• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.722-727
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• 2003

Xylitol is a 5-carbons carbohydrate, which can be replaced with sucrose for preventing caries. The effect of carbohydrates and their combinations with xylitol was studied for the replication of oral bacteria such as Streptococcus oralis and Streptococcus salivarius. The replication of Streptococcus oralis and Streptococcus salivarius was inhibited according to the increased concentration of xylitol. When Streptococcus oralis was incubated for 8 hours in the media added with lactose or sucrose, the optical density was 0.915 and 1.107, repectively. while being 0.127 and 0.104, respectively in the media combined with xylitol. When Streptococcus salivarius was incubated for 8 hours in the media added with lactose or fructose, the optical density was 1.550 and 0.420, repectively. while being 0.271 and 0.905, respectively in the media combined with xylitol. These results indicated that the replication of Streptococcus oralis and Streptococcus salivarius was changed according to kinds of carbohydrates and combined addition of xylitol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1346-1351
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• 2014

We propose a novel approach for stereophonic acoustic echo suppression using spectro-temporal filtering based on soft decision. Unlike the conventional approaches estimating the echo pathes directly, the proposed technique can estimate stereo echo spectra without any double-talk detector. In order to improve the estimation of echo spectra, the extended power spectrum density matrix and echo overestimation control matrix are applied on this method. In addition, this echo suppression technique is based on soft decision technique using speech absence probability in STFT domain. Experimental results show that the proposed method improves compared with the conventional approaches.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.3
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• pp.116-121
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• 2004

Treatability tests were conducted to study the feasibility of EMMC process as a recycling-water treatment system in high density seawater aquaculture farm. To study the effect of organic and ammonia nitrogen loading rate on system performance, hydraulic retention time was reduced gradually from 12hr to 10min. The conclusions are can be summarized as follows. When the system HRT was reduced from 12hr to 2hr gradually, there was little noticeable change(reduction) in ammonia nitrogen removal efficiencies. However, removal efficiencies were decreased dramatically when the system was operated under the HRT of less than 2hr. In case of organics(COD), there was no dramatic change in removal efficiencies depending on HRT reduction. COD removal efficiencies were maintained successfully higher than 9％ when the system was operated at tile HRT of 10 min. System performances depending on media packing ratio in the reactors were also evaluated. There were little differences in each reactor performances depending on media packing ratio in reactor when the reactors were operated under the HRT of longer than 1hr. However, differences in reactor performances were considerably evident when the reactors were operated under the HRT of shorter than 1hr. When comparing reactor performance among 25％, 50％,7 5％ packed reactor, it can be judged that media packing ratio more than 50％ plays no significant role in increasing reactor performance. For this reason, packing the media less than 50％ is more reasonable way in view of economic. Such a tendency shown in COD removal efficiencies well agreed with the variation of ammonia-nitrogen removal efficiencies according to the media packing ratio in reactors at each HRT. Difference in effluent ammonia-nitrogen concentration between 50％ media packing reactor and 75％ media packing reactor was negligible. When comparing with the results of 25％ packing reactor, difference was not so great.

• The Korean Journal of Mycology
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• v.18 no.1
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• pp.42-49
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• 1990

The cultural characteristics and some factors such as nutrient sources and supplements effecting on mycelial growth and density were investigated to study the possibility of an artificial cultivation of P. cocos. The optimum pH for P. cocos was 4.0-4.5. The optimal growth temperature ranged from $25^{\circ}C$ to $29^{\circ}C$. Myceial growth of P. cocos was better in SPD than PD media. Adding the nurient sources such as dextrose, yeast and potato infusion to pine extract media practically stimulated the mycelial growth and density of P. cocos comparing to pine extract media alone. When P. cocos was cultured on sawdust media added 3 different supplements composed of corn meal, rice bran and wheat bran, corn meal was the best and its percentage was 30 (w/w) for mycelial growth. On culturing in sawdust media added by varying the mixture ratio of them, the media mixed corn meal and wheat bran (3:1, w/w) supported more vigours for mycelial growth. In inoculation test to pine stem, the fungal growth was good in under or inside pine bark and xylem, but the sclerotium was not observed in the stem. Mycelial growth was also observed in central part of pine stem by cross section.

• Korean Journal of Plant Resources
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• v.12 no.3
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• pp.171-178
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• 1999

The purpose of this study was to investigate the optimal mixture ratio for the mycelial culture of the Pleurotus ostreatus. The chief cultural media in this study were cotton hull, sawdust and rice straw and the supplemental media were zeolite, corn cob, defatted rice bran, white cotton, tobacco trash powder, rice hull and peat. The results of this study were as follows; the optimal mixture ratio of the chief cultural media were effective in 6 : 3 : 1(V/V, %), and the mycelial growth and density in the supplemental media were considerably better 1% zeolite,3% corn cob, 5% defatted rice bran, 1% white cotton, 1% tobacco trash powder, 7% rice hull in good order. The optimal mixture ratio be to the mixed supplemental media in the chief cultural media were as follows ; 2 : 2(V/V, %) at the conditions of mixed zeolite and corn cob; 3 : 2(V/V, %) at the conditions of mixed defatted rice bran and white cotton; 1 : 3(V/V, %) at the conditions of mixed tobacco trash powder and rice hull. At the conditions of the whole cultural media mixed, the mycelial growth and density were in good conditions ; cotton hull, sawdust, rice straw, zeolite, corn cob, defatted rice bran, white cotton, tobacco trash powder, rice hull, and peat were mixed 43.0 : 17.2 : 25.8 : 2.0 : 2.0 : 3.0 : 2.0 : 1.0 : 3.0 : 1.0 (V/V, %).

