• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.359-372
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• 1988

Characteristics of twin spray ejected from two swirl spray nozzles were studied experimentally. By using a patternator for measuring volumetric flux of drop flow at various locations inside the spray, variation of the twin spray pattern along the axial direction was studied with changing the injection pressure and the distance between the nozzles. The general findings from the experiments are as follows: (i) as axial distance from the nozzles increases, the spray pattern in x-z plane which contains both nozzles changes significantly. On the other hand the spray pattern in y-z plane which passes the midpoint between two nozzles remains almost unchanged at outer region as axial distance and injection pressure vary; (ii) at the downstream of the twin spray with spray interaction, the maximum volumetric flux in y-z plane (q$_{max}$)$_{y}$, has tendency to become larger than that of x-z plane (q$_{max}$)$_{x}$, due to a characteristic(hollow cone shape) of the constituting swirl sprays, and this trend is pronounced at higher injection pressure since the cross-section of each single spray remains hollow at the longer axial distance from each nozzle with higher injection pressure; (iii) at a certain axial distance from the nozzles, the cross-sectional shape of the boundary of the twin spray tends to be circular similar to that of the single spray with twice the flow-rate, and that distance is not proportional to the distance between two nozzles; (iv) though there are some collisions between droplets from each nozzles of twin spray, in present experimental range, the flow pattern of gas including the entrainment effect plays the key role in spray interaction.n.ion.n.

• Journal of Environmental Science International
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• v.20 no.5
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• pp.667-672
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• 2011

The purpose of this work is to present the experiment results by a dynamic adsorption of water vapor on pelletized zeolites (ADZ300, ADZ400, and ADZ500) in fixed bed. The breakthrough curves of water vapor with several different concentrations and temperature in the range of 25~45 $^{\circ}C$ on zeolite bed were investigated. In the same conditions, the breakthrough time on ADZ400 and ADZ500 were little longer than ADZ300, and the equilibrium adsorption capacity on ADZ500 was highest. The higher the concentration of water vapor was, the faster the breakthrough time was, and the slope of breakthrough curves showed a tendency to increase. The faster the flow rate of water vapor was, the faster the breakthrough time was relatively, but variations between flow rate and breakthrough time did not have a proportional relationship. The breakthrough curve maintained constant gradient in spite of variation of flow rate in the same concentration. The temperature rise in zeolite bed by adsorption heat was occurred in the early stage of adsorption. After water molecule layers were formed on the surface of zeolite, the temperature was slowly cooled by water vapors continuously flowed in as constant temperature. The greater the concentration of water vapor and adsorption temperature were, the temperature difference in zeolite bed was increased.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.1
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• pp.15-27
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• 2015

The collection of fine particulate matter samples was made at Gosan site of Jeju Island, one of the background sites of Korea, during a year of 2013, and their water-soluble ionic species were analyzed in order to examine the chemical compositions and pollution characteristics. The concentrations of $nss-SO_4{^{2-}}$, $NH_4{^{+}}$, $NO_3{^{-}}$, and $K^+$ had occupied 66.0% of water-soluble ionic species in $PM_{10}$, especially 94.3% in $PM_{2.5}$ fine mode, however the $nss-Ca^{2+}$ and $Na^+$ showed high concentrations in $PM_{10-2.5}$ coarse mode. $NO_3{^-}/nss-SO_4{^{2-}}$ concentration ratios in $PM_{10}$ and $PM_{10-2.5}$ were 0.30 and 0.13, showing less significant effect from automobile and local pollution sources. The sulfate and nitrate compounds were presumed to be long-range transported to Gosan area by the relatively high SOR and NOR values. The trajectory cluster analysis showed the higher concentrations of the major secondary pollutants ($nss-SO_4{^{2-}}$, $NO_3{^{-}}$, $NH_4{^{+}}$) and $nss-Ca^{2+}$ when the air masses had moved from China continent and Korean peninsula into Gosan area.

• Korean Journal of Materials Research
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• v.21 no.3
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• pp.144-148
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• 2011

We have investigated the structural and optical properties of Ga-doped ZnO (GZO) thin films deposited by RF magnetron sputtering at various deposition temperatures from 100 to $500^{\circ}C$. All the GZO thin films are grown as a hexagonal wurtzite phase with highly c-axis preferred parameter. The structural and electrical properties are strongly related to deposition temperature. The grain size increases with the increasing deposition temperature up to $400^{\circ}C$ and then decreases at $500^{\circ}C$. The dependence of grain size on the deposition temperature results from the variation of thermal activation energy. The resistivity of GZO thin film decreases with the increasing deposition temperature up to $300^{\circ}C$ and then decreases up to $500^{\circ}C$. GZO thin film shows the lowest resistivity of $4.3{\times}10^{-4}\;{\Omega}cm$ and highest electron concentration of $1.0{\times}10^{21}\;cm^{-3}$ at $300^{\circ}C$. The mobility of GZO thin films increases with the increasing deposition temperature up to $400^{\circ}C$ and then decreases at $500^{\circ}C$. GZO thin film shows the highest resistivity of 14.1 $cm^2/Vs$. The transmittance of GZO thin films in the visible range is above 87% at all the deposition temperatures. GZO is a feasible transparent electrode for the application to the transparent electrode of thin film solar cells.

