• Korean Journal of Materials Research
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• v.15 no.8
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• pp.508-513
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• 2005

[ $TiO_2-Fe_2O_3$ ] nanocomposite powders for magnetic photocatalyst were synthesized by sol-gel process, in which $TiO_2$ photocatalytic layer was formed on the surface of $\gamma-Fe_2O_3$ magnetic core. Transmission electron microscopy (TEM) observation and X-ray diffractometry (XRD) analysis revealed that$\gamma-Fe_2O_3$ nanoparticles, $10\~20nm$ in diameter, were coated by $TiO_2$ shell of 5nm in thickness and $TiO_2$ was anatase phase. Also hydroxyl group (-OH) used to decompose organic compounds was detected by Fourier transformation infrared spectrometry(FT-IR) analysis. UV-Visible spectrophotometry results showed that light absorption occurred in the wavelength range of $400\~700 nm$, and the band gap energy $(E_g)$ of powder was 1.8 eV. Finally it was found that the coercivity $(H({ci})$ and saturation magnetization $(M_s)$ of the powder were 79 Oe and 14.8 emu/g, respectively as experimental vibrating sample magnetometer (VSM) measurements.

• Journal of Powder Materials
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• v.25 no.5
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• pp.379-383
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• 2018

Silica is used in shell materials to minimize oxidation and aggregation of nanoparticles. Particularly, porous silica has gained attention because of its performance in adsorption, catalysis, and medical applications. In this study, to investigate the effect of the density of the silica coating layer on the color of the pigment, we arbitrarily change the structure of a silica layer using an etchant. We use NaOH or $NH_4OH$ to etch the silica coating layer. First, we synthesize ${\alpha}-FeOOH$ for a length of 400 nm and coat it with TEOS to fabricate particles with a 50 nm coating layer. The coating thickness is then adjusted to 30-40 nm by etching the silica layer for 5 h. Four different shapes of ${\alpha}-FeOOH$ with different colors are measured using UV-vis light. From the color changes of the four different shapes of ${\alpha}-FeOOH$ features during coating or etching, the $L^*$ value is observed to increase and brighten the overall color, and the $b^*$ value increases to impart a clear yellow color to the pigment. The brightest yellow color was that coated with silica; if the sample is etched with NaOH or $NH_4OH$, the $b^*$ value can be controlled to study the yellow colors.

• Archives of Pharmacal Research
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• v.29 no.6
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• pp.520-524
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• 2006

Ibuprofen-loaded gelatin microcapsule, a solid form of microcapsules simultaneously containing ethanol and ibuprofen in water-soluble gelatin shell was previously reported to improve the dissolution of drug. In this study, to retard the initial high dissolution of ibuprofen from gelatin microcapsule, the ibuprofen-loaded cross-linked gelatin microcapsule was prepared by treating an ibuprofen-loaded gelatin microcapsule with glutaraldehyde and its dissolution was evaluated compared to ibuprofen powder and gelatin microcapsule. The ibuprofen-loaded crosslinked microcapsule treated with glutaraldehyde for 10 and 60 sec gave significantly higher dissolution rates than did ibuprofen powder. Furthermore, the dissolution rate of ibuprofen from the cross-linked microcapsule treated for 10 sec was similar to that from gelatin microcapsule. However, the dissolution rate of ibuprofen from the cross-linked microcapsule treated for 60 sec decreased significantly compared to gelatin microcapsule, suggesting that the treatment of gelatin microcapsule with glutaraldehyde for 60 sec could cross-link the gelatin microcapsule. Furthermore, the cross-linking of gelatin microcapsule markedly retarded the release rate of ibuprofen in pH 1.2 simulated gastric fluid compared to gelatin microcapsule. However, the cross-linking of gelatin microcapsule with glutaraldehyde hardly changed the size of gelatin microcapsules, ethanol and ibuprofen contents encapsulated in gelatin microcapsule. Thus, the ibuprofen-loaded cross-linked gelatin microcapsule could retard the initial high dissolution of poorly water-soluble ibuprofen.

