• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.131-137
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• 2015

This paper relates with the VSS-MMA (Variable Step Size-Multiple Modulus Algorithm) adaptive equalization algorithm which is possible to improving the equalization performance by use the nonlinear fuction of error signal in the MMA adaptive equalization algorithm that are used for the minimization of the intersymbol interference due to the distortion which occurs in the time dispersive channel for the transmission of QAM signal in the system.. In the conventional MMA, we obtains the tap coefficient of adaptive equalizer using the fixed step size, but in the VSS-MMA, we obtains the tap coefficient of adaptive equalizer using the variable step size based on a nonlinear function of error signal. By adapting the variable step size, it was confirmed that the improved equalization performance were obtained by computer simulation. For this, the equalizer output signal constellation, residual isi, maximum distortion, MSE and SER were used in the performace index.

• Journal of Korean Society of Transportation
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• v.33 no.3
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• pp.294-303
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• 2015

This paper describes a method that can be used for estimating future carbon emissions and environmental effects. To forecast future land use and transportation changes under various low carbon policies, a DELTA and OmniTRANS combination (a land use-transport integrated model) was applied. Appropriate emission estimation methods and dispersion models were selected and applied in the method. It was designed that the estimated emissions from land use and transportation activity as well as the estimated concentrations of air pollutants and comprehensive air quality index (CAI) are presented on a GIS-based map. The prototype was developed for the city of Suwon and the outcome examples were presented in this paper; it demonstrates what kinds of analysis results are presented in this method. It is expected that the developed method will be very useful for decision makers who want to know the effect of environmental policies in cities.

• Carbon letters
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• v.10 no.1
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• pp.14-18
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• 2009

We measured the degree of macrodispersion of the various single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using UV-VIS-NIR absorption spectroscopy. CNTs were dispersed with SDS of 2 wt % in deionized water using the homogenizer and then were further centrifugated at 6000 g for 10 min. The degree of macrodispersion, expressed by $D_m({\lambda})=A_a({\lambda})/A_b({\lambda})^*100$ (%), where ${\lambda}$ is the wavelength and $A_a({\lambda})$ and $A_b({\lambda})$ are the absorbance of the sample after and before centrifugation, respectively. In the case of MWCNTs, we evaluated the degree of macrodispersion by the average degree of macrodispersion ($D_m({\lambda})$) between 1000 and 1200 nm. The degree of macrodispersion of SWCNTs was evaluated at the wavelength in which van Hove singularity-related transition regions were excluded, i.e., the range was chosen between ${E_{11}}^S$ and ${E_{22}}^S$ peaks. We have estimated six samples with the same method. The standard deviation of each sample was lower than 5. Therefore, we presented a reliable evaluation method for the macrodispersion of CNTs for standardization.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2048-2061
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• 1991

As compared with other cutting types, the ball end milling process causes a complexity in cutting system and a falling-off of machinability. In order to increase the productivity and efficiency in th NC machining of sculptured surfaces, this study carried out the qualitative linearized evaluation about the ball end milling system and applied their practical expressions to the technological processor at the cutter path planning stage. The evaluated expressions were proved to be adequate for practical use from an accuracy point of view and the estimation models were applied to sculptured surface machining processes for finding variable machining conditions. Consequently, it was recognized that variable machining conditions bring about the dispersion of force system and the reduction of machining time by more than 50%.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.458-465
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• 2009

In general, ultrasonic guided wave techniques that used for an evaluation of the internal defect have been applied without considering energy loss. It can be found out that the significant attenuation is observed in the signal of structure with defect by the scattering and absorption. Even in the signal acquired from defect-free structure, this attenuation can be also significant. Therefore, it is very essential to determine the Lamb wave propagation characteristics depending on modes because the dispersibility of Lamb wave can be easily influenced by the attenuation effect with frequency and thickness. For this reason, changing the propagation distance, attenuation coefficient of each Lamb wave mode needs to be investigated by the contact pitch-catch method with PZT(piezoelectric) sensors. In this paper, the experimental attenuation coefficient is measured by choosing the following three different variables; mode, thickness and plate materials. As a result, experimental attenuation coefficient is obtained as the function of variables.

• Korean Journal of Veterinary Research
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• v.32 no.3
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• pp.421-427
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• 1992

The study was basically carried out to establish the appropriate condition for applying the Westergren method for erythrocyte sedimentation rate(W-ESR) in Throughbred racehorses at recess. To do this, we examined the correlationship among some factors including the kind of anticoagulants, optimal ambient temperature and reading time for W-ESR in healthy racehorses. The difference between the blood samples treated with only 3.8% solution of sodium citrate(SC) and both EDTA and SC as a coagulant, there was not recognized any significant difference(p<0.05) in the levels of W-ESR irrespective of the ambient temperature of $20^{\circ}C$ or $30^{\circ}C$. The best optimal ambient temperature for W-ESR in horses was proved at $30^{\circ}C$ resulting from the tendency of the most reduced dispersion in mean values analyaed from repeatly 4 times to the same blood samles compared with those of $10^{\circ}C$ and $20^{\circ}C$. The optimal reading time was determined as 60 minutes(Y=237.2~4.1X, $r^2=0.998$) and 70 minutes(Y=247.8~4.2X, $r^2=0.999$) under the same temperature of $30^{\circ}C$; the latter showed the better result on the basis of the correlation of packed cell volume(PCV) and ESR values. About 13 healthy racehorses, we compared the real values of W-ESR respectively obtained at 60 minutes and 70 minutes at $30^{\circ}C$ with the anticipated values of PCV by means of the analysis of linear regression equitation. As the result of this, the strong correlation between both of them was confirmed. For practical use of W-ESR in Thoroughbred racehorese, we can recommend the condition of 60 or 70 minutes for the optimal reading time as well as $30^{\circ}C$ for the best ambient temperature.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.50-55
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• 2011

