• Mycobiology
• /
• v.28 no.1
• /
• pp.54-56
• /
• 2000

A black scab disease occurred on sword bean (Canavalia gladiata) in plastic film houses around Chinju area during the spring season of 1999. The disease started from flower bud, then moved to flower stalk, pod, petiole, cirrus, stem and leaves. The lesions started with small dark brown spots then were gradually expanded. Severely infected plants reached 37.4% of whole plant covered with scab. Numerous conidia were produced on the diseased flower disk, pod, floral axis, stem and leaves. Most of the conidia were appeared to be readily dispersed in the air, but the mycelia were not suggested causing of sooty mold by ectoparasitism. A fungus was isolated from the diseased stem, and inoculated to healthy plants to satisfy the Koch's postulates and proved the fungus was the causal agent of the disease. The isolated fungus grew on potato dextrose agar, forming greenish black to pale brown colonies. Conidia were ellipsoidal, fusiform or subspherical, mostly one-celled but occasionally septated. The conidia were $3.9{\sim}34.1{\times}2.7{\sim}5.1\;{\mu}m$ in size and formed in long branched chains on the erected conidiophores which were pale olivaceous brown and variable in length between $7.2{\sim}210.7\;{\mu}m$ in size. Ramoconidia were $7.6{\sim}29.2{\times}3.2{\sim}14.4\;{\mu}m$ in size. The fungus was identified as Cladosporium cucumerinum based on the above morphological characteristics. The optimum temperature for mycelial growth and conidial formation was about 15 to $25^{\circ}C$. Cladosporium scab of sword bean caused by the fungi has not been reported in Korea previously.

• Journal of the Korean institute of surface engineering
• /
• v.49 no.4
• /
• pp.331-338
• /
• 2016

In this work, anodic oxidation behavior of AZ31 Mg alloy was studied as a function of $Na_2CO_3$ concentration in electrolyte by voltage-time curves and observation of surface appearances and morphologies after the anodic treatments, using optical microscopy and confocal scanning laser microscopy (CSLM). The voltage-time curves of AZ31 Mg alloy surface and surface appearances after the anodic treatments showed three different regions with $Na_2CO_3$ concentration : region I, below 0.2 M $Na_2CO_3$ where shiny surface with a number of small size pits; region II, between 0.4 M and 0.6 M $Na_2CO_3$ where dark surface with relatively low number of large size burned or dark spots; region III, more than 0.8 M $Na_2CO_3$ where bright surface with or without large size dark spots were obtained. The anodically treated AZ31 Mg alloy surface became significantly brightened with increasing $Na_2CO_3$ concentration from 0.5 M to 0.8 M which was attribute to the formation of denser and smoother surface films. Pits and porous protruding reaction products were found at relatively large size and small size spots, respectively, on the AZ31 Mg alloy surface in low concentration of $Na_2CO_3$ less than 0.2 M. The formation of pits is attributed to the result of repetition of the formation and detachment of porous anodic reaction products. Based on the experimental results obtained in this work, it is concluded that more uniform, denser and smoother surface of AZ31 Mg alloy could be obtained at more than 0.8 M $Na_2CO_3$ concentration if there is no other oxide forming agent.

• Korean Chemical Engineering Research
• /
• v.57 no.1
• /
• pp.22-27
• /
• 2019

Nail polish is used to decorate nail beautifully however, it contains lots of toxic materials. Generally, Nail polish consists of film-forming agent, colorant, solvent, surfactant and stabilizer. In this study, to replace toxic chemicals to low irritative, eco-friendly ingredients, we prepared 4 kinds of nail polish and tested safety, stability and performance. Nail polish including shellac/gelatin showed best performance in water-resistance, friability and drying time. When cell toxicity test is done by MTT assay, shellac-gelatin nail polish showed over 70% cell viability at $1,000{\mu}g/mL$ whereas control nail polish in market showed 50% cell viability. At 4 weeks temperature stability test, color was stable at low temperature however it needs formulation improvement at higher temperature.

