• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.58.2-58.2
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• 2015

We investigate the decaying incompressible MHD turbulence by including the effect of the expansion and contraction of background medium. In such an environment, incompressible MHD turbulence has two kinds of time scale. One is the eddy turn-over time (teddy), the other is the expansion/contraction time (texp-cntr). The turbulence is expected to behave differently according to the relationship between the two time scales. For instance, for teddy < texp-cntr, the turbulence would be decay more or less as in a static medium. On the other hand, for teddy > texp-cntr, the effects of expansion and contraction would be dominant. We examine the properties of turbulence in these two regime cases. Based on it, we derive a scaling for the time evolution of flow velocity and magnetic field. (i) In the decay effect dominant case, the velocity and magnetic field scale as $\sqrt{{\rho}v}{\sim}a^{-3}$, $b{\sim}a^{-2.5}$(expanding media) and $\sqrt{{\rho}v}{\sim}a^{-2}$, $b{\sim}a^{-1.5}$(contracting media). The total energy and residual spectra follow the $E^T_k{\sim}k^{-5/3}$, $E^R_k{\sim}k^{-7.3}$ in the inertial range. (ii) In the expanding and contracting dominant case, the velocity and magnetic field scale as $\sqrt{{\rho}v}{\sim}a^{-2.5}$, $b{\sim}a^{-2}$ (expanding/contracting media). The Kinetic and magnetic energy spectra follow the $E^K_k{\sim}a^{-5}$, $E^M_k{\sim}a^{-4}$. We have confirmed that scaling of velocity and magnetic filed is almost the same from the analytic estimates and computational models

• Journal of Microbiology and Biotechnology
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• v.27 no.10
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• pp.1744-1752
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• 2017

Myeolchi jeotgals (MJs) were prepared with purified salt (PS), solar salt aged for 1 year (SS), and bamboo salt (BS) melted 3 times at 10% and 20% (w/w) concentrations, and fermented for 28 weeks at $15^{\circ}C$. BS MJ showed higher pH and lower titratable acidities than the other samples because of the alkalinity of bamboo salt. Lactic acid bacteria counts increased until 4-6 weeks and then decreased gradually, and were not detected after 20 weeks from MJs with 10% salt. Yeast counts of PS MJs were higher than those of BS and SS MJs. Bacilli were detected in relatively higher numbers throughout the 28 weeks, like marine bacteria, but archae were detected in lower numbers during the first 10 weeks. When 16S rRNA genes were amplified from total DNA from PS MJ (10% salt) at 12 weeks, Tetragenococcus halophilus was the major species. However, Staphylococcus epidermidis was the dominant species for BS MJ at the same time point. In SS MJ, T. halophilus was the dominant species and S. epidermidis was the next dominant species. BS and SS MJs showed higher amino-type nitrogen, ammonia-type nitrogen, and volatile basic nitrogen contents than PS MJs. SS and BS were better than PS for the production of high-quality MJs.

• Korean Journal of Environment and Ecology
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• v.22 no.5
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• pp.530-535
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• 2008

This study was carried out to analyze the vegetation and soil characteristic, and ordination of Wasabia japonica population at Ulleung-Do. The Wasabia japonica population is distributed in altitudes of 440m to 570m at Seo-Myon and also in altitudes of 340m near Nari-valley. In the study sites, soil organic matter, nitrogen, available phosphorous, exchangeable potassium, exchangeable calcium, exchangeable magnesium concentration, cation exchange capacity, and soil pH were 15.01%, 0.48%, 44.19ppm, 2.00(me/100g), 7.19(me/100g), 4.44(me/100g), 22.55(me/100g), and 6.17, respectively. The Rumohra standishii dominant population was mainly found in high in soil nitrogen, organic matter, CEC, and exchangeable calcium concentration in comparison with Boehmeria spicata dominant population. The Boehmeria spicata dominant population was mainly found in high in soil pH.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.622-630
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• 2016

In the operation of a low earth orbit satellite, a series of antenna commands are transmitted from a ground station to the satellite within a visibility window (i.e., the time period for which an antenna of the satellite is visible from the station) and executed to control the antenna. The window is a limited resource where all data transmission is carried out. Therefore, minimizing the transmission time for the antenna commands by reducing the data size is necessary in order to provide more time for the transmission of other data. In this paper, we propose a geometric compression method based on B-spline curve fitting using dominant points in order to compactly represent the antenna commands. We transform the problem of command size reduction into a geometric problem that is relatively easier to deal with. The command data are interpreted as points in a 2D space. The geometric properties of the data distribution are considered to determine the optimal parameters for a curve approximating the data with sufficient accuracy. Experimental results demonstrate that the proposed method is superior to conventional methods currently used in practice.

• Microbiology and Biotechnology Letters
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• v.39 no.4
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• pp.374-381
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• 2011

The beneficial effects of Eisenia fetida on soil properties have been attributed to their interaction with soil microorganisms. The bacterial diversity of the intestinal tract of E. fetida was investigated by culture-dependent and culture-independent methods including denaturing gradient gel electrophoresis (DGGE) and pyrosequencing analyses. In a pure culture, Lysinibacillus fusiformis (51%), Bacillus cereus (30%), Enterobacter aerogenes (21%), and L. sphaericus (15%) were identified as the dominant microorganisms. In the DGGE analyses, B. cereus (15.1%), Enterobacter sp. (13.6%), an uncultured bacterium (13.1%), and B. stearothermophilus (7.8%) were identified as the dominant microorganisms. In the pyrosequencing analyses, Microbacterium soli (26%), B. cereus (10%), M. esteraromaticum (6%), and Frigoribacterium sp. (6%) were identified as the dominant microorganisms. The other strains identified were Aeromonas sp., Pseudomonas sp., Borrelia sp., Cellulosimicrobium sp., Klebsiella sp., and Leifsonia sp. The results illustrate that culture independent methods are better able to detect unculturable microorganisms and a wider range of species, as opposed to isolation by culture dependent methods.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.3
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• pp.227-233
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• 2010