• Steel and Composite Structures
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• v.33 no.1
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• pp.111-122
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• 2019

This paper presents an experimental work on the post-fire behavior of two kinds of innovative composite stub columns under eccentric compression. The partially precast steel reinforced concrete (PPSRC) column is composed of a precast outer-part cast using steel fiber reinforced reactive powder concrete (RPC) and a cast-in-place inner-part cast using conventional concrete. Based on the PPSRC column, the hollow precast steel reinforced concrete (HPSRC) column has a hollow column core. With the aim to investigate the post-fire performance of these composite columns, six stub column specimens, including three HPSRC stub columns and three PPSRC stub columns, were exposed to the ISO834 standard fire. Then, the cooling specimens and a control specimen unexposed to fire were eccentrically loaded to explore the residual capacity. The test parameters include the section shape, concrete strength of inner-part, eccentricity ratio and heating time. The test results indicated that the precast RPC shell could effectively confine the steel shape and longitudinal reinforcements after fire, and the PPSRC stub columns experienced lower core temperature in fire and exhibited higher post-fire residual strength as compared with the HPSRC stub columns due to the insulating effect of core concrete. The residual capacity increased with the increasing of inner concrete strength and with the decreasing of heating time and load eccentricity. Based on the test results, a FEA model was established to simulate the temperature field of test specimens, and the predicted results agreed well with the test results.

• Advances in nano research
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• v.15 no.4
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• pp.315-328
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• 2023

The main goal of the present study was to assess the effects of eggshell powder (ESP) and halloysite nanotubes (HNTs) on the mechanical properties of abaca fiber (AF)-reinforced natural composites. For this purpose, a limited number of indentation tests were first performed on the AF/polypropylene (PP) composites for different HNT and ESP loadings (0 wt.% ~ 6 wt.%), load amplitudes (150, 200, and 250 N), and two types of indenters (Vickers or conical). The Young's modulus, hardness and plasticity index of each specimen were calculated using the indentation test results and Oliver-Pharr method. The accuracy of the experimental results was confirmed by comparing the values of the Young's modulus obtained from the indentation test with the results of the conventional tensile test. Then, a feed-forward shallow artificial neural network (ANN) with high efficiency was trained based on the obtained experimental data. The trained ANN could properly predict the variations of the mentioned mechanical properties of AF/PP composites incorporated with different HNT and ESP loadings. Furthermore, the trained ANN demonstrated that HNTs increase the elastic modulus and hardness of the composite, while the incorporation of ESP reduces these properties. For instance, the Young's modulus of composites incorporated with 3 wt.% of ESP decreased by 30.7% compared with the pure composite, while increasing the weight fraction of ESP up to 6% decreased the Young's modulus by 34.8%. Moreover, the trained ANN indicated that HNTs have a more significant effect on reducing the plasticity index than ESP.

• Journal of Sericultural and Entomological Science
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• v.47 no.1
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• pp.31-35
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• 2005

This study had done to find an easily-dyeing method for novices because the dyeing method of traditional indigo has not been general to the public so that only an expert could dye the fibers. The results are as the following. When the powders after burning the shell of cockle (tegillarca granosa) were added. pH of the solution was 12.35 The k/s value of 2.49 was the highest in the dye after dipping in the solution of indigo for 1-2 days and the k/s value was 3.10 when adding 20 g/l of the starch (55% corn-starchy products in Korean market) into the solution of indigo. In addtion, the k/s value was the highest when fermenting temperature was $30^{\circ}C$ and when the powders after burning the cockle shell were 4 g/l. There were no differences between water and lye of rice straw which had used for the ferment of indigo. The components of two dye which has traditionally made of the cockle shell and which has made of calcium hydroxide were all the same.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.831-840
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• 1997

Core/shell structured composite metal oxides of Fe2O3/MgO were prepared by thermal decomposition of Fe(acac)3 adsorbed on the surface of MgO cores. The morphology of the composites conformed to that of the MgO used as the cores. Broad powder X-ray diffraction peaks shifted toward larger d, large BET surface area (∼350 m2/g), and the size of crystalline domains in nano range (4 nm), all corroborate to the nanocrystallinity of the Fe2O3/MgO composite which was prepared by using nanocrystalline MgO as the core. By use of microcrystalline MgO as the core, microcrystalline Fe2O3/MgO composite was prepared, and it had small BET surface area of less than 35 m2/g. AFM measurements on nanocrystalline Fe2O3/MgO showed a collection of spherical aggregates (∼80 nm dia) with a very rough surface. On the contrary, microcrystalline Fe2O3/MgO was a collection of plate-like flat crystallites with a smooth surface. The nitrogen adsorption-desorption behavior indicated that microcrystalline Fe2O3/MgO was nonporous, whereas nanocrystalline Fe2O3/MgO was mesoporous. Bimodal distribution of the pore size became unimodal as the layer of Fe2O3 was applied to nanocrystalline MgO. The macropores in a wide distribution which the nanocrystalline MgO had were absent in the nanocrystalline Fe2O3/MgO. The decomposition of CCl4 was largily enhanced by the overlayer of Fe2O3 on nanocrystalline MgO making the reaction between nanocrystalline Fe2O3/MgO and CCl4 be nearly stoichiometric. The reaction products were environmentally benign MgCl2 and CO2. Such an enhancement was not attainable with the microcrystalline samples. Even for the nanocrystalline MgO, the enhancement was not attained, if not with the Fe2O3 layer. Without the layer of Fe2O3, it was observed that the nanocrystalline domain of the MgO transformed into microcrystalline one as the decomposition of CCl4 proceeded on its surface. It appeared that the layer of Fe2O3 on the particles of nanocrystalline Fe2O3/MgO blocked the transformation of the nanocrystalline domain into microcrystalline one. Therefore, in order to attain stoichiometric reaction between CCl4 and Fe2O3/MgO core/shell structured composite metal oxide, the morphology of the core MgO has to be nanocrystalline, and also the nanocrystalline domains has to be sustained until the core was exhausted into MgCl2.