• The Korean Journal of Mycology
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• v.37 no.2
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• pp.150-154
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• 2009

The diversity of microflora according to growth stage of Pleurotus ostreatus and the correlation between microbe and medium fermentation were investigated. In farmhouse I, the aerobic bacteria and fungi as longer of growing period were increased. And, thermophilic bacteria and fluorescent Pseudomonas sp. showed high density at the early stage of spawn inoculation. The thermophilic actinomycetes were distributed evenly during all the growing period, but mesophilic actinomycetes were not observed. In farmhouse II, thermophilic actinomycetes were not observed in fermented medium and density of fungi were suddenly increased at 60 days after spawn inoculation. And also, mushrooms can hardly be harvested due to Penicillium spp. After medium fermentation, density of aerobic bacteria, thermophilic bacteria, and fluorescent Pseudomonas sp. was higher at farmhouse I than those of farmhouse II. In farmhouse I, Bacillus sp. and Pseudomonas sp. dominated at early stage of mushroom growth but as time goes by, density of Bacillus sp. was higher than the others. And also, the kind of microbe showed a few at early stage of mushroom growth but increased as time goes by. In farmhouse II, Bacillus sp. was dominated at early stage of mushroom growth. And the growth of Bacillus sp. and Pseudomonas sp. showed intersect aspect each other in the farmhouse I but Bacillus sp. dominated during all growth periods in the farmhouse II.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.3 s.116
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• pp.1-6
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• 2006

The increasing use of newsprints in the media and an advertisement have brought the needs to improve the printing quality of the advance full-color newspaper. The printability coefficients used in this research such as Ymax for the density and Tollenaar's density smoothness constant value $\ulcorner$m$\lrcorner$ were introduced early in Europe and have been in use to control printing quality. In order to improve printing quality of domestic full-color newsprints, those printability coefficients could be used to control printing quality. This study was carried out to measure the printability coefficients of domestic full-color newspapers. Four kinds of domestic newspapers and two kinds of newspaper printing inks were tested by IGT printability tester. The printed density smoothness coefficient $\ulcorner$m$\lrcorner$ value showed good results when the samples have low porosity and roughness. The printability coefficients obtained are expected to be useful to the korean newspaper printing industry.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.12
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• pp.820-824
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• 2008

Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, the electret filter is made by electrospinning process using Polystyrene which is dissolved by 5 : 5 of Tetrahydrofuran (THF) and Dimethylformamide (DMF). Also the electrical properties and the filtration performances of electrospun filter media are Quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. The surface charge potential and the surface charge density of electrospun PS filters are increased with increasing applied voltage and saturated at 30 kV of applied voltage. Also collection efficiency of electro spun filters is increased with increasing surface charge potential and surface charge density. But the surface charge potential is decreased by natural decay and it causes deterioration of particle collection efficiency.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.11a
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• pp.169-172
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• 2001

There are many people who suffer from simulation sickness when immersing in virtual reality. In this study, we analyzed two photoplethysmogram(PPG) parameters - a second derivative parameter and power spectral density ratios - in order to relate PPG parameters with simulation sickness. 36 young, healthy subjects were participated in the experiment, and each subject was equipped with a PPG electrode during his or her immersion. Simulation sickness section was defined as a 7 - second section which starts from the point where a subject reported simulation sickness, and normal section as a same-length section where no physical stimuli was presented to him or her. We compared the PPG parameters of the simulation sickness sections with the normal sections, - d/a ratio is believed to have lower value during vasodilation and higher value during vasoconstriction, however, we could not find much difference in the parameter between normal and simulation sickness sections. We also compared 1 to 10Hz power spectral density ratios in normal sections with in simulation sickness section, and found that 6 density ratios among them have different value. Therefore, the density ratios might be utilized as parameters to detect simulation sickness of subjects.

• Korean Journal of Plant Resources
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• v.14 no.3
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• pp.196-205
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• 2001

The results of examining cultivation of tlyster mushroom using NSM(Non Sterilized Media) for determining the condition of artificially culturing oyster mushroom(Pleurotus ostreatus) are as follows. Mycelial growth an[1 density of oyster mushroom. were the highest in the medium of waste cotton(spinning) : corn cob(80 : 20, V/V) followed by the order of rice bran, beet pulp. Expecially, mycelial growth and density of oyster mushroom is the lowest at the mixture rate of 80% waste cotton(spinning) : 10% beet pulp. Mycelial growth and density of oyster mushroom. were the highest in the medium of cotton seed hull and beet pulp mixture followed by the order of rice bran, corn cob. Expecially, mycelial growth and density of oyster mushroom is the lowest at the mixture rate of 80% cotton seed hull : above 20% rice bran. Mycelial growth and density of oyster mushroom were the highest in the medium rate of 70% waste cotton(spinning), 10% corn cob and 10% beet pulp(V/V). Mycelial growth and density of oyster mushroom were the highest in the medium rate of 70% cotton seed hull , 10% corn cob and 10% beet pulp(V/V). Optimal concentration of NSM for the mycelial growth and density of oyster mushroom were shown to be 500 times concentration. Optimal water contents for the mycelial growth and density of NSM was 70%.