This study examined microbial community structures (MCSs) according to environmental factors through DGGE analysis and comparison in various soils collected from near army bases and gas stations. As a result, the similarities based on DGGE band profiles showed the closer relationship in regional properties than in pollution characteristics, probably due to the degree of weak contamination. The highly contaminated samples with oil revealed low MCS similarities with others in the same region and very low with all the other samples in the other regions. Thus the microbial community structure would more be affected by region-based natural factors than by contamination factors in case of minor pollution. All the dominant culturable bacterial species were involved in firmicutes or high GC Gram+ in a major portion of soil samples and the highly oil-contaminated samples contained Arthrobacter, Bacillus, Methylobacterium, Clavibacter, Streptomyces and Nocardia as reported genera, and Leifsonia as a unreported genus.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.5
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• pp.415-421
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• 2013

CGI is gaining popularity in applications that require either greater strength, or lower weight than cast iron. Recently, compacted graphite iron has been used for diesel engine blocks, turbo housings and exhaust manifolds. This paper were assessed acoustic emission characteristics according to the mechanical properties change of degraded CGI340 during 1-24 hours at 873~1173 K. In results of pencil lead fracture test, the dominant frequency and the velocity of base metal were 97 kHz and 5490 m/sec, respectively. The base metal in a tensile test was obtained relatively high dominant frequency. However, the heat treated materials, the longer the heat treatment time, the higher the heat treatment temperature, were obtained in the area of lower frequencies. This phenomenon appears by long-term use.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.2
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• pp.63-71
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• 2010

This study was carried out to analyze the vegetation and soil characteristic, and ordination between Calanthe discolor and C. sieboldii population, Jeju Island. The C. discolor population was classified into Cryptomeria japonica dominant population, Miscanthus sinensis dominant population, and C. discolor typical population. The C. discolor population was located in elevation of 156m to 430m, and C. sieboldii was located in elevation of 424m to 604m in Jeju Island. In the study sites, soil organic matter, nitrogen, exchangeable potassium, exchangeable calcium, exchangeable magnesium, cation exchange capacity, and soil pH were 30.05~53.58%, 0.74~1.64%, 0.80~1.95cmol$^+$/kg, 4.35~22.53cmol$^+$/kg, 4.00~6.63cmol$^+$/kg, 25.60~51.33cmol$^+$/kg, and 4.83~5.70, respectively. C. discolor population was found in the low elevation and steep sloped area that has less organic matter, total nitrogen, and cation exchange capacity than C. sieboldii population. C. discolor typical population was found in the high elevation area that has more organic matter and total nitrogen in the C. discolor. Miscanthus sinensis dominant population was found in the shade of west direction of japanese black pine. C. sieboldii was found in a high elevation and a gentle sloped area that has high percentage organic matter, total nitrogen, and cation exchange capacity.

• Journal of Korean Society of Forest Science
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• v.98 no.5
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• pp.539-547
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• 2009

This study was conducted to investigate the arbuscular mycorrhizal fungal biodiversity, spore density and root colonization in relation to site ages at expressway cut-slopes in Korea. Stabilization of exposed surface involved soil amendments and spraying seed mixture of turf grasses and/or nitrogen-fixing shrub species. Eighteen sites were selected with varying ages (2 to 16 years). Soil samples collected in October from each site were analyzed for fungal diversity and spore counts. Fine root samples from the plants were assayed for fungal colonization. Of the total 37 plants inspected in the sites, 26 species had endomycorrhizal colonization with an average root colonization rate of 18%, and with a range from 1 to 67%. The average endomycorrhizal colonization rate of initially introduced Festuca arundinacea which became the most dominant grass in later stage showed 22.8%, while that of Lespedeza bicolor which became the most dominant woody species were 21.6%. Naturally-invading Robinia pseudoacacia showed higher colonization rate in the old sites. Although site age did not show significant effects on fungal diversity, the root colonization rates of initially introduced plants decreased with the site aging, while those of invading plants increased with aging of the sites. The soil chemical properties, pH, N, and P contents, were negatively correlated with spore density, root colonization and endomycorrhizal species diversity. A total of forty arbuscular mycorrhizal fungal species in seven genera were identified. Of the 40 species, Acaulospora lacunosa, Glomus aggregatum, Glomus constrictum, Scutellospora erythropa, and Acaulospora spinosa were the five most dominant species in the decreasing order.

• The Journal of the Acoustical Society of Korea
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• v.29 no.5
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• pp.325-331
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• 2010

Categorical perception has been noted as characteristic properties of linguistic stimuli. In this study, Korean monosyllabic minimal pairs (consonant-vowel-consonant, CVC) were analyzed to understand perception boundaries between clinically confusing words. An efficient scheme has been developed to systematically synthesize temporal transition waveforms (11 steps) from one word to the target word for the pairs of /gom/-/gong/, /non/-/noon/, and /don/-/non/. The corresponding slopes, widths, and non-dominant factors of perception boundaries were analyzed for the total of 40 young normal subjects (20 males and 20 females). Results showed that there were relative pattern differences among confusing monosyllabic minimal pairs under categorical perception. For instance, the vowel difference within CVC pairs led to the lowest boundary performance in this experiment set. Data also indicated the potential application of the overall procedure for evaluating auditory functions and assisting rehabilitation programs.