• Applied Chemistry for Engineering
• /
• v.17 no.3
• /
• pp.243-249
• /
• 2006

Porous polymer gel electrolytes (PGEs) based on poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) as a polymer matrix and polyvinylpyrolidone (PVP) as a pore-forming agent were prepared and electrochemical properties were investigated for an electric double layer capacitor (EDLC) in order to increase a permeability of an electrolyte into the PGE. Propylene carbonate (PC) and ethylene carbonate (EC) as plasticizers, and tetraethylammonium tetrafluoroborate ($TEABF_4$) as a supporting salt for the PGE were used. EDLC unit cells were assembled with the PGE and electrode comprising BP-20 and MSP-20 as activated carbon powders, Super P as a conducting agent, and P(VdF-co-HFP)/PVP as a mixed binder. Ion conductivity of PGEs increased with an increased PVP content and was the best at 7 wt% PVP, whereas electrochemical characteristics such as AC-ESR of unit cell were better in 3 wt%. And electrochemical characteristics of the unit cell with PGE were the best at a 33 : 33 weight ratio of PC to EC. Specific capacitance of a mixed plasticizer system of PE and EC was higher than that of pure PC. Ion conductivity of PGEs with a film thickness of $20{\mu}m$ was higher, but electrochemical characteristics of unit cells were higher for a $50{\mu}m$ membrane thickness. Also, the unit cell has shown the highest capacitance of 31.41 F/g and more stable electrochemical performance when PGE and electrode were hot pressed. Consequently, the optimum composition ratio of PGE for EDLCs was 23 : 66 : 11 wt% such as P(VdF-co-HFP) : PVP = 20 : 3 wt% and PC : EC = 44 : 22 wt%. In this case, $3.17{\times}10^{-3}S/cm$ of ion conductivity was achieved at the $50{\mu}m$ thickness of PGE for EDLCs. And the electrochemical characteristics of unit cells were $2.69{\Omega}$ of DC-ESR, 28 F/g of specific capacitance, and 100% of coulombic efficiency.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2005.09a
• /
• pp.201-212
• /
• 2005

[ $Epoxy/BaTiO_3$ ] composite embedded capacitor films (ECFs) were newly designed fur high dielectric constant and low tolerance (less than ${\pm}15\%$) embedded capacitor fabrication for organic substrates. In terms of material formulation, ECFs are composed of specially formulated epoxy resin and latent curing agent, and in terms of coating process, a comma roll coating method is used for uniform film thickness in large area. Dielectric constant of $BaTiO_3\;&\;SrTiO_3$ composite ECF is measured with MIM capacitor at 100 kHz using LCR meter. Dielectric constant of $BaTiO_3$ ECF is bigger than that of $SrTiO_3$ ECF, and it is due to difference of permittivity of $BaTiO_3\;and\;SrTiO_3$ particles. Dielectric constant of $BaTiO_3\;&\;SrTiO_3$ ECF in high frequency range $(0.5\~10GHz)$ is measured using cavity resonance method. In order to estimate dielectric constant, the reflection coefficient is measured with a network analyzer. Dielectric constant is calculated by observing the frequencies of the resonant cavity modes. About both powders, calculated dielectric constants in this frequency range are about 3/4 of the dielectric constants at 1 MHz. This difference is due to the decrease of the dielectric constant of epoxy matrix. For $BaTiO_3$ ECF, there is the dielectric relaxation at $5\~9GHz$. It is due to changing of polarization mode of $BaTiO_3$ powder. In the case of $SrTiO_3$ ECF, there is no relaxation up to 10GHz. Alternative material for embedded capacitor fabrication is $epoxy/BaTiO_3$ composite embedded capacitor paste (ECP). It uses similar materials formulation like ECF and a screen printing method for film coating. The screen printing method has the advantage of forming capacitor partially in desired part. But the screen printing makes surface irregularity during mask peel-off, Surface flatness is significantly improved by adding some additives and by applying pressure during curing. As a result, dielectric layer with improved thickness uniformity is successfully demonstrated. Using $epoxy/BaTiO_3$ composite ECP, dielectric constant of 63 and specific capacitance of 5.1nF/cm2 were achieved.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.6
• /
• pp.503-516
• /
• 2021

Autonomous fire detection and suppression system requires advanced technology for complex detection technology and injection/control technology for accurate hitting by fire location. Also, foam spraying should be included to respond to oil fires. However, when a single spray monitor is used in common, water and foam spray properties appear different, so for accurate fire suppression, research on the spray trajectory and distance will be required. In this study, experimental studies and numerical analysis studies were combined to analyze the foam spray characteristics through the spray monitor developed for the establishment of an autonomous fire extinguishing system. For flow analysis of foam injection, modeling was performed using OpenFOAM analysis software, and the commonly used foaming agent (Aqueous Film-Forming Foam) was applied for foam properties. The injection distance analysis was performed according to the injection pressure and the injection angle according to the form of the foam, and at the same time, the results were verified and presented through the injection experiment.