• Sleep Medicine and Psychophysiology
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• v.3 no.1
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• pp.15-24
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• 1996

After rapid eye movement(REM) sleep was idenified in 1953, a lively interest developed concerning a possible role of this kind of sleep in memory processes. The author reviewed studies relating REM to memory/learning. Many studies in animals and humans gave substantial evidence for relating REM sleep to memory function. The evidence supporting the position taken in this paper comes from experiments showing that : (1) learning session is followed by the significant augmentation of REM sleep : (2) REM sleep deprivation, prior to learning or immediately thereafter, impairs the formation of a permanent memory/learning : (3) there is a vulnerable period of time(eg, REM sleep "window") following succussful learning, during which REM sleep deprivation results in memory impairment : (4) theta rhythm which develops during REM sleep induces long-term potentiation in hippocampus : (5) there are some evidences providing the relationship of neurotransmitter systems to the maintenance of REM sleep and memory storage processes.

• Journal of Ecology and Environment
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• v.41 no.3
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• pp.78-84
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• 2017

Recently, great demands are rising around the globe for monitoring and studying of long-term ecological changes. To go with the stream, many researchers in South Korea have attempted to share and integrate ecological data for practical use. Although some achievements were made in the meantime, we still have to overcome a big obstacle that existing ecological data in South Korea are mostly spread all over the country in various formats of computer files. In this study, we aim to handle the situation by developing a semi-automatic data conversion tool for Korean ecological data standardization, based on some predefined protocols for ecological data collection and management. The current implementation of this tool works on only five species (libythea celtis, spittle bugs, mosquitoes, pinus, and quercus mongolica), helping data managers to quickly and efficiently obtain a standardized format of ecological data from raw collection data. With this tool, the procedure of data conversion is divided into four steps: data file and protocol selection step, species selection step, attribute mapping step, and data standardization step. To find the usability of this tool, we utilized it to conduct the standardization of raw five species data collected from six different observatory sites of Korean National Parks. As a result, we could obtain a common form of standardized data in a relatively short time. With the help of this tool, various ecological data could be easily integrated into the nationwide common platform, providing broad applicability towards solving many issues in ecological and environmental system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4023-4043
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• 2016

Network virtualization has been regarded as a core attribute of the Future Internet. In a network virtualization environment (NVE), multiple heterogeneous virtual networks can coexist on a shared substrate network. Thus, a substrate network failure may affect multiple virtual networks. In this case, it is increasingly critical to provide survivability for the virtual networks against the substrate network failures. Previous research focused on mechanisms that ensure the resilience of the virtual network. However, the resource efficiency is still important to make the mapping scheme practical. In this paper, we study the survivable virtual network embedding mechanisms against substrate link and node failure from the perspective of improving the resource efficiency. For substrate link survivability, we propose a load-balancing and re-configuration strategy to improve the acceptance ratio and bandwidth utilization ratio. For substrate node survivability, we develop a minimum cost heuristic based on a divided network model and a backup resource cost model, which can both satisfy the location constraints of virtual node and increase the sharing degree of the backup resources. Simulations are conducted to evaluate the performance of the solutions. The proposed load balancing and re-configuration strategy for substrate link survivability outperforms other approaches in terms of acceptance ratio and bandwidth utilization ratio. And the proposed minimum cost heuristic for substrate node survivability gets a good performance in term of acceptance ratio.

• Journal of Information Management
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• v.41 no.2
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• pp.1-30
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• 2010

This study analyzed research output in dominant research areas of 19 national research institutions. Policy knowledge produced by the institutions during the past 5 years mainly concerned 10 policies dealing with economy and society issues. Similarities between the research subjects of the institutions were displayed by MDS mapping. The study also identified issue attention cycles of the 5 chosen policies and examined the correlation between the issue attention cycles and the yields of policy knowledge. The knowledge structure of each policy was mapped using co-word analysis and Ward's clustering. It was also found that the institutions performing research on similar subjects demonstrated citation preferences for each other.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.24.4-24.4
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• 2011

Frozen orbit concept is very useful in designing particular mission orbits including the Sun-synchronous and minimum altitude variation orbits. In this work, variety of frozen and Sun-synchronous orbit conditions around the Moon is investigated and analyzed. The first two zonal harmonics of the Moon, J2 and J3, are considered to determine mean orbital elements to be a frozen orbit. To check the long-term behavior of a frozen orbit, formerly developed YonSei Precise Lunar Orbit Propagator (YSPLOP) is used. First, frozen orbit solutions without conditions to be the Sun-synchronous orbit is investigated. Various mean semi-major axes having between ranges from 1,788 km to 1,938 km with inclinations from 30 deg to 150 deg are considered. It is found that a polar orbit (90 deg of inclination) having 100 km of altitude requires the orbital eccentricity of about 0.01975 for a frozen orbit. Also, mean apolune and perilune altitudes for this case is about 136.301 km and 63.694 km, respectively. Second, frozen orbit solutions with additional condition to be the Sun-synchronous orbit is investigated. It is discovered that orbital inclinations are increased from 138.223 deg to 171.553 deg when mean altitude ranged from 50 km to 200 km. For the most usual mission altitude at the Moon (100 km), the Sun-synchronous orbit condition is satisfied with the eccentricity of 0.01124 and 145.235 deg of inclination. For this case, mean apolune and perilune altitudes are found to be about 120.677 km and 79.323 km, respectively. The results analyzed in this work could be useful to design a preliminary mapping orbit as well as to estimate basic on-board payloads' system requirements, for a future Korea's lunar orbiter mission. Other detailed perturbative effects should be considered in the further study, to analyze more accurate frozen orbit conditions at the Moon.