• Korean Journal of Poultry Science
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• v.51 no.1
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• pp.1-9
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• 2024

To reduce salt content and enhance calcium in chicken patty, shell calcium powder (SCP) was added, and transglutaminase (TG) was included to improve its properties. Five different treatments were prepared to assess the effects: CON (2% salt), T1 (0.75% salt + 0.2% SCP), T2 (0.75% salt + 0.2% SCP + 0.2% TG), T3 (0.5% salt + 0.4% SCP), and T4 (0.5% salt + 0.4% SCP + 0.2% TG). Reducing salt led to decreased ash content and increased cooking loss. The addition of SCP and TG raised pH levels. Meat color remained consistent with different salt, SCP, and TG levels. However, when salt was reduced to 0.5% and SCP was added at 0.4% without TG, the patty's hardness and chewiness decreased. Sensory evaluations showed reduced juiciness when salt was reduced to 0.5% and SCP was added at 0.4%, but no significant differences were observed in overall acceptability. Salt had no impact on TBARS results, but salt reduction to below 0.5% increased susceptibility to microbial contamination. In summary, reducing salt and adding SCP had minimal sensory impact, but when salt is reduced to 0.5% or lower, consider adding TG. Also, when decreasing salt, additional preservatives should be considered to address potential microbial contamination during manufacturing.

• Korean Journal of Poultry Science
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• v.33 no.1
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• pp.15-24
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• 2006

This experiment was conducted to investigate the effects of dietary safflower seed (SFS) powder and chitosan on hatching egg production and eggshell qualify in aged egg-type breeder hens. A total of four hundred 54-week-old Hy-Line Brown breeder hens were divided into five the groups and fed experimental diets either with addition of 0.25 and 0.50% SFS powder or 0.10 and 0.20% chitosan or devoid of all for 6 weeks. There were no significant differences in feed intake and laying performances among the groups. The rate of sellable egg in the groups fed diets containing SFS powder or chitosan was significantly increased compared to that of control (P<0.05), irrespective of dose-dependent manner. The addition of SFS powder or chitosan significantly improved the eggshell strength (P<0.01). Eggshell thickness was also significantly increased in the groups 134 diets containing chitosan as compared with that of control (P<0.01). Fertility and hatchability of egg set were significantly improved by dietary chitosan that those of control (P<0.05). ike contents of tibial Ca and P were significantly increased in the groups fed diets containing 0.5% SFS powder, 0.1 and 0.2% chitosan as compared with those of control. The levels of blood estrogen, calcitonin and parathyroid hormone were not affected by the dietary treatments. The overall results indicated that the proper use of some feed additives such as safflower seed powder and chitosan might provide means of improving eggshell quality and reproductive performances in aged egg-type breeder hens.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2546-2552
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• 2012

A novel biguanide-functionalized $Fe_3O_4/SiO_2$ magnetite nanoparticle with a core-shell structure was developed for utilization as a heterogeneous organosuperbase in chemical transformations. The structural, surface, and magnetic characteristics of the nanosized catalyst were investigated by various techniques such as transmission electron microscopy (TEM), powder X-ray diffraction (XRD), vibrating sample magnetometry (VSM), elemental analyzer (EA), thermogravimetric analysis (TGA), $N_2$ adsorption-desorption (BET and BJH) and FT-IR. The biguanide-functionalized $Fe_3O_4/SiO_2$ nanoparticles showed a superpara-magnetic property with a saturation magnetization value of 46.7 emu/g, indicating great potential for application in magnetically separation technologies. In application point of view, the prepared catalyst was found to act as an efficient recoverable nanocatalyst in nitroaldol and domino Knoevenagel condensation/Michael addition/cyclization reactions in aqueous media under mild condition. Additionally, the catalyst was reused six times without significant degradation in catalytic activity and performance.