructures
Hong, Seungbum,Klug, Jeffrey A.,Park, Moonkyu,Imre, Alexandra,Bedzyk, Michael J.,No, Kwangsoo,Petford-Long, Amanda,Auciello, Orlando American Institute of Physics 2009 JOURNAL OF APPLIED PHYSICS - Vol.105 No.6