• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.782-788
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• 2018

Submicron copper-silver core-shell (Cu@Ag) particles were synthesized using the sonochemical combined transmetallation reaction and the application to printed electronics as a low cost conductive paste was evaluated. $Cu_2O$ of the $Cu_2O/Cu$ composite used as a core in the reaction for the synthesis of core-shell was sonochemically reduced to Cu, and Cu atoms functioned as a reducer for silver ions in transmetallation to achieve the copper-silver core-shell structure. The characterization of submicron particles by TEM-EDS and TG-DSC confirmed the core-shell structure. Conductive pastes in which 70 wt% Cu@Ag was dispersed in solvents were prepared using a binder and wetting agents, and coated on the polyamide film using a screen-printing method. Printed paste films containing synthesized Cu@Ag particles with 8 at% and 16 at% Ag exhibited low resistivity of 96.2 and $38.4{\mu}{\Omega}cm$ after sintering at $180^{\circ}C$ in air, respectively.

• Clinical and Experimental Pediatrics
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• v.52 no.3
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• pp.351-355
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• 2009

Purpose : This study compared bone ages measured by the Greulich-Pyle (GP) and Tanner-Whitehouse 3 (TW3) methods and investigated the differences in predicted adult heights measured by Bayley-Pinneau (BP) and TW3 methods. Methods : Bone ages were assessed from left-wrist radiographs by two investigators, one for each GP and TW3 methods in 85 normal children, 30 precocious puberty girls, and 30 constitutional growth delay boys. The differences between the measured predicted adult heights using the BP and TW3 methods were compared in each group. Results : The bone age measured by the TW3 method was less than that by the GP method in normal children. The predicted adult heights measured by the two methods showed no significant difference in normal boys, while the predicted adult height measured by the TW3 method was higher than that by the BP method for normal girls ($156.4{\pm}4.7$ cm vs. $158.9{\pm}3.8$ cm, P<0.01) and for precocious puberty girls ($156.3{\pm}4.0$ cm vs. $159.3{\pm}4.2$ cm, P<0.01). In contrast, the predicted adult height was higher from the BP method than from the TW3 method in constitutional growth delay boys ($173.3{\pm}4.4$ cm vs. $169.7{\pm}3.2$ cm, P<0.01). Conclusion : There were significant differences in predicted adult heights between the BP and TW3 method in normal girls, precocious puberty girls, or constitutional growth delay boys. In precocious puberty and constitutional growth delay, the BP method might be preferred to predict adult height, but further studies on final adult height are needed.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.5
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• pp.353-362
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• 2016

Thermal barrier coating (TBC) is an essential element consisting of a super-alloy base and ceramic coating designed to achieve long operational time under a high temperature and pressure environment. However, the top coat of TBC can be delaminated at certain temperatures with long operation time. As the delamination of TBC is directly related to the blade damage, the coupling status of the TBC should be assured for reliable operation. Conventional studies of nondestructive evaluation have been made for detecting generation of thermally grown oxide (TGO) or qualitatively evaluating delamination in TBC. In this study, the ultrasonic C-scan method was developed to obtain the damage map inside TBC by estimating the delamination in a quantitative way. All specimens were isothermally degraded at $1,100^{\circ}C$ with different time, having different partial delamination area. To detect partial delamination in TBC, the C-scan was performed by a single transducer using pulse-echo method with normal incidence. Partial delamination coefficients of 1 mm to 6 mm were derived by the proportion of the surface reflection signal and flaw signal which were theoretical signals using Rogers-Van Buren and Kim's equations. Using the partial delamination coefficients, the partial delamination maps were obtained. Regardless of the partial delamination coefficient, partial delamination area was increased when degradation time was increased in TBC. In addition, a decrease in partial delamination area in each TBC specimen was observed when the partial delamination coefficient was increased. From the portion of the partial delamination maps, the criterion for delamination was derived.