A simple and rapid method was developed for monitoring of Gram-positive bacteria in the wastewater treatment system. Culture suspensions of 4 Gram-positive and 4 Gram-negative strains were filtrated and stained with a polyethersulfone membrane filter and Toluidine Blue-O. To establish quantitative color image analysis, the intensity value of RGB (red-green-blue) color of a scanned filter image was analyzed with a photographic program. Red and green color values of Gram-positive bacteria were higher than those of Gram-negative bacteria. This method was applied to the activated sludge mixed with the Gram-positive bacteria. Although evaluation was difficult due to the irregular size and shape of flocs, the population of Gram-positive bacteria in the activated sludge could be monitored with floc dispersion technique. The more amounts of Gram-positive bacteria in the activated sludge led to the increase of red and green color values. This method provides a rapid and quantitative measurement of Gram-positive bacteria within the wastewater treatment systems.

• Journal of Pharmaceutical Investigation
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• v.22 no.4
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• pp.267-279
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• 1992

Microencapsulations of amoxicillin and cephalexin, using Eudragit RS, RL, E, S and L were investigated. The microcapsules were prepared by the solvent evaporation process in liquid paraffin phase, which is based on dispersion of acetone/isopropanol containing the drug in liquid paraffin. Aluminium tristearate was used as an additive for the preparation of microcapsules. The size distribution, dissolution test and observation by SEM were examined. Good reproducibility in microcapsule preparation was observed. The microcapsules obtained were spherical and free-flowing particles. The dissolution rates of amoxicillin and cephalexin from the microcapsules were considerably decreased as compared with those from amoxicillin and cephalexin powder, respectively. As the dispersing agents (aluminium tristearate) increased, the particle size of microcapsules decreased and the dissolution rate increased. In order to control the release rate of drugs, microcapsules were prepared by mixing Eudragit RS/RL or Eudragit S/L. As Eudragit RL ratio in microcapsule of Eudragit RS/RL increased, the dissolution rate increased. As Eudragit L ratio in microcapsule of Eudragit S/L increased, the dissolution rate increased. Furthermore, the release rates of drugs from Eudragit RS/L or RS/polyelthylene glycol 1540 (PEG 1540) were examined. The dissolution rate of drugs increased with increasing of Eudragit L or PEG 1540 ratio. In conclusion, the release rates of drugs from Eudragit RS/RL or RS/PEG 1540 microcapsule could be controlled, and these microcapsules will be convenient for reducing frequency of administration.

• Journal of Navigation and Port Research
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• v.37 no.3
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• pp.269-273
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• 2013

Underwater acoustic channels are generally recognized as one of the most difficult communication media because of the multipath propagation, dispersion, and so on. MIMO (Multiple-input multiple-output) techniques have been actively pursued in underwater acoustic communications recently to increase the data rate over the bandwidth-limited channels. The transmit diversity techniques can be applied in this case, and one of them is Alamouti's scheme. In this paper the performances of the transmit diversity technique are evaluated via experiment. Two transmitters and two receivers were used in experiment, and the experiment was performed in indoor water tank. The error rate 5~8% was confirmed in experimental results, and these are the improved values than the error rate 14.8% for SISO(Single-input single-output) channel under same data rate condition.

• Journal of Pharmaceutical Investigation
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• v.32 no.2
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• pp.73-80
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• 2002

Cefuroxime axetil is a cephalosporin antibiotic having a high activity against a wide spectrum of Grampositive and Gram-negative microorganisms. It is a cephalosporin antibiotic which exist as 2 diastereoisomers: diastereoisomer A and B. It shows polymorphism of three forms: a crystalline form having a melting point of about $180^{\circ}C$, a substantially amorphous form having a high melting point of about $135^{\circ}C$ and a substantially amorphous form having a low melting point of about 70^{\circ}C$. The crystalline form of cefuroxime axetil is slightly soluble in water because diastereoisomer A has lower solubility than B in water. Substantially amorphous form of which there are no difference in solubility between diastereoisomer A and B has better solubility than crystalline form, but it forms a thicker gel than crystalline form upon contact with an aqueous medium. Based on this reason, cefuroxime axetil is not readily absorbable in the gastrointestinal tract, rendering its bioavailability on oral administration very low. The object of this study was to develop an improved non-crystalline cefuroxime axetil composition having a high physicochemical stability and bioavailability. A non-crystalline cefuroxime axetil solid dispersant showing no peak on a Differential Scanning Calorimetry (DSC) scan is prepared by dissolving cefuroxime axetil and a surfactant in an organic solvent; suspending a water-insoluble inorganic carrier in the resulting solution; and spray drying the resulting suspension to remove the organic solvent, said solid dispersant having an enhanced dissolution and stability of cefuroxime axetil and being useful for the preparation of a pharmaceutical composition for oral administration. Tablet was formulated with this cefuroxime axetil solid dispersant, disintegrants and other ingredients. It disintegrated and dissolved easily and dynamically in dissolution medium, so showed a good dissolution profile.