• Journal of the Korean Society for information Management
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• v.22 no.3 s.57
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• pp.37-53
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• 2005

The terminology management is absolutely necessary for maintaining the efficiency of thesaurus. This is because the creating, differentiating, disappearing, and other processes of the descriptor become accomplished dynamically, making effective management of thesaurus a very difficult task. Therefore, a device is required for accomplishing methods to construct and maintain the thesaurus. This study proposes the methods to construct the thesaurus management using the basic elements of a topic map which are topic, occurrence, and association. Second, the study proposes the methods to represent the basic and specific instances using the systematic mapping algorithm and merging algorithm. Also, using a hub document as a standard, this study gives the methods to expand and subsitute the descriptors using the topic type. The new method applying fixed concept for double layer management on terms is developed, too. The purpose of this method is to fix the conceptual term which represents independent concept of time and space, and to select the descriptor freely by external information circumstance.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.540-548
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• 2016

Microbially induced calcium carbonate precipitation (CCP) is a long-standing but re-emerging environmental engineering process for production of self-healing concrete, bioremediation, and long-term storage of CO₂. CCP-capable bacteria, two Bacillus strains (JH3 and JH7) and one Sporosarcina strain (HYO08), were isolated from two samples of concrete and characterized phylogenetically. Calcium carbonate crystals precipitated by the three strains were morphologically distinct according to field emission scanning electron microscopy. Energy dispersive X-ray spectrometry mapping confirmed biomineralization via extracellular calcium carbonate production. The three strains differed in their physiological characteristics: growth at alkali pH and high NaCl concentrations, and urease activity. Sporosarcina sp. HYO08 and Bacillus sp. JH7 were more alkali- and halotolerant, respectively. Analysis of the community from the same concrete samples using barcoded pyrosequencing revealed that the relative abundance of Bacillus and Sporosarcina species was low, which indicated low culturability of other dominant bacteria. This study suggests that calcium carbonate crystals with different properties can be produced by various CCP-capable strains, and other novel isolates await discovery.

• 보존과학연구
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• s.34
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• pp.32-48
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• 2013

This study examined the applicability of deterioration monitoring techniques to establish efficient conservation and management system for stone cultural heritage which conservation treatment has been done. It was confirmed that deterioration mapping combined with photography and grid work, and adhesive tape test for the surface were very applicable to investigate the surface change due to deterioration, and assess the degree of granular disintegration quantitatively. The portable microscopic survey and ultrasonic measurement were efficient techniques to observe mineral looseness and microcrack, and to track the strength change of the stone before-and-after the conservation treatment. These techniques can be easily used by manage practitioners in the field through simple guidance and technical education. Also, it can contribute to build a long-term and methodical conservation and management system of the stone cultural heritage.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.76.4-77
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• 2017

We have been performing a long term AGN Monitoring project, to measure the time lag of H beta line with respect to AGN optical continuum based on the reverberation mapping method. From October 2015, 69 AGNs have been monitored with BVR band photometry, using the MDM 1.3m & 2.4m and LOAO 1m telescopes, and long-slit spectroscopy, using the Lick 3m and MDM 2.4m telescopes. In this poster, we report the preliminary results of the variability study of a subsample of 9 AGNs, particularly with a few of tentative time rag measurements between B band magnitude and H beta luminosity based on the 1st year data set from February 2016 - January 2017.

• Journal of KSNVE
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• v.9 no.1
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• pp.196-205
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• 1999

The existence. bifurcation. and the orbital stability of periodic motions, which is called nonlinear normal mode, in a nonlinear dual mass Hamiltonian system. which has 6th order homogeneous polynomial as a nonlinear term. are studied in this paper. By direct integration of the equations of motion. Poincare Map. which is a mapping of a phase trajectory onto 2 dimensional surface in 4 dimensional phase space. is obtained. And via the Birkhoff-Gustavson canonical transformation, the analytic expression of the invariant curves in the Poincare Map is derived for small value of energy. It is found that the nonlinear system. which is considered in this paper. has 2 or 4 nonlinear normal modes depending on the value of nonlinear parameter. The Poincare Map clearly shows that the bifurcation modes are stable while the mode from which they bifurcated out changes from stable to unstable.