• Journal of Mushroom
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• v.12 no.4
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• pp.299-303
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• 2014

This study was to comparative analysis that different methods of extraction about total sugar content which the major functional components of edible and medicinal mushrooms. Through the phenol-sulfuric acid method was measured that Hot water extraction, acid extraction, and alkaline extraction. Drawing the standard curve to obtain the concentration of the glucose solution and the sample by applying the measured absorbance on the standard curve. Total sugar contents was measured after extraction with different solvents.(Hot water, 70% EtOH, 80% MeOH). The level of total sugar in Cordyceps militaris is highest in the hot water extraction with 658.4(${\mu}g/g$) and Coriolus versicolor in 649.7(${\mu}g/g$) and 679.0(${\mu}g/g$) was found as the highest in the acid extraction and the alkaline extraction. C. militaris and ASI 7025 showed the highest level in the hot water extraction. Finally, C. versicolor, Sparassis crispa showed that higher than the other mushrooms at the 1hr, 2hr microwave extraction. It was varied total sugar content according to the different extraction solvent and the extraction method.

• Journal of Mushroom
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• v.5 no.1
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• pp.1-6
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• 2007

A new commercial strain "Hambak" of Grifola frondosa was developed by di-mono crossing between dikaryon of ASI 9031 and monokaryotic strain derived from ASI 9021. It can be cultivated in plastic bottle and bag filled with oak and poplar sawdust substrate which supplemented with 15% rice bran or 10% corn bran. Improvement of cultivation methods was required for shortage of mycelium incubation period and management of humidity in growing room. The optimum temperature of mycelial growth was $25^{\circ}C$ and that of fruiting body development was $15{\sim}18^{\circ}C$. The color of pileus surface was brown and fine pores, whitish to cream-colored, were underside. Primordia formation of Hambak was two days faster than that of Yipsae 1. The yield was $97g/850m{\ell}$ bottle, a bunch of fruiting body was bigger and the quality was better than Yipsae 1.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.4
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• pp.165-171
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• 2002

The study on the adsorption, the surface properties and the antibacterial effects of the metal-treated pitch based activated carbon fibers was carried out. From the adsorption studies on the series of metal-treated activated carbon fiber, the specific surface areas of the metal treated activated carbon fiber obtained from BET equation were in the range of 113.2~1574 $m^2$/g for the Ag-ACFs. And that of Cu treated ACF are distributed to 688.2-887.8 $\m^2$/g. And, the specific surface areas of the Ni-treated pitch based ACFs were in the range of 692.6~895.2 $\m^2$/g. From the ${\alpha}_s$- method, 0.06~1.1 cm^3/g of the micropore volumes were obtained from Ag-ACFs. And, 0.1~0.2 cm^3/ and 0.2~0.6 cm^3/g of the micropore volumes were obtained from Cu and Ni-ACFs, respectively. And, from the SEM morphology results, it was observed that the surface of activated carbon fiber are partially blocked and coated by metal after the treatment. Finally, from the antibacterial effects of metal-treated activated carbon fiber against E. coli, the areas of antibacterial effect become larger with the increase in mole ratio of metal treated. And, from the antibacterial effects using Shake flask method against E. coli, the percentage of the effects was 92.5~100 % and the antibacterial effect was increased with the increase in mole concentration of metal treated.

• Journal of Mushroom
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• v.9 no.3
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• pp.110-115
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• 2011

Trichoderma disease of oyster mushroom has not been effectively detected in the field for testing its resistance against the disease with its varieties. In this study, we investigated the methods to detect its resistance in the laboratory by using media, which enables us to understand the relevant characteristics (e.g., lysis, toxin enzyme, mycelial growth rate). In coculturing with strains of Trichoderma and oyster mushroom, it is possible to observe the difference in the resistance of oyster mushroom against Trichoderma with the phenomena of barrage reaction, overgrowth and lysis. We also observed the inhibition of mycelial growth of oyster mushroom using the dilution method with 48-well plate, but could not observed the inhibition of mycelial growth using the filter paper method of cultural supernatant. In simultaneously culturing both Trichoderma and oyster mushroom, it was possible to detect the inhibition of the mycelial growth of oyster mushroom, but Trichoderma mycelium did not overgrow against oyster mushroom. We found that the pathogenicity was efficient in using solid medium with the phenomena of overgrowth and lysis by inoculating Trichoderma on top of mycelia of oyster mushroom. In conclusion, the methods (e.g., coculture method, dilution method with 48-well plate, post-inoculation method) are recommended to detect the resistance of oyster mushroom against Trichoderma disease.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.28-34
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• 2021