• The Plant Pathology Journal
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• v.36 no.5
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• pp.440-449
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• 2020

The purpose of this study was to analyze the genetic and pathogenic characteristics of Ralstonia pseudosolanacearum in roses in Korea, and to examine the similarities and differences between Korean isolates and the first-reported European strains. Between 2017 and 2019, seventeen isolates from rose plants were identified as R. pseudosolanacearum using Ralstonia-specific primers. All 17 isolates were identified as race 1 using race-specific primers, and were confirmed as biovar 3 due to their ability to utilize carbon sources. Multiplex PCR using phylotype discriminating specific primers identified the 17 isolates as phylotype I. Sequevar comparison with reference sequevars using the sequences of the egl, mutS, and fliC genes, and only the egl gene, revealed that the strains evaluated in this study corresponded to sequevar I-33. The pathogenicity in roses differed depending on the rose cultivars. The different methods used for the genetic characterization of R. pseudosolanacearum indicate that the 17 rose bacterial wilt isolates had the same genetic characteristics. The lack of genetic variation in these isolates indicates their recent introduction from other countries (likely European countries). Therefore, appropriate quarantine and control measures should be taken in order to avoid further increases in the pathogenicity and/or secondary host range of R. pseudosolanacearum through genetic mutation.

• Korean Journal of Food Science and Technology
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• v.20 no.5
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• pp.704-710
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• 1988

This study was, firstly, to investigate water holding capacity in terms of variation of moisture sorption isotherms of seasoned squid treated with sodium lactate, glycerol, propylene glycol, sorbitol, mannitol, sodium benzoate, potassium sorbate and calcium propionate, and secondly, the effect of humectant treatments on storage stability was studied. The criteria for storage stability was based on three quality factors, namely, lipid oxiations, color development by non-enzymatic browning reactions and lipid oxidation, and mold growth. The effect of humectants on equilibrium moisture content was in the following increasing order; mannitol < sorbitol < sodium lactate < propylene glycol < glycerol. The experimental data indicated that sodium lactate has, in practice, potentially positive effect on processing of seasoned squid. During the storage period of 60 days, TBA values increased in all samples tested as humectants concentrations increased up to 10%. However, in the range of 1-7% sodium lactate treatment, the degree of lipid oxidation, browning reactions and mild growth were not high enough to affect the quality of seasoned squid, when compared with conventionally manufactured ones.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.4
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• pp.189-195
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• 1989

The ecological studies of the benthic polychaetes were carried out in the follow Sea for the period of August 1982 through February 1986. Special emphasis were placed on quantitative species composition and the importance of polychaetes in the benthic community. Polychaete group ranked numerically high, composing $35.1\~46.4\%$ of the total benthos. In the biomass, echinoderms or mollusks showed as a dominant group, but the range of its seasonal variation was very large. Due to the use of sampling gear, the relative importance of polychaetes was somewhat different. The case of a dredge showed a little lower composition rate of polychaetes than a grab one. This result was caused by high density of benthic animals because the dredge would tow only much more surface sediments than the grab sampler. The present studies included a total of 141 species and the representative polychaetes in this area were Spiophanes bormbyx, Ampharete arctica, Geniada maulata, Nephtys caeca, Nothria iridescens.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.524-527
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• 2007

[ $Bi_2Sr_2Ca_{n-1}Cu_nO_x$ ](n=0, 1, 2) thin films have been fabricated by co-deposition at an ultra-low growth rate using ion beam sputtering(IBS) method. Bi 2212 phase appeared in the temperature range of 750 and $795^{\circ}C$ and single phase of Bi 2201 existed in the lower region than $785^{\circ}C$. Whereas, $PO_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with $T_c$(onset) of about % K and $T_c$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as $ CaCuO_2$ was observed in all of the obtained films.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2141-2148
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• 2000

This study is to investigate changes of pore structure with different burn-off degree of steam activated carbons manufactured from domestic anthracite. The activated carbons were characterized by adsorption of nitrogen at 77 K. Steam activation substantially enhanced the porosity of the activated carbons. Burn-off increased linearly according to increasing activation time, and total pore volume and BET surface area increased with burn-off. Activation at $800^{\circ}C$ increased more micropore volume than that at $950^{\circ}C$. Activated carbons manufactured at high temperature had less microporosity than that at lower temperature, but had more developed macroporosity. The steam activation produced an enlargement of pore below $100{\AA}$ diameter in the activated carbons. Furthermore, the porosity in the $6{\sim}40{\AA}$ pore diameters range increased considerably with the degree of burn-off.

• Korean Journal of Optics and Photonics
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• v.18 no.5
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• pp.317-322
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• 2007

We performed injection-locking by two independent semiconductor lasers and investigated the spectral modes of the injection-locked laser From the observation of the saturated absorption spectrum in the $^{85}Rb$ D1 transition line, we have confirmed that the frequency of the injection-locked slave laser is synchronized by the frequency of the master laser, and the slave laser has a narrow linewidth after injection-locking. According to the intensity injected into the slave laser, we measured the variation of the injection-locking range and the mode of the injection-locked slave laser by using the confocal Fabry-Ferret interferometer. In the case of the incomplete injection-locking, we observed the competition between the free running mode of the slave laser and the mode of the master laser and analyzed the modes of the injection-locked slave laser.