SiO2/Ag core-shell nanoparticles were synthesized by combining modified Stöber process and reverse micelle method using acetoxime as a reducing agent in water/dodecylbenzenesulfonic acid (DDBA)/cyclohexane reverse micells. The SiO2/Ag core-shells were studied for structure, morphology and size using UV-visible spectroscopy, XRD, SEM and TEM. The size of a SiO2/Ag core-shell could be controlled by changing the [water]/[DDBA] molar ratio (WR) values. The size and the polydispersity of SiO2/Ag core-shells increased with increase of the WR value. The resultant Ag nanoparticles exhibit a strong surface plasmon resonance (SPR) peak at 430 nm over the amorphous SiO2 nanoparticles. The SPR peak shifted to the red side with increase in nanoparticle size. Conductive pastes with 70 wt% SiO2/Ag core-shell were prepared, and the pastes were coated on the PET films using a screen-printing method. The printed paste film of the SiO2/Ag core-shell showed higher surface resistance than the commercial Ag paste in the range of 460~750 µΩ/sq.

• Analytical Science and Technology
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• v.21 no.1
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• pp.58-63
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• 2008

Nano-sized ZnO crystals were successfully incorporated using ion exchange method in TMA-A zeolite synthesized by the hydrothermal method. The optimal composition for the synthesis of TMA-A zeolite was resulted in a solution of $Al(i-pro)_3$ : 2.2 TEOS : 2.4 TMAOH : 0.3 NaOH : 200 $H_2O$. 0.3 g of TMA-A zeolite and 5 mol of $ZnCl_2$ solution were employed for the preparation of ZnO incorporated TMA-A zeolite. The crystallization process of ZnO incorporated TMA-A zeolite was analyzed by X-ray diffraction (XRD). The incorporated nano-sized ZnO crystals and the crystallinity of TMA-A zeolite were evaluated by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The size of the incorporated nano-sized ZnO crystals was 3~5 nm, while the TMA-A zeolite was 60~100 nm. The bonding structure and absorption of the ZnO incorporated TMA-A zeolite were compared with the ZnO and TMA-A zeolite by the FT-IR analysis. Subsequentlly, the ZnO incorporated TMA-A zeolite showed the photoluminescent characteristics on the wavelengths of 330~260 nm and 260~230 nm by measurement of UV spectrophotometer.

• Journal of Mushroom
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• v.9 no.4
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• pp.170-179
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• 2011

In coculturing with strains of Trichoderma and oyster mushroom, we could detect the difference in the resistance of oyster mushroom against Trichoderma with the phenomena of barrage reaction, overgrowth and lysis. We selected the isolates ASI 2183, ASI2504 and ASI 2477 as varieties that showed the resistance. The isolates ASI 2240, ASI 2479 and ASI 2181 were the best in their resistance against Trichoderma in the method using culture filtrate. In common, the isolates ASI 2479 and ASI 2240 were selected in both methods. In post-inoculation method, the isolates ASI 2479, ASI 2333 and ASI 2181 were selected and ASI 2302 was susceptible. For the same isolate of Trichoderma, the resistance varied depending on the isolates of oyster mushroom used in the experiments. Because we could detect the interactions between Trichoderma and oyster mushroom, it is possible to detect the level of the resistance that differs in the varieties. However, there were the cases of detecting the level of the resistance in repetitions with the same isolate, which may be caused by the vitality of isolates of Trichoderma and oyster mushroom. It is efficient to test the resistance with the resistant isolate of Pleurotus salmoneostramine and the susceptible isolate of ASI 2302.